A Glass Fibre Reinforced Composite (GFRP) panel has thermal diffusivity 0.25106m2s1. It is found that a large area delamination defect at 2.8mm depth in this panel is just detectable thermal imaging with a temperature contrast of T=0.2C. Sketch on the same graph the evolution of temperature contrast with time for large area delamination defects at 0.8mm deep and 1.2 mm deep. Include the magnitude of the expected maximum temperature contrast in each case. Use the approximate relation tCmax=zdeff2 where tCmax is the time of maximum contrast, zdef is defect depth and is the thermal diffusivity. Also note that contrast decreases with z3