Topology Design Of Multi-material Compliant Mechanisms Based On Parallel Strategy

With the development of science and technology, people put forward higher and higher requirements for the use of materials, single metal and non-metal or organic polymer materials are often unable to meet the needs of people’s design, and multifunctional materials composed of a variety of different material properties has increasingly extensive application prospect in engineering practice. Therefore, how to reasonably configure all kinds of materials and holes with different characteristics, and optimize the structure of the microstructure of the material, then get the new structure that can meet the design requirements and save the material will be favored by people. Under this background, this paper studies the topology optimization design of compliant mechanism based on parallel strategy.Firstly, the linear additive theory of material stiffness is discussed in detail, which provides a theoretical basis and a reasonable proof for the linear calculation of the stiffness in the multi-material topology optimization. Then the hierarchical optimization theory from the control decision making system is introduced, and the optimization problem of the multi-material compliant mechanism is solved by the combination of the most extensive application of the two-level hierarchical system theory and the topology optimization theory. A parallel method for solving topology optimization of compliant mechanisms with multiple materials is presented, which not only allowing the original complex multi-material optimization problem to be reduced to set of low order single-material optimization sub-problems, but also solving a plurality of single metal material problems independently and efficiently in parallel. A stiffness spreading method is proposed to solve the problem of over-saturated elements in the topology optimization of multi material compliant mechanism with parallel strategy. A number of discrete single material problems can be coordinated by this method, finally obtained the solution of multi-material optimization problems.On the basis of the parallel strategy theory, a kind of new material-target output corresponding relation with the setting of the one-to-one corresponding relationship between the material and the output target at the start of the optimization is presented, and the multi-output optimization problems in the field of multi material compliant mechanism is studied. Based on the parallel theory and the sequential coupling analysis method, a method of multi-material thermo mechanical coupling topology optimization is presented, which focuses on the thermo mechanical coupling problem of multi-material thermal actuator design problem and the reliability of thermo mechanical coupling topology optimization problem.Finally, several methods of eliminating the gray units in the topology optimization based on the SIMP are introduced, a comparative analysis of the advantages and disadvantages of them is made. Then a boundary reconstruction algorithm is proposed, which can ensure the volume ratio constantly and mainly including three aspects of gray scale unit contraction, boundary movement after boundary element searching and boundary smoothing. In the stage of the boundary smoothing, three spline interpolation is used to smooth the new boundary. At last, this method is applied to the reconstruction of the boundary of the multi material compliant mechanism.