Strength and Failure Modes of Hoop Wound CFRP Tubes Under Compressive High Rates of Loading

Abstract

A study was undertaken to investigate the response of hoop wound carbon fibre reinforced plastic (CFRP) tubes to dynamic compressive loading at strain rates in the range of 5–200/sec. An experimental rig was designed and built to test short tubular specimens under external radial pressure with minimum end constraints. The load was applied by detonating a small explosive charge inside a water filled, steel, cylindrical chamber enclosing the test specimen. For each test the external pressure and the strains, in both circumferential and longitudinal directions, were recorded on suitable digital processing equipment. Two distinct modes of failure were identified; material and structural (buckling). The mode of failure was dependent on the rate of loading and the tube diameter/thickness ratio. For 100 mm diameter tubes with diameter/thickness=40, buckling failure dominated at strain rates below 10/s. However, at higher strain rates, material failure and a considerable enhancement in burst strength was observed. For 100 mm diameter tubes, with diameter/thickness=80, a buckling mode of failure was in evidence in all the tests, irrespective of the rate of loading.