Sensitivity Studies of Evaluating Partial De-Bonding Using Laser Flash Method

Abstract

Delamination in the interlayers of multi-layer systems can cause a degradation in functionality, stability and life span of that system. This is even more pertinent for systems at high temperature. Laser flash analysis (LFA) has long been used for thermophysical properties measurements at high temperatures. Multi-layer reference artefacts, with and without, debonded regions are required for validating the thermal characterization of such systems using LFA. To aid in the design of these reference artifacts a numerical model was developed to simulate LFA of multi-layer systems, with and without, defects. This paper discusses a sensitivity study that was conducted to determine if a defect in the interlayer can be detected and if so what are the most sensitive parameters. It was found that the area and thermal conductance of the defect had the greatest effect on the simulated half-rise time of the system, with shape and radial location having a significant but lesser effect in comparison. To be able to observe a change of 10% in the half-rise time, a circular defect equivalent to 5 μm air gap with an area of 25% of the measurement area in the radial centre of the sample would have to be present.