Thanks very much for your help
Some other questions:
1. I have done the 2D model of the PCB with only one but not 2 IC chips mounted on it. I have no idea about how could you slice them in DesignModeler? could you please give me some help or suggestion? I will also attach the model that I have done with the SpaceClaim, After you take a look at it, you will know where my question is.
2. Like you stated, if the condition is fixed edges and the acceleration load, then you will need the sine function since at the time zero the acceleration is zero as well. while as for the condition with the fixed edges and the displacement, you would like to use the cosine function, but consin0=1, how could the input displacement be zero at time zero? did I misunderstand your points?
3. I also asked one of the professors working with vibration, he told me that the nonlinear geometry is vert important for my simulation, even I do not give any nonlinear materials, the nonlinear vibration effect will also occur. besides I have also read some papers which said that if the external load is large enough(large amplitude) then the nonlinear vibration effect will happen.while my research is only focused on the nonlinear vibratory effect(just the demonstration of the nonlinear vibration effect) still no any relation to the failure or fatigue.
4. The 3D model that simulated in the harmonic response is the real model that I would like to use, the reason why I use only the PC board is because I would like to make the problem simple and take less time to solve, then I will use both the PC board and IC chips to do the next simulation. but is it possible that I could get the nonlinear vibration effect with only the PC board?
5. Since from the modal analysis, the first mode of the PCB with the IC chips is bending, as for the meshing, I applied the nonlinear mechanical for physics preference, quad elements, curvature for sizing function, quadratic for element order and the quality-error limits-aggressive mechanical. is it good enough for the nonlinear analysis of the PCB with the IC chips?
6. The IC chips will be simplified as the rigidly connected with the PC board, there will be no any contact nonlinearity within my simulation.