Numerical Simulation Of Welding Cracks For Aluminum Alloy Plate Structure Based On XFEM

Aluminum Alloy welding structure is widely used in industrial production.However,Due to the local thermal effect on the structure in welding production process,it is easy to produce stress concentration,thermal deformation and thermal crack formation and propagation,which affect seriously the quality of Aluminum Alloy welding structure.Therefore,the temperature field,stress field and the parameters and influence factors near field of thermal crack are studied and mastered under local thermal effect in welding process of aluminum alloy structure.It is great meaning in theory and engineering to ensure the welding quality of Aluminum Alloy by guidance for inhibition of Aluminum Alloy welding structure deformation and crack.In this paper,the welding temperature field,stress field and near field parameters of aluminum alloy structure under the action of welding heat are studied.On the basis of thermoelasticity,the thermos-mechanical coupling model of the cracked aluminum alloy plate structure was established.The finite element numerical simulation method was used to calculate the temperature field and stress field of aluminum alloy flat plate structure by indirect coupling method.On the basis of this,the near-field parameters of the welding heating and cooling process of the aluminum alloy plate with an initial crack are calculated and analyzed.The variation of the near-field parameters of the aluminum alloy plate structure during the welding heating and cooling process is discussed.The results are studied to realize inhibition of Aluminum Alloy welding structure deformation and crack as theoretical basis.The main research contents are as follows:Firstly,based on the thermos-elasticity kinematics and heat conduction equation,the Gaussian heat source model was selected to establish the crack propagation dynamics model under the thermal process of aluminum alloy plate structure welding process.At the same time,based on extended finite element method(XFEM),the welding thermodynamic coupling model and the method of solving aluminum alloy plate structure under the action of mobile heat source are established.Secondly,the calculation and analysis model of the three-dimensional temperature field of the aluminum alloy with an initial crack was established.The distribution of temperature field during the heating and cooling process of the aluminum alloy with the initial crack was calculated and analyzed.The thermal distribution curve of the welding temperature field and the thermal cycling curve were obtained.The results of the welding temperature field of the aluminum alloy flat plate structure were verified by comparing the calculation and experiment during the welding process.Thirdly,the indirect thermodynamic coupling analysis method was used to calculate the temperature field as the load input,and the numerical simulation of the stress and strain field of the aluminum alloy plate structure was realized.The distribution of residual stress field in different paths was analyzed.The accuracy of the calculated results was verified bycomparing the calculation and experiment during the welding process.Fourthly,the near-field parameters of the thermal crack tip of the aluminum alloy plate under the local heat of the welding process were calculated and analyzed.Based on the near-field stress and stress intensity factors(SIFs)calculation data of the thermal crack tip,the dynamic variation laws of the near-field parameters of the thermal cracking of the aluminum alloy plate is analyzed and summarized during the welding heating and cooling process.