基于流—固耦合的汽车减振器动态特性仿真分析

Simulative Analysis of Dynamic Characteristics of Automobile Shock Absorbers Based on Fluid-structure Interaction

对减振器的流—固耦合建模和求解技术进行研究。基于多求解器的流—固耦合方法,建立精度较高的阻尼阀流场网格模型和叠加阀片有限元接触模型,并联合有限体积法和有限元法对减振器流—固耦合模型进行求解和分析,获取了减振器的速度特性和示功图,对阻尼阀内部压力场、速度场进行详细分析,对叠加阀片非线性动力学特性进行分析。仿真结果表明:由于高速油液对阻尼阀壁面的冲击作用,阻尼阀核心区域的压力场急剧变化;阀片在开启和关闭瞬间,速度有一个跳跃,这使得节流通道迅速变化,具体表现为开阀点附近的速度特性曲线向下弯折。因此,阻尼阀核心区域的流场网格模型和叠加阀片的接触模型对仿真精度影响最大。计算中考虑了油液的湍流流动,阀片的接触滑移和大挠度变形,使得流—固耦合模型尽可能地贴近物理事实,仿真结果与试验吻合较好。

The fluid-structure interaction（FSI） modeling and solving techniques of shock absorbers are studied. The fluid field grid model of damper valve and the finite element contact model of superposition throttle-slices with higher accuracy are established based on FSI method with multi-solvers. The FSI model of shock absorbers is solved and analyzed combined by finite volume method（FVM） and finite element method（FEM）. The speed characteristic and indicator diagram of shock absorbers are obtained. The internal pressure field and velocity field of damper valve are analyzed. The nonlinear dynamic characteristics of superposition throttle-slices are analyzed. The simulation results show that the pressure field of core region of damper valve changes rapidly because of the impact of high speed oil. The velocity of throttle-slices steps when the valve opens and closes. It makes the throttle channel change suddenly, and makes the indicator diagram bend down at the valve-opening point. The fluid field grid model of core region of damper valve and the finite element contact model of superposition throttle-slices have great influence to the accuracy of simulation. The FSI model is closed to the physical reality because of the consideration of turbulent flow of oil and the contact slip and large deflection of throttle-slices. The simulation results are in good agreement with the experimental results.