Determination of Coulomb's friction coefficient directly from cylinder compression tests

Abstract

In this paper, a new method is proposed for the determination of Coulomb's friction coefficient directly from cylinder compression tests. It is based on measuring the immigrated contact area (ICA), which is defined as the lateral surface that comes into contact with the platens after deformation. Preliminary sensitivity analyses showed that ICA is only a function of friction and the strain-hardening exponent at room temperature when a power law relation between the true stress and the true plastic strain is considered. Through intensive numerical simulations by using a code-driven simulation environment, an inverse calculation is done which makes the determination of the friction coefficient possible by using ICA and the strain-hardening exponent of the investigated material. At the end of compression, ICA is usually clearly visible without any precautions; thus, a simplified script is supplied which calculates ICA through digital image analysis made on the end faces of the compressed specimens. This paper includes the complete procedure to determine Coulomb's friction coefficient and a script in which the proposed method is embedded entirely. In addition, practical case studies demonstrated the ease of applicability of the proposed method by employing different materials.