Heat emitting layers for enhancing NDE of composite structures

A new technique using hybrid polymer composites with infrared thermography is presented as a potential method for enhanced non-destructive evaluation (NDE) of polymer composite materials and structures. This fully integrated approach is a concept aimed at adding an NDE functionality to the composite. Termed HELTHY (Heat Emitting Layer for THermographY), the technique utilises an embedded heat emitting layer (HEL) to input thermal energy from within the composite structure. After activation of the HEL, surface temperature readings can be captured using an infrared detector. The idea was based on the fact that variations in the surface temperature relate to non-uniformities, i.e. defects, that are within the laminate, which can then be detected. The concept is first simulated using finite element analysis to help determine the main parameters that influence HELTHY. An experimental investigation follows in order to verify the results of the simulations. The concept proves to be very tolerant of a number of input parameters giving early signs that the technique is relatively robust. Finally, a two smallscale application case studies are investigated to examine the effect of the concept on more complex real-life structures. (c) 2008 Elsevier Ltd. All rights reserved.