Simulation of the Manufacturing Process of Sheet Metal Assemblies

Sammanfattning: The increased complexity of products and narrow lead times for product development have intensified the use of virtual prototyping, also called simulation-based design. The simulation of each individual manufacturing process is an important part of product development, However it is also necessary to study the complete sequences of manufacturing processes. By studying the complete sequence, the properties of the entire manufacturing process and the final product can be evaluated. The quality of the results from each individual process simulation is improved by supplying initial conditions that closer match the reality. Thus, greater benefits can be gained from using simulation as a tool within process and product development.In this thesis the manufacturing process chain of a sheet metal assembly is studied. A methodology of sequentially simulating each step in the manufacturing process of the assembly is proposed. Each step of the proposed methodology is described, and a validation of the prediction capabilities is performed by comparisons with results from a physically manufactured assembly. Furthermore a simulation based sensitivity study is performed in order to investigate the influence of the forming history on the predictions of the assembly properties. In the study, several simulations of the assembly stage are performed in which different types of forming histories are retained from the forming stage.This study demonstrates that it is possible to predict the final shape of an assembled structure by using virtual prototyping. It is found that the most influential factor from the forming stage is the residual stress state. Especially for components with a more complex geometry in which large residual stresses can be retained. It is also shown that it is important for the quality of the prediction to retain as much information as possible from the previous manufacturing steps. The proposed simulation procedure is a useful tool during product development phases in order to evaluate the properties of both the manufacturing processes and of the final assembly.