Jim Day
Ansys Employee
I don't know of any comprehensive set of guidelines for setting of GAMMA and BETA aside from what follows. GAMMA,BETA=0.60,0.38 are not mandatory but are commonly used to introduce numerical damping into the implicit transient solution. Numerical damping can help to stabilize an otherwise unstable simulation. I don't have a definitive reference explaining the significance of those two particular values. Numerical damping will be included when values greater than the default values of GAMMA and BETA are input. For further details, please see Remark 2 under *CONTROL_IMPLICIT_DYNAMICS in the LS-DYNA Manual Vol. I, which can be downloaded here ... https://lsdyna.ansys.com/manuals/