An efficient axisymmetric hybrid-stress-displacement formulation for compressible/nearly incompressible material

Abstract

Based on Spilker's concept, an efficient four-noded quadrilateral hybrid-stress-displacement axisymmetric element is developed for mechanical, thermal and body force loads. The present finite element has several advantages compared to the familiar displacement formulation for examining the structural behaviour of compressible/nearly incompressible solid rocket motor propellant and insulation materials, under various loading environments. Several structural problems are solved to demonstrate the efficiency of the present method, by comparing the results with those obtained from the existing analytical and other finite element solutions based on displacement formulation, using the MARC software package. The Hermann element in MARC has mean pressure as one of the nodal degrees of freedom with the other two degrees of freedom tied at the interface. The present element has only two degrees of freedom per node and there is no necessity of tying. Also, the present element gives accurate results even with a coarse mesh compared to MARC.