Topology Optimization Design Of Additive Manufacturing Parts Considering Thermal Effect

The current carbon emissions from the aviation transportation industry account for about2% of global carbon emissions,and the growth rate is fast,which is one of the key areas for energy saving and emission reduction.Carbon reduction in the aviation industry can be done from aircraft weight reduction and structural light weight,in which the aircraft single aero engine weighs about 2 tons,and its quantification is currently a hot issue of concern for the industry and scholars.And a single aircraft engine in about about 3000 ～ 4000 blades,the total number of the largest proportion.Due to the traditional manufacturing process limitations,it is difficult to achieve a higher level of blade lightweight.The combination of laser-selective melting technology and topology optimization design method can realize the lightweight design and fabrication of blades.However,there exists a more serious heat accumulation phenomenon and complex thermal effect process in the additive manufacturing process,which has a certain impact on the blade forming effect.Therefore,the research of SLM and topology optimization design method for aero-engine blade has further improved the adaptability of topology optimization design results and additive manufacturing technology,which is of great practical significance for the low carbon,green and high quality development of China’s aviation industry.Based on this,this thesis takes an aero-engine low-pressure turbine blade as the research object,and proposes an aero-engine blade SLM and topology optimization design method considering thermal effects for its extreme service conditions and severe demand of force load,the main research contents are as follows:(1)To solve the problem that the thermal effect of SLM process is complex and variable,and the dynamic nonlinear transient heat transfer change law is still unclear,establish the thermal coupling mathematical model of aerospace blade SLM forming process by applying heat conduction and thermoelastic deformation related theories,explore the evolution law of temperature distribution and stress distribution inside the deposition layer,reveal the thermal accumulation phenomenon in the forming process,and lay the theoretical foundation for the subsequent establishment of a topology optimization model of aerospace blade considering thermal effect.(2)To address the problem that it is difficult to combine the requirements of multiobjective topology optimization design considering thermal load and structural stiffness,the topology optimization model of the aerospace blade considering thermal effects is constructed with the end of SLM forming and the temperature distribution of blade service conditions as the thermal load,and the objective is to improve the mechanical properties and lightweight of the blade under thermal load to obtain the optimal configuration of its topology optimization design.On this basis,a reconstruction method based on projection and curve fitting is proposed to solve the reconstruction problem of internal holes and closed cavities of the blade optimization results and to meet the requirements of the optimized aerospace blade SLM additive manufacturing process.(3)To verify the effectiveness and feasibility of the topology optimization design method proposed in this thesis,the optimal combination of process parameters was explored to realize the optimized aeronautical blade SLM additive manufacturing with the optimal configuration.By comparing the quality before and after the optimization,as well as the mechanical properties and microstructure,the effect of the topology optimization design method and the improvement of the mechanical properties of the parts were verified.