Testing facilities for multiaxial loading of tubular specimens

The development of a new multiaxial testing machine is presented. The testing machine is capable of applying axial load, differential pressure, and torsion to a tubular specimen under independent servohydraulic control. Relative merits of various loading configurations are described. Stress/strain controlled, monotonic/cyclic, and in-phase/out-of-phase (nonproportional) tests under ambient temperature conditions can be performed with this system. The associated computer control hardware and software allows for a number of complex user-defined loading and acquisition schemes. Monotonic and cyclic tests on tubular specimens made of glass fiber-reinforced epoxy with fiber orientations of +/-45 degrees and 0 degrees, are presented. Details of the experimental apparatus and representative test results are discussed in this paper.