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*WINCH

Data format:

One line with 4 values

NSPR SPEED NBGR NWSTAT

Status :

Optional

Purpose :

To define winch pay-out rates

Restrictions :

A spring element must have been created

Details :

Parameter	Description
NSPR	the spring element number to which the winch is linked. The reference length of the element is increased/decreased with time. If NSPR=0, the winch is applied on a group of elements
SPEEED	the velocity requested to compute the reference length. In that case, the length increases or decrease linearly. The value may be either positive (pay-out) or negative.
NBGR	number of a group of elements which length is modified is NSPR=0
NWSTAT	static winch number (to be defined with *WINCHSAT) to have a static variation of the winch

Warning

The velocity is interpolated between two time-steps of the file. Note that if no data is given at t=0, the velocity is assumed to be 0. If final time step in data file is smaller then computational time, the velocity is considered constant equal to the last velocity value in the file from the last time step of the file.

Note

A winch can be considered as a kinematic relationship between a reference point (master) and a second point (slave) requiring that, at time t, the slave is located at distance R(t) of the master point in the three dimensional space. As the force applied by a spring element is K (xl-x0), we obviously have xl->x0 as K->∞. Therefore, K can be considered as a penalization factor in order to obtain our kinematic condition.