Optimization Design And Method For Self-supporting Structure Of Metal Additive Manufacturing

SLM(selective laser melting)is one of the most wildly used metal addictive manufacturing technologies.It is able to manufacture metal components with complex geometries,and shorten the processing cycle,which is beneficial to the industrial development.This paper is to propose an approach to achieve self-supporting structural design for in SLM process.Main tasks as follows:First,through the stainless steel metal powder material(stainless steel 316L)in the Riton D-280 SLM metal 3D printer,a large number of test members were printed,and the relationship between the overhanging angle of the metal member and the printable overhang height is investigated to figure out the maximum allowable overhang heights under different overhang angles.A standard database between the height of the overhang and the overhanging height is found to be self-supporting and can be self-supporting with a periodic curved boundary.Next,statistical data on the relationship between the overhanging angle of the metal member and the printable overhang height is fitted to the sample data using a polynomial fitting technique to establish an explicit expression between the overhanging angle and the overhanging height,and based on both The relationship between the designs creates a periodic curved boundary to achieve an infinite printable height.Then,the self-supporting structure optimization algorithm for SLM technology is implemented through MATLAB programming,and the corresponding structure optimization column and drape feature filtering mechanism is established.In order to apply the periodic bending boundary to the design of the overhanging feature of the self-supporting structure,based on SIMP(Solid Isotropic Material with Penalization),the boundary filtering mechanism of the overhanging feature is embedded in the topology optimization process.A set of boundary rule techniques are used to determine the manufacturing and self-supporting structural boundaries to eliminate unsupported materials where the overhang angle is less than COA.The boundary element of the component filters the original zigzag boundary into smooth curves and straight lines with a designed periodic curved boundary and a 45° oblique straight line.We creat the self-supporting optimized structure and apply it to the optimization design of the specific example.Finally,the optimal design components of 2-3 typical structures(MBB-beam and cantilever beam)are printed to verify the validity and correctness of the self-supporting design method of the metal component structure through SLM.The examples with smooth boundary made by metal 3D printer have no collapse of the overhanging surface during printing,and both have smooth and smooth boundary surface,which further validates the validity and correctness of the proposed method.The objective of optimization is to minimize the compliance of components.The results show that the method can be effectively controlled the overhanging features and the optimized design boundaries can be successfully manufactured with self-supporting.The self-supporting optimization design method of the structure is a structural optimization method for the SLM,and can meet the processing requirements of the components and designing a high-quality structure at the same time.The method can be further applied to the other metal 3D printers and the design is optimized according to the parameters of each printer through the boundary design scheme,which can realize structural self-support.