Rigid Element Analysis For Stamping Springback Simulation

Spring-back is a ubiquitous phenomenon during cold pressing. Spring-back usually cause a product's dimensions different from the designing dimensions more or less. How to deal with the departures from designing dimensions is an important problem which engineers are working on all the time. Take stamping for an example, while designing reasonable dies, designers will do with repairing parameters which are got from experiences at product designers'request on dimensions. Then die designer try on the die from the first design. If the experimental results doesn't content peoples'need, die designer modify the die designing parameters according to the last experimental results and try on the new die. They do in this cycle over and over until experimental results are satisfying. That's so time-consuming. If designers predict the spring-back nicely, they can design with more accurate parameters, and all that cause to a shorter die designing cycle, less cost and more benefit.In these years computers are used in engineering more and more, especially to simulate and predict. Successful simulation means to give a demonstration of the performance in manufacturing processes vividly and offer designers parameters accurately, so that designers can add precise repairing parameters while designing dies. Some finite element analysis software can already stimulate stamping forming and spring-back. These kinds of software calculate in ways which represent some simulation models and yielding principle which are gained from some kind of material models, so the calculation results all are worth referencing very much. In chapter 3, I presented two kinds of finite element model and three kinds of yielding principle. But representationlism of a model also determines its localizationlism. So nearly every kinds of simulation is not accurate in all fields all the time.In the incremental-iterative analysis of elastic nonlinear structures, great saving in computation can be achieved if distinction is made between the predictor and corrector phases. In this study it will be demonstrated that the use of the linear stiffness matrix [k e ] and a rigid-body qualified geometric stiffness matrix [kg] in the predictor is sufficient for most purposes.The actual calculation in One-step aims at natural deformations and neglects rigid displacements. Though generally the rigid displacements constitute a great portion of the incremental displacements of each element of the structure, the calculation results are not accurate all the same. In chapter 4, I presented"the Rigid Element Method"to demonstrate the rigid displacements. In chapter 5, I demonstrated the calculation course of both natural deformation and rigid displacement briefly. At last in chapter 5 I demonstrate the difference between two kinds of calculation and the benefit of the new one.