Response of composite material shallow arch to concentrated load

Abstract

The large displacement static response of shallow, specially orthotropic composite panels subjected to lateral loading is examined both theoretically and experimentally. The panels are thin, circular cylindrical shells with the straight edges simply supported at a fixed distance apart, and the curved edges are free. The lateral load is a spatially uniform line load acting along the generator, or axial, direction of the cylinder, and it is directed radially inward toward the center. Under the conditions described, the response of the panel is independent of the axial coordinate, and is dependent on the circumferential coordinate only. Hence, the panel analysis is onedimensional, and it is qualitatively the same as a shallow circular arch under a concentrated load. The load induces a circumferential thrust, and the panel can, and does, snap-through to an inverted configuration at the buckling load. The influence of load position on the response is also examined. A test fixture was carefully designed to duplicate these conditions. The test panels discussed are [(90/0)3]5 graphite-epoxy laminates. Very good agreement between theory and experiment is achieved. Much of the discrepancy between theory and experiment is due to geometric imperfections in the initial shape of the panels tested.