Numerical Simulation And Bridging Laws Of Welding Pore During Linear Friction Welding

Linear friction welding is an intense thermal coupling process. The materialexperience repeated deformation, flow, tearing, and local welding. When theplastic flow layer around the welding head had a certain thickness, the materialmight slit in the plastic zone or inside the plastic zone-heat affected zoneinterface due to the uneven deformation, and it is always accompanied with thegeneration of defects such as pores and bridge. It is inevitable to generate themicroscopic defects during the friction welding. Therefore, the welding processcan be seen as a process of micropore descending to zero. These microporousbridging defect law is changing under different thermodynamic conditions. Toidentify the key factors to bridge the micro defects in different processes forimproving the friction welding quality is important.But the linear friction welding process is very complex. A lot of physicalphenomena and mechanisms as the main research questions in this topic-bridging the law microporous defects is difficult to directly observe and analyze.We need to analyze them from a microscopic point of view known throughexperimental means. Owing to plastic deformation and strong thermal coupling,the measurement and characterization of the joint stress, strain field, temperaturefield is difficult. So it is particularly important to choose the right numericalsimulation method. This topic will be simulated using finite element method forlinear friction welding process in the evolution of pore defects simulation toanalyze the effect of process parameters on the material to plastic de formation,plastic flow and defect bridging process. The summary of the law of microporousbridging defects and the optimization of linear friction welding processparameters would improve the quality of linear friction welding and provide atheoretical reference at the same time.In this paper, different changes in pore size of defects were simulated indifferent temperature, pressure, vibration frequency, amplitude, upset pressureand other process parameters. To summarize up, we get that Micro Bridging ismore sensitive to temperature than others. That is to say that the temperature ofthe material has a significant effect on the time variation during bridging. However, the temperature is not an external process parameters, but a combinedresult of the pressure, the amplitude and frequency of vibration. In these threeparameters, the pore defects have similar sensitivity coefficients on the vibrationfrequency and amplitude, but the biggest sensitivity coefficients on the pressure.However, welding stress is easy to form welding defects during the linear frictionwelding process. The amplitude of the actual welding process tend to be small,about a few millimeters. Although the increase in the frequency of the periodicvibration to some extent promotes the plastic deformation and flow of thematerial, the oscillation frequency increases as the rate of deformation of thematerial increases, the deformation resistance of the material is improved, andtherefore expected to be suitable for plastic deformation and interface layer, andthereby improving the quality of the joint. Ultimately, we believe, it can be usedthat with a large high pressure welding periodic vibration frequency, frictionwelding while forging force can be applied to the top of a large bridge. And itwill also help promote micro defects and improve the quality of linear frictionwelded joints.