Nowadays, the automotive industry is oriented toward the production of new generation devices, such as magnetorheological fluid (MR fluid) dampers, which have a proven simplicity of design combined with reduced maintenance. Being devices powered by steady-state electric current, MR fluid dampers develop steady-state magnetic induction fields with associated steady-state thermal stresses and a consequent constant yield stress. In this work, an asymmetric MR damper has been studied using the finite-element method (FEM). Specifically, since steady-state electric current circulates in the coil of the device, a magneto-static analysis of the device and particularly of the strip of MR fluid contained therein is performed using the FEM. Furthermore, as the device is subject to heating during operation, a thermo-static analysis was also carried out using finite elements when different external temperatures were considered. Both analyses, performed by ANSYS ToolbBox, highlighted the areas of the device most subject to magnetic stress providing useful indications on the influence of temperature both on the magnetization of the magnetic particles and on the MR fluid as a whole.

A Magneto-Thermo-Static Study of a Magneto-Rheological Fluid Damper: A Finite Element Analysis

In this study, among 180 possible hydraulically interconnected suspension configurations, non-symmetric cases were eliminated and 24 potential configurations were selected for further investigation...

Configuration development and optimization of hydraulically interconnected suspension for handling and ride enhancement

The high-speed train needs excellent curve-passing performance, reducing wheel/rail force and wear, and sufficient hunting stability. According to the mechanism of self-steering radial bogie, the I...

Dynamics simulation of the high-speed train using interconnected hydro-pneumatic suspension as a self-steering system

A new vibration isolator integrating tunable stiffness-damping and active driving properties based on radial-chains magnetorheological elastomer

Aiming at the problem that the damping coefficient of the traditional hydro-pneumatic spring cannot be adjusted in real-time, the magnetorheological (MR) damping technology was introduced into the traditional hydro-pneumatic spring with single gas chamber. A new shear-valve mode MR hydro-pneumatic spring was proposed. And its dynamic performance was analyzed based on multi-physical coupling simulation and mechanical property test. Firstly, a structural scheme of MR hydro-pneumatic suspension was proposed to ensure the original height adjustment function based on the working principle of traditional hydro-pneumatic suspension with single gas chamber. Secondly, based on the design requirements, the parameter of MR hydro-pneumatic spring damping structure was designed by using MR damper design method. Thirdly, the multi-physical coupling dynamic performance of the MR hydro-pneumatic spring damping structure was analyzed based on the electromagnetic field analysis theory, flow field analysis theory and thermal field analysis theory. The analysis results showed that the designed MR hydro-pneumatic spring has reasonable magnetic circuit structure and excellent working performance. Then, the mechanical properties of MR hydro-pneumatic spring were tested. The results showed that the maximum damping force can reach 20 kN, and the dynamic adjustable multiple can reach 6.4 times. It has good controllability and meets the design requirements. Finally, a nonlinear model of MR hydro-pneumatic spring was established based on the elastic force calculation model of the gas and the Bouc–Wen model. The simulation results of the established model agree well with the experimental results, which can accurately describe the dynamic properties of the hydro-pneumatic spring. The proposed design and modeling method of the MR hydro-pneumatic spring can provide a theoretical basis for the related vibration damping devices. 

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Design and dynamic performance research of MR hydro-pneumatic spring based on multi-physics coupling model

The dynamic properties of two types of interconnected hydro-pneumatic struts (HPSs), which are designed based on two different types of the HPSs with integrated gas chamber, have been investigated through the setup experiment on the designed prototypes and established numerical model on the basis of the AMEsim software in this research work. Detailed analysis of the dynamic properties has been posted on the experimental data, including the in-phase and out-of-phase tests. Special emphasis has been placed on the analysis of some unusual phenomenon shown in the experiment, such as the negative output force, output force distortion, and small stiffness, and so on, which are seldom reported by researchers in this area. Then, the effect of the structural parameters, which include the length/diameter of the interconnected pipes and the size of orifices, to the dynamic properties, especially to the unusual phenomenon shown in the experiment, will be discussed through the established AMEsim model, in which the validity of the AMEsim model has been verified through the experiment. The presented research work provides the fundamental investigation on two types of interconnected HPSs, which have great potential application in the area of a vehicle suspension system.

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Experimental Investigation of Two Types Interconnected Hydro-Pneumatic Struts

The dynamic properties of a compact hydro-pneumatic suspension strut integrating the gas chamber are investigated analytically and experimentally. A comprehensive experiment was designed to experimentally characterize the dependence of friction force on the strut operating pressure in addition to the pressure/force–displacement and pressure/force–velocity properties of the prototype under broad ranges of excitations. An analytical model of the strut is formulated to incorporate the polytropic gas process, nonlinear and hysteretic friction force and turbulent flows across the piston orifices. Owing to dominant effect of friction due to seals of the floating piston separating the gas and oil media, and strong dependence of friction force on the operating pressure, the Coulomb and Stribeck friction effects are described by a nonlinear function in the operating pressure. Furthermore, the viscoelastic O-ring-type seals contributed to notable hysteresis at very low velocities, which is described by a hyperbolic tangent function in velocity. The discharge coefficient of flows through orifices is also identified from the measured fluid pressures. The validity of the proposed model is demonstrated through comparisons of force–displacement and force–velocity responses of the model with the corresponding measured data under broad ranges of excitations. The comparisons revealed that the model could predict dynamic behavior of the strut reasonably well. The effects of charge pressure and gas volume are further investigated to seek guidance on tuning of the strut for realizing desired load carrying capacity and suspension stiffness.

Design and experimental modeling of a compact hydro-pneumatic suspension strut

Magnetoactive elastomers (MAEs), one kind of typical novel magnetoactive driver applied in the soft robotic area, have become one of the research hotspots as they can provide biologically friendly driving methods with safe, preprogrammed, and easy-to-implement properties. In this study, novel MAEs embedding soft magnetic iron microparticles with radial chains, which can be molded in one piece, achieve 3D deformation, and co-work between multiple MAEs under single homogeneous stimuli, are proposed. Then, two kinds of novel magnetoactive drivers are established based on the proposed MAEs, which can achieve the synchronous pumping behavior of heart and the extension behavior of muscle under applied homogeneous magnetic fields. The experimental data show that (1) for the pumping behavior, the maximum instantaneous flow rate and total pumping volume can reach 200.1 and 52.3 mL/min, respectively, under 120 BPM applied harmonic magnetic field with 0-300 mT amplitude; (2) the muscle extension behavior can achieve a strain of 0.925 without a loading mass and carry a load of 40 times its own weight with a pronounced dynamic movement. It should be emphasized that the behavior of the proposed magnetoactive drivers can be excited by remote homogeneous magnetic fields, and it has great application potential in biomimetic or bioinspired soft driving systems.

Magnetoactive Soft Drivers with Radial-Chain Iron Microparticles

The utility model provides a follow -up optical path transmission system for laser cutting device, including the mounting platform and set up in laser instrument on the mounting platform, laser instrument following mechanism, first speculum, the second mirror, third speculum, still include cutting head and cutting head following mechanism, the cutting head includes the focusing mirror, laser instrument length place direction is the first direction, second direction perpendicular to first direction, the first direction is on a parallel with with the plane that the second orientation is formed mounting platform place plane, the third party is to perpendicular to mounting platform place plane, still include a controller and a servo motor, the 2nd servo motor, applied this technical scheme shortens the biggest transmission distance of laser beam in can realizing large -span cutting process, reduces the loss of laser energy volume, improves energy utilization, promotes processingquality toit is compact to make overall structure.

Follow -up optical path transmission system for laser cutting device

The dynamic properties of one kind of Inter-Connected Hydro-Pneumatic Struts (IC HPS), which is designed based on the developed double-gas-chamber compacted Hydro-Pneumatic Struts (HPS) integrating double inner gas chambers, will be investigated in this research. Comparing with the traditional IC HPS designs based on single gas chamber compacted HPS, the proposed IC HPS can postpone the force distortion, and then increase the working envelop, provide good stiffness performance and be stable in both In-Phase and Out-of-Phase working condition. The equation of motion of the proposed IC HPS will be derived firstly. And then based on the established dynamic model, the related simulating model will be established utilizing the AMEsim software, and the validity of the established simulating model will be verified on the basis of experimental data and available literatures. The validity and performance of the proposed IC HPS will be verified and investigated through comprehensive comparison with traditional IC HPS designs. Finally, the detailed sensitivity analysis of the essential design parameter of the proposed IC HPS will be presented to illustrate the advantage of the proposed IC HPS design.

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Lin Dezhao

Papers

Experimental Investigation of Two Types Interconnected Hydro-Pneumatic Struts

Design and experimental modeling of a compact hydro-pneumatic suspension strut

Magnetoactive Soft Drivers with Radial-Chain Iron Microparticles

Follow -up optical path transmission system for laser cutting device

Dynamic Properties Analysis of a New Kind of Inter-Connected Hydro-Pneumatic Strut