Simulation Research On Multi-layer WAAM Process Based On Layered Variable Linear Energy Density

Large metal components used in aviation often have complex local structures and the materials used are difficult to deform.If these large components are formed using traditional method,there are problems such as long blanking process,many tooling molds,and severe wear of local mold areas,which greatly shortens the service life of the mold.In order to reduce production costs,the use of WAAM on the forged substrate to complete the formation of small areas with complex shapes can significantly reduce production costs.Therefore,it is of great significance to reduce the thermal effect of the WAAM process on the substrate and reduce the overall residual stress for realizing high performance,low cost and high efficiency manufacturing of large aviation components with complex shapes.The residual stress and the thermal effect of the additive process on the substrate are closely related to the process parameters of WAAM.Therefore,according to the characteristics of the simulation process of WAAM in ABAQUS software,the finite element automatic modeling and solving program of multi-layer WAAM process is developed.Based on the layered line energy density strategy,the influence of process parameters on WAAM process are studied by finite element simulation.The response surface method is used for optimization analysis to obtain the optimal process parameters.The main research contents and conclusions of the paper are as follows:? In view of the multi-layer WAAM process in ABAQUS environment,a finite element automatic modeling and solving program with the function of "element birth and death" is established.The pre-processing modeling program of multi-layer WAAM process is compiled.The parameterized generation program of heat source load and path control file is established.Design and write the graphical user interface(GUI)of the preprocessor.Write the registration file of finite element automatic modeling and solving program in ABAQUS software.? Through the comparison of simulation results,the applicability of the coupled thermal-stress analysis method to the process of multi-layer WAAM is analyzed.The results of analysis show that the sequential coupled thermal-stress analysis method with faster calculation speed can be preferred,when studying the overall temperature field of the multi-ayer WAAM process and the residual distribution inside the weld beads.In order to ensure the accuracy,Fully coupled thermal-stress analysis method should be selected for the calculation,when the research involves the distribution of residual stress in the weld toe area and the substrate.?The influence of process parameters on the temperature and residual stress in the process of WAAM is investigated.According to the strategy of layered variable linear energy density,the finite element simulation of WAAM process with three-layer weld bead was carried out,and the influence of various process parameters on the temperature and residual stress of the weld bead and substrate was studied.?Optimization of process parameters for multilayer WAAM process.Based on the Design-Expert 8.0 and the principle of BBD test design,and the three-factor and threelevel multilayer WAAM test scheme was simulated.According to the test results,the response surface function of WAAM process parameters to residual stress and temperature is established,and the optimal process parameter combination is obtained.The interlayer cooling time tc is 60s.The line energy density EL2 is 214.5J/mm.The line The energy density EL3 is 252J/mm.