The Method of Testing Cylindrical Specimen for Torsion in Order to Determine the Rheological Properties of Materials Sensitive to the Strain Rate

Abstract

The article provides an overview of existing methods of testing specimen for torsion, in order to determine the rheological properties of materials. In addition, the approaches to the post-processing experimental data, obtained in the form of torque-twist angle curve, are reviewed. It is shown that there is no universal and reliable method to study the rheological properties of materials that are sensitive to the strain rate. This paper proposes the new testing method that takes into account the effects of strain rate hardening initially. This method is that the torsion tests are carried out with the variable grips acceleration. The post-processing of obtained experimental data can be carried out with the use of modified Nadai method. In addition, with the use of mathematical modeling it is shown that the new method is reliable, regardless of material properties. The application for invention of the new testing method No2018132149 was directed in Federal Institute of Industrial Property on September, 7, 2018.

The Ways of Reaching the Specified Mode of Testing Samples for Torsion with Variable Strain Rate

“…In works [14][15][16][17], the method for determining the flow stress of a material during the testing of samples for torsion was proposed. The method involves the twisting of samples with a cylindrical gauge of a length l and continuous circular cross section of radius r in a hot state at a temperature θ.…”