The theory of wedge indentation of ductile materials

Abstract

The theoretical solution for the deformation produced by a rigid frictionless wedge penetrating a plastic material is presented in this paper. The solution determines the form of the lip and the deformation in the material squeezed out towards the surface. The variation with wedge angle of the force required for penetration is determined in terms of the yield stress in a tensile test. The deformation of a grid of squares on a plane normal to the axis of the wedge is shown in figure 9 for a 30° semi-angle wedge. Close agreement is obtained with experiments as shown by comparing figure 9 with the photographs in figure 10 (plate 4). Lead blocks were used with a grid of squares scribed before penetration. This investigation is a first step towards the correlation of hardness test results with the deformation properties of a material under other conditions of stress, e.g. the tensile test. The average strain due to wedge indentation is shown to correspond to an equivalent reduction of area in a tensile test which increases with increasing wedge angle.