TESTS OF RING-STIFFENED AND SANDWICH COMPOSITE CYLINDERS UNDER EXTERNAL HYDROSTATIC PRESSURE

Abstract : Four cylindrical models were tested under external hydrostatic pressure to determine the structural behavior of ring-stiffened and sandwich hulls of composite construction. Of particular interest in this series of tests were the effects of compartment length on collapse strength in the plastic general-instability mode and the relative strength-weight characteristics of ring-stiffened and sandwich cylindrical hulls. The test results demonstrated the importance of representing the actual prototype compartment length when testing a model which may collapse in the plastic general instability mode. These tests also demonstrated that a semi-infinite sandwich hull normally will have less than a 10-percent strength advantage over an optimum semi-infinite ring- stiffened hull of the same material and weight. Based on these and earlier results, the strength-weight characteristics of composite semi-infinite cylindrical hulls of various combinations of materials are estimated.