NONLINEAR-ANALYSIS OF LAMINATED NONCIRCULAR CYLINDRICAL-SHELLS

The nonlinear analysis of laminated initially imperfect non-circular c ylindrical shells is presented. The analytical model is based on Donne ll's nonlinear kinematic relations. The equations are derived via the Hu-Washizu mixed formulation, and are expressed in terms of the transv erse displacement and the Airy stress function. The curvature of the n on-circular cross-section is expanded into a Fourier series, allowing for representation of arbitrary closed cross-sections. The solution pr ocedure is based on expansion of the variables into truncated trigonom etric series in the circumferential direction and a finite difference scheme in the longitudinal one. Errors introduced by the truncated ser ies are minimized by the Galerkin procedure and the equations are line arized by the Newton-Raphson method. Solutions beyond the limit point are obtained by Riks' constant are-length algorithm. Results of both i sotropic and laminated, axially loaded oval and elliptic shells are pr esented. The non-circular configurations are found to be less imperfec tion sensitive than the circular ones, and for largely eccentric cross -sections the shells are insensitive to initial imperfections.