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

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Prediction Model of Magnetorheological (MR) Fluid Damper Hysteresis Loop using Extreme Learning Machine Algorithm

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

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

In this paper dynamic characteristics of the magneto-rheological (MR) fluid damper has been established based on the LuGre mode. The validity of the proposed model has been verified through the experimental study, the result shows that the proposed model can describe the dynamic properties of the MR damper accurately.

LuGre model for a magneto-rheological (MR) fluid damper

Functional soft materials, exhibiting multiple types of deformation, have shown their potential/abilities to achieve complicated biomimetic behaviors (soft robots). Inspired by the locomotion of earthworm, which is conducted through the contraction and stretching between body segments, this study proposes a type of one-piece-mold folded diaphragm, consisting of the structure of body segments with radial magnetization property, to achieve large 3D and bi-directional deformation with inside-volume change capability subjected to the low homogeneous magnetically driving field (40 mT). Moreover, the appearance based on the proposed magnetic-driven folded diaphragm is able to be easily customized to desired ones and then implanted into different untethered soft robotic systems as soft drivers. To verify the above points, we design the diaphragm pump providing unique properties of lightweight, powerful output and rapid response, and the soft robot including the bio-earthworm crawling robot and swimming robot inspired by squid to exhibit the flexible and rapid locomotion excited by single homogeneous magnetic fields. 

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Di Gong

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

LuGre model for a magneto-rheological (MR) fluid damper

Bio-inspired magnetic-driven folded diaphragm for biomimetic robot