Analysis And Optimization For Insulation Performance Of Vehicle Firewall Assembly Based On Uncertainty

NVH(Noise、Vibration and Harshness)plays a key role in the passenger comfort,which is one of the main research areas for vehicle works.For the middle and high frequency noise in the vehicle,the most common way to reduce the noise is to use the acoustic package with sound absorption and sound insulation performance.Usually,for the conventional development process,researchers don’t consider the inevitable errors during the actual production,processing,measurement,and so on.How to reduce the influence of the uncertainty has a great significance for improving the sound insulation performance of the firewall.Based on the stochastic uncertain optimization theory,a robust optimization method for the Sound package performance of firewall under uncertain conditions is proposed in this paper.By optimizing the material coverage,the noise reduction is optimized,and the robustness of performance is further improved.The main research includes:(1)The statistical energy analysis model of the vehicle firewall assembly is established.And the composition of the acoustic package material is analyzed.The corresponding plate sample is tested for sound absorption and insulation,and the measured data is used for the model.The effectiveness of the model is verified by comparing the simulation value and the experimental value of the insertion loss of firewall assembly.(2)Through the secondary development of the acoustic simulation software VA One,the model parameters are automatically modified and the results are output,thus laying a technical foundation for the optimization work.(3)In order to improve the efficiency of optimization calculation,an automobile firewall assembly insertion loss response surface model is established by optimizing Latin hypercube sampling.The accuracy of the model response is verified by error analysis of the approximate model.(4)The coverage rate of firewall assembly with 5 kinds of acoustic package materials is used as the random variable,and its firewall assembly insertion loss and total mass are used as the analysis objectives.Based on the multi-island genetic algorithm,the noise reduction and quality are optimized.(5)This paper aims to find a robust optimization scheme that the acoustic insulation performance of firewall assembly package meets the requirements and has the smallest variance,so as to reduce the influence of various uncertainties on the actual acoustic insulation performance of firewall assembly package.The results show that the performance of the robust optimization scheme is more robust and reliable compared with the deterministic optimization scheme.(6)The statistical energy analysis model of the vehicle is established to test the static transfer function of the vehicle and the dynamic acoustic load of the vehicle.The test results areused to verify the effectiveness of the simulation model in predicting the in-car noise.The interior noise level before and after the application of firewall acoustic packet optimization scheme is predicted,and the effectiveness of the robust optimization scheme for firewall acoustic packet acoustic insulation performance proposed in this paper is verified.