| Abstract Scope |
This presentation will review the state of the science of metal forming with respect to simulation of the deformation process. Reliable models are required to describe the constitutive behaviour and failure modes (necking and fracture limits) for the complex deformations that automotive metal components are exposed during the manufacturing process and later in the performance of the vehicle. The demand to reduce, minimize, and eventually eliminate the need for physical testing of manufacturing processes and the performance of products through simulation in early stages of the VDP has raised the bar on what is considered acceptable level of reliability of simulations. This has increased the need for more advanced material models, and consequently more advanced testing and test methods. After demonstrating the improvements in accuracy of predictions that can be achieved with more advanced constitutive and failure models, Digital Image Correlation Technology will be demonstrated to enable the acquisition of orders of magnitude more data from otherwise traditional material tests routinely used to characterize automotive sheet metals. The orders of magnitude increase in data from each test specimen in which DIC Technology is employed is compared what information can be obtained from these tests without DIC to traditional standard tests. In many cases, DIC Technology enables measurement of properties and employment of analytical methods that are simply not possible for conventional test methods. For example, it will be shown how a single uniaxial specimen can provide information on the variability of important material properties, such as its strain hardening and R Values, which are fundamental to the calibration of plasticity models. The same monotonically loaded specimen can be used to measure the changes to elastic properties with plastic strain model. It can also be analysed to decouple the strain-rate and strain hardening effects. Lastly, DIC Technology enables the detection of the onset of localized necking, which is not even possible with conventional uniaxial tension testing. Necking is the most important failure mode in sheet metal stamping, and DIC Technology makes it practical for the first time to reliably measure the necking limit in every test we conduct, and making it practical, for the first time, to calibrate an anisotropic necking limit for sheet materials. To realize all these benefits would require many more uniaxial tests, or other types of tests, or tests done under non-monotonic loading conditions, to acquire the same amount of information that DIC enables to be acquired from a single test specimen. |