Analysis of the delamination detection capabilities of pulse stimulated thermographic nondestructive testing techniques

The delamination detection capabilities of both flash and long pulse excitation thermographic nondestructive testing (TNDT) techniques have been obtained using an analytical expression that involves delamination size and depth, thermophysical properties and the inspection system excitation energy. The possibility of using long pulse excitation in place of traditional flash excitation is discussed and considered quantitatively. It has been found that long pulse TNDT becomes an effective alternative where the delamination image contrast peak obtained in the flash variant of TNDT occurs at a time that approaches or is greater than one second. Images of simulated delaminations in aluminum alloy, mild steel, stainless steel and carbon fiber composite obtained by both TNDT techniques are presented.