Research On The Fast Simulation Method Of The Stress And Deformation Of The Large Structure By Electron Beam Wire Additive Manufacturing

As an emerging manufacturing technology,electron beam fuse additive manufacturing is widely used in aerospace,automotive,bioengineering and other fields.However,structural parts often undergo multiple and complex thermal cycles during forming,resulting in severe deformation and concentrated residual stress cracking.Fast and accurate prediction of stress and deformation of large-scale additive structural parts is the key to additive manufacturing.But at present,there is a lack of suitable algorithms to realize highprecision and high-efficiency simulation of large-scale additive structures.In response to this problem,this paper proposes a stress and deformation simulation method for large-scale structural parts based on equivalent heat sources.Combined with energy conservation,an equivalent heat source for rapid thermal-mechanical calculation of large-scale structures is constructed;and on this basis,an additive manufacturing simulation solver with completely independent intellectual property rights developed,and realized the prediction of the deformation and residual stress of a large short beam structure of a certain type of aircraft.The main contents are as follows:(1)Based on the heat flux distribution law and the principle of energy conservation,an equivalent heat source model is derived,and a fast simulation method for stress and deformation of large-scale additive manufacturing structures based on the combination of the equivalent heat source model and the Thermal-elastic-plastic is proposed;based on the thermal-mechanical coupling,the finite element solution format of the Thermal-elasticplastic theory is derived,and the Newton-Raphson iterative solution strategy for nonlinear problems is established,which improves the convergence speed of the finite element calculation.Taking the electron beam fuse additive forming process as an example,the simulation calculation of the equivalent heat source and the mobile heat source are respectively carried out,and it is found that the error between the structural deformation predicted by the equivalent heat source model and the actual measurement is within 10%,and the calculation efficiency is 17 times higher than that of the mobile heat source model.(2)Based on the CAE simulation software design concept,the frame structure is designed for the stress and deformation simulation of large-scale additive manufacturing structural parts,the operation logic of pre-processing-solver-post-processing is determined,the interactive format of the data files between the modules is unified,and the underlying data structure is constructed;based on the C++ programming language and a fast simulation algorithm for stress and deformation of large-scale additive structures,a full-process finite element thermal-elastic-plastic solver is established,which includes pre-processing parameters(material properties,heat source model and other process parameters)reading and identification,temperature,stress,strain matrix equation assembly and NR iterative solution,and specified format result file output and other functions.(3)The stress and deformation simulation of the large-scale complex electron beam fuse additive structure is carried out to verify the effectiveness of the equivalent heat source model and the solver.On a personal PC,a simulation analysis of residual stress and deformation of a large short beam structure of a certain type of aircraft is completed in 6hours,and the error of predicted deformation and actual measurement is within 10%;at the same time,the internal stress distribution law of the component is analyzed,the structural deformation trend after forming is studied,and the maximum area of deformation and residual stress concentration are determined,which provides a basis for process optimization.