The influence of temperature on the forming behavior of metal/polymer laminates in sheet metal forming

The influence of temperature on the forming behavior of an aluminum/polypropylene/aluminum (APA) sandwich sheet was studied. Shear and tensile tests were performed to determine the mechanical properties of the laminate and the component materials as a function of process temperature. The forming limit diagram (FLD) of the laminate was established for two different temperatures, and its springback behavior was examined in four-point bend and channel bend tests. Cup forming tests were performed at various test temperatures to determine the limiting drawing ratio (LDR) and the tendency for wrinkling at these temperatures. Although there was only a minor influence of temperature on the mechanical properties and the FLD values of the laminate, the bend test results reveal that springback can be reduced by forming at higher temperature. The decreasing strength of the core material with rising process temperature led to an increased tendency of the laminate to wrinkle in the heated cup drawing tests.

Knowledge based optimisation techniques for sheet metal forming die design

A knowledge based optimism technique has been developed to predict solutions for quality issues found in an initial draw die design. Post processing of the initial design yields all the features applying forces, and major quality issues. Using the geometric relationship between the two, a knowledge-base is interrogated to determine the possible corrective actions. These actions are then passed through a fast semi-analytical model to determine the level of change required. Results from a 2D forming are presented to highlight the advantage of the new algorithms over current optimisation techniques.

Sheet forming simulation for AHSS components in the automotive industry

The trend in the automotive industry towards new advanced high strength steels (AHSS), combined with the ongoing reduction in program lead times have increased the need to get tool designs right, first time. Despite the fact that the technology used by sheet metal stamping companies to design and manufacture tooling is advancing steadily, finding optimal process parameters and tool geometries remains a challenge. Consequently, there has been a transition from designs based largely on trial and error techniques and the experience of the stamping engineer, to the increased use of virtual manufacturing and finite element (FE) simulation predictions as an indispensable tool in the design process. This work investigates the accuracy of FE techniques in predicting the forming behavior of AHSS grades, such as TRIP and dual phase, as compared to more commonly used conventional steel grades. Three different methods of simulation, one-step, implicit and explicit techniques, were used to model the forming process for an automotive part. Results were correlated with experimental strain and thickness measurements of manufactured components from the production line.