On the feasibility of defect detection in composite material based on thermal periodic excitation

Detecting Material Defects Using a Scanning Laser Beam

“…Another modulating heat source was used by Lascoup et al [9] to locate material defects. This work continued the efforts started in Reference [6] but concentrated on an approach for finding small defects over a very small area. Necsulescu et al [10] used a sinusoidal heating system much like References [6,9] and Mulaveesala [11] and Arora [12] where oscillating heating sources were used.…”

“…Varis et al [5] examined a moving linear laser heat source applied to a two-layer material. In this reference, as in both Reference [3] and Lascoup et al [6], finding delaminations between the two layers of material was the focus of the work. The temperatures were measured using an infrared scanner and this data was compared with a mathematical model based on published thermal properties for the material.…”

“…The temperatures were measured using an infrared scanner and this data was compared with a mathematical model based on published thermal properties for the material. In addition to the emphasis on the detection of delaminations in Reference [6], the distinction between this reference and the current research is the use of non-linear regression and other function fitting methods to determine defect locations. One unique aspect of the latter paper is the use of a sinusoidal heat source as a means of providing heat.…”

“…These involved areas of low thermal resistance indicating the breakdown the of bonding of the thermal protection system tiles in spacecraft. The objective of Reference [16] is similar to the delamination studies presented in References [3,6,9] but used laser pulses as the primary heating source. In contrast to the specialized application of these methods, the research presented herein is aimed at finding any type of defect or void, either within a material or on the surface.…”

“…In contrast to the specialized application of these methods, the research presented herein is aimed at finding any type of defect or void, either within a material or on the surface. Another compositematerial NDT method was presented by Vavilov [18] which was much like References [6,15,9,7]. El Ballouti and Belattar [19] dealt with adhesion between layers, much like References [3,6], except that material under investigation was used for roadways.…”