Shear-Strength and Friction Measurement on Thin Layers under High Pressure

Abstract

Rotating‐anvil type shear presses have been used by several investigators in studies of shear strength and friction on thin samples. The essential design features and operating procedures used by previous investigators are briefly reviewed. A new apparatus of this general type is then described which incorporates a high‐sensitivity, strain‐gauge instrumented, combination load and torque cell. The new device was designed specifically for measurements on very weak solids at pressures up to about 20 kbar. Operation of the apparatus is illustrated with measurements at pressure up to 5 kbar on thin sheets of the polymer polyvinylidene fluoride. The results are interpreted in terms of the friction and shear strength of the sample material by making use of concepts from the adhesion theory of friction.