I've run a physical shaker test on a model truss structure and simulated it in SW. My results were nearly identical, so it is possible in some cases. I used beam elements in my model and performed a simple natural frequency analysis (requesting the first 5 modes). As you have posted your question currently, I don't think there is nearly enough information to help you. What does your model look like? What type of elements? Are you running a noise signal or a frequency analsysis?
We've been able to analyze and measure a calibration beam that was put on our shaker bench for sine sweep and random vibration. This way, you can pre-determine the damping ratioes you would need for the dynamic analyses.
Some helpful tips:
If evaulating amplitudes, as it appears you are doing, this would be a linear "harmonic analysis" not a frequency response analysis. In this regard, assume the damping ratios are initially .05 (5%) for all modes. The shaker bench may amplify effects at lower frequencies than at higher frequencies, so don't be surprised if the amplitudes vary if you have not pre-calibrated the bench with a test piece!
One major observation: We've found that fully bonding torqued bolts and other fasteners seem to provide closer values to the resonant modes. I.e. bond the bottom head of the bolts to their contact surfaces. In the real world, one would need to make sure the torque values don't cause the surface to move around under normal operation under a hand analysis, etc.
Values above 1000 Hz can get real murky comparing to the shaker bench, and analysis results may not be great.
Search on that page for the video Dynamic Analysis for Vibration Testing in SolidWorks Simulation Premium. It may be helpful for you.
Hi James: We recently developed a video tutorial and put on our YouTube Channel (GoEngineer). It covers set up and walk-through. Title is:
SolidWorks Simulation- Sine Sweep Dynamics Tutorial
There are also some other videos on Harmonic Advanced settings and how they work on GoEngineer's YouTube Channel. I hope it can help, if even a little.