On design of element evaluators in OOFEM

This paper presents the advanced object-oriented design of finite element representations in a complex multi-physics finite element environment OOFEM [1], [2] and [3]. The focus is on reuse of existing single-physics capabilities when implementing elements for coupled simulations. This has been achieved by decoupling the description of element geometry, element problem specific capabilities, element interpolation, and integration schemes. The individual problem specific capabilities, represented by a hierarchy of classes derived form ElementEvaluator, can be assembled together to define an evaluator for coupled analysis. The presented design leads to an extremely flexible implementation, with clean modular design. The application is demonstrated on an implicit gradient formulation of a damage-plastic model and on coupled heat and mass transfer.