Material yield strain identification using energy absorption

Abstract

The current gold standard of identifying yield points from stress strain curves involves identifying a significant change in elastic modulus or using an arbitrary strain offset (0.1%, 0.2% or 2%) of the elastic modulus. The development of the offset method was due to the ambiguous definitions of yield point. The result is an arbitrary yield point which is prone to various human-related errors. This article presents a method to identify a unique yield point consistently using energy absorbed by the material up to first peak stress. This mathematical process idealises the stress strain curve for easy identification of the yield point. The method was tested on three possible types of stress strain curves with either a distinct yield point or without a distinct yield point (with peak stress closer to elastic region or closer to fracture). The yield points obtained by the proposed method are shown to be robust, consistent and unaffected by variations of the stress strain curves and data noises.