Vibration Testing and Acceleration Loads

[Anonymous]

I am attempting to run FEA on an assembly that is to be vibration tested (Accelerated to 3 G's). The assembly is fixed at 6 bolt holes at the bottom and the load is applied within the same plane that the assembly is fixed. I have tried using an enforced motion, but only displacement shows up in the sub type (I think this is because the force isn't applied to the face). I have tried converting the acceleration of 3 G's to a force applied to an entire side of the assembly, but there is an error meshing now. I have also tried using a remote force to move the base (acting as a shaker plate).

Does anyone have any recommendations on how to simulate a vibration test best using Nastran in CAD? Any tips would be helpful.

Thanks

[John_Holtz]

Hi @Anonymous. Welcome to the In-CAD forum.

We need a little more information to understand what you are trying to do, such as:

1. What type of vibration testing are you performing? (A sine-sweep? random vibration? something else?)
2. What type of analysis are you using in In-CAD? This may be affecting what options are available for the enforced motion subtype.

[Anonymous]

Hey, thanks for the response.

I am attempting to perform a sine sweep where input accelerations shall be .25 g at 5 HZ, then ramp to 5 g at 20 Hz, then remain at 4.2 g to 200 Hz. If necessary, that can be simplified to 4.2 g (1622 in/s^2) at 200Hz. I am doing a modal frequency analysis, so the acceleration option for enforced motion works. I want to find the resonance points.

My main problem now is trying to get my mesh to work again. The assembly has a lot of parts, and when it meshes, it clumps them in places where they shouldn't be.

Thanks again for the help