EAS-ELEMENTS FOR 2-DIMENSIONAL, 3-DIMENSIONAL, PLATE AND SHELL STRUCTURES AND THEIR EQUIVALENCE TO HR-ELEMENTS

The enhanced assumed strain (EAS) method, recently proposed by Simo and Rifai13, is used to develop new four-node membrane, plate and shell elements and eight-node solid elements. The equivalence of certain EAS-elements with Hellinger-Reissner (HR) elements is discussed. For instance, the seven-parameter element EAS-7 with 2 x 2 integration is identical to the HR-element of Pian and Sumihara2. Eight-node solid elements which are free of volumetric locking and four-node shell elements which have an improved membrane and bending behaviour, compared to the Bathe-Dvorkin shell element7, are introduced. Numerical tests for linear elastic problems show an improved performance of the EAS-elements.