Input to OUTMOD

1. General Information

The post-processing module OUTMOD has two main purposes:

  • Generate result printout from the INPMOD, STAMOD and DYNMOD modules.

  • Prepare a plot file (IFNPLO) for later use by the plot module (PLOMOD). Note that this functionality is deprecated.

Locations for result presentation are identified by the line identifier and segment and element numbers specified as input to INPMOD for all single riser systems (i.e. SA, SB, SC, SD and AR systems).

The user chooses the amount of printout by giving the appropriate options as input data to OUTMOD. As for the other modules, input data to OUTMOD are organised in groups. Some groups consist of the data group identifier only, whilst other groups have additional input lines. The first part of the input data is data groups selecting data to be printed. Then a command must be given to start the printing. Then a new set of data groups selecting data may be given etc, see the figure below.

um io fig299
Figure 1. Organization of OUTMOD input

2. Data Group A: OUTMOD Identification and Control Data

2.1. OUTMOD identification text

If you want an identification text to be printed on the front page of the OUTMOD printout, the following data group may be given as the first data group:

2.1.1. Data group identifier, one input line

OUTMod IDENTIFICATION TEXT CHVERS
  • CHVERS: character(8): RIFLEX output file version, e.g. 3.2

2.1.2. Identification text, three input lines

Identification text, line no 1
Identification text, line no 2
Identification text, line no 3

If the data group is given, all three lines must be given, but they may be blank.

2.2. The PRINT command

When OUTMOD is used for print generation, the following data group identifier must be given subsequent to the specifications:

PRINT

After printing, all specifications will be deleted. Subsequent to the print command, a new sequence of specifications and a new print command may be given. This is useful if you want to repeat one or more specifications with different parameters.

2.3. Plot generation

This functionality is deprecated!

If you want to have plots from STAMOD or DYNMOD, you have to run OUTMOD first to produce the plot file, IFNPLO, which is the only file the plot module PLOMOD reads when plotting from the above mentioned modules.

It is not possible to generate plots of all data groups. This is marked by the word Plot or NoPlot in the right part of the data group identifier frame:

WFMOtion TIME SERies        Plot

can be plotted, while the following can not:

INFIrr CONTRol INFOrmation      NoPlot

When you want to use OUTMOD to build up file IFNPLO, the data group identifiers and print options are exactly the same as when you use OUTMOD for normal printout, except for the following:

  • IFNPLO must be initialized by one of the data group identifiers described in Initialization of the plot file IFNPLO (below).

  • Instead of the PRINT command, the PLOT command must be given (see The PLOT command). The OUTMOD print file will contain the same information as if the PRINT command was given, i.e. the PLOT command may be considered as an extension to the PRINT command.

Normally, one specification gives one plot which may consist of up to three graphs. In some cases, e.g. when one specification gives results for six degrees of freedoms, two plots are produced per specification.

2.3.1. Initialization of the plot file IFNPLO

When OUTMOD is to be used for plot generation, one of the following initialization commands must be given after specification of OUTMOD identification text (if given), but before any specification described in Sections Data Group B: Output from STAMOD, or Data Group C: Output from DYNMOD:

NEW PLOT FILE

or

APPEnd PLOT FILE

If the command NEW PLOT FILE is given, OUTMOD writes the plot arrays from the beginning of the file, i.e. the previous contents of the file, if any, are overwritten. It is, however, possible to append new plots after already existing plots on file IFNPLO. This is achieved by giving the command APPEND PLOT FILE. A check is carried out to ensure that the file already contains plots.

A maximum of 100 plots may be stored in one IFNPLO file.

If more than one initialization command is given throughout an OUTMOD run, they are simply ignored.

2.3.2. The PLOT command

When OUTMOD is used for plot generation, the following command is given instead of the PRINT command (see The PRINT command):

PLOT

If a plot command is given for a data group that cannot be plotted, a warning message is issued on OUTMOD print file and execution continues with the next data group specified.

There may be more than one PLOT within one run of OUTMOD, following the same rules as for the PRINT command. PRINT and PLOT commands may be mixed within one run.

If the PLOT command is given, and neither NEW PLOT FILE nor APPEND PLOT FILE has been given, the program will terminate with an error message.

2.4. Communication with the STARTIMES programs

The following command has been included for communication with the STARTIMES programs for statistical analysis of time series

STARtimes FILE      NoPlot

This command specifies that time series of a selected response quantity shall be written to a file in STARTIMES format (i.e. to a file readable by the STARTIMES programs). The STARTIMES FILE command can be used in connection with the following data group identifiers:

  • WAVE ELEVATION

  • WFMOTION TIME SERIES

  • LFMOTION TIME SERIES

  • TOMOTION TIME SERIES

  • DYNDISP TIME SERIES

  • TOTDISP TIME SERIES

  • DYNFORC TIME SERIES

  • DYNCURV TIME SERIES

  • SUPPF TIME SERIES

  • ELMANGLE TIME SERIES

  • TOTFORC TIME SERIES

  • DISTANCE TIME SERIES

  • CALCURV TIME SERIES

  • STRESS TIME SERIES

  • STROKE TIME SERIES

A response quantity is written to the STARTIMES file by giving STARTIMES FILE immediately before the PRINT or PLOT command.

The name of the STARTIMES file is <prefix>_outmod.ts, and it is stored in the current working directory. A description of this file is found in Description of STARTIMES file.

2.5. The END command

To terminate the input data, the following data group identifier is given as the last input line on the OUTMOD input file.

END

The END data group is mandatory

3. Data Group B: Output from STAMOD

Description of result presentation from static analyses is given in the following.

3.1. Results from static fixed parameter analysis

Displacement and force data from static fixed parameter analysis are established by the STAMOD module and stored on file IFNSTA.

Specifying this output after a parameter variation run will produce the results of the last parameter variation step.

3.1.1. Static dimension information

If you want dimension parameters, such as no of load steps, no of nodes etc, to be printed, give

STATic DIMENsion PARAmeters         NoPlot

3.1.2. System information

If you want information about the connection between the local line, segment and element number given as input to INPMOD and the global FEM element/nodal numbers generated by STAMOD, give

STATic SYSTem INFOrmation       NoPlot

A more detailed description is given on the STAMOD print file.

3.1.3. Coordinates of final static configuration

Data group identifier, one input line
STATic COORdinates      Plot
Print options, one input line
ICONF LINE-ID IPROJ
  • CONF: integer: Configuration switch

    • ICONF=1: Initial configuration (catenary configuration)

    • ICONF=2: Final configuration (Results from FEM or CATFEM analysis)

  • LINE-ID: character(8): Line identifier for which coordinates are wanted. You may specify ALL to include all lines in the system.

    • Note that specifying a specific line gives a 2D-plot, while specifying ALL gives a 3D-plot

    • LINE-ID=0: Plot of 2D geometry of all lines

  • IPROJ: integer: Projection code

    • dummy if LINE-ID=ALL

    • IPROJ=1: Output of x-y coordinates

    • IPROJ=2: Output of x-z coordinates

    • IPROJ=3: Output of y-z coordinates

3.1.4. Axial forces from catenary analysis

Note that no moments are included in the catenary analysis.

Data group identifier, one input line
INITial AXIAl FORCe         Plot
Line specification, one input line
LINE-ID
  • LINE-ID: character(8): Line identifier for which forces are wanted. You may specify ALL to include all lines in the system

3.1.5. Forces from static fixed parameter analysis

Forces are printed as force, bending and torsional moments.

Data group identifier, one input line
FINAl STATic FORCes         Plot
um io fig300
Figure 2. Pipe wall force calculation

Pipe wall force, axial:

\(\mathrm {T_W=T_e+p_iA_i-p_eA_e[+m_iv_i^2]}\)

(In cases with high pressure(s) it may be important to include the radial stress when material strain is to be evaluated)

This is identical with the flange force in case of a double seal (at \(\mathrm {r=ri}\) and \(\mathrm {r=re}\))

  1. \(\mathrm {T_F=T_W}\)

In the case of an inner seal only:

  1. \(\mathrm {T_F=T_e+p_iA_i-p_eA_i[+m_iv_i^2]}\)

Any other sealing radius:

  1. \(\mathrm {T_F=T_e+(p_i-p_e)A_s[+m_iv_i^2]}\)

Where: - \(\mathrm {A_s=\pi r_s^2}\) - \(\mathrm {r_s=}\) sealing radius

rs = sealing radius

\(\mathrm {m_iv_i^2}\) is an additional term for cases with internal fluid flow.

Print options, one input line
LINE-ID IDOF1 IDOF2 IDOF3 IDOF4
  • LINE-ID: character(8): Line identifier for which forces are wanted. You may specify ALL to include all lines in the system.

  • IDOF1: integer: Degree of freedom for first figure

    • IDOF1=0: Not included

    • IDOF1=1: Axial force

    • IDOF1=2: Torsional moment

    • IDOF1=3: Bending moment about local y-axis

    • IDOF1=4: Bending moment about local z-axis

    • IDOF1=5: Pipe wall force, incl hydrostatic pressures

    • IDOF1=6: Shear force in local y-direction

    • IDOF1=7: Shear force in local z-direction

  • IDOF2: integer: Degree of freedom for second figure

    • Interpretation as for IDOF1

  • IDOF3: integer: Degree of freedom for third figure

    • Interpretation as for IDOF1

  • IDOF4: integer: Degree of freedom for fourth figure

    • Interpretation as for IDOF1

No of figures in one plot may vary from 1-3 depending on the number of response quantities specified (e.g. IDOFi).

Note that the print part of this option always will produce results for all stored degrees of freedom, i.e. axial force, torsional moment and bending moments about local y- and z-axes. The parameters are used to specify the dof’s to be plotted.

3.1.6. Stress from static analysis

Data group identifier, one input line
FINAl STATic STREsses       Plot
Output options, one input line
LINE-ID IDOF
  • LINE-ID: character(8): Line identifier for which stresses are wanted. You may specify ALL to include all lines in the system.

  • The following parameter is used to specify the dof to be considered

    • IDOF: integer: Stress component

      • IDOF=1: Axial stress

      • IDOF=2: Torsional stress

      • IDOF=3: Bending stress

      • IDOF=4: Axial + bending stress

      • IDOF=5: Shear stress

      • IDOF=6: Shear + torsional stress

      • IDOF=7: Equivalent stress

      • IDOF=8: Hoop stress

      • IDOF=9: Radial stress

Effect of internal/external pressure and fluid velocity are included

Specification of point for stress calculation, one input line
IMAX THETA INEX
  • IMAX: integer, default: 1: Stress location option

    • IMAX=1: Maximum stresses in cross section estimated

    • IMAX=0: Stresses calculated at location specified by THETA and INEX

  • THETA: real, default: 0: Angle (in degrees) from local y-axis for stress calculation.

    • Dummy for IMAX=1

  • INEX: integer, default: 2: Location code

    • Dummy for IMAX=1

    • INEX=1: Inner wall

    • INEX=2: Outer wall

For IMAX=1, the maximum stresses of type IDOF in the cross section are estimated. The equivalent stress (von Mises) is supposed to be maximum where the bending stress is maximum or minimum.

3.2. Output from static parameter variation analysis

Displacement and force data from static parameter variation analysis are established by the STAMOD module and stored on file IFNSTA. Result presentation from static parameter variation analysis is described in the following.

3.2.1. System geometry from parameter variation analysis

Data group identifier, one input line
PARAmeter VARIation COORdinates         Plot
Line specification, one input line
LINE-ID IOTYP IPV1 NVP
  • LINE-ID: character(8): Line number for which geometry are wanted. You may specify ALL to include all lines in the system.

    • ALL gives a 3D plot of all lines.

    • LINE-ID = 0 gives a 2D plot of all lines

  • IOTYP: integer: Degree of freedom specification

    • Dummy if ILINE = ALL

    • IOTYP=1: x-y coordinates

    • IOTYP=2: x-z coordinates

    • IOTYP=3: y-z coordinates

  • IPV1: integer: First parameter variation step to be included

  • NVP: integer: No of parameter variation steps to be included

The first plot to appear will be for step no NSTEP+IPV1 where NSTEP is total number of load steps used in the static analysis with fixed parameters.

Negative value of IPV1 is possible, which allows for plotting of static configuration at all load steps in static analysis with fixed parameters.

It is also possible to plot static configurations from 1st load step to last successful solution when static analysis fails, which can be very useful for detection of possible instability problems.

3.2.2. Displacement of selected nodes from parameters variation analysis

Data group identifier, one input line.
PARAmeter VARIation DISPlacements       Plot
Output code, one input line
IPV1 NPV IDOF1 IDOF2 IDOF3 NNODC
  • IPV1: integer: First parameter variation step to be included

  • NPV: integer: No of parameter load steps to be included. (A large number includes the remaining steps)

  • IDOF1: integer:

    • IDOF1=1: Translation in x-direction

    • IDOF1=2: Translation in y-direction

    • IDOF1=3: Translation in z-direction

  • IDOF2: integer:

    • Interpretation as for IDOF1

  • IDOF3: integer:

    • Interpretation as for IDOF1

  • NNODC: integer: No. of input lines used for node specification

No of figures on each plot may vary from 1 to 3, depending on IDOFi

The first plot to appear will be for step no NSTEP+IPV1 where NSTEP is the total number of load steps in the static analysis with fixed parameters.

Negative value of IPV1 is allowed (see System geometry from parameter variation analysis).).

Node specification, NNODC input lines
LINE-ID ISEG INODE
  • LINE-ID: character(8): Line identifier.

    • You may specify ALL to include all lines

  • ISEG: integer/character: Segment number.

    • You may specify ALL to include all segments.

    • ENDS includes the end segments on the line

  • INODE: integer/character: Node number.

    • ALL includes all nodes

    • ENDS includes end nodes on the above specified segment

3.2.3. Forces on selected elements from parameter variation analysis

Data group identifier, one input line
PARAmeter VARIation FORCes      Plot
Output options, one input line
IPV1 NPV IDOF1 IDOF2 IDOF3 NNELC
  • IPV1: integer: First parameter variation step to be included

  • NPV: integer: No of parameter load steps to be included. (A large number includes the remaining steps)

  • IDOF1: integer: Degree of freedom specification for Figure 1

    • IDOF1=0: No output

    • IDOF1=1: Axial force

    • IDOF1=2: Torsional moment

    • IDOF1=3: Bending moment about local y-axis

    • IDOF1=4: Bending moment about local z-axis

  • IDOF2: integer:

    • Interpretation as for IDOF1

  • IDOF3: integer:

    • Interpretation as for IDOF1

  • NNELC: integer: No. of input lines used for element specification

The first plot to appear will be for step no NSTEP+IPV1 where NSTEP is the total number of load steps used in the static analysis with fixed parameters.

Negative value of IPV1 is allowed (see System geometry from parameter variation analysis).

No of figures in one plot may vary from 1 to 3, depending on the number of response quantities specified (e.g. IDOFi).

Element specification, NNELC input lines
LINE-ID ISEG IELM
  • LINE-ID: character(8): Line identifier.

    • You may specify ALL to include all lines

  • ISEG: integer/character: Segment number.

    • You may specify ALL to include all segments.

    • ENDS includes the end segments on the line

  • IELM: integer/character: Element number.

    • ALL includes all elements

    • ENDS includes end elements on the above specified segment

4. Data Group C: Output from DYNMOD

4.1. Results from irregular wave analysis

Results from the irregular wave analysis consists of: - sampled Fourier components of waves stored on file IFNIRR at global origin, x=y=z=0 - motion of the support vessel, stored on file IFNIRR - motion transfer functions for the support vessel

4.1.1. Control information

Data group identifier, one input line
IFNIrr CONTrol INFOrmation      NoPlot

In addition to dimension parameters, control information also consists of directions and frequencies for which Fourier components are stored.

4.1.2. Sampled Fourier components

Data group identifier, one input line
FOURier COMPonents WAVEs        Plot
Output parameters, one input line
ICOMP IDIR ISEC IW1 NW IJP
  • ICOMP: integer: Component code

    • ICOMP=1: Wind sea

    • ICOMP=2: Swell

  • IDIR: integer: Direction no wanted

  • ISEC: integer: Sequence no wanted (dummy)

  • IW1: integer: Number of the first frequency for which Fourier components are wanted

  • NW: integer: No of frequencies for which Fourier components are wanted

  • IJP: integer, default: 1: Jump parameter

Fourier components are printed for frequencies no IW1, IW1+IJP, IW12x`IJP`, …, `IW1`(NW-1)x`IJP`

The components are printed/plotted as amplitude and phase angle (degrees)

4.1.3. Wave elevation

Data group identifier, one input line
WAVE ELEVation      Plot
Output parameters, one input line
ICOMP IDIR ISEC IT1 NTS XP1 XP2
  • ICOMP: integer: Component code

    • ICOMP=1: Wind sea

    • ICOMP=2: Swell

  • IDIR: integer: Direction no wanted

  • ISEC: integer: Sequence no wanted (dummy)

  • IT1: integer: First time step included

  • NTS: integer: Number of time steps included

  • XP1: real, default: 0: Global x-coordinate for wave elevation

  • XP2: real, default: 0: Global y-coordinate for wave elevation

A Fourier transformation of the wave spectrum is performed. Maximum number of time steps will be (NWIMAX-1)*2. Use the option IFNIRR CONTROL INFORMATION (see Control information).

In case of longcrested sea one direction is applied. In case of shortcrested sea, 11 directions are used and mean wave direction is no. 6. The other directions are spread around the mean direction in the interval \(\mathrm {[-75^{\circ},75^{\circ}]}\) in intervals of \(\mathrm {15^{\circ}}\).

4.1.4. Wave frequency motion time series

Data group identifier, one input line
WFMOtion TIME SERIes        Plot
Output options, one input line
IOP IMOT IDERIV ISEQ1 NSEQ IT1 NTS ITJMP IVES
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IMOT: integer: Direction

    • IMOT=1: Displacement in global x-direction

    • IMOT=2: Displacement in global y-direction

    • IMOT=3: Displacement in global z-direction

    • IMOT=4: Rotation about x-axis

    • IMOT=5: Rotation about y-axis

    • IMOT=6: Rotation about z-axis

  • IDERIV: integer: Code for derivative of response

    • IDERIV=0: Analyse original series

    • IDERIV=1: Analyse 1st derivative

    • IDERIV=2: Analyse 2nd derivative

  • ISEQ1: integer: First sequence to be included (dummy)

  • NSEQ: integer: No of sequence to be included (dummy)

  • IT1: integer: First time step of each sequence to be included

  • NTS: integer: No of time steps of each sequence to be included

  • ITJMP: integer, default: 1: Jump parameter

    • Time step nos. IT1, IT1+ITJMP, IT1+2xITJMP,…​, IT1+(NTS-1)xITJMP are included

  • IVES: integer, default: 1: Vessel number reference in case of multivessel systems.The vessels are numbered from 1 to NVES

Note that IMOT refers to the global coordinate system, not the vessel coordinate system.

Transformation of wave frequency motion time series, one input line
ITRANS XP YP ZP
  • ITRANS: integer, default: 0: Transformation code

    • ITRANS=0: No transformation, motions of vessel reference point

    • ITRANS=1: Transformation gives motion IMOT (see previous input line) of point defined by XP, YP and ZP

  • XP: real, default: 0: X-coordinate in global system, relative to the vessel reference point

  • YP: real, default: 0: Y-coordinate in global system, relative to the vessel reference point

  • ZP: real, default: 0: Z-coordinate in global system, relative to the vessel reference point

If ITRANS=0, XP, YP and ZP are dummy parameters

Options for the output distribution functions of the high frequency motion time series statistics, one input line

This input line is given only if IOP=2.

NCL XCMIN XCMAX
  • NCL: integer: No of classes in the output distribution functions (i.e. no of points on the abscissa axis)

    • 0<NCL<41

  • XCMIN: real: Range of argument values for output distribution functions is XCMIN*sx(1) - XCMAX*sx(1) in which sx(1) is the standard deviation of x estimated from the first sequence.

  • XCMAX: real:

Spectrum smoothing parameter for the spectral analysis of the high frequency motion, one input line

This input line is given only if IOP=3.

MSM
  • MSM: integer, default: 0: Smoothing parameter

    • MSM=0: No smoothing

    • MSM>0: Smoothing by averaging over 2*MSM+1 values.

4.1.5. Low frequency motion time series

Data group identifier, one input line
LFMOtion TIME SERIes        Plot
Output options, one input line
IOP IMOT IDERIV ISEQ1 NSEQ IT1 NTS ITJMP IVES
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IMOT: integer: Direction code

    • Legal values:

      • IMOT=1: Surge

      • IMOT=2: Sway

      • IMOT=6: Yaw

  • IDERIV: integer: Code for derivative of response

    • IDERIV=0: Analyse original series

    • IDERIV=1: Analyse 1st derivative

    • IDERIV=2: Analyse 2nd derivative

  • ISEQ1: integer: First sequence to be included (dummy)

  • NSEQ: integer: No of sequence to be included (dummy)

  • IT1: integer: First time step of each sequence to be included

  • NTS: integer: No of time steps of each sequence to be included

  • ITJMP: integer, default: 1: Jump parameter

    • Time step nos. IT1, IT1+ITJMP, IT1+2xITJMP,…​, IT1+(NTS-1)xITJMP are included

  • IVES: integer, default: 1: Vessel number reference in case of multivessel systems.The vessels are numbered from 1 to NVES

Transformation of the low-frequency motion time series, one input line
Options for the output distribution functions of the low frequency motion time series statistics, one input line

This input line is given only if IOP=2.

Spectrum smoothing parameter for the spectral analysis of the low frequency motion time series, one input line

This input line is given only if IOP=3.

4.1.6. Total motion time series

Data group identifier, one input line
TOMOtion TIME SERIes        Plot
Output options, one input line
IOP IMOT IDERIV ISEQ1 NSEQ IT1 NTS ITJMP IVES
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IMOT: integer: Direction code

    • IMOT=1: Displacement in global x-direction

    • IMOT=2: Displacement in global y-direction

    • IMOT=6: Rotation about z-axis

  • IDERIV: integer: Code for derivative of response

    • IDERIV=0: Analyse original series

    • IDERIV=1: Analyse 1st derivative

    • IDERIV=2: Analyse 2nd derivative

  • SEQ1: integer: First sequence to be included (dummy)

  • NSEQ: integer: No of sequence to be included (dummy)

  • IT1: integer: First time step of each sequence to be included

  • NTS: integer: No of time steps of each sequence to be included

  • ITJMP: integer, default: 1: Jump parameter

    • Time step nos. IT1, IT1+ITJMP, IT1+2xITJMP,…​, IT1+(NTS-1)xITJMP are included

  • IVES: integer, default: 1: Vessel number reference in case of multivessel systems.The vessels are numbered from 1 to NVES

Transformation of total motion time series, one input line
Options for the output distribution functions of the time series statistics of total motion, one input line

This input line is given only if IOP=2.

Spectrum smoothing parameter for the spectral analysis of the total motion, one input line

This input line is given only if IOP=3.

4.1.7. Vessel motion transfer functions

group identifier, one input line
WFTRansfer FUNCtion DOF      Plot

DOF means degree of freedom, and may be XG, YG, ZG, XGROT, YGROT or ZGROT.

Output options, one input line
IOP IDIR1 NDIR ITRAN IVES
  • IOP: integer: Code for type of output

    • IOP=1: Complex form (real, imaginary)

    • IOP=2: Real form (amplitude ratio, phase (degrees))

    • IOP=3: Real form (amplitude ratio, phase (radians))

  • IDIR1: integer: First direction to be included

  • INDIR: integer: No of directions to be included

  • ITRAN: integer: Code for transformation

    • ITRAN=0: No transformation

    • ITRAN=1: Transformation of origin motion to point (XV1, XV2, XV3), see next input line.

    • Dummy if degree of freedom is XGROT, YGROT or ZGROT

  • IVES: integer, defaul: 1: Vessel number

The coordinates of the point on the vessel for which the vessel motion transfer functions are wanted, one input line

If ITRAN=0, or the degree of freedom is XGROT, YGROT or ZGROT, this input line is skipped.

XV1 XV2 XV3
  • XV1: real: X-coordinate of the point

  • XV2: real: Y-coordinate of the point

  • XV3: real: Z-coordinate of the point

The coordinates are referred to the global coordinate system, relative to the vessel reference point.

The transfer functions for different degrees of freedom may be given without the PRINT or PLOT statement between.

4.2. Results from time domain dynamic analysis

4.2.1. Storage information

Data group identifier, one input line
TIME DOMAin PARAmeters
Print options, one input line
IDNOD IFNOD ICNOD
  • IDNOD: integer, default: 1: Switch for printing of nodes for which displacements are stored

    • IDNOD=0: No print

    • IDNOD=1: The nodes, for which displacements are stored, are printed

  • IFNOD: integer, default: 1: Switch for printing of elements for which force data are stored

    • IFNOD=0: No print

    • IFNOD=1: The nodes, for which force data are stored, are printed

  • ICNOD: integer, default: 1: Switch for printing of elements for which curvature data are stored

    • ICNOD=0: No print

    • ICNOD=1: The elements, for which curvature data are stored, are printed

4.2.2. Snapshot plot from time domain analysis

This option will create pictures of the dynamic configuration at several time steps.

Data group identifier, one input line
DYNAmic SNAPshot PLOT       Plot (only)
Plot options
IPROJ IT1 NTS NLIC IJUMP
  • IPROJ: integer: Project in code

    • IPROJ=1: x-z coordinates

    • IPROJ=2: y-z coordinates

    • IPROJ=3: x-y coordinates

  • IT1: integer: First stored time step to be included

  • NTS: integer/character: No of stored time steps to be included.

    • You may specify REST to include the remaining time steps

  • NLIC: integer: No. of input lines to describe line specification

  • IJUMP: integer, default: 1: Plot every IJUMP stored time step

Line specification, NLIC input lines
LINE-ID
  • LINE-ID: character(8): Line identifier to be plotted. You may specify ALL to include all lines in the system

The lines are plotted only if at least the end node coordinates are stored. Line configurations for all stored time steps are plotted.

4.2.3. System snapshot plot from time domain analysis

This option is an extension to the option DYNAMIC SNAPSHOT PLOT. You are able to plot the wave particle motion, the vessel motion and the riser motion in one plot.

Data group identifier, one input line
SYSTem SNAPshot PLOT        Plot (only)
Plot options, one input line
IPROJ IT1 NTS IJUMP NLIC NPVESP NPWAPO IVES XCGVES YCGVES ZCGVES
  • IPROJ: integer: Projection code

    • IPROJ=1: X-Z coordinates

    • IPROJ=2: Y-Z coordinates

    • IPROJ=3: X-Y coordinates

  • IT1: integer: First stored time step to be included

  • NTS: integer: No of stored time steps to be included. You may specify REST to include the remaining time steps

  • IJUMP: integer: Include every IJUMP stored time steps

  • NLIC: integer: No. of input lines to describe line specification

    • NLIC=0: No riser snapshot plot

  • NPVESP: integer: No of coordinates to describe the vessel

    • NPVESP=0: No vessel snapshot plot

  • NPWAPO: integer: No of coordinates to describe the wave particle motion

    • NPWAPO=0: No wave particle snapshot plot

  • IVES: integer, default: 1: Vessel number

  • XCGVES: real: Static X coordinate of the vessel

  • YCGVES: real: Static Y coordinate of the vessel

  • ZCGVES: real: Static Z coordinate of the vessel

Line specification, NLIC input lines
LINE-ID
  • LINE-ID: integer/character(8): Line identifier to be plotted. You may specify ALL to include all lines in the system

The lines are plotted only if at least the end node coordinates are stored.

Vessel description, NPVESP input lines. The specified points are connected by one line to illustrate a part of the vessel contour
IPV XVT YVT ZVT
  • IPV: integer: Coordinate no.

  • XVT: real: Vessels X-coordinate in global system referred from vessel origin \(\mathrm {[L]}\)

  • YVT: real: Vessels Y-coordinate \(\mathrm {[L]}\)

  • ZVT: real: Vessels Z-coordinate \(\mathrm {[L]}\)

Wave particle description, NPWAPO input lines
IPW XPW YPW ZPW
  • IPW: integer: Coordinate no.

    • If IPW<0, then the intermediate coordinates between the previous coordinate specification and this one are automatically calculated. The intermediate coordinates are equally spaced on a straight line

  • XPW: real: X-coordinate of the wave particle \(\mathrm {[L]}\)

  • YPW: real: Y-coordinate of the wave particle \(\mathrm {[L]}\)

  • ZPW: real: Z-coordinate of the wave particle \(\mathrm {[L]}\)

The wave particle coordinates are given in the global coordinate system in calm water, i.e. (0.,0.,0.) is wave at global origin. Specifying ZPW \(\mathrm {\equiv}\) 0. for all points will create a plot of the wave surface elevation.

4.2.4. Dynamic displacement time series from time domain analysis

Results include only the dynamic time dependant displacements (static values are not included).

Data group identifier, one input line
DYNDisp TIME SERIes         Plot
Output options, one input line
IOP IDOF IT1 NTS NNODC      Plot
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IDOF: integer: Code for degree of freedom

    • Rotational degrees of freedom are only to be presented from linearized dynamic analysis.

    • IDOF=1: Translation in x-direction

    • IDOF=2: Translation in y-direction

    • IDOF=3: Translation in z-direction

    • IDOF=4: Rotation about x-axis

    • IDOF=5: Rotation about y-axis

    • IDOF=6: Rotation about z-axis

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps

  • NNODC: integer: No. of input lines used for node specification

For IOP=3 an FFT analysis is carried out. If NTS is not an integer power of 2, a reduced time series will be analysed. In order to get an effective analysis, IT1 and NTS should be selected so that - \(\mathrm {IT1=NT-2^M+1}\) - \(\mathrm {NTS=2^M}\)

Where \(\mathrm {NT}\) is the total number of stored time steps and \(\mathrm {M}\) is the largest integer so that \(\mathrm {NTS\<=NT}\). Normally it is preferable to omit the first part of the time series due to transients

Node specification, NNODC input lines
LINE-ID ISEG INODE
  • LINE-ID: character(8): Line identifier.

    • You may specify ALL to include all lines

  • ISEG: integer/character: Segment number.

    • You may specify ALL to include all segments.

    • ENDS includes the end segments on the line

  • INODE: integer/character: Node number.

    • ALL includes all nodes

    • ENDS includes end nodes on the above specified segment

Displacements are not necessarily stored for all nodes, see data group File storage of displacement response for storage information. If the user specifies nodes for which displacements are not stored, these nodes are ignored.

The data group Storage information may be used to obtain an overview of the stored data.

Options for the output distribution functions of the displacement time series statistics, one input line

This input line is given only if IOP=2.

NCL XCMIN XCMAX
  • NCL: integer: No of classes in the output distribution functions (i.e. no of points on the abscissa axis)

    • 0<NCL<41

  • XCMIN: real: Range of argument values for output distribution functions is XCMIN*sx(1) - XCMAX*sx(1) in which sx(1) is the standard deviation of x estimated from the first sequence

  • XCMAX: real: See above

Spectrum smoothing parameter for the spectral analysis of the displacement time series, one input line

This input line is given only if IOP=3.

MSM
  • MSM: integer, default: 0: Smoothing parameter

    • MSM=0: No smoothing

    • MSM>0: Smoothing by averaging over 2*MSM+1 values

4.2.5. Dynamic resulting force time series from time domain analysis

The results include only the dynamic time dependent force. Static values are not included.

Data group identifier, one input line
DYNForce TIME SERIes        Plot
Output options, one input line
IOP IDOF IT1 NTS NNELC
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IDOF: integer: Code for degree of freedom

    • IDOF=1: Axial force

    • IDOF=2: Torsional moment

    • IDOF=3: Bending moment about local y-axis, end 1

    • IDOF=4: Bending moment about local y-axis, end 2

    • IDOF=5: Bending moment about local z-axis, end 1

    • IDOF=6: Bending moment about local z-axis, end 2

    • IDOF=7: Shear force in local y-direction, end 1

    • IDOF=8: Shear force in local y-direction, end 2

    • IDOF=9: Shear force in local z-direction, end 1

    • IDOF=10: Shear force in local z-direction, end 2

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps.

  • NNELC: integer: No. of input lines used for element specification

For IOP=3 an FFT analysis is carried out. If NTS is not an integer power of 2, a reduced time series will be analysed. In order to get an effective analysis, IT1 and NTS should be selected so that - \(\mathrm {IT1=NT-2^M+1}\) - \(\mathrm {NTS=2^M}\)

Where \(\mathrm {NT}\) is the total number of stored time steps and \(\mathrm {M}\) is the largest integer so that \(\mathrm {NTS\<=NT}\). Normally it is preferable to omit the first part of the time series due to transients

Element specification, NNELC input lines
LINE-ID ISEG IELM
  • LINE-ID: character(8): Line identifier.

    • You may specify ALL to include all lines

  • ISEG: integer/character: Segment number.

    • You may specify ALL to include all segments.

    • ENDS includes the end segments on the line

  • IELM: integer/character: Element number.

    • ALL includes all Elements

    • ENDS includes end elements on the above specified segment

Forces are not necessarily stored for all elements, see data group File storage for internal forces for storage information. If the user specifies elements for which forces are not stored these elements are ignored.

The data group Storage information may be used to obtain an overview of the stored data.

Options for the output distribution functions of the force time series statistics, one input line

This input line is given only if IOP=2.

NCL XCMIN XCMAX
  • NCL: integer: No of classes in the output distribution functions (i.e. no of points on the abscissa axis)

    • 0<NCL<41

  • XCMIN: real: Range of argument values for output distribution functions is XCMIN*sx(1) - XCMAX*sx(1) in which sx(1) is the standard deviation of x estimated from the first sequence

  • XCMAX: real:

Spectrum smoothing parameter for the spectral analysis of the force time series, one input line

This input line is given only if IOP=3.

MSM
  • MSM: integer, default: 0: Smoothing parameter

    • MSM=0: No smoothing

    • MSM>0: Smoothing by averaging over 2*MSM+1 values

4.2.6. Curvature time series from time domain analysis

Results include only the dynamic time dependant curvature (static values are not included)

Data group identifier, one input line
DYNCURV TIME SERIES         Plot
Output options, one input line
IOP IDOF IT1 NTS NNELC
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IDOF: integer: Code for degree of freedom

    • IDOF=1: Curvature about local y-axis, end 1

    • IDOF=2: Curvature about local y-axis, end 2

    • IDOF=3: Curvature about local z-axis, end 1

    • IDOF=4: Curvature about local z-axis, end 2

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps.

  • NNELC: integer: No. of input lines used for element specification

For IOP=3 an FFT analysis is carried out. If NTS is not an integer power of 2, a reduced time series will be analysed. In order to get an effective analysis, IT1 and NTS should be selected so that - \(\mathrm {IT1=NT-2^M+1}\) - \(\mathrm {NTS=2^M}\)

Where \(\mathrm {NT}\) is the total number of stored time steps and \(\mathrm {M}\) is the largest integer so that \(\mathrm {NTS\<=NT}\). Normally it is preferable to omit the first part of the time series due to transients

Options for the output distribution functions of the curvature time series statistics, one input line

This input line is given only if IOP=2.

Spectrum smoothing parameter for the spectral analysis of the curvature time series, one input line

This input line is given only if IOP=3.

4.2.7. Curvature time series calculated from dynamic nodal displacements

See also Curvature time series from time domain analysis for curvature component time series.

This option gives absolute value of curvature in 3D space at a specified node. Calculation of curvature is based on the interpolating polynomial through the positions of 3 adjacent nodes in the same line. Curvature can therefore only be calculated if displacement time series are stored for the specified node and two neighbouring nodes (see data group File storage of displacement response for storage information). The data group Storage information may be used to obtain an overview of the stored data.

Calculation of curvature at line ends is omitted.

Data group identifier, one input line
CALCurv TIME SERIes         Plot

Total curvature calculated from the selected node and the two neighbouring nodes.

Output options, one input line
IOP IT1 NTS NNODC
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps.

  • NNODC: integer: No. of input lines used for element specification

For IOP=3 an FFT analysis is carried out. If NTS is not an integer power of 2, a reduced time series will be analysed. In order to get an effective analysis, IT1 and NTS should be selected so that - \(\mathrm {IT1=NT-2^M+1}\) - \(\mathrm {NTS=2^M}\)

Where \(\mathrm {NT}\) is the total number of stored time steps and \(\mathrm {M}\) is the largest integer so that \(\mathrm {NTS\<=NT}\). Normally it is preferable to omit the first part of the time series due to transients.

Options for the output distribution functions of the curvature time series statistics, one input line

This input line is given only if IOP=2.

Spectrum smoothing parameter for the spectral analysis of the curvature time series, one input line

This input line is given only if IOP=3.

4.2.8. Displacement envelope curves

Envelope curves of displacements from time domain analysis are presented as: - Minimum, static and maximum x, y and z displacements for regular analysis - Mean, static and mean + standard deviation for irregular analysis.

Static values are identified as dashed lines while the others are solid.

Data group identifier, one input line
DISPlacement ENVElope CURVes        Plot
Print options, one input line
LINE-ID IPDOF1 IPDOF2 IPDOF3
  • LINE-ID: character(8): Line identifier for which displacements are wanted.

    • You may specify ALL to include all lines in the system.

    • The print part of this option will always produce results for all stored degrees of freedom, i.e. x-, y- and z-displacements. The following parameters are used to specify the dof’s to be plotted

  • IPDOF1: integer: Degree of freedom for first figure

    • IPDOF1=0: Not included

    • IPDOF1=1: x-displacement

    • IPDOF1=2: y-displacement

    • IPDOF1=3: z-displacement

  • IPDOF2: integer: Degree of freedom for second figure.

    • Interpretation as for IPDOF1

  • IPDOF3: integer: Degree of freedom for third figure.

    • Interpretation as for IPDOF1

Each figure is presented on separate plot.

4.2.9. Force envelope curves

Envelope curves of forces from time domain analysis are presented as:

  • Minimum, static and maximum axial force torsional moment or bending moments for regular analysis

  • Mean, static and mean + standard deviation for irregular analysis

Static values are identified as dashed lines while the others are solid.

Data group identifier, one input line
FORCe ENVElope CURVes       Plot
Print options, one input line
LINE-ID IDOF1 IDOF2 IDOF3
  • LINE-ID: character(8): Line identifier for which forces are wanted.

    • You may specify ALL to include all lines in the system.

    • The print part of this option will always produce results for all stored degrees of freedom, i.e. axial force, torsional moment and bending moments about local y- and z-axes. The following parameters are used to specify the dof’s to be plotted

  • IDOF1: integer: Degree of freedom for first figure.

    • IDOF1=0: Not included

    • IDOF1=1: Axial force

    • IDOF1=2: Torsional moment

    • IDOF1=3: Bending moment about local y-axis

    • IDOF1=4: Bending moment about local z-axis

    • IDOF1=5: Pipe wall force, incl. hydrostatic pressures

      • Pipe wall force is only avaivable for PLOT

    • IDOF1=6: Shear force in local y-direction

    • IDOF1=7: Shear force in local z-direction

  • IPDOF2: integer: Degree of freedom for second figure.

    • Interpretation as for IPDOF1

  • IPDOF3: integer: Degree of freedom for third figure.

    • Interpretation as for IPDOF1

Each figure is presented on separate plot.

4.2.10. Curvature envelope curves

Envelope curves of curvatures from time domain analysis are presented as: - Minimum, static and maximum values of curvatures for a regular analysis - Mean, static and mean + standard deviation for irregular analysis

Static results are dashed, while the others are solid.

Data group identifier, one input line
CURVature ENVElope CURVes       Plot
Print options, one input line
LINE-ID IDOF1 IDOF2 IDOF3
  • LINE-ID: character(8): Line identifier for which curvatures are wanted.

    • You may specify ALL to include all lines in the system.

    • The print part of this option will always produce results for all stored degrees of freedom, i.e. local y- and z-curvatures and resulting curvature. The following parameters are used to specify the dof’s to be plotted

  • IPDOF1: integer: Degree of freedom for first figure

    • IDOF1=0: Not included

    • IDOF1=1: Curvature about local y-axis

    • IDOF1=2: Curvature about local z-axis

    • IDOF1=3: Resulting curvature

    • Resulting curvature is taken as the vector sum of the curvatures about local y- and z-axis and will therefore always be positive

  • IPDOF2: integer: Degree of freedom for second figure.

    • Interpretation as for IPDOF1

  • IPDOF3: integer: Degree of freedom for third figure.

    • Interpretation as for IPDOF1

Each figure is presented on separate plot.

4.2.11. Support forces

Forces in both ends of specified lines are analyzed and presented in the global coordinate system. Forces due to static and dynamic loads are included. Forces due to hydrostatic pressures are not included, i.e. the axial component is the effective tension.

Data group identifier, one input line
SUPPf TIME SERIes       Plot
Output options, one input line
IOP IDOF IT1 NTS NLINC
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IDOF: integer: Code for degree of freedom

    • IDOF=1: Global x-direction

    • IDOF=2: Global y-direction

    • IDOF=3: Global z-direction

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included

  • NLINC: integer: Number of input lines used for line specifications

For IOP=3 an FFT analysis is carried out. If NTS is not an integer power of 2, a reduced time series will be analysed. In order to get an effective analysis, IT1 and NTS should be selected so that - \(\mathrm {IT1=NT-2^M+1}\) - \(\mathrm {NTS=2^M}\)

Where \(\mathrm {NT}\) is the total number of stored time steps and \(\mathrm {M}\) is the largest integer so that \(\mathrm {NTS\<=NT}\). Normally it is preferable to omit the first part of the time series due to transients.

Element specification, NLINC input lines
LINE-ID
  • LINE-ID: character(8), default: 0: Line number. You may specify ALL to include all lines

Options for the output distribution functions of the force time series statistics, one input line

This input line is given only if IOP=2.

NCL XCMIN XCMAX
  • NCL: integer: No of classes in the output distribution functions (i.e. no of points on the abscissa axis)

    • 0<NCL<41

  • XCMIN: real: Range of argument values for output distribution functions is XCMIN*sx(1) - XCMAX*sx(1) in which sx(1) is the standard deviation of x estimated from the first sequence

  • XCMAX: real, default: 0:

Spectrum smoothing parameter for the spectral analysis of the force time series, one input line

This input line is given only if IOP=3.

MSM
  • MSM: integer, default: 0: Smoothing parameter

    • MSM=0: No smoothing

    • MSM>0: Smoothing by averaging over 2*MSM+1 values

4.2.12. Element angle time series from time domain analysis

Data group identifier, one input line
ELMAngle TIME SERIes        Plot
Output options, one input line
IOP IT1 NTS NNELC
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps

  • NNELC: integer: No. of pairs of input lines used for element specification

Two of the subsequent input lines (Code for element specification and either Global or vessel axis and element specification or Element pair specification) given NNELC times.

Code for element specification
IRELCO
  • IRELCO: integer: Code for type of output

    • IRELCO=0: Angle between fixed global axis and one specified element

    • IRELCO=1: Angle between support vessel coordinate axis and one specified element

    • IRELCO=2: Angle between two elements

Global or vessel axis and element specification

This input line is given only for IRELCO=0 or 1.

IAXIS IVES LINE-ID ISEG IELM HEAD
  • IAXIS: integer: Code for axis

    • IAXIS=1: x-axis

    • IAXIS=2: y-axis

    • IAXIS=3: z-axis

  • IVES: integer, default: 1: Vessel number if IRELCO=1 else dummy

  • LINE-ID: character(8): Line identifier

  • ISEG: integer: Segment number

  • IELM: integer: Element number

  • HEAD: integer: Vessel heading in final static position if IRECLCO=1, else dummy \(\mathrm {[deg]}\)

The angle output is between 0 and 180 degrees. If the element direction (from end 1 to end 2) is along the specified axis, the relative angle is 0. Otherwise, if the element direction is along the negative axis direction, the angle is 180 degrees. The element direction is calculated as the direction along the secant from local end no 1 to local end no 2 (i.e. local element x-axis).

Element pair specification

This input line is given only for IRELCO=2.

LINE-ID1 ISEG1 IELM1 LINE-ID2 ISEG2 IELM2
  • LINE-ID1: character(8): Specification of first element

  • ISEG1: integer:

  • IELM1: integer:

  • LINE-ID2: character(8): Specification of second element

  • ISEG2: integer:

  • IELM2: integer:

The angle output is between 0 and 180 degrees. If the element direction (from end 1 to end 2) is along the specified axis, the relative angle is 0. Otherwise, if the element direction is along the negative axis direction, the angle is 180 degrees. The element direction is calculated as the direction along the secant from local end no 1 to local end no 2 (i.e. local element x-axis).

4.2.13. Total displacement time series from time domain analysis

Results include the total dynamic displacements (static values are included)

Data group identifier, one input line
TOTDisp TIMe SERIes         Plot
Output options, one input line
IOP IDOF IT1 NTS NNODC
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IDOF: integer: Code for degree of freedom

    • IDOF=1: Translation in x-direction

    • IDOF=2: Translation in y-direction

    • IDOF=3: Translation in z-direction

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps.

  • NNODC: integer: No of input lines used for node specification

For IOP=3 an FFT analysis is carried out. If NTS is not an integer power of 2, a reduced time series will be analysed. In order to get an effective analysis, IT1 and NTS should be selected so that - \(\mathrm {IT1=NT-2^M+1}\) - \(\mathrm {NTS=2^M}\)

Where \(\mathrm {NT}\) is the total number of stored time steps and \(\mathrm {M}\) is the largest integer so that \(\mathrm {NTS\<=NT}\). Normally it is preferable to omit the first part of the time series due to transients.

Options for the output distribution functions of the displacement time series statistics, one input line

This input line is given only if IOP=2.

Spectrum smoothing parameter for the spectral analysis of the displacement time series, one input line

This input line is given only if IOP=3.

4.2.14. Total resulting force time series from time domain analysis

The result force includes both the dynamic time dependent force and the static force.

Data group identifier, one input line
TOTForce TIME SERIes        Plot
Output options, one input line
IOP IDOF IT1 NTS NNELC
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IDOF: integer: Code for degree of freedom

    • IDOF=1: Axial force

    • IDOF=2: Torsional moment

    • IDOF=3: Bending moment about local y-axis, end 1

    • IDOF=4: Bending moment about local y-axis, end 2

    • IDOF=5: Bending moment about local z-axis, end 1

    • IDOF=6: Bending moment about local z-axis, end 2

    • IDOF=7: Shear force in local y-direction, end 1

      • Nonlinear dynamic analysis only in present version

    • IDOF=8: Shear force in local y-direction, end 2

      • Nonlinear dynamic analysis only in present version

    • IDOF=9: Shear force in local z-direction, end 1

      • Nonlinear dynamic analysis only in present version

    • IDOF=10: Shear force in local z-direction, end 2

      • Nonlinear dynamic analysis only in present version

    • IDOF=11: Axial wall force

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps

  • NNELC: integer: No of input lines used for element specification

For IOP=3 an FFT analysis is carried out. If NTS is not an integer power of 2, a reduced time series will be analysed. In order to get an effective analysis, IT1 and NTS should be selected so that - \(\mathrm {IT1=NT-2^M+1}\) - \(\mathrm {NTS=2^M}\)

Where \(\mathrm {NT}\) is the total number of stored time steps and \(\mathrm {M}\) is the largest integer so that \(\mathrm {NTS\<=NT}\). Normally it is preferable to omit the first part of the time series due to transients.

Options for output distribution functions. Given only if IOP=2

This input line is given only if IOP=2.

Spectrum smoothing parameter. Given only if IOP=3

This input line is given only if IOP=3.

4.2.15. Distance time series calculated from the time domain analyses

This option is mainly to be used in order to perform a check of collision risk between two risers, between a riser and the vessel or between a riser and a fixed structure. The minimum distance is calculated for only a part of the riser. All elements within the specified segments are searched to find this minimum distance at each time step.

Note that the distances are absolute, they are always positive values. The program cannot identify a line crossing situation.

Data group identifier, one input line
DISTance TIME SERIes        Plot
Output options, one input line
IOP IT1 NTS IDITYP IMETH IVES XCGVES YCGVES ZCGVES
  • IOP: integer: Code for type of output

    • IOP=1: Time series

    • IOP=2: Time series statistics

    • IOP=3: Spectral analysis

  • IT1: integer: First stored time step to be included

  • NTS: integer: No of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps

  • IDITYP: integer: Type of distance to be calculated

    • IDITYP=1: Distance between specified segments on lines

    • IDITYP=2: Distance between specified segments on a line and a globally fixed line

    • IDITYP=3: Distance between specified segments on a line and a line fixed on the vessel

  • IMETH: integer, default: 1: Method option

    • IMETH=1: Distance between elements are calculated

    • IMETH=2: Distance between nodes are calculated

  • IVES: integer, default: 1: Vessel number in case of multivessel analysis and IDITYP = 3

  • XCGVES: real, default: 0: Static X coordinate of the vessel in case of IDITYP = 3

  • YCGVES: real, default: 0: Static Y coordinate of the vessel in case of IDITYP = 3

  • ZCGVES: real, default: 0: Static Z coordinate of the vessel in case of IDITYP = 3

With the distance, we here mean the minimum distance. All elements within the specified segment(s) are scanned for each time step in order to find the one with the minimum distance.

Method 1 is more accurate, but more time consuming than method 2.

Specification of segments on lines which the minimum distance should be calculated from, one input line
LINE-ID NSEG ISEG1 ISEG2 . . ISEG(NSEG)
  • LINE-ID: character(8): Line identifier

  • NSEG: integer/character: No of segments for which the minimum distances are to be calculated from

    • You may specify ALL in order to include all segments

  • ISEG: integer: The included segment numbers

Searching through all elements may cause rather large computation time.

Specified segments to which the minimum distance are calculated, to be given only if IDITYP=1. One input line
LINE-ID NSEG ISEG1 ISEG2 ... ISEG(NSEG)
  • LINE-ID: character(8): Line identifier

  • NSEG: integer/character: No of segments for which the minimum distances are to be calculated to

    • You may specify ALL in order to include all segments

  • ISEGj: integer: The included segment numbers

Searching through all elements may cause rather large computation time.

Specification of a line in the global coordinate system to which the minimum distance are to be calculated, to be given only if IDITYP=2. One input line
XG1 YG1 ZG1 XG2 YG2 ZG2
  • XG1: real: Global x-coordinate, end 1

  • YG1: real: Global y-coordinate, end 1

  • ZG1: real: Global z-coordinate, end 1

  • XG2: real: Global x-coordinate, end 2

  • YG2: real: Global y-coordinate, end 2

  • ZG2: real: Global z-coordinate, end 2

Specification of a line in the global coordinate system relative to the vessel reference point to which the minimum distance are to be calculated, to be given only if IDITYP=3
XV1 YV1 ZV1 XV2 YV2 ZV2
  • XV1: real: Vessel x-coordinate, end 1

  • YV1: real: Vessel y-coordinate, end 1

  • ZV1: real: Vessel z-coordinate, end 1

  • XV2: real: Vessel x-coordinate, end 2

  • YV2: real: Vessel y-coordinate, end 2

  • ZV2: real: Vessel z-coordinate, end 2

Options for the output distribution functions of the distance time series statistics, one input line

This input line is given only if IOP=2.

NCL XCMIN XCMAX
  • NCL: integer: No of classes in the output distribution functions (i.e. no of points on the abscissa axis)

    • 0<NCL<41

  • XCMIN: real: Range of argument values for output distribution functions is XCMIN*sx(1) - XCMAX*sx(1) in which sx(1) is the standard deviation of x estimated from the first sequence

  • XCMAX: real:

Spectrum smoothing parameter for the spectral analysis of the distance time series, one input line

This input line is given only if IOP=3.

MSM
  • MSM: integer, default: 0: Smoothing parameter

    • MSM=0: No smoothing

    • MSM>0: Smoothing by averaging over 2*MSM+1 values

4.2.16. Generate snapshot file from time domain analysis (special option)

This is a special option specified and commissioned by Norsk Hydro, for generation of input files for an animation program used by Norsk Hydro.

Nodes coordinates, element forces and curvatures from dynamic analysis are written to the following files: - SNAPSNxx.DAT - Node coordinates - SNAPFOxx.DAT - Element forces - SNAPCUxx.DAT - Element curvatures

Element forces and/or curvatures will only be written for lines for which the storage coincide with the storage of node displacements.

Data group identifier, one input line
GENERATE SNAPSHOT FILE      Plot
IT1 NTS IJUMP NLIC NPVESD IVES LFORCE LCURV IASCII XCGVES YCGVES ZCGVES
  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included.

    • You may specify REST to include the remaining time step

  • IJUMP: integer: Include every "IJUMP" stored time step

  • NLIC: integer: No. of input lines to describe the line specification

    • NLIC=0: No riser snapshot

  • NPVESD: integer: No of coordinates to describe the vessel

    • NPVESD=0: No vessel snapshot

  • IVES: integer, default: 1: Vessel number in case of multi-vessel analysis

  • LFORCE: integer, default: 0: Control parameter

    • LFORCE=0: Element forces are not written to file

    • LFORCE=1: Element forces are written to file

  • LCURV: integer, default: 0: Control parameter

    • LCURV=0: Element curvatures are not written to file

    • LCURV=1: Element curvatures are written to file

  • IASCII: integer, default: 0: Control parameter

    • IASCII=0: Unformatted snapshot files

    • IASCII=1: Formatted snapshot files

  • XCGVES: real: Static X coordinate of vessel CG

  • YCGVES: real: Static Y coordinate of vessel CG

  • ZCGVES: real: Static Z coordinate of vessel CG

Line specification, NLIC input lines
LINE-ID
  • LINE-ID: character(8): Line identifier to be written to file. You may specify ALL to include all the lines in the system

The lines are written only if at least the displacements of the end nodes are stored, see data group File storage of displacement response for storage information.

Vessel description, NPVESD input lines. The specified points are connected by one line to illustrate a part of the vessel contour
IPV XVT YVT ZVT
  • IPV: integer: Coordinate number

  • XVT: real: Vessel’s X-coordinate in global system, relative to the vessel reference point \(\mathrm {[L]}\)

  • YVT: real: Vessel’s Y-coordinate \(\mathrm {[L]}\)

  • ZVT: real: Vessel’s Z-coordinate \(\mathrm {[L]}\)

The vessel points are in global system, but they are relative to the vessel reference point (the attachment point).

4.2.17. Stress time series calculated from the time domain analysis

This option allows for calculation of stresses in circular metallic homogeneous risers.

The stress time series are calculated based on the stored force time series from DYNMOD and the component properties specified in INPMOD. Stresses may only be calculated for CRS1 and CRS0 components.

Stress time series are calculated for specified points on the tube circumference.

Data group identifier
STREss TIME SERIes
Output options, one input line
IOP IDOF IT1 NTS ISUBST NNELC
  • IOP: integer: Code for type of output

    • IOP = 1: Time series

    • IOP = 2: Time series statistics

    • IOP = 3: Spectral analysis

    • IOP = 1 in present version

  • IDOF: integer: Stress components type 1

    • IDOF = 1/11: Axial stress at end 1/2

    • IDOF = 2/12: Torsional stress at end 1/2

    • IDOF = 3/13: Bending stress at end 1/2

    • IDOF = 4/14: Axial + bending stress at end 1/2

    • IDOF = 5/15: Shear stress at end 1/2

    • IDOF = 6/16: Shear stress + torsional stress at end 1/2

    • IDOF = 7/17: Equivalent stress at end 1/2

    • IDOF = 8/18: Hoop stress at end 1/2

    • IDOF = 9/19: Radial stress at end 1/2

    • IDOF = 21/22: External pressure at end 1/2

    • IDOF = 23/24: Internal pressure at end 1/2

  • IT1: integer: First stored time step to be included

  • NTS: integer: Number of stored time steps to be included (from IT1).

    • A large number includes the remaining time steps

  • ISUBST: integer, default: 0: Code for subtracting the static stress contributions

    • ISUBST = 0: Total stresses calculated

    • ISUBST = 1: Static stress is subtracted

  • NNELC: integer: Number of lines used for element specification

Point for stress calculation, one input line
THETA INEX IOPPRE
  • THETA: real, default: 0.0: Angle from local y-axis for stress calculation \(\mathrm {[Deg]}\)

  • INEX: integer, default: 2: Stress location switch

    • INEX = 1: Inner wall

    • INEX = 2: Outer wall

  • IOPPRE: integer, default: 1: Code for updating inner and outer pressure values.

    • |IOPPRE| = 1: Static inner and outer pressure used.

      • Outer pressure is calculated as hydrostatic pressure from MWL.

    • |IOPPRE| = 2: Updated inner and outer pressure used.

      • Outer pressure is calculated as hydrostatic pressure from MWL.

    • IOPPRE < 0: Wall forces calculated using outer area given by the pipe diameter or the alternative cross section diameter.

      • Corresponds to evenly distributed shear forces between buoyancy material and pipe.

      • Warning: This option is under development!

Nonlinear time domain analysis only.

In the present version, the external pressure is calculated as a hydrostatic pressure from the MWL. The external pressure is updated for all structural elements.

The internal pressure is updated for all elements that are part of a Main Riser Line.

Element specification, NNELC input lines
LINE-ID ISEG IELM
  • LINE-ID: character(8): Line identifier.

    • You may specify ALL to include all lines

  • ISEG: integer/character: Segment number.

    • You may specify ALL to include all segments.

    • ENDS includes the end segments on the line

  • IELM: integer/character: Element number.

    • ALL includes all elements, and

    • ENDS includes end elements on the above specified segment

Stresses may only be calculated for elements for which forces are stored, see data group File storage for internal forces for storage information. If the user specifies elements for which forces are not stored, these elements are ignored.

The data group Storage information may be used to obtain an overview of the stored data.

Options for the output distribution functions of the stress time series statistics, one input line

This input line is given only if IOP=2.

 NCL XCMIN XCMAX
  • NCL: integer: No of classes in the output distribution functions (i.e. no of points on the abscissa axis)

    • 0<NCL<41

  • XCMIN: real: Range of argument values for output distribution functions is XCMIN*sx(1) - XCMAX*sx(1) in which sx(1) is the standard deviation of x estimated from the first sequence.

  • XCMAX: real:

Spectrum smoothing parameter for the spectral analysis of the stress time series, one input line

This input line is given only if IOP=3.

MSM
  • MSM: integer, default: 0: Smoothing parameter

    • MSM=0: No smoothing

    • MSM>0: Smoothing by averaging over 2*MSM+1 values.

4.2.18. Stress envelope curves

This option allows for calculation of stress envelopes from the element forces stored in DYNMOD, see data group File storage for internal forces for storage information.

The data group Storage information may be used to obtain an overview of the stored data.

Data group identifier
STREss ENVElope CURVes      Noplot
Print options, one input line
LINE-ID IDOF1 IDOF2 IDOF3
  • LINE-ID: character(8): Line identifier

    • ILINE = ALL: Stresses in all lines calculated

  • IDOF1:integer: Stress component type 1

    • IDOF1 = 1: Axial stress

    • IDOF1 = 2: Torsional stress

    • IDOF1 = 3: Bending stress

    • IDOF1 = 4: Axial + bending stress

    • IDOF1 = 5: Shear stress

    • IDOF1 = 6: Shear + torsional stress

    • IDOF1 = 7: Equivalent stress

    • IDOF1 = 8: Hoop stress

    • IDOF1 = 9: Radial stress

  • IDOF2:integer: Stress component type 2

    • See IDOF1

    • Dummy at present

  • IDOF3:integer: Stress component type 3

    • See IDOF1

    • Dummy at present

Stress calculations options, one input line
TSTA TEND IOP DUR
  • TSTA: real, default: 0: Start time in stress time series \(\mathrm {[T]}\)

  • TEND: real, default: 0: End time in stress time series \(\mathrm {[T]}\)

    • TEND = 0.0: Until last time step used

  • IOP: integer, default: 0: Code for envelope type

    • IOP = 1: Min and max values presented

    • IOP = 2: Maximum range

    • IOP = 3: Standard deviations

    • IOP = 4: Estimated extreme values (not yet implemented)

  • DUR: real, default: 10800: Duration used in extreme value estimation \(\mathrm {[T]}\)

    • Dummy parameter in present version

Stress calculation location, one input line
NPCS IOPPR THETA INEX IOPPRE
  • NPCS: integer, default: See below: Number of points around the cross-section

    • = 0: max stresses estimated

  • IOPPR: integer, default: 0: Print option

    • IOPPR = 0: Print maximum stresses only

    • IOPPR > 0: Print stresses at all NPRCS points

  • THETA: real, default: 0: Angle for stress calculation \(\mathrm {[Deg]}\)

    • Dummy for NPCS>1

  • INEX: integer, default: 2: Stress loction switch

    • INEX = 1: Inner wall

    • INEX = 2: Outer wall

  • IOPPRE: integer, default: 1: Code for updating inner and outer pressure values.

    • |IOPPRE| = 1: Static inner and outer pressure used.

    • |IOPPRE| = 2: Updated inner and outer pressure used.

    • Outer pressure calculated as hydrostatic pressure from MWL.

    • IOPPRE < 0: Wall forces calculated using outer area given by the pipe diameter or the alternative cross section diameter.

      • Corresponds to evenly distributed shear forces between buoyancy material and pipe.

      • Warning: This option is under development!

Nonlinear time domain analysis only.

The default value for NPCS is dependent on the value specified above for IOP: Default is 0 for IOP = 1, otherwise it is 4.

In the present version, the external pressure is calculated as a hydrostatic pressure from the MWL. The external pressure is updated for all structural elements.

The internal pressure is updated for all elements that are part of a Main Riser Line.

Stress calculation parameters, one input line
IOPSTR ASTI WSTI DIASTI THSTI EMOD
  • IOPSTR: integer, default: 0: Option for stress calculation

    • IOPSTR=0: Stresses calculated from bending moment (recommended)

    • IOPSTR=1: Stresses calculated from curvatures

  • ASTI: real, default: 0: Alternative cross sectional area \(\mathrm {[L^2]}\)

  • WSTI: real, default: 0: Alternative cross section modulus \(\mathrm {[L^3]}\)

  • DIASTI: real, default: 0: Alternative cross section diameter \(\mathrm {[L]}\)

  • THSTI: real, default: 0: Alternative cross section wall thickness \(\mathrm {[L]}\)

  • EMOD: real, default: 0: Modulus of elasticity \(\mathrm {[F/L^2]}\)

    • Bending stresses are calculated from curvature, diameter and EMOD if IOPSTR=1 and EMOD>0

    • \(\mathrm {WST=\frac{2}{EMOD\times DIAST}}\)

The default values of 0 for ASTI, WSTI, DIASTI, THSTI and EMOD are interpreted as no change from the cross-sectional properties given in INPMOD.

4.2.19. Riser stroke time series from time domain analysis

The riser stroke is calculated for the supernode specified in DYNMOD from the motions of the vessel and the vertical displacement of specified supernode.

This option is not of interest if the terminal point of the riser is vertically fixed to the vessel.

Data group identifier, one input line
STROKe TIME SERIes      Plot
Option to calculate the riser stroke time series, one input line
IOP IMOT IDERIV IT1 NTS
  • IOP: integer: Code for type of output

    • IOP = 1: Time series

    • IOP = 2: Time series statistics

    • IOP = 3: Spectral analysis

  • IMOT: integer:

    • IMOT = 1: Stroke

    • IMOT = 2: Platform heave motion only

    • IMOT = 3: Risers upper end heave motion only

  • IDERIV: integer:

    • IDERIV = 0: Original

    • IDERIV = 1: First derivative

    • IDERIV = 2: Second derivative

  • IT1: integer: First stored time steps to be included

  • NTS: integer: Number of stored time steps to be included

4.2.20. Code check curves

This option allows for code check of the response.

Data group identifier
CODE CHECk CURVes
Main output options, one input line
LINE-ID IOPCOD IOP IDIST DUR PROB
  • LINE-ID: character(8): Line identifier

    • LINE-ID = ALL: All lines checked

  • IOPCOD: integer, default: 1: Option for type of code check

    • IOPCOD = 1: titanium code check

  • IOP: integer, default: 2: Option for using maximum or estimated extreme values

    • IOP = 1: Maximum values from stress time series used

    • IOP = 2: Estimated extreme values used

  • IDIST: integer, default: 2: Distribution type used in extreme value estimation

    • IDIST = 1: Rayleigh distribution used

    • IDIST = 2: Three parameter Weibull used

    • Dummy for IOP = 1

  • DUR: real, default: 10800: Duration used in extreme value estimation \(\mathrm {[T]}\)

    • Dummy for IOP = 1

  • PROB: real, default: 0: Probability level used in extreme value estimation

    • PROB = 0.0: Expected maximum value used

    • Dummy for IOP = 1

Time range and cross-section points, one input line
TSTA TEND NPCS IOPPR
  • TSTA: real, default: 0: Start time in stress time series \(\mathrm {[T]}\)

  • TEND: real, default: 0: End time in stress time series \(\mathrm {[T]}\)

    • TEND = 0.0: Until last time step used

  • NPCS: integer >= 0, default: see below: Number of points around the cross-section

  • IOPPR: integer, default: 0: Print option

The default value for NPCS is dependent on the value specified above for IOP:

Default is 0 for IOP = 1, otherwise it is 4.

Static load step and load factors, one input line
ISTEPF GAMF GAMC GAME GAMR
  • ISTEPF: integer, default: 0: Static step number for functional loads

    • ISTEPF = 0: Final static load step is used

  • GAMF: real, default: 1: Load factor for functional loads

  • GAMC: real, default: 1: Load effect factor for condition

  • GAME: real, default: 1: Load factor for environmental loads

  • GAMR: real, default: 1: Resistance factor

Stress calculation parameters, one input line
SMYS EMOD NU F0 SMYSB TADD
  • SMYS: real > 0: Specified minimum yield stress \(\mathrm {[F/L^2]}\)

  • EMOD: real > 0: Modulus of elasticity \(\mathrm {[F/L^2]}\)

  • NU: real, default: 0.3: Poisson’s ratio

  • F0: real, default: 0.005: Initial ovality

    • \(\mathrm {=(D_{max}-D_{min})/D}\)

  • SMYSB: real, default: SMYS: Specified minimum stress used in axial capacity \(\mathrm {[F/L^2]}\)

  • TADD: real, default: 0: Additional torsion moment \(\mathrm {[FL]}\)

Typical values of SMYS and EMOD for steel are in the order of \(\mathrm {[SMYS=220.0E3kN/m^2]}and\) if the units m and kN were chosen in INPMOD.

Cross-section parameters, one input line
ASTI WSTI DIASTI THSTI
  • ASTI: real, default: 0: Alternative cross sectional area \(\mathrm {[L^2]}\)

  • WSTI: real, default: 0: Alternative cross section modulus \(\mathrm {[L^3]}\)

  • DIASTI: real, default: 0: Alternative cross section diameter \(\mathrm {[L]}\)

  • THSSTI: real, default: 0: Alternative cross section wall thickness \(\mathrm {[L]}\)

The default values of 0 are interpreted as no change from the cross-sectional properties given in INPMOD

4.2.21. Time domain fatigue damage

This option allows for calculation of fatigue damage calculation from axial and bending stresses in circular metallic homogeneous risers using a specified SN curve and rainflow cycle counting.

The calculated fatigue damage is per year of the specified environmental conditions.

The fatigue damage is calculated based on the stored force time series from DYNMOD (see data group File storage for internal forces for storage information) and the component properties specified in INPMOD. Stresses may only be calculated for CRS1 and CRS0 components.

The fatigue damage is calculated for a specified number of points on the tube circumference.

Data group identifier, one input line
TIMEdomain FATIgue DAMAge       NoPlot
Control data, one input line
NSECT NPCS IOPPR TBEG TEND IOPSTR FAT-ID
  • NSECT: integer: Number of riser cross sections to be considered

    • NSECT = 0: All cross section where forces are available is included in the analysis

  • NPCS: integer: Number of points in the cross section where fatigue is calculated

  • IOPPR: integer: Print option for fatigue results

    • IOPPR = 0: Print results only for most critical point in cross section

    • IOPPR > 0: Print results for all NPCS points

  • TBEG: real: Beginning of stored stress time series for fatigue calculation Number \(\mathrm {[T]}\)

  • TEND: real: End of stored stress time series for fatigue calculation \(\mathrm {[T]}\)

    • Default is the last stored time step

  • IOPSTR: integer, default: 0: Option for stress calculation

    • IOPSTR=0: Bending stresses calculated from bending moment (recommended)

    • IOPSTR=1: Bending stresses calculated from curvatures. EMOD and DIAST must be given

  • FAT-ID: character(16): Identifier for fatigue calculation. Used in result presentation only

The remaining of the time series is used if TEND is less or equal to TBEG (Default is full time series).

Cross-sectional data, one input line
DSCFA DSCFY DSCFZ ASI WSTI DIAST EMOD CFRS LFRS TEFF
  • DSCFA: real, default: 1: Default stress concentration factor for axial force contribution

  • DSCFY: real, default: DSCFA: Default stress concentration factor for bending about the local Y axis

  • DSCFZ: real, default: DSCFA: Default stress concentration factor for bending about the local Z axis

  • ASI: real, default: See below: Optional cross-sectional area \(\mathrm {[L^{2}]}\)

  • WSTI: real, default: See below: Optional section modulus \(\mathrm {[L^{3}]}\). Dummy if stresses are are calculated from curvature (IOPSTR = 1)

  • DIAST: real, default: See below: Cross section diameter. Used to calculate tresses from curvature if IOPSTR = 1. Otherwise not used.

  • EMOD: real, default: See below: Modules of elasticity. Used to calculate tresses from curvature if IOPSTR = 1. Otherwise not used.

  • CFRS: real, default: 0: Constant correction coefficient, friction stress \(\mathrm {[FL^{-2}]}\)

  • LFRS: real, default: 0: Linear correction coefficient \(\mathrm {[L^{-2}]}\)

  • TEFF: real, default: See below: Effective thickness used together with the reference thickness TREF given below in thickness correction \(\mathrm {[L]}\)

The cross-sectional area, modulus and thickness defined for each cross section in INPMOD are used as defaults for ASI, WSTI and TEFF.

Stress range correction due to friction is given as:

\(\mathrm {\Delta \sigma _f=CFRS+LFRS\times T_{avg}}\)

\(\mathrm {T_{avg}}\) is the static value of the tension. The friction stress correction is added after Rainflow counting of the stress time series due to axial force and bending

\(\mathrm {\sigma _{tot}(t)=\sigma _{axial}(t)\times SCFA+\sigma _{Y-bending}(t)\times SCFY+\sigma _{Z-bending}(t)\times SCFY}\)

The units of the friction correction coefficients must be consistent with the Selection of unit system physical constant in INPMOD.

SN curve data, two input lines

Fatigue capacity curve description

NOSL LIMIND FATLIM RFACT TREF KEXP
  • NOSL: integer <= 5, default: 1: Number of straight lines defining the SN curve

  • LIMIND: integer, default: 0: Fatigue limit indicator

    • LIMIND < 0: Fatigue limit in terms of stress cycles is specified

    • LIMIND = 0: No fatigue limit for present curve

    • LIMIND > 0: Fatigue limit in terms of stress range is specified

  • FATLIM: real, default: 0: Fatigue limit, interpretation dependent on LIMIND. See Example 1: 2 segments and fatigue limit.

    • LIMIND < 0: Base 10 logarithm of number of stress cycles for which the SN curve becomes horizontal

    • LIMIND = 0: FATLIM is dummy

    • LIMIND > 0: Stress range level for which the SN curve becomes horizontal \(\mathrm {[S]}\)

    • See RFACT below

  • RFACT: real, default: 1: Factor between the stress unit \(\mathrm {[S]}\) used to define the SN curve and the force and length units \(\mathrm {[F]}\) and \(\mathrm {[L]}\) chosen in INPMOD

    • \(\mathrm {S\times RFACT=\frac{F}{L^2}}\)

  • TREF: real, default: 0: Reference thickness for thickness correction \(\mathrm {[L]}\).

    • TREF = 0: No thickness correction

  • KEXP: real, default: 0: Exponent for thickness correction.

    • KEXP = 0: No thickness correction

If \(\mathrm {kN}\) and \(\mathrm {m}\) were chosen as force and length units while the SN curve is given in \(\mathrm {MPa}\), RFACT should be set to 0.001.

If the SI units \(\mathrm {N}\) and \(\mathrm {m}\) were chosen for force and length and the SN curve is in \(\mathrm {MPa}\), RFACT should be set to 1.0E-6.

TREF`and `KEXP must either both be zero, no thickness correction, or both positive, thickness correction included.

Fatigue capacity curve constants

RM1 RC1 RMi RNCi ...
  • RM1: real: Slope of the SN curve. First curve segment for NOSL>1, total curve for NOSL=1. (log cycles / log stress)

  • RC1: real: Constant defining the SN curve. First segment or total curve

  • RMi: real: Slope of curve segment i, i=2, …, NOSL

  • RNCi: real: Transition point between curve segment (i-1), and i, i=2,…, NOSL| (log cycles)

See Frequency domain fatigue damage for details of the fatigue curve specification.

For a single slope SN curve, log cycles as a function of log stress:

\(\mathrm {logN=RC1-|RM1|\times log\Delta S}\)

Where:

  • \(\mathrm {N}\): Number of cycles to failure

  • \(\mathrm {\Delta S}\): Stress range

or log stress as a function of log cycles:

\(\mathrm {log\Delta S=\frac{RC1}{|RM1|}-\frac{logN}{|RM1|}}\)

Cross section specification, NSECT input lines
LINE-ID ISEG IEL IEND SCFA SCFY SCFZ
  • LINE-ID: character(8): Line identifier

  • ISEG: integer >= 0: Segment number on line

    • = 0: All segments in specified line

  • IEL: integer >= 0: Local element number on specified segment

    • = 0: All elements in specified segment

  • IEND: integer:

    • IEND = 0: Cross sections at both ends checked

    • IEND = 1: Cross section at end with smallest node number checked

    • IEND = 2: Cross section at end with largest node number checked

  • SCFA: real, default: DSCFA: Stress concentration factor for axial force contribution

  • SCFY: real, default: SCFA: Stress concentration factor for bending about local Y axis

  • SCFZ: real, default: SCFA: Stress concentration factor for bending about local Z axis

Time domain forces for the specified elements must be stored in DYNMOD, see data group File storage for internal forces for storage information.

The data group Storage information may be used to obtain an overview of the stored data.

If several specifications match an element, the first specification will be used.

4.2.22. Time domain longterm data

This option allows for calculation of transfer function modulus and, in the future, also distribution parameters for the stresses from axial and bending force in circular metallic homogeneous risers. The results are intended to be processes in a longterm analysis like in LONFLX and LOSSTA.

The results are calculated based on the stored force time series from DYNMOD (see data group File storage for internal forces for storage information) and the component properties specified in INPMOD. Stresses may only be calculated for CRS1 and CRS0 components.

The transfer functions are calculated for a specified number of points on the tube circumference.

Data group identifier, one input line
TIMEdomain LONGterm DATA        NoPlot
Control data, one input line
NSECT NPCS TBEG TEND
  • NSECT: integer, default: 0: Number of riser cross sections to be considered

    • NSECT = 0: All cross section where forces are available is included in the analysis

  • NPCS: integer, default: 16: Number of points in the cross section where fatigue is calculated

  • TBEG: real, default: 0: Beginning of stored stress time series for fatigue calculation Number \(\mathrm {[T]}\)

  • TEND: real, default: 0: End of stored stress time series for fatigue calculation \(\mathrm {[T]}\)

    • Default is the last stored time step.

The remaining of the time series is used if TEND is less or equal to TBEG (Default is full time series).

Calculation control data, one input line
MXFRQ FLOW FHIG IDIST
  • MXFRQ: integer: Maximum number frequencies in the output of transfer functions

  • FLOW: real: Lower frequency limit in the printing

  • FHIG: real: Upper frequency limit in the printing

  • IDIST: integer: Distribution type (Future use)

The actual number of frequencies in the output will usually be somewhat less than MXFRQ because the printing is going in integer steps over the calculated Fourier components. The intermediate points is used for smoothing of the transfer function

Cross sectional data, one input line
DSCFA DSCFY DSCFZ ASI WSTI
  • DSCFA: real, default: 1: Default stress concentration factor for axial force contribution

  • DSCFY: real, default: DSCFA: Default stress concentration factor for bending about Y axis

  • DSCFZ: real, default: DSCFA: Default stress concentration factor for bending about Z axis

  • ASI: real, default: 0: Optional cross sectional area

  • WSTI: real, default: 0: Optional section modulus

The cross sectional area and modulus defined in INPMOD is used by default.

Cross section specification NSECT input lines
ILIN ISEG IEL IEND
  • ILIN: integer: Line number

  • ISEG: integer: Segment number on line

  • IEL: integer: Local element number on specified segment

  • IEND: integer:

    • IEND = 1: Cross section at end with smallest node number checked

    • IEND = 2: Cross section at end with largest node number checked

Time domain forces for the specified elements must be stored in DYNMOD, see data group File storage for internal forces for storage information.

The data group Storage information may be used to obtain an overview of the stored data.

5. Data Group D: Output from FREMOD

5.1. Frequency domain layer damage

This data group may be used to calculate wear and fatigue of tendons in a nonbonded flexible pipe cross section.

5.1.1. Data group identifier, one input line

FREQuency domain LAYEr DAMAge       NoPlot

5.1.2. Control data, one input line

NLAYER NSECT
  • NLAYER: integer: Number of layers to be considered

  • NSECT: integer: Number of riser cross sections to be considered

5.1.3. Layer data, 2 × NLAYER input lines

Axial stress and friction per unit (pressure/axial force/curvature)

IDLAY ALFA1 ALFA2 ALFA3 ALFA4 ALFA5
  • IDLAY: integer: Unique identification number for the layer data

  • ALFA1: real: Axial stress in helix per unit pressure (difference)

  • ALFA2: real: Axial stress in helix per unit axial force

  • ALFA3: real: Axial stress in helix per unit pipe curvature \(\mathrm {[1/bendingradius]}\)

  • ALFA4: real: Friction stress per unit pressure (difference)

  • ALFA5: real: Friction stress per unit axial force

5.1.4. Wear and geometrical data; 1 data string:

BETA1 BETA2 THICK WSAFE SIGUL SIGLI
  • BETA1: real: Wear factor per unit curvature and pressure

  • BETA2: real: Wear factor per unit curvature and axial force

  • THICK: real: Thickness of layer

  • WSAFE: real <= 1: Safety factor for wear

  • SIGUL: real: Ultimate stress

  • SIGLI: real: Limit stress

5.1.5. Cross section specification, NSECT input lines

LINE-ID ISEG IEL IEND IDLAY1 ... IDLAYn
  • LINE-ID: character(8): Line identifier (dummy for IEL < 0)

  • ISEG: integer: Segment number (dummy for IEL < 0)

  • IEL: integer: Element number

    • IEL > 0: local element number

    • IEL < 0: global element number

  • IEND: integer:

    • IEND = 1: Cross section at end with smallest node number checked

    • IEND = 2: Cross section at end with largest node number checked

  • IDLAY1: integer: First layer to be checked

  • IDLAYn: integer: Last layer to be checked

Frequency domain results for the specified element/ends must be stored on the FREMOD result file ifnfre.

5.2. Frequency domain fatigue damage

5.2.1. Data group identifier, one input line

FREQuencydomain FATIgue DAMAge      NoPlot

5.2.2. Control data, one input line

NOFC NSECT IRES
  • NOFC: integer: Number of SN curves

  • NSECT: integer: Number of riser cross sections to be considered

  • IRES: integer: Response print option

    • IRES>0: print of total fatigue damage only

    • IRES<0: print of fatigue contributions

5.2.3. SN data, 2 × NOFC input lines

Fatigue capacity curve description

ISNC NOSL LIMIND FATLIM RFACT
  • ISNC: integer: SN curve number - must be given in ascending order

  • NOSL: integer, default: 1: Number of straight lines defining the SN curve

  • LIMIND: integer, default: 0: Fatigue limit indicator

    • LIMIND < 0: Fatigue limit in terms of stress cycles is specified

    • LIMIND = 0: No fatigue limit for present curve

    • LIMIND > 0: Fatigue limit in terms of stress range is specified

  • FATLIM: real, default: 0: Fatigue limit, interpretation dependent on LIMIND. See Example 1: 2 segments and fatigue limit.

    • LIMIND < 0: Base 10 logarithm of number of stress cycles for which the SN curve becomes horizontal

    • LIMIND = 0: FATLIM is dummy

    • LIMIND > 0: Stress range level for which the SN curve becomes horizontal

  • RFACT: real, default: 1: Factor between the stress unit \(\mathrm {[S]}\) used to define the SN curve and the force and length units \(\mathrm {[F]}\) and \(\mathrm {[L]}\) chosen in INPMOD

    • \(\mathrm {S\times RFACT=\frac{F}{L^2}}\)

If \(\mathrm {kN}\) and \(\mathrm {m}\) were chosen as force and length units while the SN curve is given in \(\mathrm {MPa}\), RFACT should be set to 0.001.

If the SI units \(\mathrm {N}\) and \(\mathrm {m}\) were chosen for force and length and the SN curve is in \(\mathrm {MPa}\), RFACT should be set to 1.0E-6.

Fatigue capacity curve constants

RM1 RC1 RMi RNCi
  • RM1: real: Slope of the SN curve. First curve segment for NOSL>1, total curve for NOSL=1

  • RC1: real: Constant defining the SN curve. First segment or total curve

  • RMi: real: Slope of curve segment i, i=2, …​, NOSL

  • RNCi: real: Transition point between curve segment (i-1), and i, i=2, …​, NOSL (log cycles)

Explanation of the input parameters in input lines SN data, 2 × NOFC input lines (above). All parameters are found in figure below.

Example 1: 2 segments and fatigue limit. Note that FATLIM can be alternatively specified

Example 2: 3 segments and not fatigue limit. Illustration of input data for fatigue capacity curve definition

The SN curves defined by input parameters are always assumed to relate \(\mathrm {\Delta S}\) (stress range) to number of cycles before failure.

A straight-lined SN curve in log-log scale is in general defined as

\(\mathrm {N=C\times \Delta S^m}\)

or

\(\mathrm {logN=logC+m\times log\Delta S}\)

Where:

  • \(\mathrm {N}\): Number of cycles to failure

  • \(\mathrm {\Delta S}\): Stress range

The two input parameters used to define the SN curves are directly found in the equation above, namely

  • \(\mathrm {RC=logC\quad }\) (always positive)

  • \(\mathrm {RM=m\quad }\) (always negative)

If the user has an SN curve without having these parameters explicitly defined, they can be calculated as follows:

um io fig329

Using the two points A and B on the figure to define the straight line, we have

\(\mathrm {logN=\frac{logN_2-logN_1}{log\Delta S_2-log\Delta S_1}\times log\Delta S-\frac{logN_2-logN_1}{log\Delta S_2-log\Delta S_1}\times log\Delta S_1+logN_1}\)

Hence:

  • \(\mathrm {RM= \frac{logN_2-logN_1}{log\Delta S_2-log\Delta S_1}}\) (always negative)

  • \(\mathrm {-RM\times log\Delta S_1+logN_1}\) (always positive)

The relation between these parameters specified for different unit systems is easily found from the equations above.

5.2.4. Cross section specification, NSECT input lines

LINE-ID ISEG IEL IEND SCF IFAT1 ... IFATn
  • LINE-ID: character(8): Line identifier

  • ISEG: integer: Segment number in line

  • IEL: integer: Local element number in specified segment

  • IEND: integer:

    • IEND = 1: Cross section at end with smallest node number checked

    • IEND = 2: Cross section at end with largest node number checked

  • SCF: real, default: 1: Stress concentration factor

  • IFAT1: integer: First SN curve to be checked

  • .

  • .

  • .

  • IFATn: integer: Last SN curve to be checked

Frequency domain results for the specified element/ends must be stored in FREMOD

5.3. Frequency domain force results

5.3.1. Data group identifier, one input line

FREQuency FORCe RESUlts         NoPlot

5.3.2. Specification of number of sections, one input line

NSECT
  • NSECT: integer: Number of sections to be specified

5.3.3. Section specification, NSECT input lines

LINE-ID ISEG IELM IEND
  • LINE-ID: character(8): Line identifier

  • ISEG: integer: Segment number

  • IELM: integer: Element number

  • IEND: integer: Element end (1 or 2)

Both local (LINE-ID SEG ELML) numbering and global element numbering (-ELMG) can be given

This option is valid for linear bending stiffness only, i.e. IEJ=1 in INPMOD.

Example:

parameter/numbering line-id iseg ielm iend

local:

1

2

4

1

Eqv.global:

0

0

-25

1

6. Description of STARTIMES File

6.1. Description of STARTIMES file generated by OUTMOD

6.1.1. General comments

A time series generated by OUTMOD is identified by a time series number and a version number. Response type is identified by the time series number, see description below. The selected node number or element number is identified by the version number.

For one response type versions are numbered 1,2,3,4…​…​N according to:

  • version 1 for 1st selected element/node,

  • version 2 for 2nd selected element/node,

  • …​

  • version N for last selected element/node

Time series number and version number are printed to OUTMOD result file for each selected response. In addition, FEM element/node number is included in identification text for each time series stored on STARTIMES file.

6.1.2. Example

Output of time series of dynamic axial force for element 1, 33, 45 is specified in OUTMOD. Identifiers to generated time series are:

  • Element 1: 40.01 (time series number 40, version number 1)

  • Element 33: 40.02 (time series number 40, version number 2)

  • Element 45: 40.03 (time series number 40, version number 3)

6.2. Description of time series numbers

Time series number Contents

WF motion time series

1

HF surge

2

HF sway

3

HF heave

4

HF roll

5

HF pitch

6

HF yaw

LF motion time series

7

LF surge

8

LF sway

9

LF yaw

WF and LF motion time series

10

HF + LF surge

11

HF + LF sway

12

HF + LF yaw

Wave elevation time series

13

Wave elevation

Wave kinematics

(Not implemented in OUTMOD)

14

Water particle velocity: x-direction

15

Water particle velocity: y-direction

16

Water particle velocity: z-direction

17

Water particle acceleration: x-direction

18

Water particle acceleration: y-direction

19

Water particle acceleration: z-direction

Dyndisp time series

20

Dynamic displacement: global x-direction

21

Dynamic displacement: global y-direction

22

Dynamic displacement: global z-direction

23

Dynamic rotation about: x-direction

24

Dynamic rotation about: y-direction

25

Dynamic rotation about: z-direction

Calcurv time series

26

Total curvature calculated from nodal coordinates

Element angle time series

27

Element angle \([\mathrm {deg}]\)

IRELCO = 1: Angle between global z-axis and one element

IRELCO = 2: Angle between support vessel axis and one element

IRELCO = 3: Angle between two elements

Distance time series

28

Distance

IDITYP = 1: Distance between specified segments

IDITYP = 2: Distance between specified segments on a line and a globally fixed line

IDITYP = 3: Distance between specified segments on a line and a line fixed on the vessel

Stroke time series

29

Stroke

IMOT = 1: Stroke

IMOT = 2: Platform heave motion only

IMOT = 3: Riser heave motion only

Support force time series

30

Support force component: global x-direction

31

Support force component: global y-direction

32

Support force component: global z-direction

Dynforce time series

40

Dynamic axial force

41

Dynamic Torsional moment

42

Dynamic bending moment about local y-axis: End 1

43

Dynamic bending moment about local y-axis: End 2

44

Dynamic bending moment about local z-axis: End 1

45

Dynamic bending moment about local z-axis: End 2

46

Dynamic shear force in local y-direction: End 1

47

Dynamic shear force in local y-direction: End 2

48

Dynamic shear force in local z-direction: End 1

49

Dynamic shear force in local z-direction: End 2

Dyncurv time series

50

Dynamic curvature about local y-axis: End 1

51

Dynamic curvature about local y-axis: End 2

51

Dynamic curvature about local z-axis: End 1

53

Dynamic curvature about local z-axis: End 2

Totforce time series

54

Axial force

55

Torsional moment

56

Bending moment about local y-axis: End 1

57

Bending moment about local y-axis: End 2

58

Bending moment about local z-axis: End 1

59

Bending moment about local z-axis: End 2

60

Shear force in local y-direction: End 1

61

Shear force in local y-direction: End 2

62

Shear force in local z-direction: End 1

63

Shear force in local z-direction: End 2

64

Axial wall force

Totdisp time series

65

Total displacements in global x-direction

66

Total displacements in global y-direction

67

Total displacements in global z-direction

Stress time series

75

Axial + Bending stress: End 1

76

Axial + Bending stress: End 2

77

Torsional stress

78

Equivalent stress: End 1

79

Equivalent stress: End 2