Applying infrared thermography and heat source reconstruction for the analysis of the portevin-le châtelier effect in an aluminum alloy

Abstract

This study deals with the Portevin-Le Châtelier (PLC) effect in an aluminum alloy. Tensile tests are performed and the temperature variations are measured at the specimen surface during the loading by infrared thermography. In order to improve the spatio-temporal identification of the plastic instabilities, the heat sources are estimated by processing the temperature fields by using a two-dimensional version of the heat diffusion equation. Filtering is a key-point of the technique since the goal is calculate both temporal and spatial derivatives from noisy temperature fields. The idea is to convolve the temperature variation fields with a kernel chosen as a first and a second derivative of a Gaussian, in order to estimate the first-order temporal derivative and the second-order spatial derivative, respectively. The study focuses on the effect of the strain rate in terms of heat source band patterns associated with the PLC effect.