Here is a simple way to prescribe sinusoidal motion using *DEFINE_CURVE_FUNCTION.

*PARAMETER
ramp, 10.0
rfreq, 600
rshift, 0.0
*DEFINE_CURVE_FUNCTION
curve_id
&*sin(&freq*TIME+&shift)

The parameter “amp” is the amplitude, “freq” is the frequency of the oscillation (2PI/T, T is the time period), and “shift” is the phase shift. TIME is the simulation time that will be replaced with the current simulation time by LS-DYNA. The curve id can be referenced by any of *LOAD or *BOUNDARY_PRESCRIBED keywords.