Modeling Analysis And Research On Nonlinear Characteristics Of Hydragas Suspensions

With the increasing requirements of the vehicle performance, the hydragas suspension, which has superior nonlinear elastic properties and good damping characteristic, could better satisfy the demands of performance of ride comfort and handling stability. So it is widely used in the advanced car, engineering vehicle and special vehicle.In this paper, a methodology based on the previous study is introduced to solve the problem of the hydragas suspension's design and application, and the research contents include the dynamic characteristic, the non-destructive testing and the distinction of the non-linear characteristic curve of the hydragas suspension. The main contexts are listed as follows:1. According to the actual situation of the suspension, the R-K equation which can accurately describe the gaseous state and the Blasius equation that compute turbulent resistance coefficient have been used in establishing the mathematical model of the hydragas suspension. We have also studied the influence of the excitation parameters, structure parameters and working parameters on the characteristic of its displacement and velocity.2. Based on combination of mathematical model and genetic algorithm, a new inverse method is introduced to get the volatile work parameters of the hydragas suspension. It is used to solve the problem that several parameters shall change after the hydragas suspension has been manufactured or used for a certain time, which can not be easily measured. The stability and validity of the proposed method has been verified by some tests.3. To forecast the performance of the output force, the non-parameter model of the hydragas suspension is built based the methods of RBF network and the genetic BP, respectively. In the model, the response of displacement, speed and working temperature are used as input layer, while the output layer is the force response. We have also developed a forecasting platform of the hydragas suspension based on the two methods, respectively.4. In order to solve the problem that the elastic force and damping force of the hydragas suspension can not be measured directly, a new inverse method based on genetic algorithm has been introduced to distinguish elastic force from damping force. Numerical simulation summarize that the influence of the excitation parameters and working parameters on the characteristic of its elastic force and damping force.