Lines which represent stress joints are specified in data group Stress joint line specification.

The total number of line types and stress joints has to be less or equal to 500 in the present version.

NSTRPS and NSTRPD are used only for the cross-section type CRS5

If the stress free length of the line (sum of the segment SLGTH) is not equal to the distance between the stress free coordinates of the supernodes that the line is attached to, the stress free line length will be modified according to the following rules:

Length modification will always be done on the last segment within the line. Therefore the first task is to check if it is possible to modify this segment to obtain a line length equal the to the distance. If this is not possible the program will terminate with error message. Then the difference between the length and the distance is within the preset length tolerance: - Difference larger than 1% gives error termination. - Difference between 0.1% and 1% gives modification and written warning. - Difference less than 0.1% gives modification but no warning.

Specifying SLGTH0 \(\mathrm {\neq }\) SLGTH enables the user to use initially stressed segments at the start of the static analysis. This feature is useful for modelling elastic springs between element nodes. SLGTH will be interpreted as stressed segment length by the program.

The following NSEG input lines is to be given if IADDTWI = 1.

The relative twist for elements within the segment is calculated by use of linear interpolation. The twist angle is constant over the element length. The twist angle of the actual line will relate to the line local Y-axis.

The local Y-axis may be set using the data group LOCAL ELEMENT AXIS, be determined by shaft and blade orientation for a wind turbine blade or the default procedure may be used. See Line, line type and supernode connectivity for details.

If IADDBEND = 1 the following NSEG-1 input lines are to be given. Offsets at the last node of the last segment are set to zero.

If IADDBEND = 2 the following NSEG input lines are to be given.

This feature enables the user to model a curved stress-free configuration of a line type by specifying transverse offsets at end 2 of all line segments, i.e. transverse offsets from the straight line between the line ends. The offsets DY and DZ refer to the initial local line Y and Z axes, disregarding any specified relative twist.

Note! If only NSEG-1 input lines are given, the offsets are set to zero for the second end of the last segment.

Specified twist will be applied around the updated local element X-axis after the offsets have been accounted for.

The stressfree segment lengths SLGTH will be modified according to the specified offsets. If a segment consist of more than one element, the intermediate nodes will be placed along the straight line between the segment nodes.

The cross-section properties will not be changed, e.g. the specified mass per unit length will be used together with the modified segment length.

Note! If non-zero offset is specified at the second end of the last segment, no other line may be connected to this supernode

The local Y-axis may be set using the data group LOCAL ELEMENT AXIS, be determined by shaft and blade orientation for a wind turbine blade or the default procedure may be used. See Line, line type and supernode connectivity for details.