Comsol Transient Vibration Analysis

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Initial conditions and forces in COMSOL for transient vibration analysis can be challenging to define, particularly when trying to replicate waveforms like ramp or parabolic shapes. Users have noted difficulties in setting initial displacements, leading to unexpected results such as damped oscillations despite no damping being present. The manual lacks clear guidance on implementing time-stepped forces similar to ANSYS. Although a function for force input was defined, the output waveform did not match expectations, appearing more like a sawtooth signal rather than a sinusoid. Clarification on these issues is sought to achieve accurate simulation results.
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hi all..
How can i describe initial conditions or initial forces in comsol(like wave forms such as ramp or parabolic)? I couldn't find it in the manual.
in ansys, i do it in time steps(in solution options).(like t=0, F=10 t=0.001 F=0)
I tried to give initial displacements to the points but it didnt work,either.. It gave ridiculous results..like damped oscillations when there was no damping..
thank you for help..
 
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I defined a function for the force input (at the options menu).. i thought it worked.. but still the output waveform is not correct(not a full sinusoid.. a more like saw signal.. and although there is no damping, its a damped signal..) help : \
 
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