Effects of Couple Stresses on Stress Distributions in a Ring Test Specimen

Abstract

The ring test is often used to estimate the tensile strength of rock-like materials. The results of the test, however, are not well interpreted by the classical theory of elasticity. The present paper, with the .intention of a better interpretation of the results, discusses the effects of couple stresses on the stress distributions in a ring test specimen. An analytic solution was obtained by the Fourier-Bessel expansion method. Results show that the effects of couple stresses are remarkable. As the intrinsic internal length of material increases, the stresses rapidly decrease and become more uniform. The Poisson's ratio decreases, and more uniform stresses are developed. However, its effects are secondary in comparison with the intrinsic internal length of material.