On the Displacement-Stress Continuous Finite Elements

For the analysis of composite media, three different compatible and mixed finite element formulations are presented which apriori enforce the continuity of stresses as well as displacements at the element interfaces. The formulations are applied for the analysis of hi-material interfaces in two problems often encountered in the field of orthopaedic biomechanics, that is the fixation analysis in the cemented tibial implants and that in the push-out tests with attached interface. The results reveal that, in contrast to the conventional displacement-based finite element method which yields very significant stress discontinuities, the new techniques predict interface stresses that are both continuous and accurate.