Triaxial fatigue testing machine for polymeric materials

Abstract

Part 1 of this paper is concerned with the design and development of a multiaxial fatigue testing machine. The machine structure is considered in some detail to emphasize the dynamic as well as the static stability essential in machines applying fatigue loading. The machine is capable of testing specimens of the same geometry in torsion, push-pull, and internal pressure (if hollow), either statically or dynamically. These test modes can be operated independently or in combination, both in phase and out of phase. Each mode can be stress or strain dependent. Part 2 deals with the associated extensometry, test procedures, and preliminary tests on polymethylmethacrylate. These preliminary tests, originally undertaken to test the capability of the machine, whilst not extensive enough to be considered rigorous, are included to illustrate some of the interesting potentialities of multiaxial testing.