The hydraulic suspension lumped parameter model hydraulic suspension is a complex device composed of liquid-solid coupling, and its dynamic characteristics are very complicated. In order to effectively analyze the dynamic characteristics of the hydraulic mount, R. Singh et al. established the basic structural model of the hydraulic suspension lumped parameter model 3 hydraulic suspension, as shown. In the figure, K r ​​and B r are the stiffness and damping coefficient of the rubber primary spring respectively, and A r is the equivalent piston area of ​​the rubber primary spring. m 1 and m 2 are the mass of the liquid in the upper and lower liquid chambers, respectively, ie, m 1 =ÏV 1, m 2 =ÏV 2. C 11, C 12, C 21, and C 22 are the volumetric flexibility of the upper and lower liquid chambers, respectively; p 11, p 12, p 21, and p 22 are the liquid pressures in the upper and lower liquid chambers, respectively. Suspended lumped parameter model I Based on the model shown, the following mechanical equation can be derived: F (t) - K rx (t) - B rx (t) - A rp 11 ( t) = mrx (t) (1 According to the momentum equation of the incompressible fluid, we can draw: (p 11 (t) - p 12 (t)) A r = m 1 x1 (t) (2) p 12 (t) - p 21 (t) = I d qd( t) +R dqd( t) =I i qi( t) +R iqi( t)(3)A r = m 2 x2( t) According to the continuity equation of the incompressible fluid, it can be concluded that: A r = C 11 p11( t)(5)A r x1( t) − qd( t) − qi( t) = C 12 p12( t)(6 Qd(t) + qi(t) - A r x2(t) = C 21 p21(t)(7)A r x2(t) = C 22 p22(t)(8) For a fixed decoupled diaphragm hydraulics The suspensions are: qd(t) = 0, defining mi = A 2 r I i, bi = A 2 r R i, k 11 = A 2 r /C 11, k 12 = A 2 4 /C 12, k 21 = A 2 r /C 21, k 22 = A 2 r /C 22, xi( t) = qi( t) /A r, collate the previous equations to get: F (t) - k 11 - B rxt ) - K rx (t) = mrx (t) (9) k 11 - k 12 = m 1 x1(t)- bix Because m 1 and m 2 are small relative to mi, they can be ignored. From this, the lumped parameter model shown can be derived. Where C 1 = C 11 + C 12, C 2 = C 21 + C 22. 5 Hydraulic Suspension Lumped Parameter Model II Similarly, according to the model shown, from the momentum equations and continuity equations of the incompressible fluid, it can be concluded that 2( t) defines the hydraulic suspension dynamics for a fixed decoupled diaphragm hydraulic mount. Features Simulation Analysis and Test Testing 3. 1 Introduction to ADAM S Software ADAMS software is a mechanical system dynamics simulation software developed by MD I of the United States. It includes ADAMS/View, ADAMS/Solver, ADAMS/Car, ADAMS/Engine, and ADAMS/V ibration. ADAMS/Hydraulic, ADAMS/Controls and many other modules. With ADAMS software, almost any mechanical system can be modeled and simulated. The establishment of a dynamic simulation model This paper uses a fixed decoupled diaphragm hydraulic suspension as an example, and uses ADAMS software to establish a liquid-solid coupled dynamic analysis model. It is a dynamic simulation model with a fixed decoupled mode hydraulic suspension. The model consists of two parts, the solid and the liquid. The solid rubber part of the solid part is simplified as a simple spring damping system, while the liquid part is built using the ADAMS/Liquid module in ADAMS. The model assumes uniform pressure distribution in the upper and lower chambers. Fixed decoupling model hydraulic suspension dynamics simulation model can be seen from the model, the force transmitted to the body through the hydraulic suspension is composed of two parts, one part is transmitted through the rubber primary spring, and the other part is due to the upper and lower liquid Room liquid pressure generated. Therefore, the calculation formula of the branch reaction force of the hydraulic suspension fixed end is as follows: FT( jω) and x( jω) are Fourier transforms of F t(t) and x (t), respectively. The dynamic stiffness of the suspension is defined as: K dyn = K 2 1(ω) + K 2(ω) The lag angle is defined as: θ = arctan(K 2(ω)K 1(ω) Hydraulic pressure calculated by simulation using this model Suspended dynamic stiffness curve and lag angle curve, as shown. Fig.7 Simulation results of dynamic stiffness of hydraulic mountFig.8 Simulation results of hydraulic mount lag angle 3. 3 Dynamic characteristics test The dynamic characteristics of the engine's hydraulic suspension were tested on the Instron 8800 servo hydraulic vibration test bench, as shown. During the experiment, connect the two ends of the hydraulic suspension to the test bench, and then apply a displacement excitation x (t) = X 0 sin(ωt) to one end, and the other end is fixed on the test bench to record the movement end. The displacement sensor signal x (t) and the fixed-end force sensor signal F (t) are shown as 0. In this way, the dynamic stiffness and lag angle at a certain frequency can be obtained. Tested hydraulic suspension dynamic stiffness and lag angle curve, as shown in 1,2. By comparing the dynamic stiffness and lag angle curves of the hydraulic suspension of the simulation calculation and experimental test, it can be seen that the two are more consistent, thus verifying the correctness of the model. An ideal suspension requires dynamic characteristics such as low frequency, high stiffness, large damping, and high frequency, low stiffness, and small damping. Instron 8800 Servo-Hydraulic Vibration Test Bench Figure 10 Hydraulic Mounting Dynamic Characteristics Test System Figure 11 Hydraulic Mounting Dynamic Stiffness Test Results Figure 12 Hydraulic Mounting Hysteresis Angle Test Results The model for hydraulic mounts established in ADAMS can be passed The suspension is optimized by changing some parameters of the hydraulic suspension, such as the static stiffness of the rubber primary spring, the length and cross-sectional area of ​​the inertia channel, and the characteristics of the liquid, so as to design an ideal hydraulic suspension. End (1) The hydraulic-hydraulic coupling dynamics simulation model was established using ADAMS, and the dynamic characteristics at low frequencies were simulated and analyzed. Comparing the simulation results with the actual measurement results, the analysis shows that the simulation results of the low-frequency characteristics of the hydraulic suspension are in good agreement with the measured results, which verifies the correctness of the model. (2) The dynamic simulation model of liquid-solid coupling established by ADAMS can predict the dynamic characteristics of the hydraulic suspension well, and can improve the dynamic characteristics of the suspension by changing certain parameters when designing the hydraulic suspension. Optimize the design to shorten the product development cycle and improve product design quality. (3) Using the ADAMS/Controls module in ADAMS, you can also add control parts to the model, and co-simulate with software such as Matlab, so that for some semi-active, active suspension (such as ER fluid, magnetorheological fluid suspension) The dynamic characteristics of etc. are simulated. 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