Issues and Limitations of Time Step Schemes in Non-linear Explicit FE Codes as Applied in FCRASH 971529

A scheme which addresses the determination of the time step for time integration of non-linear explicit structural dynamic equations is described. Explicit time integration algorithms based on nodal partitions and mass scaling for crash applications are presented. This allows for greater advantage to be taken of local stability criteria, and thus improves the efficiency of the explicit time integrator. Consistency, convergence and stability analyses of this algorithm for first order systems are given. Issues relating to the effect of user selection of the proper technique on the outcome of the analysis, are discussed. The adequacy of the technique is evaluated by measuring its performance in various benchmark model problems. Example problems are included to demonstrate the accuracy and stability of the method. The stability conditions for general integration parameters in an element partition are also discussed.