I have a flexure mechanism that contains a voice coil actuator, very similar to a speaker. Some parts of the mechanism are grounded by a fixed support, others are moved by the actuator. I want to calculate the stress in the system during the applied dynamic load. The force input is available in the time domain 4kHz (10sec) and can easily be converted into a spectrum (FFT) or PSD curve. What type of analysis do I need to perform? Spectrum analysis only allows the load to be applied at the boundary conditions as a,v,d. But I have a force and don't want to apply the load into my fixed supports. Transient would work but my model is complex and has many elements so that a transient is not appropriate even when only analyzing a second of my 4kHz signal. A harmonic analysis allows to apply a force, however I'm not looking for the stress at a specific frequency but the stress caused by the whole spectrum. What type of analysis do you recommend?