冲击载荷作用下磁流变阻尼器的建模与分析

以某12．7 mm机枪的磁流变(MR)后坐阻尼器为研究对象,基于Herschel-Bulkley本构模型,建立了该MR后坐阻尼器的轴对称一维层流模型。运用ANSYS软件,对该阻尼器的MR阀进行了磁场有限元分析,求得了环状间隙间MR流体的磁通密度。将MR流体流动模型和MR阀有限元结果相结合,建立了不同磁场作用下阻尼力随活塞速度的变化规律,利用这些规律对该阻尼器的落锤撞击试验和实弹射击试验进行了数值仿真。理论与试验结果的对比指出,在低磁场作用的情况下,理论与试验结果具有较好的一致性。     

冲击载荷下磁流变阻尼器设计和仿真

提出了冲击载荷下磁流变阻尼器的设计方法和约束条件,并使用MATLAB优化结构参数.针对某型号火炮,实际设计了一阻尼器,从结构和磁场方面进行了验证.结果表明:所设计的阻尼器满足约束条件,活塞间隙内的磁流变液被充分激励,且磁场分布均匀,铁芯工作在高磁导率范围内.火炮后坐过程仿真结果表明阻尼器能够有效减小最大后坐阻力峰值.     

某火炮磁流变制退机设计与研究

以某型火炮磁流变制退机为研究对象,利用CFX对其内部粘塑性流场和牛顿流场建立一体化模型,使用CEL方法定义了Bingham粘塑性流体特性,分析得到了磁流变制退机后坐总阻力与活塞杆速度之间的关系。使用ADAMS软件对磁流变制退机的后坐过程和复进过程进行仿真,通过分析磁流变制退机的理论后坐总阻力与普通制退机试验的后坐总阻力的变化规律曲线,分析了磁流变制退机的后坐效果。     

冲击载荷下磁流变阻尼器动态特性分析及模型参数辨识

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.     

基于Eyring本构模型的磁流变液阻尼器设计原理与试验研究

根据试验得出的Bingham塑性流体模型的模型参数, 建立了磁流变液切应力的误差函数,利用多参数优化理论和数据拟合方法对Eyring本构模型的参数进行辨识。建立了基于Eyring模型的环状混合准稳态流动方程,得出了磁流变液在环形通道中流动的速度分布函数。在给定活塞速度和环形通道的几何尺寸条件下,对混合工作模式的汽车磁流变液阻尼器产生的阻尼力进行理论预测研究。按照长安之星微型汽车前悬架的技术要求,设计和制作了微型汽车磁流变液阻尼器,并对此进行了试验测试,试验结果表明：应用所提出的理论分析方法预测磁流变液阻尼器的特性是可行的。     

新型磁流变阻尼器抗冲击载荷性能分析

针对工程领域中高冲击载荷作用下的磁流变阻尼器存在流体通道拥堵,轴向磁场单一等问题,设计了新型的磁流变阻尼器.相比以前阻尼器,新阻尼器整体结构缩小,各级线圈匝数减少且独立连接.完成了磁流变阻尼器电磁模型的计算与PID控制算法的仿真分析,并根据仿真结果对新旧阻尼器进行了比较.结果表明,新设计的磁流变阻尼器较之前的阻尼器,能够产生轴向随时间变化的磁场,缓解了因磁场增强导致的流体通道拥堵的现象,在相同的冲击载荷作用下,实现了位移与能耗的同时下降.     

榴弹发射器后坐缓冲系统仿真与控制

论述基于磁流变阻尼器的半主动振动控制的一般方法,针对某榴弹发射器后坐缓冲系统的设计要求,建立了缓冲系统的数学模型,对发射器的后坐过程进行了动力学仿真。提出了一种基于设计目标的加权计算方法,通过参数化设计,并计算控制因子D,找到阻尼器的最佳弹簧刚度系数和可控阻尼系数匹配,满足了后坐力和后坐行程的设计要求,为缓冲装置用的磁流变阻尼器的设计提供依据;进行了ADAMS与Simulink的联合控制研究,对比了外加开关(on-off)控制算法和PID控制算法时的控制效果,为磁流变阻尼器的电流控制提供了指导。     

一种新型复合MR阻尼器的设计与磁路仿真分析

针对土木工程的特点,从保证磁流变阻尼器的阻尼性能、节省控制系统的能耗和提高阻尼器的安全稳定性能出发,设计了一种具有较好的被动和半主动控制功能的新型复合结构磁流变阻尼器,并建立了这种磁流变阻尼器的力学模型.根据电磁场理论,设计了具有永磁体与通电线圈的复合结构磁流变阻尼器的磁路,再利用ANSYS软件对该磁路与结构参数进行仿真分析,结果表明复合结构MR阻尼器比传统普通结构MR阻尼器具有更优越的可控性及安全稳定性能,为设计具有适当力值需求的复合磁流变阻尼器提供有效手段.     

基于神经网络的磁流变阻尼器逆控制研究

为了解决阻尼器的非线性问题,设计了一种纯剪切型磁流变阻尼器,并针对其非线性特性,提出了利用径向基函数（RBF）神经网络的非线性映射能力,以建立磁流变阻尼器的逆模型。由已训练的磁流变（MR）阻尼器的逆向神经网络模型和MR阻尼器组成的控制单元,在给定所需控制力的情况下,使MR阻尼器产生相应的阻尼力,实现了MR阻尼器提供连续可调输出力的目的,也使得纯剪切型MR阻尼器在一些需要精确控制的场合能够方便使用。仿真结果表明,神经网络逆控制的方法是有效的、可行的。     

高耗能自解耦式MR阻尼器的设计及性能试验

为设计制作基于土木建筑结构振动控制的高耗能自解耦式磁流变(magneto-rheologcal,简称MR)阻尼器,通过对阻尼器设计的关键技术、阻尼器的性能试验及力学模型的参数识别进行研究,得知在副活塞中设置解耦装置可使阻尼器在不同的振幅下具有不同的刚度和阻尼特性,在主活塞中将永久磁场和电流磁场结合起来实现阻尼器的逆向控制的设计思路是可行的,铜制隔磁环的设置保证了磁力线沿理论设计的路径穿行,又使线圈避免与磁流变液的长期接触腐蚀,从而提高其耐久性。通过对阻尼器采用基于反正切函数的MR阻尼器模型进行参数识别,得到了与试验结果吻合的MR阻尼器的力学模型。     

基于MATLAB的某机枪缓冲器数值计算及仿真

建立了某机枪缓冲器动力学模型,对其动态特性进行了分析,然后基于数值分析软件MATLAB对其后坐过程进行数值分析计算,并对其结果进行仿真,得到了缓冲过程中缓冲器的位移、速度和后坐阻力与时间的变化关系。仿真结果表明:该机枪缓冲器可有效降低枪身后坐位移和后坐速度,保证了射击时的稳定性;可大幅度降低机枪发射时的后坐阻力,从而可在一定程度上提高武器的射击精度。     

Optimal design of Magneto-Rheological damper comparing different configurations by finite element analysis

Magnetorheological (MR) damper is one of the most advanced applications of semi active damper in controlling vibration. Due to its continuous controllability in both on and off state its practice is increasing day by day in the vehicle suspension system. MR damper’s damping force can be controlled by changing the viscosity of its internal magnetorheological fluids (MRF). But still there are some problems with this damper such as MR fluid’s sedimentation, optimal design configuration considering all components of the damper. In this paper both 2-D Axisymmetric and 3-D model of MR Damper is built and finite element analysis is done for design optimization. Different configurations of MR damper piston, MR fluid gap, air gap and Dampers housing are simulated for comparing the Dampers performance variation. From the analytical results it is observed that among different configurations single coil MR damper with linear plastic air gap, top and bottom chamfered piston end and medium MR fluid gap shows better performance than other configurations by maintaining the same input current and piston velocity. Further an experimental analysis is performed by using RD-8041-1 MR Damper. These results are compared with the optimized MR Damper’s simulation results, which are clearly validating the simulated results.     

Modeling and testing of a field-controllable magnetorheological fluid damper

In this study, an experimental and a theoretical study were carried out to predict the dynamic performance of a linear magnetorheological (MR) fluid damper. After having designed and fabricated the MR damper, its dynamic testing was performed on a mechanical type shock machine under sinusoidal excitation. A theoretical flow analysis was done based on the Bingham plastic constitutive model to predict the behavior of the prototyped MR damper. The theoretical results were then validated by comparing them against experimental data, and it was shown that the flow model can accurately capture the dynamic force range of the MR damper. In addition to the flow model, a modified parametric algebraic model was proposed to capture the hysteretic behavior of the MR damper. The superiority of the proposed modified model was shown by comparing it with the Alg model as well as with a widely adopted modified Bouc-Wen model through an error analysis. It is observed that although all the three models are comparable at the excitation velocities of 0.05, 0.10, and 0.15 m/s, the mAlg model is remarkably successful at the highest excitation velocity of 0.2 m/s over the other two. The improvements in the predictions were found to be over 50%, relative to unmodified model especially at lower current inputs. Therefore, it was concluded that the present flow model can be successfully adopted to design and predict the dynamic behavior of MR dampers, while the mAlg model can be used to develop more effective control algorithms for such devices.     

基于虚拟样机技术和灵敏度分析的地面火炮射击稳定性优化研究

传统的火炮设计和分析均基于“平面、对称和静平衡”三个基本假设，实际上是一种静态的分析方法，尽管在工程实践中引入了多种经验符合系数，但是火炮分析结果和试验的一致程度不能令人满意。这是因为火炮的射击过程是一个动力学过程，需要采用动力学分析方法。虚拟样机技术的出现为火炮射击稳定性研究提供了新的方法，文中在建立火炮动力学模型的基础上，通过选取火炮结构参数对火炮射击稳定性进行研究，利用虚拟样机分析高低机刚度和阻尼、大架刚度和阻尼、土壤介质刚度和阻尼、后坐质量偏心和耳轴位置偏心对火炮射击稳定性的影响。通过引入改进的相对灵敏度分析公式，解决具有不同量纲的影响因素的比较问题，进而确定影响火炮射击稳定性的重要结构参数。针对目前优化技术存在的局限性，以火炮射击稳定性为目标，采用优化子空间的逐层优化方法对火炮射击稳定性进行研究，找到一组使火炮稳定性最优的结构参数，证明虚拟样机技术对火炮系统动态特性仿真的可行性和优越性。最后，展望了虚拟样机技术在武器装备领域应用的前景。     

Vibration control of a structure using Magneto-Rheological grease damper

This paper describes an application study of Magneto-Rheological (MR) grease damper to a structure with three stories. MR fluid is known as one of successful smart materials whose rheological properties can be varied by magnetic field strength, and has been applied to various kinds of device such as dampers, clutches, engine mounts, etc. However, ferromagnetic particles dispersed in MR fluid settle out of the suspension after a certain interval due to the density difference between the particles and their career fluid. To overcome this defect, we have developed a new type of controllable working fluid using grease as the career of magnetic particles. Network of thickener in grease is expected to hold the magnetic particles and prevent them from settled down. No or little sedimentation was observed in MR grease whose characteristics could be controlled by the magnetic field strength. MR grease was introduced into a cylindrical damper and its performance was studied. As a result, it was confirmed that the damping force of MR grease damper could be controlled by the applied electric current to the coil in the cylinder of damper. Furthermore, vibration response of a three-story model structure equipped with MR grease damper was investigated experimentally, and it was shown that MR grease damper worked effectively as a semi-active damper.     

Study on damping properties of magnetorheological damper

To research the properties of a new kind of smart controllable MR (magnetorheological) fluid, in this paper, the rheological models are discussed. On the basis of analyzing the structural forms of MR dampers, an improved structure of the MR damper is introduced; the properties of the novel MR damper are then tested. The experimental results reveal that the Herschel-Bulkley model predicts the force-velocity well; the damping properties of the ameliorated structure of the MR damper have improved; when the excitation is a trigonal signal, the MR damper reveals a thinning effect at high velocity; and when the excitation is a sinusoidal signal, the MR damper reveals a nonlinear hysteretic property between the damping force and relative velocity. Finally, the main unsolved problems have been put forward. __________ Translated from Ningxia Engineering Technology, 2005, 24 (4) (in Chinese)     

Input advanced control of semi active half car heave model

This paper deals with an input-based half car vehicle model moving with constant velocity over a terrain surface, where MR damper is fixed in both the wheels. The half car model fixed in a rolling dynamometer is operated with various input frequencies corresponding to various speeds. To design and develop control algorithms that will give optimum benefits of the unique features of the MR damper, models have been developed which adequately characterize the damper’s genuine, natural nonlinear behavior. The controller controls both the dampers according to variations in parameters of road surface, speed and load etc., with an advanced time with a particular time bound, through input (pre-programmed) based skyhook on/off control system. Comparison of experimental results of input based and ordinary skyhook on/off results indicates that the model is more functional and rewarding for vibration suppression over a wide range of operating conditions and is passable for control design and analysis.