Computed tomography investigations of 3D aluminum-GMT hybrid profiles manufactured by compression molding

The main work issue is to optimize the manufacturing of hybrid profiles bearing loads defined by the automotive application, based on the monitoring of the production quality using computed tomography (CT). This offers an efficient, accurate and non-destructive inspection of the products in terms of time and costs in order to prove the production quality. The investigated parts consisted of glass mat reinforced thermoplastic (GMT) 3D structures covered by aluminum straps (AA5754) with different thicknesses. They were manufactured at varied process temperatures by compression molding. The profiles quality was evaluated by CT, where the designed and actual dimensions were compared and the porosity and the fiber distribution inside the profiles were examined. In a next step, quasi-static three point bending tests were carried out on the produced profiles in order to evaluate the impact of the production effects on the mechanical behavior. First CT results showed an inhomogeneous distribution of the fibers in the matrix especially for the profiles fabricated at lower tool temperature. Pores were also found in the areas with low concentration of fibers. After bending, the cracks tended to propagate along the fiber orientation. Consequently, the main failure mechanisms consisted in inter fiber fracture and delamination of the aluminum strap.