*FREQDOM

Data format:

A single line with a 9 parameters, as follows:

MINPER MAXPER NBPER TOL MAXIT REL XDAMP PERCUTOFF DISPMAX

Status :

Optional

Purpose :

To define frequency domain analysis calculation parameters.

Details :

Parameter	Description
MINPER	Lower bound for the periods range (in seconds)
MAXPER	Upper bound for the periods range (in seconds)
NBPER	Number of periods within the periods range
TOL	Error tolerance for convergence checks
MAXIT	Maximum number of iterations
REL	Relaxation coefficient
XDAMP	Global damping. Note: The damping is added to the diagonal terms of the matrix of the free degrees of freedom. If the stiffness term is Kii then a term of the form (0,1)wXDAMP*Kii is added to the damping matrix.
PERCUTOFF	Maximum period for low frequency calculations Note: The Maximum period for low frequency calculations avoids taking too low frequencies. If the minimum wave spectrum frequency is Tmin, the law frequency will then be defined in terms of periods between Tmin and PERCUTOFF. If PERCUTOFF is lower than Tmin, PERCUTOFF is ignored.
DISPMAX	Maximum displacement for imposed motion Note: The maximum imposed displacement is used to compute the contribution of imposed displacements on the free ddls of the system. To stay linear the displacement should be small. The default displacement is 1mm. The corresponding rotational displacement is obtained by dividing the maximum imposed displacement by the maximum arm levers of all slave/master relationship (p/180 m is default value).

Example :

*FREQDOM
4 23 20 0.01 0 300 0.4

A frequency domain analysis will be performed for 23 different periods ranging from 4s to 23s.