| With the aging of our country becoming more and more serious,the physical function of the elderly gradually degenerates with the growth of age,and the lower limb mobility becomes worse.As a tool to assist the elderly walking or rehabilitation training of the lower limb,walker is in great demand,and there are many kinds.At present,there is a single function of Walker products in the market,and the design and application are often out of touch,resulting in the product can not be well adapted to the elderly,the training effect is poor,and there are certain security risks.As the most commonly used rehabilitation aids for the elderly,the existing products are often designed according to experience,lacking rigorous theoretical basis.How to ensure safety on the basis of functional realization is particularly important.In this thesis,a kind of powerless limb coordinated walking aid for the elderly designed and developed by our research group is taken as the research object,and based on topology optimization method,the weak links of walker are optimized.Topology optimization mainly relies on algorithms.At present,there are many topology optimization algorithms.By comparing the advantages and disadvantages of various algorithms,this thesis adopts bi-directional evolutionary structural optimization algorithm(BESO),which takes volume fraction as constraints and maximum stiffness as the optimization objective,and realizes the topology optimization design of seat support components by coordinating the various factors that affect the optimization.Firstly,the system model of the powerless four-limb coordinated walker for the elderly is established,and the finite element analysis software ABAQUS is used to simulate and analyze the two states of the walker,i.e.the whole standing and sitting posture.Through the whole force analysis,it is found that there are serious stiffness and strength problems in the seat supporting parts,in order to further refine the analysis and re-analysis.Comparing the design results,the finite element model of the seat supporting parts is established separately,and the accuracy of the finite element model is verified by modal experiment.Next,the original optimization model of seat support parts is reconstructed,and the BESO algorithm is used to optimize the topology.Finally,the topology optimization results are redesigned from the point of view of processing and cost.The newly designed seat support parts are compared with the original structure,and the other unreasonable parts of the walker are redesigned.The results of topology optimization guide the redesign of the seat supporting parts.The stiffness and strength of the new structure are significantly improved.The maximum comprehensive stress is reduced from 232.8 MPa to 69 MPa,and the maximum comprehensive displacement is reduced to 0.33 mm.The redesigned Walker ultimately improves the stiffness and strength of seat support components,chassis structure,emergency braking and comfort of standing posture training,and the overall mechanical performance is greatly improved compared with the original structure,which verifies the rationality of the redesign. |
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