While running the code for the take home exam II, I found that my simEngine2D is very sensitive to the time step, gamma and beta values in Newmark-beta. If possible can you tell me which method and time step was used in the text book. Also, what is the best way to find healthy time step?
Abdul Aziz Khaja.
Work with \beta=0.3025, and \gamma=0.6. Don't change these.
About step size: there is no universal rule for choosing one. Think of a slider crank that starts moving faster and faster and faster. In the beginning, a large step size will suffice. But as the motion gets quicker, in order to capture what's going on you'll have to gradually decrease the step size.
So for your problem, keep decreasing the step size until for two successive step sizes the results look the same.
Finally, the results in the book were not generated with Newmark. They were generated with a method called "Coordinate Partitioning", which we didn't discussed in class since it's a little bit beyond the scope of ME451.
I hope this helps.