Application of Strain Non-Uniformity Index (SNI) Based Approach to Predict Failure in Sheet Metal Components

Abstract

Industrial components are far too complex in shape and far too large in size compared to the laboratory scale test samples used to establish failure criteria like the forming limit diagram (FLD). These have been traditionally used to predict failure, but are found to often make wrong predictions due to their sensitivity to strain path, and forming conditions like temperature. The Strain Nonuniformity Index (SNI), a single parameter determined from the spatial strain distribution, may be used to predict failure and identify locations of failure or even imminent failure. This is possible regardless of temperature or even the method of forming (cold forming, hot forming, superplastic forming etc.). The paper presents a few results demonstrating successful applications of this novel SNI based technique.