Testing non-magnetic materials using Oberst Beam method utilising electromagnetic excitation

Abstract

The use of a non-contact electromagnetic excitation system is highly recommended in the literature to identify the mechanical properties of materials using the Oberst Beam Method. However, it is not possible to test a specimen made of non-magnetic material using the Oberst beam test rig, comprising of an electromagnetic exciter, unless the specimen is modified using some magnetic particles or small discs made of a ferromagnetic material. Although doing so makes it possible to perform the test, this results in an undesirable modification to the test specimen, leading to unquantified levels of errors in the estimated material properties. This study proposes an approach for eliminating the adverse effects of such mass modification to the test specimen, and also allows subsequent removal of the electromagnetic stiffening effects produced by the electromagnetic exciter. The proposed method is validated using both finite element (FE) simulations and experimental data. Results confirm that the proposed method for the removal of the adverse effects of mass modification, combined with the subsequent removal of the electromagnetic stiffening effects, is very effective, making it possible to determine the material properties of non-magnetic materials with a very good accuracy.