Comparison of the defect detection capabilities of flash thermography and vibration excitation shearography

The defect detection capabilities of transient thermography and shearography have been compared using optimum excitation methods for each technique: short pulse heating for thermography and vibration excitation using a piezoelectric transducer for shearography. A signal-to-noise ratio and limit of detection analysis has been performed on defect images obtained by the two techniques using the different excitation methods. Test samples considered ill this paper are flat-plate samples made from aluminium, mild steel, stainless steel, CFRP and thermoplastic, containing flat-bottomed hole artificial defects of 20 mm diameter at depths ranging from 0.5 mm to 3.0 mm.