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Polymeric parts produced by Fused Deposition Modelling (FDM) Additive Manufacturing (AM) has no special safety requirements, and therefore, NDT is not required. However, the use of AM to produce Fibre Reinforcement Thermoplastics (FRTP) parts means that structural applications with safety requirements are envisaged, demanding reliable NDT methods. This paper presents experimental results and numerical simulation by Finite Element Method (FEM) of the NDT inspection of different parts of polymeric and RFTP composite materials. The parts were produced by FDM Additive Manufacturing and different delamination defects were introduced at different positions and with different dimensions and morphologies. Two different NDT techniques were used, exploiting different inspection parameters: air-coupled ultrasound, using frequencies between 50 and 400 kHz and active transient thermography, in both reflection and transition modes. The influence of the curvature of the parts was analysed, from the experimental point of view, and the results were compared with different numerical simulation strategies. It was shown that, both NDT techniques can detect the defects, with good spatial resolution, being the thermography reflection mode the fastest and expedite for curvature parts. The numerical simulation corroborates the experimental results allowing a deeper insight on the physical phenomena involved.

The use of non-destructive evaluation (NDE) techniques for assessing microstructural changes in processed materials is of particular importance as it can be used to assess, qualitatively, the integrity of any material/structure. Among the several NDE techniques available, electrical conductivity measurements using eddy currents attract great attention owing to its simplicity and reliability. In this work, the electrical conductivity profiles of friction stir processed Ti6Al4V, Cu, Pb, S355 steel and gas tungsten arc welded AISI 304 stainless steel were determined through eddy currents and four-point probe. In parallel, hardness measurements were also performed. The profiles matched well with the optical macrographs of the materials: while entering in the processed region a variation in both profiles was always observed. One particular advantage of electrical conductivity profiles over hardness was evident: it provides a better resolution of the microstructural alterations in the processed materials. Moreover, when thermomechanical processing induces microstructural changes that modify the magnetic properties of a material, eddy currents testing can be used to qualitatively determine the phase fraction in a given region of the material. A qualitative relation between electrical conductivity measurements and hardness is observed.