Research On Sheet Metal Forming Limit Stress Diagram

Forming Limit Diagram (FLD) is widely used as the criterion in sheet metalforming analysis. But FLD cannot be used to predict when and where the wrinkle orfracture will occur accurately during the forming process, especially in the applicationof multi-stage sheet metal forming process because of its strain path dependentcharacteristic. Some foreign scholars developed the concept of Forming Limit Stress Diagram(FLSD) on the basis of FLD. FLSD is considered as strain path independent。Moststudies are focused on theory now. Only some scholars researched the transformationfrom FLD to FLSD based on the data collected from different documents, and explainthe deviation as test error. The FLDs under linear and non-linear strain path were measured respectively inthis project, and were transformed to FLSDs according to the plastic theory。Researchwill be carried out to check if the FLSD is really strain path independent. The innovation of this research is to take the lead in passing an all-sided judgmenton the replacement of FLD by FLSD as the criterion in sheet metal forming analysis. This project concluded that the FLSD is strain path independent and can be use as abetter criterion in sheet metal forming process, especially in the application ofmulti-stage sheet metal forming.