Manufacture of a suspension subframe through CAPROCAST technology (T-RTM)

Abstract

The main objective of this work has been the manufacture , and subsequent flexural and fatigue  tests, of automotive real parts, made of thermoplastic composites. This has been achieved by incorporation continuous carbon fiber (textile) to polyamide matrix, through an specific process very similar to a thermoplastic  RTM. The fatigue behaviour of any composite is governed by the toughness of the material. Because of this and the low cost, the polyamide has been considered as a polymer matrix. The process involves an in-situ polymerization, that the low viscosity of the monomer,e-caprolactama (e-CL), allows the infiltration of preforms and textiles. The demonstration part has been completely redesigned by BATZ and TECNALIA to fullfill mechanical requirements and  manufacture ability. In particular, it has been fabricated a suspension subframe with an 52%vol. of a commercial carbon fiber and thickness variations from 3 to 8mm within the same part, obtaining a significant reduction in weight relative to the metal part (6,8 kg vs 3,48 kg) and the established mechanical requirements. As far as the fatigue/durability test are concerned, they have been performed to evaluate the strength of the composite and to increase the correlation between CAE analysis and the real behavior of the hybrid component. All the tested parts support 2.000.000 cycles (the stipulated for this part in metal) without break, only with small deformations in the bushings holes. As far as the flexural test are concerned, they evaluate the maximum quasi-static strength of the component. All the parts tested deform considerably, recovering much of this deformation once the load is removed.

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