I have a structural system weighing approximately 40 kips that is to be accelerated axially to 18G's. The system is pushed by a propulsive structure that is aft of the main structure. In order to simulate the main structure as a "pushed" system, I applied sliding constraints on the bottom of the main structure, and fixed constraints on the aft portion of the structure (where it would mate with the propulsion structure). I then applied an 18G axial accel through the CG of the system (Simulation express this quantity as in/sec^2). No other loading is applied. This should result in axial reactions only at the constraints.
Now unless I've messed up my high school physics, I would expect to so a total reactive loading of 720 kips (18G's x 40kips) in the axial direction of my aft constraints. When I use the List Resultant Force tool, Simulation reports about 3,200 kips. This would suggest my system weighs around 177 kips, which is contrary to what mass properties reports. I do have some suppressed items, but they don't make up the difference in mass needed to achieve that kind of reactive loads.
I ran some smaller, simple assemblies and ran them against a hand check, and they computed fine. That might suggest something wrong with my model. Has anyone experienced something similar when applying accel loads? Any ideas on what I should look out for?
Unfortunately I can't provide a whole lot of detail or images of the system...
Well, it turns out, not only should you cross reference Simulation outputs with some hand calcs, you should also cross reference material props from Solidworks to Simulation When you use the correct material props...suddenly everything places. Good thing no one responded to my query, otherwise I would have felt bad