An assumed strain finite element model for large deflection composite shells

Abstract

A nine node finite element model has been developed for analysis of geometrically non-linear laminatelt composite shells. The formulation is based on the degenerate solid shell concept and utiliLes a set of assumed strain fields as well as assumed dkplacement. Two different local orthogonal co-ordinate systems were used to maintain invariance of the element stiffness matrix. The formulation assumes strain and the determinant of the Jacobian matrix to be linear in the thickness direction. This allow~s analytical integration in the thickness direction regardless of ply layups. The formulation also allows the reference plane to be different from the shell midsurface. The results of numerical tests demonstrate the validity and the effectiveness of the present approach.

Nonlinear elastic buckling and postbuckling analysis of cylindrical panels

“…It is shown that many previous studies of a commonly used benchmark cylindrical panel [25][26][27][28][29][30][31][32][33][34][35] overestimated the buckling load and failed to identify the correct buckling mode shape. A numerical pro- Even when the same constraint is applied to the nodes on different layers in the thickness direction, the limit loads on the primary path, and the number and location of secondary paths are dramatically different.…”

“…Due to the symmetric geometry, loading and boundary conditions of the panel, many researchers [25][26][27][28][29][30][31][32][33][34][35] intuitively assumed that this problem only has symmetric solutions and performed the analysis on one quarter of the panel to save computational time. Such approach completely eliminates the possibility of identifying possible bifurcation points and secondary paths.…”

“…Here, the bifurcation buckling load is 537.10 N, which identifies the critical load at 90 % of the limit load (595.20 N), the overestimated critical value predicted by [25][26][27][28][29][30][31][32][33][34][35]. Fig.…”

“…A circular cylindrical panel, studied by Sabir [25], was afterwards used by many researchers [26][27][28][29][30][31][32][33][34][35] as a benchmark example to demonstrate the capability of shell or shell-like elements in simulating large deformations buckling and postbuckling processes. All these researchers successfully identified the limitpoint buckling and the corresponding symmetric postbuckling responses by utilizing path following methods.…”

Vibration Analysis of Twisted Cantilevered Conical Composite Shells

“…Assumed strain elements based on Hellinger}Reissner principle have proved to be highly successful in eliminating the detrimental shear locking [16].…”