Triangles and tetrahedra in explicit dynamic codes for solids

Explicit dynamic codes which are used currently for the study of plastic deformations in impact, or with some modiÞcation for metal forming, su¤er two serious limitations. First, only quadrilateral or hexahedral linear elements can be used thus limiting the possibilities of adaptive reÞnement and adaptive meshing. Second, even with the use of such elements, special devices such as reduced integration must be introduced to avoid locking and reduce costs. These necessitate complex hour glass control, mending-type procedures. The main di¦culties are those due to the need of treatment of (almost) incompressible deformation modes. Recently, similar di¦culties have been overcome in the context of ßuid dynamics4,5 and soil dynamics18~20 and we show here how the processes introduced there can be adopted e¤ectively to the present problem, thus allowing an almost unrestricted choice of element interpolations