Modeling Of Displacement-sensitive Shock Absorber And Its Vertical Vehicle Dynamic Analysis

The demand for the safety and ride of the vehicle is a contradiction .If a vehicle requires good safety ,it must be matched with a hard suspension ,so it can get more damping force and adhesion force .On the other hand, If a vehicle requires good ride , it must be matched with a soft suspension ,thus the damping force is small ,so the passenger will feel comfortable because the input of the road can be weakened.It is a very important subject to to find out how , without adding too much cost , to make the damper coefficient of the shock absorber vary reasonably to enhance the ride of the vehicle while assuring the safety of vehicle .This thesis is mainly about displacement-sensitive shock absorber(DSSA), which is also called stroke-dependent shock absorber ,and it is developed from conventional passive shock absorber .Via cutting grooves on the cylinder wall , the DSSA has additional flow passages such as displacement-sensitive orifice , so it has two modes of damping force according to piston stroke . The DSSA is low-cost and easy to install ,without electric elements as special control .The ride comfort of the vehicle which installed DSSA can be improved because the damping force is small in the short stroke when it is driven on the paved road driving condition , while the safety of it can be improved on the bumping road driving condition .In this thesis ,a DSSA model is built and it is validated by experiments .Also a quarter car model is built ,and analyse the frequency characteristics of the DSSA in the quarter car model by a sinusoidal sweep function .What have been obtained as follows:Built mathematical modeling of DSSA via analyzing the schematic diagram of it .Built a hydraulic model of DSSA via ADAMS/View and its plug-in , ADAMS/Hydraulics.Do experiments about DSSA and processed the data, the analyse the F-S and F-v curves of DSSA . The hydraulic model of DSSA is tested to be correct by experiments.To analyse the frequency characteristics of the DSSA ,the input excitation signal is applied .Also the parameters of displacement-sensitive orifice is anslysed.A dynamics model of quarter car is established via ADAMS/View . The input excitation signal is applied to analyse the frequency characteristics of the quarter car model . When the vehicle installed the DSSA is driving at a fairly good road, because of the the displacement-sensitive orifices , the damping force is small ,and at this time the acceleration response of sprung mass will be acted as soft mode characteristics ,so the ride comfort of vehicle can be improved . In addition, the suspension deformation amplitude frequency response characteristics and dynamic wheel load amplitude frequency response characteristics of the and amplitude frequency response characteristics can be improved in a certain frequency range .