Speaker
Description
With the increased focus on reducing carbon emissions in the automotive industry, more advanced materials are introduced to reduce the vehicle weight, and more complex component geometries are designed to both satisfy customer demands and to optimize the vehicle aerodynamically. With the increase in component complexity, the strain paths produced during the forming operation of car body components often display a highly non-linear behavior which makes the task of failure prediction during the manufacturing feasibility studies more difficult. Therefore, CAE engineers need better capabilities to predict failure induced by strain path nonlinearity.
In order to develop these capabilities however, an experimental setup that can generate non-linear strain paths is needed. This study proposes a new simple tool design for the pre-straining of sheet metal in the three main loading directions – uniaxial, plane strain, and biaxial. The tool is designed to allow for subsequent Nakajima testing with a reasonable uniform strain distribution in a circular area Ø200 [mm] allowing for full-sized Nakajima specimens to be blanked out of the deformed specimen. From the blanked Ø200 [mm] specimen, further blanking operations can be performed to reduce the width of the Nakajima specimen to obtain all needed directions for the characterization of the pre-strained Forming Limit Curve, or reproduce critical strain paths i.e. strain paths direction changes with respect to the rolling direction of the sheet.