Process Constraint Study And Configuration Design Of SLM Based Self-Supporting Overhanging Structure

In recent years,Additive Manufacturing(AM)has achieved rapid development.Selective Laser Melting(SLM)is a metal additive manufacturing technology based on metal powder forming for powder beds,its biggest advantage is that it is possible to form a metal component that is close to 100% dense without being restrained by the shape of the structure.In the process of SLM,under the circumstance of without the support structure,the components that with the overhanging structure are more likely to generate imperfection such as deformation,slag,collapse.In order to improve the quality of the forming component,the method of most researches are limit the inclination angle,as a result,this method can produce a over-constraint and the structural design space will be limited.Therefore,in this paper,considering the influence of local features of the structure,based on the forming mechanism of selective laser melting,the influence of the inclination angle and geometrical dimension of the self-supporting overhanging structure on the forming quality of the component is studied,and establish the dependence relationship of the forming quality of the self-supporting overhang structure on the inclination angle and the geometrical dimension,and the constraint description model of the self-supporting overhanging structure is established.Then add the overhanging structural constraint model to the structural topology optimization model to build the self-supporting structural design method.The main research contents and results are listed as follows:(1)Analysis model of selective laser melting(SLM)additive manufacturing process.Combined with the various stages of the additive manufacturing process,the applicable CAE analysis tools are selected to assist in the design and research of the process.Based on the forming mechanism of the selective laser melting technology,The numerical simulation model of the selective laser melting(SLM)process is established based on the Simufact.Additive analyzed software and the manufacturing process is simulated and analyzed,and analyzed the stress contours and displacement contours,the tendency of stress distribution and displacement distribution were basically consistent compared with the existing experimental results,and the applicability of the results was verified.(2)Study on the dependence relationship of the forming quality of the overhang structure on the inclination angle and the local geometrical dimension.Aiming at the inclination angle and geometrical dimension of the overhanging structure,studied the effects of inclination angle and structure geometrical dimension on the residual stress and residual deformation of the structure after SLM forming.The results show that the larger the inclination angle of the overhanging structure,the smaller the deformation of the forming result;the larger the structure geometrical dimension,the larger the deformation of the forming result,when the inclination angle is sufficiently large,the degree of the influence of the geometrical dimension is smaller.(3)Self-supporting process constraint description model of overhanging structure based on SLM process.Based on the study of influencing factors about the overhanging structure,establish the allowing the inclination angle constraint model based on the local geometrical dimensions of the overhanging structure,a new self-supporting overhanging structure constraint description model is designed,and summarized a curve boundary constraint model,then establish a corresponding model and run a simulation by commercial software,and the feasibility of the design is verified,realize the design of the self-supporting overhanging structure.(4)Design method of self-supporting overhanging structure based on topology optimization.Based on the topology optimization design method and self-supporting structure,firstly,the topology optimization design is carried out,the lightweight structure which meets the requirement of mechanical properties is obtained,and apply the self-supporting overhanging structure constraints to the topology optimization results to achieve the self-supporting requirements,ultimately achieve lightweight design of the structure and self-supporting additive manufacturing design.A corresponding model is established in this paper,and the topology optimization design and self-supporting design are carried out,then perform a simulation analysis,the results verify the feasibility of the method.