Stress Relaxation in Solids

Abstract

THE purpose of this communication is to direct attention to a similarity in the shape of stress–log time graphs relating to static stress relaxation in solid materials. For a number of high polymers and metals the following relation between the inflexion slope F of the stress–log time curves and the total decrease in stress Δσ was found: F is defined as (dσ/d ln t)_inflexion. A condition for the applicability of equation (1) seemed to be absence of internal stresses, that is, careful annealing. The substances investigated were rubber hydrochloride¹, polyethylene^2,3, cellulose and paper⁴, polycrystalline and single crystal cadmium, indium, lead and tin⁵, and polycrystalline molybdenum⁶. Experiments have also been carried out on a number of other substances including polyisobutylene, polyvinyl acetate, beryllium, aluminium, Lipowitz's alloy, cetyl alcohol, and single crystals of lithium fluoride⁷.