Membrane locking and assumed strain shell elements

An explanation of membrane locking behaviour in shell elements and also the use of reduced and selective integration is described. To overcome the conflict between the locking and mechanism problems the author proposed the degenerated shell elements with assumed transverse shear and membrane strains. The location of sampling points for the assumed strain fields is given in the present work. In the formulation of the new elements, assumed transverse shear strains in the natural coordinate system are used to overcome the shear locking problem. Also, assumed membrane strains in the orthogonal curvilinear coordinate system are applied to avoid membrane locking behaviour. Some numerical tests are presented to illustrate the good performance of the assumed strain shell elements.