Non-Destructive Testing for Polymer Matrix Composites produced by Additive Manufacturing

Abstract

The increased use of composite materials produced by Additive Manufacturing (AM), in fields like automotive and aerospace, raises new demands in characterizing a variety of defects that may appear during its production and service life and which have an impact on the structural performance of the component. Conventional Non-destructive testing (NDT) cannot fulfil these new requirements, motivating the research and development of new, innovative approaches that increase the inspection reliability. The purpose of this work is to apply and test the reliability of two innovative NDT techniques, Double Active Transient Thermography (DATT) and reflection mode Air-coupled Ultrasound (ACU), and its inspection parameters to evaluate polymer matrix composites produced by AM. In the DATT experiments, the samples were excited by two heat sources, a cold flow and a heat flow, six different parameters were used (the instant for starting the cold flow and its duration, different defects and the influence of the lid, exposure time, curvature, and instant when the vortex is turned on) and the goal of developing this technique was to observe, with the same level of temperature contrast and at the same time, different defects at different depths and locations. In the ACU experiments, three parameters were studied (, d and dp), and the goal was to understand their effect in the reflection echo of the wave. The DATT results are promising, allowing an increased understanding of the influence of each parameter and a clearer observation of the three defects with different locations and depths at the same time. The ACU results allow to understand the effect of the studied parameters but future improvements on equipment structure and assembly and the usage of different probes and samples will play a role in better understanding not only the wave’s behaviour but also the advantages of the technique.