Hybrid/mixed assumed stress element for anisotropic laminated elliptical and parabolic shells

A variety of elliptical/parabolic dome type structures are used in important aerospace and civil structural systems such as underwater vehicles, stadium covers, exhibition halls, auditoriums and museum halls. For the analysis of such structures, a shear deformable four-noded finite element based on a hybrid/mixed assumed stress is presented in this paper. The element called iHES (improved Hybrid and Enhanced Shell element) is developed assuming the most general arbitrary orthogonal coordinate system. The element is based on a first-order shear flexible formulation and essentially consists of a combination of drilling degrees of freedom with assumed stress and enhanced strain techniques. Using the element developed here, a detailed parametric study of anisotropic elliptical and parabolic shells of various configurations is carried out to investigate the effects of aspect and height ratios as well as layer lay-up schemes.