Extended variational formulations and F .E models for non-linear non-conservative mechanical problems

For non-conservative mechanical systems classical variational principles do not hold true; however, recent results on the so-called ‘inverse problem’ of calculus of variations lead to extended variational formulations, which can be provided even for non-conservative systems. In this contribution, f.e. models derived from extended variational principles are discussed in a significant case of an illconditioned balance equation. It appears that extended mixed variational formulations could improve the numerical performance of f.e. methods for this class of problems.