Research On The Key Techniques Of The Suspension And Vibration Reduction System For The Vehicle Considering Uncertainties

The suspension-damping system is an important part of the vehicle,connecting the body and the chassis and reducing the vibration energy generated by the relative motion between the body and the chassis.It is necessary to research it.The great precision does not be pursued by the traditional research.And most of the traditional research focuses on the deterministic research,ie,all variables of the vehicle suspension-damping system are defined as certain values.In reality,the uncertainties of the material parameters,the geometric parameters and the physical parameters are widespread,making the variables of the suspension-damping system uncertain.Threrfore,there is a gap between the traditional research and engineering practice.To obtain the mathematical models which are more consistent with the engineering practice,the uncertainty theory is introduced for the investigation.In this paper,the uncertainties of the suspension vibration are studied in part,and the uncertainties of the vibration reduction unit of the suspension are mainly focused on.The uncertainties of suspension vibration and the uncertainties of the physical processes commonly used in vibration reduction units(these physical processes are parallel relationship)constitute the overall structure of this paper.According to the obtained information of the input variables,the input variables are divided into the unascertained quantities,the interval variables,and the stochastic variables.The main contents and results of this paper are as follows:(1)The mass,stiffness and damping are defined as unascertained variables.The unascertained-dynamic model of vehicle suspension is established with the unascertained theory.And then the laws of dynamic response are obtained.The results of the unascertained-dynamic model and the traditional model are compared with Monte-Carlo method.The research shows that the unascertained-dynamic model is superior to the traditional model.(2)The fluid inertia coefficient and the flow damping coefficient are defined as interval variables.The interval dynamic stiffness model of the hydraulic bushing is developed with the interval uncertainty theory.The results of the interval dynamic stiffness model are compared with the experimental results,indicating that the interval model is correct.The variation curves of the interval dynamic stiffness are optimized with subinterval combination method.(3)The hydraulic oil density,the thermal conductivity,the specific heat capacity and the kinematic viscosity are defined as random variables.The stochastic thermodynamic model of shock absorber is established with the stochastic factor method and the algebraic synthesis method.And the laws of heat-transfer process about oil are obtained.The results of the stochastic thermodynamic model and the traditional model are compared with the test.The research shows that the stochastic thermodynamic model is more excellent than the traditional model.(4)The inner diameter of the working cylinder,the outer diameter of the working cylinder,the inner diameter of the storage cylinder,the outer diameter of the storage cylinder,the piston diameter,the piston rod diameter and the heat transfer length are defined as stochastic variables.The stochastic thermodynamic model of the hydraulic cylinder is established with the stochastic factor method and the algebraic synthesis method.That the stochastic thermodynamic model is superior to the traditional model is obtained by the experiment.(5)According to the stochastic factor method,the variables such as the thickness,the inner radius,the outer radius,Poisson’s ratio and the elastic modulus of the throttle slice are defined as stochastic variables.By the algebraic synthesis method,the stochastic elastic deformation model is established.An experiment is performed for verifying the superiority of the proposed model to the traditional model.The variation rules of the mean deformation,the mean square error for the deformation,the maximum deformation and the relative error are revealed.(6)The piston diameter,the piston rod diameter,the orifice diameter and the length of the orifice are defined as stochastic variables by the stochastic factor method.The stochastic Bingham model is established by the algebraic synthesis method.The superiority verification of the stochastic Bingham model is performed by the experimental results.