Design of a high pressure rig for biaxial and triaxial compression testing of composite tubes

This paper describes the design and use of a new high-pressure rig for testing composite tubes under biaxial and triaxial compressive loading. The rig, which has a design pressure of 200 MPa, is capable of applying simultaneously well controlled ratios of external radial pressure, internal radial pressure and axial compressive load. The test specimens were designed to ensure fracture within the test section and to avoid structural instability. Preliminary experiments on thick +/- 55 degrees filament-wound E-Glass/epoxy tubes are reported.