Numerical Analysis of Defects in FML using Through-Transmission Mode of Active Thermography

The study mainly focuses to investigate the thermal response of defects such as delaminations and disbonds, and develop mathematical models using numerical results to obtain the optimum heat requirement and time to identify defects in GLARE type of Fibre metal laminates (FML) under a throughtransmission (TT) mode of step pulsed active thermography (SPAT) method in the type of nondestructive testing and evaluation (NDTE) technique. The influence of applied heat flux and time on various sizes and depth of defects in FML is analysed to investigate the thermal response through numerical simulations. A finite element method (FEM) is applied to simulate SPAT through ANSYS software based on 3D transient heat transfer principle with the assumption of TT mode of observation. The investigation shows that the smaller and near-surface defects located at the thermal stimulant side respond with reduced thermal contrast and vice versa. Numerical results are analysed to provide the optimum heat requirement and time to identify defects at the required MRTD even to identify defects which are not identified within the load conditions considered for the investigations. Further, a comparative study concludes that the numerical approach based on SPAT using TT mode of observation could be utilized to derive mathematical models using numerical results to analyse defects present in FML effectively.