THE USE OF FEA PACKAGES IN THE SIMULATION OF A DRAWING OPERATION WITH SPRINGBACK, IN THE PRESENCE OF RANDOM UNCERTAINTY

The springback response on a stamped part, calculated by finite element analysis has been evaluated taking into account the uncertainty of some process conditions. In fact, in the simulation of sheet metal forming and springback, a traditional deterministic approach is not able to take into account the uncertain physical variations related to material characteristics, friction conditions, tools active surfaces status, etc. During sheet metal forming operations many different sources of non-controllable process variations usually display their effect leading to a degree of uncertainty in the final parts’ quality. For this reason, statistical tools and methods are increasingly being used in combination with FE numerical simulation. Then, if one of the purposes of process design is to study and model robustness or reliability of a given process in aleatory conditions, a CAE study might become a feasible way to do it. Today, the evaluation of the performances of a sheet metal stamping process, under uncertainty of the main variables, is possible using several commercial FEA packages. These software tools automatically allow the pre-emptive evaluation of the robustness of technological decisions and the process sensitivity to a random variation of uncontrollable parameters or conditions. For accurate calculations these innovative numerical approaches usually require a considerable amount of computational work both in terms of CPU time and in terms of number of CPUs. A specific experimental and numerical activity has been developed in order to better understand the technical capabilities in terms of process simulation in stochastic conditions.