2-DIMENSIONAL NONCONFORMING FINITE-ELEMENTS - A STATE-OF-THE-ART

A state-of-the-art report on the new finite elements formulated by the addition of nonconforming displacement modes has been presented. The development of a series improved nonconforming finite elements for the analysis of plate and shell structures is described in the first part of this paper. These new plate and shell finite elements are establis hed by the combined use of different improvement schemes such as; the addition of nonconforming modes, the reduced (or selective) integratio n, and the construction of the substitute shear strain fields. The imp rovement achieved may be attributable to the fact that the merits of t hese improvement techniques are merged into the formation of the new e lements in a complementary manner. It is shown that the results obtain ed by the new elements give significantly improved solutions without a ny serious defects such as; the shear locking, spurious zero energy mo de for the linear as well. as nonlinear benchmark problems. Recent dev elopments in the transition elements that have a variable number of mi d-side nodes and can be effectively used in the adaptive mesh refineme nt are presented in the second part. Finally, the nonconforming transi tion flat shell elements with drilling degrees of freedom are also pre sented.