Assessing the joint strength of a multi-material component by mechanical interlocking of surface structures during cold rolling

The interlocking seam joining process allows to mechanically join sheet materials along a continuous seam by a geometric interlock. This is especially suitable to join dissimilar materials for multi-material components, e.g., in lightweight or thermally optimized applications. One potential use case is the application in metallic sandwich structures with corrugated core layers. The cold rolling process avoids any significant thermal influence on the base materials and consists of three steps. First, surface structures of rectangular channels are rolled into the base material. Then, the resulting ribs are flattened in a consecutive step to receive undercuts. In the third step, a softer material is embedded into the surface structure by flat rollers. The process has already been successfully applied for a DC04 steel with pure aluminum (Al99.5) and an aluminum-magnesium alloy (AlMg3). As the applicability of this method is limited by the strength ratio of the material partners, this paper presents an FE simulation study to assess the feasibility and a semi-analytical model to evaluate the resulting shear and peel joint strength. This model allows the estimation of the joint strength based on the geometric and material parameters for different material combinations and joining states. In the experimental validation, shear strengths of 16 N/mm 2 and peel strengths of 25 N/mm have been reached for a combination of DC04 with AlMg3.