Analysis And Optimization Of Noise Performance In The Cab Of A Special Vehicle

With the continuous growth of the domestic automobile industry,NVH performance of special vehicles is also paid more and more attention by the state and related enterprises.Vibrations of the special vehicle body panels caused by engine and road motivation are the main contributors to low-frequency noise in the cab.Therefore,it is very important to pay attention to the NVH characteristics of car body structure,and analyze the car body from integrity and locally so we can make it better.In addition,if the car come across an explosion,there would not only be physical damage to the crew caused by collision,overpressure and impact,the boom would also generate a large sound pressure level(SPL)in the cab to damage the occupant’s hearing system.So the large sound pressure caused by boom also needs to be considered when analyze special vehicles’ inner noise.In order to enhance the passenger comfort and protection performance of special vehicles,it is of great significance to analyze the SPL in the cab interior.Based on the research of vibration and noise analysis and control flow of vehicle body structure both at home and abroad,this paper taking a certain kind of special vehicle cab as the research object,makes use of the engineering theory of test and numerical calculation modal analysis,mechanical vibration,body panel contribution analysis,and combined with CAE analysis technologies including the structural finite element method(FEM),acoustic FEM,Arbitrary-Lagrange-Euler algorithm(ALE)and so on,has carried on analysis and optimization.And this paper pays attention to protect the passenger’s hearing system,explored a new method of research on protection of special vehicles.Firstly,the finite element model of car body in white was established.And the modal parameters of the special vehicle’s body in white obtained both from test modal analysis and FEM modal analysis were compared to verify the validity of the finite element model accuracy.Secondly,the vibration characteristics and the acoustic characteristics of the cab body were analyzed respectively to find out the sensitive parts of cab structure that greatly affect the NVH performance and provide the basis for structural optimization.,A multi-objective optimization of cab vibration characteristics is conducted in Hyperstudy using plate thickness as a variable in order to achieve a cab structure with lighter mass and better NVH performance.Then the load spectrum of the cab connecting point obtained from the vehicle road load test is used as the boundary condition to analyze the structure-acoustic coupling response.Based on the results of structure-acoustic coupling response analysis,panel contribution analysis of the cab is carried out.The weighted panel contribution method was used to obtain the target panel that need to be optimized.Adding a free damping layer to the target panel,conduct the structure-acoustic coupling response analysis again and compared the cab interior noise between before and after optimization.Finally,the ALE algorithm is used to simulate the structural response of the cab under explosion shock conditions.The cab inside sound field response is calculated by using the floor acceleration under the impact of explosion as a boundary condition.The accuracy and effectiveness of the method are verified by comparing the simulation results with the experimental results.This paper explored a new method of special vehicle protection.