Research On The Vibration Performance Of A Three-axle Heavy-duty Truck Equipped With Balanced Suspension And The Road Damage It Caused

With the rapid steady development of national economy and the substantial increasing demand for road transportation, heavy-duty trucks for transportation are more and more widely applied. Balanced suspension is widely used on heavy-duty trucks, and leaf spring balanced suspension in the two rear axles is a common form as the rear suspension system of a three-axle heavy-duty truck. The use of balanced suspension does not only affect the vibration performance of heavy-duty trucks, but also has an impact on road damage caused by heavy-duty trucks. Therefore, the vibration performance of heavy-duty trucks with balanced suspension and the road damage caused by them have gradually become a matter of concern.Scholars at home and abroad have established two models of balanced suspension system, but the mathematical model of one model has been inaccurately deduced, and there is no comparative analysis of the two models, so the conclusion based on the models needs to be validated. Aiming at the problem of establishing the models of balanced suspension system, the paper has researched deeply for improving the models and analyzing the vibration performance of heavy-duty trucks with balanced suspension and the road damage caused by them, based on the models. Firstly, two models of balanced suspension system are founded based on its structure and function; secondly, two 1/2 automobile vibration system models of a three-axle heavy-duty truck are founded based on the two models of balanced suspension system, and frequency response characteristics of two 1/2 automobile vibration system models are summarized; thirdly, the correlative basic theory about AR model and spectrum estimate arithmetic, the method of estimating AR filter coefficients are studied and summarized; finally, the model of random road excitation to the three-axle heavy-duty truck in time domain is obtained by the method of AR model, and is applied to each 1/2 automobile vibration model to analyze the ride comfort performance of the three-axle heavy-duty truck and the road damage it caused. Main research content of this paper is as follows:(1) The vibration model and the vibration performance of balanced suspension system Two vibration models of balanced suspension system are founded based on its structure and function, and the single axle model and the simplified model of balanced suspension are obtained via further analysis. Frequency response characteristics of the responses of all these models have been established and then the formulas of the PSD of the responses are computed. The result of the simulation suggests that the ride comfort can be significantly improved by the balanced suspension and the simplified model of balanced suspension can be used to analyze the vibration performance of balanced suspension system.(2) The vibration model and ride comfort simulation of a three-axle heavy-duty truck equipped with balanced suspension system in frequency domain Two 1/2 automobile vibration models of a three-axle heavy-duty truck equipped with balanced suspension system are founded based on the two models of balanced suspension system. In frequency domain, frequency response characteristics of the responses of the two 1/2 vibration models have been established and the PSD curves of the responses are close. The result of the simulation suggests that the first 1/2 vibration model which disposes the leaf spring as a whole is more reasonable.(3)The basic theory about Auto-Regressive spectral estimation The math theory about AR spectral estimation, the method of estimating AR filter coefficients, the rules to determine the order of AR model and the solution to power spectral density are studied and summarized. AR model can be used to transform the data in time domain to obtain information in frequency domain, and to analyze the ride comfort performance and the road damage.(4) Study to the vibration performance of a three-axle heavy-duty truck with balanced suspension in time domain and the road damage it caused The road pulse excitation model in time domain is established in accordance with national standards and is applied to each 1/2 vibration model for ride comfort simulation. The speed characteristic curves of the two models are almost equal.The single wheel road AR time domain model is founded by transforming displacement power spectrum density of random road excitation. Through the rigorous deduction and analysis, the corresponding arithmetic is established. The random road excitation to the wheel can be obtained. Then the PSD curves are calculated using AR spectral estimation. The model has been proved correct through comparing these PSD curves with standard PSD curves. Consider the time delay between the front, middle and rear wheel, the 1/2 vibration system road AR time domain model is founded.The 1/2 vibration system road AR time domain model is applied to the two 1/2 vibration models. The vibration differential equations are solved by Runge-Kutta method. Each response is computed in time domain, and then the PSD curves are obtained using AR spectral estimation. The PSD curves in time and frequency domain are close. It validates the feasibility of the 1/2 vibration system road AR time domain model being applied to the two 1/2 vibration models.The theory about the theoretical road damage coefficient J- one of the evaluation indexes for assessing road damage caused by heavy-duty trucks is summarized. The road AR time domain model of random excitation on each location of the pavement is founded and applied to the two 1/2 vibration models. The static axle loads and the dynamic tire forces are obtained, and then the time series of the Forth Power are computed. The theoretical road damage coefficient J is calculated finally. Attention is also given to the main features that affect the damage to the road. The research results show that the road grade and the speed of the truck affect the dynamic tire forces, and finally affect the road damage.