1. CONTACT  Contact point of roller type
Available for elastic contact surface description only.
The local coordinate system \(\mathrm {(X_L,Y_L,Z_L)}\) of the elastic contact surface is indicated. \(\mathrm {X_L}\)axis is pointing into the paper plane.
The contact point may contain several rollers.
The rollers are located in the \(\mathrm {Y_LZ_L}\)plane of
the element to which the contact point is attached. Besides the
location, each roller is described by its length, which may be infinite,
by its stiffness and dash pot damping. The location and orientation of a
roller is defined by a point and an inclination angle referred in the
local coordinate system of the contact surface element. A roller of
finite length is shown in the figure below. The roller origin (starting
point) is defined by the point \(\mathrm {(Y_R,Z_R)}\) and the
inclination angle (ROTX
) is defined by a clockwise rotation around the
contact surface \(\mathrm {X_L}\)axis.
Roller with finite length located in the local coordinate system of an element contributing to the elastic contact surface.
The \(\mathrm {X_L}\)axis is pointing into the paper plane.
1.3. Number of rollers
NROLLS

NROLLS: integer
: Number of rollers
The following 3 data groups (Location and orientation
, Stiffness
properties
and Spring stiffness, Case 1 or 2
) must be given in blocks
for each of the NROLLS
roller.
1.4. Location and orientation of roller axis
ROTX YR ZR RLENG

ROTX: real, default: 0
: Direction of roller axis. (Clockwise around the \(\mathrm {X_L}\)axis of the actual surface plane) \(\mathrm {[deg]}\) 
YR: real, default: 0
: Ycoordinate of roller origin \(\mathrm {[L]}\) 
ZR: real, default: 0
: Zcoordinate of roller origin \(\mathrm {[L]}\) 
RLENG: real, default: 0
: Length of roller \(\mathrm {[L]}\)
= 0
means infinite length

In case of infinite roller length, YR
and ZR
describe coordinates of
an arbitrary point on the roller principal axis.
1.5. Stiffness properties classification and damping
IKS DAMP

IKS: integer
: Stiffness code1
1 : Constant spring compression stiffness

N : Table with N pairs of pressure force  displacements to be specified

N > 2



DAMP: real, default: 0
: Dash pot damping coefficient \(\mathrm {[FT/L]}\)
1.6. Spring stiffness, Case 1 IKS = 1
STIFFR RADROL

STIFFR: real
: Spring compression stiffness \(\mathrm {[F/L]}\) 
RADROL: real
: Radius of roller \(\mathrm {[L]}\)
The figure below describes the interpretation of contact force in case
that IKS=1
. The spring is active when the distance between the
principal axis of the roller and the pipe is less than
\(\mathrm {\Delta _0=RADROl+RTUBE}\). The external radius of
the tube, RTUBE
, is calculated from the external area of the cross
section of the element in contact with the roller.
1.7. Spring stiffness, Case 2 IKS > 2
FS(1) ZS(1) ... FS(N) ZS(N)

FS(1): real < 0
: Pressure force corresponding to compressionZS(1)
\(\mathrm {[F]}\) 
ZS(1): real
: Spring compression \(\mathrm {[L]}\) 
.

.

.
ZS(i)
must be given in increasing order.
The figure below describes the interpretation of contact force in case
that IKS>2
. The specified stiffness characteristics is moved to
account for the external radius of the tube, RTUBE
. The external
radius of the tube, RTUBE
, is calculated from the external area of the
cross section of the element in contact with the roller.
The three data groups Location and orientation
, Stiffness properties
and Spring stiffness, Case 1 or 2
are to be repeated NROLLS
times.
2. Tensioner
Available for elastic contact surface description only.
The function of the tensioner is to grip and apply tension to the
pipeline during the lay operation. In dynamic analysis the tensioner
accounts for the pipeline pay out or pay in to prevent large
oscillations in the pipeline tension. This is modelled as a dynamic
boundary condition with respect to the applied axial force, eg. the
applied load is T0
plus/minus a dead band range. Outside the dead band
range the load is constant. The applied load which acts in the
longitudinal direction of the tube, is formulated as a discrete element
load. During static analysis the tensioner applies a constant load,
T0
, to the pipeline.