Research On Reliability Topology Optimization Method Considering Stress Constraints And Its Application In Automobile Structure Desig

Due to the continuous growth of car ownership,energy consumption and environmental pollution problems are becoming increasingly serious,and achieving energy saving and environmental protection of automobiles has become a necessary path for the development of the automotive industry.Lightweight design has significant energy-saving and emission reduction effects on both traditional and new energy vehicles.Topology optimization,as a conceptual design method,is in a key position in the field of automotive lightweight design.In addition,there are various uncertainties including material parameters and loads in the design process of automotive structures,and these uncertainties can affect the strength performance of the structure and even cause structural strength failure.In view of this,this paper proposes a reliability topology optimization method considering the strength design requirements and applies it to the lightweight design of automotive component structures,with the following main research contents.(1)A topological optimization method for the probabilistic reliability of the structure considering stress constraints.Based on the case that the structural load uncertainty satisfies the probability distribution,the probabilistic reliability topology optimization design is achieved by using density filtering technique and method of moving asymptotes(MMA)with the objective of minimizing the structural volume fraction and the constraints of structural flexibility,displacement and stress,respectively.The obtained reliability topologies have clear boundaries and are significantly different from the deterministic ones,and satisfy the permitted reliability constraints.The results of deterministic and reliability topology optimization under different constraints are compared to verify the economy and effectiveness of the reliability topology optimization design of the structure considering the effect of load uncertainty on the strength of the structure.(2)To carry out the non-probabilistic reliability topology optimization design of multimaterial structures considering stress constraints.A multi-material interpolation model for continuum structures is constructed based on ordered-solid isotropic microstructures with penalization(Ordered-SIMP).The uncertainty case with limited information on loading variables is described by constructing a convex set ellipsoidal model.The sensitivity derivation is carried out with the help of the concomitant variable method,and the relative density design variables of the cell are mapped with the help of the Heaviside function in order to constrain the minimum size of the multi-material topologically optimized structure and obtain a clear topological configuration.Finally,the topological optimized design of nonprobabilistic reliable 2D and 3D multi-material structures based on ellipsoidal model is realized under stress constraints.The numerical example shows that the proposed method can achieve the optimal arrangement of structural materials to meet the requirements of different reliability indexes under the "finite uncertainty" of structural load variables,taking into account the different properties of the selected materials.(3)A study of hybrid reliability topology optimization with probabilistic-ellipsoidal model considering stress constraints is conducted.Considering the scenarios where random load variables and finite uncertain load variables exist simultaneously,the uncertainties of the variables are quantitatively analyzed by a probabilistic-ellipsoidal hybrid model,and a mathematical model of reliability topology optimization is constructed based on it.The hybrid reliability topology optimization is solved in two formats,front-decoupled and backdecoupled,in the numerical example,and the results are compared and analyzed.Finally,the reliability topology optimization design of the automotive steering knuckle is carried out considering the mixed uncertainty of the load variables under the steering and braking conditions during the operation of the vehicle,and the feasibility and good application value of the proposed optimization design method are further verified.