Prediction of Residual Distortion in Assembly of the Stamped Parts Joined by Spot Welding and Simulation of the Assembling Process

论文摘要

Resistance Spot Welding (RSW) is a joining process widely used in the industry, especially for the joining of metal sheets in the automotive industry due to it high simplicity and repeatability. As the body of automotive vehicles, assembled by this process, contains more than 3000 weld spots, it is a critical issue to understand the RSW, and especially the variations that may result of the process. Several parameters influence the dimensional quality of the assembly; the variation of the parts resulting from the precedent process steps (especially the stamping), the tooling variations and the distortion induced by the RSW at a local scale.On one hand, current works often assumed that the RSW do not induce sensible distortion due to the heat and so only focus on a dimensional analysis of the parts and tooling variations. On the other hand, many works dealt with the local simulation of the RSW but did not extend it to the global assembly. It should be of interest to combine the knowledge of both the local behavior of a weld spot and of the global distortion of structures due to tools and parts variation. Considering the assembly of metal sheets obtained by stamping, the most of the current state of the knowledge on RSW and distortion in assembly should be made.The work presented here focus on giving a global comprehension of the spot welding process. Firstly at a local scale with a Finite Element Analysis on the software SYSWELD of the local behavior of the assembled structure during the formation of a spot weld. Then the global behavior of a structure during the assembly is studied. Part variations resulting from the stamping process are measured and used to run a FEA on the commercial software ANSYS.

论文目录

• Abstract
• Table of content
• Part Ⅰ.Introduction
• Ⅰ.1.State of the research
• Ⅰ.2.Interest of the work and objectives
• Ⅰ.3.Presentation of the model
• Ⅰ.4.Structure of this report
• Part Ⅱ.Local Simulation of the Spot Welding process
• Ⅱ.1.General presentation of the Resistance Spot Welding
• Ⅱ.1.1.Spot Welding Process
• Ⅱ.1.2.The Welding Cycle
• Ⅱ.1.3.Process Parameters
• Ⅱ.1.4.Mechanism of the nugget growth
• Ⅱ.1.5.Microstructure of a weld spot
• Ⅱ.2.Numerical model of the Resistance Spot Welding
• Ⅱ.2.1.Introduction
• Ⅱ.2.2.Physical coupling
• Ⅱ.2.3.Governing equations
• Ⅱ.2.4.Contact formulation
• Ⅱ.3.Analysis and Results
• Ⅱ.3.1.Model
• Ⅱ.3.2.Results and analysis
• Part Ⅲ.Effects of the parts variation on the distortion of the assembly of stamped sheets
• Ⅲ.1.Introduction
• Ⅲ.2.Clamping & spring back
• Ⅲ.2.1.Spring back:principle
• Ⅲ.2.2.Clamping& spring back:illustration
• Ⅲ.3.Pre-stress method
• Ⅲ.3.1.Problematic
• Ⅲ.3.2.Illustration of the method
• Ⅲ.4.Results & Analysis
• Ⅲ.4.1.Flowchart of the simulation
• Ⅲ.4.2.Mesh,Material and Real constants
• Ⅲ.4.3.Constraining the model
• Ⅲ.4.4.Results
• Conclusion
• 致谢
• 参考文献