Crash Forming of Structured Sheets with Wall Thicknesses Less Than 0.8 mm
The introduction of defined three-dimensional structures into sheet forming has several advantages compared to flat sheets.
The increase in heat transfer due to an expansion of the surface, an improved moment of inertia as well as the decrease in noise and the possibility of shock absorbency can be mentioned exemplarily. Within the scope of this ReCIMP project the application of structured ferritic chromium steel sheets for exhaust system insulation is investigated. To ensure a robust manufacturing process, the deep drawing of the sheets is analyzed numerically. Therefore, the experimental determination of the forming limit is necessary (see Figure a). Besides the Nakazima test, the principal strains are determined by tensile tests with grooved specimens. Due to the inhomogeneity of the three-dimensional structure (see Figure b), the strain distribution depends on the rolling direction of the sheets as well as the positioning of the grooves. This leads to a scattering in the forming limit diagram.