Experimental study of the change of stiffness properties during deep drawing of structured sheet metal

The structured sheet metals with hexagonal based contour and free formed bump geometry have several advantages compared to smooth sheet metal. The most important benefit is the improved stiffness. During processing of the structured sheet metals the stiffness properties are changing due to transformation of the initial geometry. In this study the change of the stiffness of the structured sheet metal during the deep drawing is investigated. Two cases are considered: deep drawing and compression. The results show a significant change of the geometry and mechanical properties of the structured sheet metal in both cases. The relationships between the flattening and stiffness properties in both cases were discussed in detail. Moreover the presented results allow the determination of the process limits for the deep drawing of the structured sheet metal to secure their improved stiffness.