quasi-static analysis

[harry123456]

Hello,
Thank you very much for your help regarding my previous post. Continuing on with the riveting analysis with Explicit. I want to do a quasi-static analysis. I am applying a 0.13 inches displacament to the rivet. I have gone through the manual on quasi-static analysis. I just had a couple of questions on that. I am not sure of the typical riveting speeds in practice. I searched on that but did not find anything useful. Right now, I am running the analysis for different time periods, 0.001 sec, 0.01 sec, 0.1 sec. As per the manual for longer times inertia effects should be negligible and the results should converge. What results exactly should one look at for comparison? The results that you are interested in? Since my analysis has all deformable bodies (aluminum + rubber) is comparing the kinetic energy and internatl energy ratio for the whole model appropriate? If at increasing time periods your results dont converge how do you determine if it is quasi-static? The manual says runing your analysis at the natural time scale of the process should ensure a quasi static analysis. I am not clear what exactly is the natural time scale (is it the actual total time required for the process?) In one analysis abaqus has introduced material damping to "smooth" the KE plot. Is this neceessary and if so for all the bodies?
thanks a lot
amar

 

[brad]

Answers: Yes, for the problem described you should compare kinetic energy to internal energy.

"IF at increasing time periods your results don't converge"--they should; I have not seen them NOT converge short of some fundamental error in assumptions. (i.e. if it's not a quasi-static process in the first place).

"Natural time scale" means that the time is self-consistent with other units, and reflective of the time that the physical process actually takes. I would expect a rivet analysis to take between .01 and 1.0 seconds (granted, that's a big ballpark range, but should suffice for your needs).
Brad