Combined External and Internal Hydroforming Process for Aluminium Load Introduction Elements in Intrinsic Hybrid CFRP Contour Joints

This paper presents the intrinsic processing technology of a hybrid carbon fibre reinforced thermoplastic/aluminium hollow structure with the focus on a novel two-step hydroforming process of the aluminium load introduction element. An overview in the design of the hydroforming tooling with a combined external and internal pressure application is given. Concepts for sealing the multi-part forming tool for a pressure up to 350 MPa were investigated and validated. Using structurally relevant combinations of meso structures and macro contours, numerical sensitivity analyses were used to determine the relationships between geometric parameters of the shape elements, the material and the process parameters. The most important influences on the hydroforming operation and the geometric limits that can be achieved are presented.