Online process monitoring and quality assurance are highly favorable for composite manufacturing processes like automated tape layup (ATL), where the productivity is largely constrained by downtime consisting of quality inspection and error mitigation. The presented work details the use of thermography as an inspection tool for such a process, using thermoplastic based tape material. A new online monitoring system is developed containing Infrared camera integrated on a purpose build ATL test rig. Surface thermal history for the layup course over time is recorded, which is then extracted along the width of the tape. The end result is a single image containing sequence of images, detailing the temperature data over the length of a single tape. Temperature gradient throughout the layup is then used to recognize foreign bodies and defects. Variation in adhesion effects of ply to the tool, ply and ply and ply and foreign bodies can be detected and areas of weak bonding can be recognized.
Carbon fiber reinforced plastic (CFRP) specimens, charged with defined loads in impact tests, have been examined with flash and inductive thermography from the front and the rear side. In the case of inductive thermography, eddy currents are induced in electrically conductive materials, usually in metals. But it can be also excellently used for inspection of CFRP, as eddy current can be induced in the carbon fibers. The fiber’s orientation regarding the magnetic field of the induction coil also has an influence on the detection results. The sequence of the temperature images, recorded during and after the short inductive heating pulse, is evaluated with a Fourier Transform, and the obtained phase image is used for localizing the impact damages. The flash thermography tests in transmission and reflection mode were evaluated using PPT and TSR methods. The results of the flash and inductive inspection techniques are compared for samples with different degrees of damage, in order to learn more about the capability of induction thermography for detecting impact damages.