Topology Optimization Design Of Support Structure For Additive Manufacturing Considering Transient Thermo-Mechanical Coupling Effect

Addictive Manufacturing enables the fabrication of complex structures through the accumulation of layers of material.However,this process typically requires the addition of a support structure to avoid collapse of the large cantilevered part during manufacturing.In addition,the large amount of heat produced in the additive manufacturing process will leave a large temperature gradient,causing severe warping and residual stress,and it is necessary to properly add support structures to limit warpage and enhance thermal diffusion to reduce temperature gradient.The support structure generated by the existing additive manufacturing technology is usually in an excessively added state of the material,and the rational design of the support to reduce the manufacturing cost becomes a key issue.Introducing advanced topology optimization technology to design a support structure with excellent structural performance and being able to be manufactured is also a major technical difficulty.In this paper,we will focus on the design of support structures,consider the influence of thermo-mechanical coupling transient effect in the additive manufacturing process,and study to establish the theory and method of topology optimization design of thermo-mechanical coupling structures considering transient effect.Based on this,the design of the macroscopic configuration of the support structures using structural topology optimization method considering thermomechanical coupling transient effect and the design of the lattice micro structure configuration of the support structures for additive manufacturing are realized to realize the relaxation of the thermal deformation and thermal stress of the structural parts.Detailed research contents and results are as follows:(1)A structural topology optimization method that considers transient thermomechanical coupling effects.During the manufacturing process of additive manufacturing,the structure undergoes strong thermo-mechanical coupling and the transient effect is significant.The design of the support structure must take into account the effects of the thermo-mechanical coupling environment and transient influence.Firstly,this paper studies the configuration design method of the support structure.Based on the transient thermo-mechanical coupling analysis,a topology optimization model and solution method for thermo-mechanical coupling structure considering transient effects is established.In order to solve the problem of introducing a large amount of computation caused by the coupling effect,this paper explores whether the design of the support structure can be realized through the design of the optimal heat dissipation structure,and the structure design model with optimal heat dissipation performance is established.Through comparative analysis of specific examples,it is found that the results achieved by the method considering the transient effect are quite different from the configuration of the structure based on the optimal heat transfer performance design method.The design of the support structure needs to consider the effects of transient influence and thermo-mechanical coupling.(2)Macroscopic configuration optimization design of thermo-mechanical coupling support structure considering transient effects.The research established a design method to optimize the support structure by designing the macro configuration of the support structure.The transient thermo-mechanical coupling analysis model of the simulated additive manufacturing process was established,and the configuration design of the support structure under various printing conditions was studied.The main idea is to minimize the time integral of the instantaneous thermal deformation of structural parts as the optimization objective.The transient thermo-mechanical coupling topology optimization model is established considering the support structure volume constraint.The sensitivity of the objective function to the design variables is derived based on the adjoint method.The gradient optimization algorithm is adopted.The optimization model is solved and the physical problem is simulated by commercial finite element software.Finally,through optimization design and numerical analysis of typical examples,the two-layer scanning and round-trip scanning modes are simulated,and the top of the support domain is printed with obstacles and the upper surface is “convex” surface,and the corresponding optimal topological design of different support structures problems are obtained which verifies the effectiveness of the method.(3)An optimized design method for microstructure configuration of lattice material support structures for additive manufacturing.The research establishes a microstructural design method of support structures with lattice material.In the optimization design method of macroscopic support structure considering transient thermo-mechanical coupling,microstructures were introduced,and the performance of the support structure was studied by taking the ratio of parameters corresponding to the thickness variation of unit cell as a variable.Based on the squared sum of the surface displacements of the support structure as the objective function,a topology optimization model that can represent the best performance of the support structure is established.We find the optimal support construction method by comparing the upper surface deformation of the optimized single-cell filled support structure with the upper surface deformation of the macro support structure.