Design, Testing, and Sensitivity Analysis of a Torsional Cyclic Test Adapter

Abstract

In this article, a torsional adapter is designed and evaluated through the comparison of analytical, numerical, and experimental tools. The adapter converts a conventional tension–compression test machine for cyclic loading to a modified application of both force-controlled and displacement-controlled torsional loading. The mechanism ensures a uniform distribution of loading application on both sides of the specimen. The determination of the durability curve can therefore be consistently carried out by acknowledging the geometric relation between the displacement of the test rig and the strain on the specimen. However, friction and clearance in the mechanism joints can cause energy dissipation; therefore, a detailed evaluation of this effect is mandatory before the use of the adapter. Here, it is shown that, using the current version of the adapter, the energy dissipation during torsional testing can be measured and later successfully considered during the determination of the torsional cyclic curve. Future improvements of the adapter will involve the reduction of the friction between the components of the mechanism.

Keywords

• torsion
• mechanism
• cyclic loading
• friction
• plasticity