1. CRS7  General cross section
1.2. Component type identifier
CMPTYPID TEMP ALFA

CMPTYPID: character(8)
: Component type identifier 
TEMP : real
: Temperature at which the specification applies
Dummy in present version


ALPHA: real
: Thermal expansion coefficient \(\mathrm {[Temp^{1}]}\)
Dummy in present version

1.3. Mass
YECC_MASS ZECC_MASS

YECC_MASS: real
: Mass center coordinate \(\mathrm {Y_m}\) in local element system \(\mathrm {[L]}\) 
ZECC_MASS: real
: Mass center coordinate \(\mathrm {Z_m}\) in local element system \(\mathrm {[L]}\)
AMS RGYR

AMS : real
: Mass per unit length \(\mathrm {[M/L]}\) 
RGYR: real
: Radius of gyration about mass center \(\mathrm {(Y_m,Z_m)}\) \(\mathrm {[L]}\)
Bouyancy and added mass contribution to the inertia forces will be applied at the specified mass center. 
1.4. Buoyancy
YECC_BUOY ZECC_BUOY

YECC_BUOY: real
: Buoyancy center Ycoordinate in local element system \(\mathrm {[L]}\)
Dummy in present version. Bouyancy center set equal to mass center.


ZECC_BUOY: real
: Buoyancy center Zcoordinate in local element system \(\mathrm {[L]}\)
Dummy in present version. Bouyancy center set equal to mass center.

AE AI

AE: real
: External crosssectional area \(\mathrm {[L^2]}\)
Basis for calculation of buoyancy


AI: real
: Internal crosssectional area \(\mathrm {[L^2]}\)
Dummy in present version

1.6. Area center and principal axes
The area center is the crosssection point where the axial force acts through. The principal axes are formally determined from the requirement \(\int_AV\,W\,\,\mathrm {d}A=0\), where \(\mathrm {V}\) and \(\mathrm {W}\) denote the principal coordinates and \(\mathrm {A}\) is the crosssection area. The orientation of the principal axes is defined in terms of a positive Xrotation \(\mathrm {\theta }\) relative to the beam element YZcoordinate system as shown in the figure General crosssection
YECC_AREACENT ZECC_AREACENT THETA

YECC_AREACENT: real
: Area center coordinate \(\mathrm {Y_a}\) in beam element system \(\mathrm {[L]}\) 
ZECC_AREACENT: real
: Area center coordinate \(\mathrm {Z_a}\) in beam element system \(\mathrm {[L]}\) 
THETA: real
: Orientation \(\mathrm {\theta }\) of principal axes V and W [deg.]. See figure General crosssection.
1.7. Shear center
The shear center represents the attack point of the shear forces.
YECC_SHEARCENT ZECC_SHEARCENT

YECC_SHEARCENT: real
: Shear center coordinate \(\mathrm {Y_s}\) in beam element system \(\mathrm {[L]}\) 
ZECC_SHEARCENT: real
: Shear center coordinate \(\mathrm {Z_s}\) in beam element system \(\mathrm {[L]}\)
1.9. Bending stiffness
The bending stiffness refers to the principal axes V and W, see figure General crosssection.
EJV EJW

EJV: real > 0
: Bending stiffness about principal Vaxis \(\mathrm {[FL^2]}\) 
EJW: real > 0
: Bending stiffness about principal Waxis \(\mathrm {[FL^2]}\)
1.10. Shear stiffness
The shear stiffness refers to the principal axes V and W, see figure General crosssection.
GAsW GAsV

GAsW: real
: Shear stiffness in principal Wdirection \(\mathrm {[F]}\) 
GAsV: real
: Shear stiffness in principal Vdirection \(\mathrm {[F]}\)
The shear stiffness, GAsW
and GAsV
, are optional input parameters.
Specified GAsW>0
and GAsV>0
will include shear deformation.
1.11. Torsion stiffness
GT

GT: real > 0
: Torsion stiffness \(\mathrm {[FL^2/Radian]}\)
For a circular crosssection the torsion stiffness is given by the polar moment of inertia. Note that this is not the case for noncircular crosssections.
1.12. Bendingtorsion geometric coupling
This data group is optional.
BTGC

BTGC: character(4)
: bendingtorsion coupling identifier.
If the BTGC
identifier is present, geometric coupling between torsion
and bending is accounted for.
1.13. Damping specification
Identical to input for crosssection type CRS2, see data group
Damping specification for CRS2, except that the bending contributions are specified
in the principal axis system and that only the damping option MATE
is allowed. This means
that the stiffness matrix used as basis for the Rayleigh damping includes
the material stiffnesses only.
The geometric stiffness matrix is not included as this would introduce damping of the rigid body motion for CRS7.
The mass proportinal Rayleigh damping is applied in the local element system, not at the center of mass. Note that use of mass proportional damping is not recommended as this would introduce damping of the rigid body motions.
1.14. Hydrodynamic load type identification, One input line
CHLOAD

CHLOAD: character
:= HYDR
 Text to identify hydrodynamic coefficients
Note: Required if nonMorison loads are to be specified
Load type identification for CHLOAD=HYDR, One input line
CHTYPE

CHTYPE: character
: Hydrodynamic load type
= NONE
: No hydrodynamic load coefficients 
= MORI
: Slender element hydrodynamic coefficients

Hydrodynamic force coefficients if CHTYPE=MORI
CDX CDY CDZ CDTMOM AMX AMY AMZ AMTOR CDLX CDLY CDLZ SCFKN SCFKT

CDX: real
: Drag force coefficient for local xdirection \(\mathrm {[F/((L/T)^2\times L)]}\) 
CDY: real
: Drag force coefficient for local ydirection \(\mathrm {[F/((L/T)^2\times L)]}\) 
CDZ: real
: Drag force coefficient for local zdirection \(\mathrm {[F/((L/T)^2\times L)]}\) 
CDTMOM: real
: Drag force coefficient for local xrotation. Not used in present version. 
AMX: real
: Added mass per length in xdirection \(\mathrm {[M/L]}\) 
AMY: real
: Added mass per length in ydirection \(\mathrm {[M/L]}\) 
AMZ: real
: Added mass per length in zdirection \(\mathrm {[M/L]}\) 
AMTOR: real
: Added mass for local xrotation \(\mathrm {[ML^2/L]}\) 
CDLX: real, default: 0
: Linear drag force coefficients in local xdirection \(\mathrm {[F/((L/T)\times L)]}\) 
CDLY: real, default: 0
: Linear drag force coefficients in local ydirection \(\mathrm {[F/((L/T)\times L)]}\) 
CDLZ: real, default: 0
: Linear drag force coefficients in local zdirection \(\mathrm {[F/((L/T)\times L)]}\) 
SCFKN: real, default: 1
: Scaling factor for the FroudeKrylov term in Morison’s equation in normal direction 
SCFKT: real, default: 1
: Scaling factor for the FroudeKrylov term in Morison’s equation in tangential direction. Only the values 0.0 and 1.0 are permitted.
The drag forces per unit length acting in the local coordinate system are computed as:

\(\mathrm {F_x=CDX\times VRELX\times VRELX+CDLX\times VRELX}\)

\(\mathrm {F_y=CDY\times VRELY\times VRELY+CDLY\times VRELY}\)

\(\mathrm {F_z=CDZ\times VRELZ\times VRELZ+CDLZ\times VRELZ}\)
where:

\(\mathrm {CDX,CDY,CDZ}\): are the input quadratic drag force coefficients in local x, y and zdirections

\(\mathrm {CDLX,CDLY,CDLZ}\): are the input linear drag force coefficients in local x, y and zdirections

\(\mathrm {VRELX,VRELY,VRELZ}\): are relative water velocities in local x, y and zdirections
The input quadratic drag force coefficients \(\mathrm {CDX}\), \(\mathrm {CDY}\) and \(\mathrm {CDZ}\) will normally be calculated as:

\(\mathrm {CDX=\frac{1}{2}\rho S_{2D}C_{dx}}\)

\(\mathrm {CDY=\frac{1}{2}\rho B_yC_{dy}}\)

\(\mathrm {CDZ=\frac{1}{2}\rho B_zC_{dz}}\)
where:

\(\mathrm {\rho }\): water density

\(\mathrm {S_{2D}}\): cross sectional wetted surface

\(\mathrm {B_y,B_z}\): projected area per. unit length for flow in local y and zdirection, respectively

\(\mathrm {C_{dx},C_{dy},C_{dz}}\): nondimensional drag coefficients in local x, y and zdirections, respectively
The input added mass per. unit length \(\mathrm {AMX}\), \(\mathrm {AMY}\) and \(\mathrm {AMZ}\) can be calculated as:

\(\mathrm {AMX=\rho AC_{mx}}\)

\(\mathrm {AMY=\rho AC_{my}}\)

\(\mathrm {AMZ=\rho AC_{mz}}\)
where:

\(\mathrm {\rho }\): water density

\(\mathrm {A}\): cross sectional area

\(\mathrm {C_{mx},C_{my},C_{mz}}\): nondimensional added mass coefficients in local x, y and zdirections, respectively
1.15. Aerodynamic load type identification, One optional input line
CHLOAD

CHLOAD: character
:= WIND
 Text to identify wind coefficients
1.16. Load type identification, One optional input line
CHTYPE

CHTYPE: character
: Type of wind load coefficients
= MORI
: Morisonlike loading, Drag term 
= AIRC
: Air foil cross section to be specified (Not implemented) 
= AIRF
: Air foil cross section, Refers to a air foil library file

CHTYPE=MORI: Morisonlike aerodynamic drag, One input line
CDXAERO CDYAERO CDZAERO

CDXAERO: real
: Dimensional quadratic drag coefficient for local xdirection \(\mathrm {[F/((L/T)^2\times L)]}\) 
CDYAERO: real
: Dimensional quadratic drag coefficient for local ydirection \(\mathrm {[F/((L/T)^2\times L)]}\) 
CDZAERO: real
: Dimensional quadratic drag coefficient for local zdirection \(\mathrm {[F/((L/T)^2\times L)]}\)
The drag forces per unit length acting in the local coordinate system are computed as:

\(\mathrm {F_x=CDXAERO\times VRELX\times VRELX}\)

\(\mathrm {F_y=CDYAERO\times VRELY\times \sqrt{VRELY^2+VRELZ^2}}\)

\(\mathrm {F_z=CDZAERO\times VRELZ\times \sqrt{VRELY^2+VRELZ^2}}\)
where:

\(\mathrm {CDXAERO,CDYAERO,CDZAERO}\): are the input quadratic drag force coefficients in local x, y and zdirections

\(\mathrm {VRELX,VRELY,VRELZ}\): are relative wind velocities in local x, y and zdirections
The input quadratic drag force coefficients \(\mathrm {CDX}\), \(\mathrm {CDY}\) and \(\mathrm {CDZ}\) will normally be calculated as:

\(\mathrm {CDXAERO=\frac{1}{2}\rho _{air}S_{2D}C_{dx}}\)

\(\mathrm {CDYAERO=\frac{1}{2}\rho _{air}B_yC_{dy}}\)

\(\mathrm {CDZAERO=\frac{1}{2}\rho _{air}B_zC_{dz}}\)
where:

\(\mathrm {\rho _{air}}\): air density

\(\mathrm {S_{2D}}\): cross sectional surface area

\(\mathrm {B_y,B_z}\): projected area per. unit length for flow in local y and zdirection, respectively

\(\mathrm {C_{dx},C_{dy},C_{dz}}\): nondimensional drag coefficients in local x, y and zdirections, respectively
If the component is part of a wind turbine tower line, only the CDY
component is used for tower shadow computation.
CHTYPE=AIRF: Coefficients on file. ID and chord length, One input line
CHCOEF CHORDL YFC ZFC ROTFAX

CHCOEF: character(32)
: Air foil coefficient identifier. Must be found on the air foil library file 
CHORDL: real
: Chord length of foil section. \(\mathrm {[L]}\)
It is used to scale the air foil load coefficients.


YFC: real, default: 0
: Ycoordinate of foil origin \(\mathrm {[L]}\) 
ZFC: real, default: 0
: Zcoordinate of foil origin \(\mathrm {[L]}\) 
ROTFAX: real, default: 0
: Inclination of foil system \(\mathrm {[deg]}\)
The blade coordinate system and origin coincides with the elastic (local) \(\mathrm {(X_L,Y_L,Z_L)}\) coordinate system. The aerodynamic coordinate system \(\mathrm {(X_{AF},Y_{AF})}\) is located at (YFC,ZFC) referred to the local coordinate system, and is rotated about the blade x axis by the angle ROTFAX, as indicated in the figure below. The \(\mathrm {X_L}\) axis is pointing into the paper plane, while the \(\mathrm {Z_{AF}}\) is pointing out of plane. Note that the air foil coefficients has to be referred to the aerodynamic coordinate system as indicated by the corresponding angle of attack in the figure. For airfoil elements that are part of a wind turbine blade, the local \(\mathrm {X_L}\)axis is pointing towards the blade tip.
Note that suppliers of wind turbine blades normally give the foil twist relative to the the areodynamic coordinate system, i.e. as twist around the \(\mathrm {Z_{AF}}\) axis.
Definition of foil center and inclination of foil system in the local cross section (strength
In coupled analysis, a SIMO
wind type with IWITYP >= 10
must be used
if the case contains elements with wind force coefficients that are not
on the blades of a wind turbine.