peteroznewman
Subscriber

Was the first mode of the structure expected to be between 20 and 2,000 Hz?

Check that the density of your material is correct.

Check that the mass you see in the model equals the mass of the physical part.

Check that the Young's modulus of your material is correct.

If the first mode is above the frequency range of the Random Vibration spectrum, then the response of the structure will be small.