Investigations on active thermographic testing techniques for manufacturing processes

Abstract

Active thermographic testing techniques based on ultrasonic, inductive or optical heating were analysed and further developed. In case of ultrasonic excitation the interplay of vibration and released heat was studied by comparing thermography and 3D-vibrometry results. Damage due to ultrasound excitation can be avoided. Eddy current induced thermography is comparable in sensitivity for crack detection to ultrasound induced thermography. Analytical and numerical modelling was applied to simulate the effect of position and geometry of various heat sources and the relation of experimental parameters to the thermal contrast. Main applications comprise carbon and glass fibre reinforced polymers, aluminium components and turbine blades with thermal barrier coatings and cooling channels.

Automated defect detection in large-scale bonded parts by active thermography

“…In contrast to thermographic inspections of welded joints, which have already successfully been introduced into industrial environment [6,7], adhesive bonds behave differently. Figure 1 shows a typical composition of an adhesive bond, which consists of up to three different kinds of material that build two interfaces.…”