Research On The Optimization Of Hard Points Of The Crossover's Rear Independent Suspension Based On Motion Characteristics

The suspension of a car is an important assembly.Its main task is to transmit the force and torque appearing between the wheel and the vehicle body,to reduce the impact load from the uneven road to the vehicle,and to attenuate the vibration of the bearing system.The design of suspension affects people's driving experience directly.The multi-link independent suspension can not only enhance the ride comfort of the vehicle,but also ensure vehicle handling and driving stability by adjusting hard points of control arm links to constraint wheel positioning parameters,so the assembly is increasingly concerned by consumers and its application in the rear suspension will become more common.Therefore,it is very important to strengthen the optimization of the multi-link independent suspension system to enhance the quality of the vehicle and expand the product market.In this thesis,the multi-link independent suspension assembly of a crossover vehicle was taken as the research object,and multi-objective optimization methods of hard points of the suspension were studied to minimize the variation range of rear wheel positioning parameters,reduce the rear tire wear and enhance the rear suspension movement characteristics.Firstly,the kinematic theory model of the trapezoidal multi-link independent suspension was established according to the connection hard points,and its characteristics were analyzed by Matlab to determine the design goals.Secondly,a virtual prototype model of the suspension was established in the Adams/Car according to the three-dimensional model and the prototype datas.The simulation analysis of Parallel Wheel Jump was done to verify the correctness of the theoretical model,and the sensitivity of hard points was analyzed to determine 4design variables of the optimization problem.Thirdly,the DOE test design optimization based on the virtual prototype model,the multi-objective genetic algorithm optimization based on the theoretical model and the multi-objective genetic algorithm optimization based on RSM approximation model were used to solve the multi-objective optimization.Their optimization accuracy and application characteristics on the rear suspension optimization problem were analyzed,and the optimal hard point adjustment scheme was determined so thatthe variation range of the toe angle,camber angle and wheel track was reduced by63.1%,29.8% and 10.9% respectively.Finally,the Adams/Car vehicle virtual prototype models were established,concluding the virtual model of the rear suspension.The simulation and evaluation of the vehicle's handling stability were carried out according to the national standard.The results showed that the hard-poitnt adjustment scheme can ensure vehicle handling stability while maximize the optimization of suspension characteristics,which verifies the feasibility of the suspension optimization scheme.