| The analysis of automobile durability and lightweight is an important part of the design and development of the automobile industry.It has become an important part of automobile structure design to use finite element method to design and transform its parts.The role of the lower support arm in the automobile structure is mainly divided into two aspects.On the one hand,it is used as a connecting component between the body and the wheel,and on the other hand,it is used to transmit forces and moments.Therefore,the structural performance of the lower arm is directly related to the operation stability,ride comfort and ride comfort of the vehicle.During the driving process,the lower arm is subjected to random dynamic excitation from the road surface,and it is extremely vulnerable to fatigue damage.Therefore,it is necessary to carry out the fatigue durability analysis of the lower arm.The research object of this paper is the lower control arm in the research and development stage.The dynamic and static performance analysis of the lower arm is carried out by combining the multi-body dynamics theory and the finite element technology.On the premise of meeting the design requirements,the fatigue life of the lower control arm is studied.According to the analysis results,the structure of the whole lower arm is optimized,and the lower arm structure meeting the requirements is obtained,which provides ideas for the design of other components.First,the vehicle model is established in Adams car.Four working conditions are selected:forward braking,cornering braking,non-directional curb impact and crater impact,and the tire contact force is calculated separately.The quasi-static load simulation of the suspension system is carried out,and the static load at the connection point is extracted.Based on the theory of pavement roughness,a C-level pavement model is established in Matlab software.Through the simulation of the vehicle model under the C-level road surface,the dynamic load spectrum of the connection position of the lower arm is obtained.Based on the 3D model of the following arm,a finite element model is established.The free modal analysis of the lower arm is carried out to obtain the first 12 vibration modes and natural frequencies,and it is verified that the lower arm will not resonate with the vehicle.The strength performance of the lower arm under four working conditions is simulated and analyzed.The analysis results show that the maximum stress is close to the yield strength of the material.It is necessary to carry out structural optimization design for it.Nastran is used to solve the stress results of the lower arm under unit load.It is imported into N code as input condition together with the load spectrum extracted under the excitation of road roughness for fatigue life prediction.Verifying whether the performance meets the design requirements.Finally,replacing the material of the lower arm.Topology optimization is performed on the lower arm to find the best design structure.The reconstructed lower arm is parameterized by mesh deformation technology.Five design variables are selected to design the test and establish the approximate model.Finally,the minimum mass and strength performance requirements of the following arm are the objective functions.Taking the strength performance of the four working conditions and the first-order modal frequency meeting the design requirements as the constraint condition.Establishing a multi-objective optimization model to find the optimal solution.A multi-objective optimization model is established to obtain the optimal solution.Comparing the performance before and after optimization,the results show that the performance of the optimized model is improved and meets the design requirements. |
