Mechanical properties and forming behaviour of laminated steel/polymer sandwich systems with local inlays - Part 2: Stretching and deep drawing

In part 1, a fundamental study on mechanical properties and deep drawing of a steel/polymer/steel sandwich (SMs) combination was accomplished investigating one type of reinforced SMs (R-SMs). In this part, the effect of reinforcements (REs) with different geometries, sizes, materials and locations on stretching and deep drawability is introduced. Additionally, the influence of reinforcing SMs with different mechanical properties and skin/core thicknesses is considered. Therefore, a deep drawable steel grade with thicknesses 0.49 mm and 0.24 mm was utilized. For the core polyolefin (PP-PE) foils with thicknesses of 0.3 mm and 0.6 mm were used.Substantial reduction of the deep drawability was found if the RE is located in the forming region (close to the punch), however, only locally if located in the flange area. Inserting the RE in the flange has no remarkable effect on the drawing force but on the forming potential represented by the cup height at failure.The stretching results show that increasing the RE size reduces the forming potential. The RE creates a sharp interface with the neighbour core layer accelerating failure. A negligible effect of the RE geometry was found, however solid REs show reduced forming limits compared to the mesh-like ones.