Simulation On The Cylinder Expanding Processing And Research Of The Crack Generation Mechanism

In recent years, mechanical expanding manufacture is widely applied in actual production, various defects will generate in shaping process, and production can not proceed in serious situation. Therefore, numerical analysis for the machining process, understanding the mechanism of emergence and development of defects in the course of processing are especially important.At first, the thesis summarizes fundamental theories, analysis methods and development conditions on the research of crack. The analysis of basic principals and application methods on finite element (FE) dynamic simulation is done. In this thesis, critical technologies including control equation, FE discretization in space and crack simulation etc are discussed importantly.By means of simulation analysis on 2D fracture modal, this thesis makes contrast research on classic formula calculation on stress intensity factor and FE analysis. The accuracy of fracture problem analysis through FE is verified by comparison on calculation result.The thesis uses 3D nonlinear FE analysis technology and ANSYS/LS-DYNA module to dynamically simulate bulging process, then gets distribution of stress and displacement quantities. In the thesis, reliability of process simulation on cylinder expanding by FE analysis software is verified, then dynamic simulation on generation and extension of crack is done.At last, extracts results of crack simulation and analyze the mechanism of crack generation by matching variation curves through post processor. Effects on crack generation by process parameters (including angle of cone on core plate and element failure length) are obtained. It provides basis for the purpose of mold structure optimization and reduction on defects generation better in bulging process.