Uncertainty Analysis And Optimization Of Automobile Suspension Considering NVH Performance

NVH(vibration,noise and harshness)performance is an important indicator for evaluating the comfort of a car.When the car is running,the interaction between the tire and the road is one of the main sources of car vibration and noise.The suspension system is a key connection part of the body and the chassis,and its design is of great significance to the NVH performance of the vehicle.Traditional suspension system design is based on certain material parameters,geometric characteristics and boundary conditions.In the actual manufacturing process,due to manufacturing errors,measurement factors,process level limitations and other reasons,the actual parameters will fluctuate around the design parameters,resulting in uncertainty in the NVH performance of the vehicle.The uncertainty values in the suspension system are small but numerous,and the coupling effect between the various uncertainty parameters will make the suspension system NVH performance consistent.Therefore,it is necessary to carry out systematic research on the uncertainty of suspension NVH characteristics to solve the problem of suspension NVH performance instability caused by uncertain parameters.In response to the problem,this paper uses the probability uncertainty model to analyze and optimize the vehicle NVH performance based on the suspension system.The main research contents are as follows.(1)The mathematical model of the two-degree-of-freedom suspension system was established and the mathematical model of random road surface was established by the filter white noise method and the harmonic superposition method.The suspension response under random road excitation is analyzed,and the suspension system vibration characteristic index is selected to analyze the suspension vibration response in the time domain and frequency domain.After analyzing the vibration characteristics of the deterministic suspension response,introduce probabilistic uncertainty parameters to the system and perform uncertainty analysis on the system.The analysis results show that the probabilistic uncertainty of the suspension system parameters will cause the suspension system vibration characteristics Volatility and probability distribution.(2)Established the vehicle NVH acoustic-structure coupling finite element model to evaluate the NVH performance of the suspension system.Based on the finite element model of the entire vehicle,the suspension system bushing stiffness was optimized by the wheel center force method combined with the transmission path analysis,and the maximum sound pressure level of the driver’s right ear position of the finite element model was successfully reduced,indicating that the optimization of the suspension system parameters can improve the overall Car NVH performance.Using the road spectrum loading method combined with flexible tires to simulate the NVH of the whole vehicle,it realizes the NVH performance simulation method based on the virtual test yard without the test vehicle for road testing.(3)In order to solve the problem that the calculation cost of the finite element model of the whole vehicle is too large,a fast calculation model for the suspension NVH performance is established.Sensitivity analysis was carried out on key parameters of the suspension,and appropriate parameters were selected as input parameters of the fast calculation model based on the sensitivity analysis results.Use the optimal Latin hypercube model to design the input parameters to obtain sample points,and substitute the sample points into the finite element model for solution.Using the radial basis function model,a fast calculation model for the NVH response of the suspension bushing parameters was established.(4)Carried out a vehicle NVH optimization study based on the uncertainty parameters of the suspension.Combining with the reliability optimization theory,a mathematical model of the suspension NVH performance reliability optimization is established and solved by the SORA method to obtain the reliability optimization results.Combining with the theory of robustness optimization,a mathematical model of suspension NVH performance robustness optimization is established and solved by a multi-island genetic algorithm,and the robustness optimization result is obtained.