Having worked with several customers, I’ve run across quite a few situations in which someone desires to analyze surface contact while in a dynamic analysis. This can be achieved with NASTRAN Advanced Nonlinear Solution 601 and 701 series. Although it can be quite expensive computationally speaking, this software allows you to analyze how your dynamic environment would affect structures that may be touching (Examples include checking circuit boards , pressure vessels for pre-load, etc.). Now how do you go about using 601/701 to do your work? It depends on your environment. It is very easy to apply the loads if you’re running a transient run that has some history to it. Shock environments work better in Adv. NL Explicit (701), while most generic lower speed environments can be handled in the Adv. NL Implicit Transient (601/129). Frequency response and random vibration type settings require a bit more work. You must transform the frequency history into time history and translate that as a transient. (Examples could be sine-sweeps, random environments, etc. ) Although it leads to a wide variety of results, and may take a long time to load, from this, you could analyze some very complex situations. Definitely contact me if you have questions on these types of analyses. I have always been fascinated with them and find each one a very unique challenge. Thank you for reading and take care.