冲击载荷下磁流变阻尼器动态特性分析及模型参数辨识

Dynamic Performance Analysis and Model Parameter Identifications of MR Dampers under Impact Load

对自行设计的长行程磁流变阻尼器进行了冲击试验,测试其在冲击载荷下的动态特性。通过采用非线性最小二乘法对试验数据拟合,得到基于Herschel-Bulkley磁流变液非线性本构特性的平行平板恒流模型能够准确描述,冲击载荷下后坐过程速度下降阶段磁流变阻尼器的动态特性。针对以上模型在高低速时函数表达不同且形式复杂的缺点,采用双曲正切函数描述低速时阻尼力随后坐速度平滑下降的特性,提出一种形式统一、表达简洁的磁流变阻尼器动态模型,并对模型中的参数进行了辨识。利用所提出的磁流变阻尼器动态模型,在Matlab/Simulink中建立磁流变阻尼器冲击后坐仿真平台,并对本次冲击试验进行数值仿真,结果表明仿真曲线与试验曲线吻合较好,证明以上简化模型的正确性。

Impact test on a self-designed long-stroke MR damper is done and the dynamic performance of MR damper is examined. By curve fitting the experimental data with nonlinear least square method, it is shown that the steady flow equations for parallel plates based on the non-linear Herschel-Bulkley fluid model are able to accurately describe the dynamic behavior of the MR damper in the falling stage of the recoil velocities under impact load. Since the mathematical expression of the above model is complicated with different forms in high and low recoil velocities respectively, a simplified d3~namic model with uniform mathematical expression is proposed, in which the hyperbolic tangent function is used to make the force-velocity curve smooth at low velocities, and parameters in this model are identified. Using the proposed MR damper dynamic model, impact simulation platform of MR damper is established in Matlab/Simulink, and numerical simulation of this impact test is done. It is shown that the simulation curves fit well with the experimental ones, and the validity of the simplified mode/of MR damper is verified.