Effect of Thickness and Ply Layup on the Collapse Characteristics of Cylindrical Composite Shells with Large Cutouts.

摘要

This study involved a numerical and experimental investigation of the geometric instability(collapse loads/displacements) of vertically unsupported graphite/epoxy cylindrical shell panels undergoing axial compression. Symmetric quasi-isotropic and cross-ply laminates, with and without 4 X4 centralized cutouts, were investigated for three thicknesses:8,16,and 24 plies. The experimental data was compared to results from SHELL, a geometrically nonlinear finite-element computer program which incorporates a parabolic transverse shear strain distribution through the thickness. Good correlation was obtained for shells with large cutouts between the SHELL numerical data and the experimental results. This research verified that the SHELL program will provide good predictions of the collapse characteristics of shell structures undergoing large displacements and moderately large rotations. It was found that the magnitudes of transverse shear strain increased with increasing panel thickness and increased significantly when a large cutout was placed in a shell. Also, there were indications that under large displacement and moderately large rotation conditions, the collapse of cross-ply shells was more affected by transverse shear strain than the collapse of quasi-isotropic shells.... Composites, Shells, Cylindrical Panels, Cutouts, Finite Elements, Nonlinear Analysis, Transverse Shear, Geometric Instability, Collapse, Graphite/Epoxy.