Study On Resonant Diagnosis Of Highway Vehicles

As one of the most important performances of the highway cargo transporting vehicles,the harshness not only affects the driver ride comfort and the integrity of the carried goods,but also affects the fatigue life of key auto assembly and parts. Therefore, theoretical andexperimental research on the vibration characteristics of road freight carriage car, and thedevelopment on comfort and resonance diagnosis system are of great significance.There are too many reasons for leading to highway cargo transporting vehicles vibratingseverely, not only from unreasonable designs of the driver seat suspension parameters,chassis suspension parameters, and powertrain mounting parameters, but also fromunreasonable transmission angle layout. And furthermore, the wheel unqualified dynamicbalance, parts manufacturing error and the consistency of a variety of parts contribute a lotto the great vibration of the highway cargo transporting vehicles and even the resonancephenomenon at certain speed.So firstly, by using the method of concentrate quality, the model of vibration mechanicssemi-truck frame, including two elastic modes, with the15degrees of freedom, isestablished. The numerical simulation method is employed to study vibration characteristicscaused by the following factors as different vehicle speeds and wheel unbalance, and alsoby the driver seat’s damping parameters and the cab front and rear suspension stiffness anddamping parameters. It is found that the vehicle unbalance has a very large impact onvehicle ride comfort and the driver’s seat vibration, and the driver’s seat vibrationacceleration increases as the speed linearly. The study also shows that the reasonabledesigns of cab suspension damping of the shock absorbers can improve vehicle ridecomfort and eliminate the resonance phenomena obviously. It is also found that theoptimization design of cab front and rear suspension stiffness can improve vehicle ridecomfort and eliminate the resonance phenomenon with certain effect.Then the experimental modal technology by hammer striking was employed and thevehicle modal parameters were obtained, which provide basic data for dynamic design andfault diagnosis of resonance; Subsequently, the fault tree diagnosis method based on ruleand condition diagnosis method based on cross spectral analysis were investigated; andfinally, the development of vehicle ride comfort and resonance the diagnosis system isintroduced, and this system was verified through the field road test.By calculating previous test datas, the results show that the resonance diagnosis system achieves the desires purpose.The experimental results show that the diagnosis system has the advantage of diagnosingcorrectly.