An Experimental Investigation into the Strength of Angle Ply GRP Tubes under High Rate of Loading

Abstract

Static and dynamic burst tests were carried out on filament wound glass reinforced plas tic (GRP) tubes. The tubes were loaded under internal pressure with minimum end con straints. In the static tests, the pressure was supplied to the rig by a Losenhausen servo hydraulic intensifier system, whereas in the dynamic tests a drop hammer apparatus was used to generate the pressure, giving medium strain rates of the order of 10 sec^-1. Higher strain rate burst tests were carried out using suitable explosives. A system for fast data acquisition was developed so that during each test, the internal pressure and strains in the central section of the specimen could be recorded, the data processed and the results auto matically plotted in the form of pressure-time, strain-time and stress-strain curves. Some high speed photographs were also taken during the dynamic bursting of the tubes to record the failure mode for each winding angle.

The results showed no significant change in the strength, strain to failure or the secant modulus of the tubes at strain rates up to about 10 sec^-1, typical to the drop hammer apparatus. There was, however, a large increase in burst strength as the strain rate was further increased to 150 sec^-1 during the explosive tests. The values of strain to failure were also increased, thus leaving the secant modulus of the tubes virtually unaltered.