Robert MacFarlane

Random Vibration - Net Section Force / Result Force Doesn't Seem Correct

Discussion created by Robert MacFarlane on Oct 23, 2019



I am running a solidworks simulation using the random vibration study type. I am trying to get the Net Section Force and Net Section Acceleration at the interfaces from the model and seem to be running into issues. (Net section force is essentially the resultant force). The way I have been doing this is by right clicking results setting units to SI and selecting Response Graph in the Result Force menu. This outputs a response graph in N^2/Hz. Shown Below. This is fine, but when I divide N^2/Hz by mass^2 and then by (9.81 m/s^2)^2 to get the result into g^2/Hz the response is less than the input. This doesn't make sense to me and was wondering if someone had any thoughts on why this might be. 


To reiterate, I would have expected the resultant acceleration to follow the input almost perfectly up to the first mode and then see a peak as shown and then I would have expected the acceleration at f>f1 to follow the input with peaks above the input acceleration levels.


Let me know if you have any ideas. The model is attached and runs very quickly. Currently I am running SW 2017 SP3.