Papers by Author: T.R. Emery

Abstract: The current paper presents a new combined technique for damage detection, localisation and establishing damage severity. The technique is based on the use of two infrared detection approaches: Pulsed Phase Thermography (PPT) and Thermoelastic Stress Analysis (TSA). A methodology is described that allows the technique to be applied to fibre reinforced composites. The usefulness of the technique is demonstrated on delaminated glass epoxy laminates. A means of developing controlled delamination damage in such specimens is developed so that real sub surface damage is evaluated in the paper.

Abstract: The application of a cyclic load on a composite material containing damage has the effect of heating due to the material viscoelasticity. This is exaggerated in the proximity of interlaminar failure because of friction between plies. Quantitatively studying a stressed component subject to these conditions using Thermoelastic Stress Analysis (TSA) has been inaccurate, as the localised heating has an effect on the thermoelastic response. Hence the thermoelastic signal from damaging composites will contain a stress-induced component and a temperature-induced component. In this paper a process is described that allows the thermoelastic signal to be de-coupled into a stress component and a temperature component. This is achieved using a combination of infra-red thermography and TSA. The process is based on the use of a special calibration device. The paper provides an experimental verification of the de-coupling using actual damaged composite components.