High-tensile joints of continuously fusion bonded hybrid structures

Abstract

Tailored hybrid structures manufactured within a continuous production process, for instance in a continuous roll forming line, offer a high potential for the automotive industry, due to its weight reduction compared to pure metal parts. Therefore, the hybrid roll formed parts consist of steel sheets reinforced by carbon fibre reinforced thermoplastic tapes (CFR-TP).Both materials are joined by fusion bonding whereby the surface of the thermoplastic matrix is melted on the steel surface. The pre-treatment of the steel with a primer, customized for joining of steel and CFR-TP, is a promising approach, due to its easy implementation into continuous coil-coating processes. Major challenges consist in achieving sufficient joint strength as well as developing of a testing method for the evaluation of the adhesion between both materials.Relating to joint strength, various process parameters (i.e. temperature of steel and CFR-TP) are examined. The fracture pattern are analysed optically by microscopy to detect possible primer damage. Furthermore, the evaluation is carried out by mechanical testing of peel specimens within climbing drum peel test to determine the production-related influence in a continuous process. The examinations show the usability of climbing drum peel test and the increase of joint strength with higher energy input.