Research On Topology Optimization Method Of Self-supporting Structure Based On SUSAN Operator

At present,in order to give full play to the advantages of high degree of freedom of structural topology optimization and high degree of freedom of reinforced manufacturing,the research of structural topology optimization for incremental manufacturing has become a research hotspot in the field of structural optimization.However,due to a series of process constraints in increasing material manufacturing,such as setting drape angle constraints to avoid the introduction of additional supporting structure in the suspended area of the structure,and minimum feature size constraints in manufacturing equipment,it is necessary to consider the above process bundle in topology optimization.At the same time,the performance of structural printing parts will change with different structural printing direction,so it is of great significance to consider the influence of molding direction on the structural performance of topology optimization.In addition,in order to improve the anti-corrosion performance of the structure,electroplating,spraying and other processes often treat the surface of the structure after forming,so it is necessary to carry out the topology optimization of the coating structure under the constraint of the manufacturing process.In view of the above three problems,this paper studies the topology optimization of self-supporting structure considering minimum feature size and drape angle constraints,the topology optimization of self-supporting structure considering forming direction and the topology optimization method of coating self-supporting structure.The main work is as follows:Firstly,a variable radius filtering projection method is proposed.The effective control of the minimum feature size of the structure is realized.This method combines traditional filtering method with Heaviside function,sets different filtering radius,uses Heaviside function and improved Heaviside function to control the minimum member and minimum cavity size in the structure respectively,and then weakens the filtering effect of structural boundary by controlling the weight function of element density gradient,and obtains better filtering effect and clear structural boundary under larger filtering radius.As a result,the topology optimization structure,which meets the manufacturing process constraints of minimum feature size,is realized.In this method,a topology optimization model based on SIMP method is established,and a numerical example is given to verify the rationality and effectiveness of the proposed variable radius filter projection method.Then,a structural drape angle constraint description method based on the minimum singlevalued segment assimilation kernel operator is proposed,and combined with the SIMP method;the topology optimization design of self-supporting structures is realized.In this method,the minimum single-valued assimilation kernel operator is used to identify the boundary contour of the structure,the gradient vector is used to represent the change of boundary density,and the drape angle constraint is described by the angle between the gradient vector and the forming direction.Combined with the SIMP method,a topology optimization model of self-supporting structure considering drape angle constraint is established,and the rationality and effectiveness of the proposed method are verified by numerical examples.Then,a topology optimization design method of self-supporting structure considering the optimal forming direction is proposed.In this method,the optimal forming direction is obtained by identifying the boundary of the traditional topology optimization structure,and the topology optimization model of self-supporting structure based on the forming direction is established.The rationality and effectiveness of the proposed method are verified by numerical examples.Finally,a topology optimization method for coated self-supporting structures is proposed.In order to solve the problem that the surface of the structure is easy to corrode and affect the performance of the structure,the surface layer of the structure is identified by the space density gradient,and the surface coating and matrix are separated by the filter projection method,and the structure is equivalent to the surface coating and the base layer structure.A self-supporting topology optimization model with surface coating structure is established,and the rationality and effectiveness of the proposed method are verified by numerical examples.