COMBINED IMPLICIT/EXPLICIT ALGORITHMS FOR CRASHWORTHINESS ANALYSIS AND METAL FORMING SIMULATION

摘要

In order to solve an industrial process, an explicit method, which is conditionally stable, is the most adopted while the non-linearities evolve rapidly (impact phase, stamping process ...). But when the dynamics become quasi-linear (post impact analysis, springback simulation ...), an implicit method, which is iterative, presents the advantage of unconditional stability. The optimal solution is then to have both implicit and explicit methods readily available in the same code and to be able to switch automatically from one to the other. Criteria that decide to switch from a method to another, depending on the current dynamic, have been developed. Implicit restarting conditions are also proposed that annihilate numerical oscillations resulting from an explicit calculation.