Design study of dynamic mechanical test bench specimen grips

Abstract

The characterization of mechanical properties of materials used in biomedical applications is essential for performance evaluation. In addition to quasi-static tests, dynamic tests extend the range of methods and allow predictions of failure, as well as information on durability. Appropriate specimen grips according to the test sample geometry are crucial for a reliable examination of mechanical testing and therefore valid experimental data. In particular, the investigation of polymers is challenging, as properties show major differences depending on temperature and applied loading rate. This could result in slipping or tearing of samples in the specimen grip area. Numerical simulations of reference grips, as well as alternative custom designs, were performed evaluating damage due to the clamping process and to provide appropriate specimen grips for future dynamic-mechanical investigations of materials with variable properties. Both the results of the numerical simulation and preliminary tests with 3D-printed prototypes show a distinct improvement in specimen clamping. Plastic deformation and local stress peaks were reduced while maintaining the same tightening torque.

Keywords

• dynamic-mechanical testing
• specimen grip
• clamping
• polymer
• design
• finite element analysis
• numerical simulation