Dynamic Analysis of Knee-Exoskeleton and Its implementation to Design of Magnetorheological Damper

In this study, a new development of knee exoskeleton is presented. Kinematic parameters of the proposed exoskeleton are analysed to find relations among forces and torques. After analysing, the damping force of magneto-rheological (MR in short) damper is carried out. The magnetic flux density and the yield stress functions are found, and these functions are bases for derivation of damping force formulation. The forces from the exoskeleton are directly related to the damping force. Hence these values are used as an objective to find the optimized geometry of the damper. The optimization process is done by using ANSYS ADPL. It is shown that the requirement of design is obtained.

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Design and Multiobjective Optimization of Magnetorheological Damper considering the Consistency of Magnetic Flux Density

Shock and Vibration ◽

10.1155/2020/7050356 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Zhizhen Dong ◽

Zhimin Feng ◽

Yuehua Chen ◽

Kefan Yu ◽

Gang Zhang

Keyword(s):

Magnetic Flux ◽

Multiobjective Optimization ◽

Flux Density ◽

Optimization Design ◽

Dynamic Range ◽

Mr Damper ◽

Magnetorheological Damper ◽

Magnetic Flux Density ◽

Damping Force ◽

Mr Dampers

The consistency of magnetic flux density of damping gap (CMDG) represents the balancing magnetic flux density in each damping gap of magnetorheological (MR) dampers. It can make influences on the performances of MR dampers and the accuracy of relevant objective functions. In order to improve the mechanical performances of the MR damper with a two-stage coil, the function for calculating CMDG needs to be found. By establishing an equivalent magnetic circuit model of the MR damper, the CMDG function is derived. Then, the multiobjective optimization function and the working flow of optimal design are presented by combining the parallel-plate model of the MR damper with the function posed before. Taking the damping force, the dynamic range, the response time, and the CMDG as the optimization objective, and the external geometric dimensions of the SG-MRD60 damper as the bound variable, this paper optimizes the internal geometric dimensions of MR damper by using a NSGA-III algorithm on the PlatEMO platform. The results show that the obtained scheme in Pareto-optimal solutions has existed with better performance than that of SG-MRD60 scheme. According to the results of the finite element analysis, the multiobjective optimization design including the CMDG function can improve the uniformity of magnetic flux density of the MR damper in damping gap, which meets the requirements of manufacture and application.

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Effect of magnetic permeability, shearing length, and shear gap on magnetic flux density of the magnetorheological damper through finite element analysis

Materials Today Proceedings ◽

10.1016/j.matpr.2020.05.714 ◽

2020 ◽

Author(s):

Ashok Kumar Kariganaur ◽

Hemantha Kumar ◽

M. Arun

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Magnetic Flux ◽

Flux Density ◽

Magnetic Permeability ◽

Magnetorheological Damper ◽

Magnetic Flux Density ◽

Element Analysis

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A novel bi-directional shear mode magneto-rheological elastomer vibration isolator

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x20942314 ◽

2020 ◽

Vol 31 (17) ◽

pp. 2002-2019 ◽

Cited By ~ 3

Author(s):

Amir Jalali ◽

Hashem Dianati ◽

Mahmood Norouzi ◽

Hossein Vatandoost ◽

Mojtaba Ghatee

Keyword(s):

Magnetic Flux ◽

Flux Density ◽

Excitation Frequency ◽

Magnetic Flux Density ◽

Shear Mode ◽

Vibration Isolator ◽

Horizontal Shear ◽

Shear Modes ◽

Magneto Rheological ◽

Mechanical Devices

In this article, a novel bi-directional shear mode magneto-rheological elastomer–based vibration isolator has been designed, fabricated, and characterized to improve the dynamic response and identification of this class of “intellectual” mechanical devices. A heuristic embodiment has been realized in order to design such an isolator wherein both the vertical and horizontal directions can be operated only in the shear mode not only individually but also simultaneously. Two fixtures have been designed for performing the characterization of the magneto-mechanical behavior of the proposed magneto-rheological elastomer isolator in the vertical and horizontal shear modes under wide ranges of strain amplitude (4%–32%), excitation frequency (1–8 Hz), and magnetic flux density (0–220 mT). Experimental results revealed maximum relative magneto-rheological effects of 35% and 27 % in the vertical and horizontal shear modes, respectively. Furthermore, basic mathematical models of single-degree-of-freedom systems, employing the magneto-rheological elastomer–based isolator in the vertical and horizontal shear modes, have been established. The proposed magneto-rheological elastomer isolator in the vertical mode exhibited natural frequency shift of 6.1% by a small increment in the magnetic flux density which approves the potential of the proposed bi-directional shear mode magneto-rheological elastomer–based vibration isolator for vibration control applications, such as seat suspension systems.

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A study of influence of material properties on magnetic flux density induced in magneto rheological damper through finite element analysis

MATEC Web of Conferences ◽

10.1051/matecconf/201814402004 ◽

2018 ◽

Vol 144 ◽

pp. 02004

Author(s):

T. M. Gurubasavaraju ◽

Kumar Hemantha ◽

Mahalingam Arun

Keyword(s):

Magnetic Flux ◽

Flux Density ◽

Low Carbon Steel ◽

Mr Damper ◽

Magnetic Effect ◽

Magnetic Flux Density ◽

Low Carbon ◽

Damping Force ◽

Piston Head ◽

Annular Gap

Magnetorheological fluids are smart materials, which are responsive to the external stimulus and changes their rheological properties. The damper performance (damping force) is dependent on the magnetic flux density induced at the annular gap. Magnetic flux density developed at fluid flow gap of MR damper due to external applied current is also dependent on materials properties of components of MR damper (such as piston head, outer cylinder and piston rod). The present paper discus about the influence of different materials selected for components of the MR damper on magnetic effect using magnetostatic analysis. Different materials such as magnetic and low carbon steels are considered for piston head of the MR damper and magnetic flux density induced at fluid flow gap (filled with MR fluid) is computed for different DC current applied to the electromagnetic coil. Developed magnetic flux is used for calculating the damper force using analytical method for each case. The low carbon steel has higher magnetic permeability hence maximum magnetic flux could pass through the piston head, which leads to higher value of magnetic effect induction at the annular gap. From the analysis results it is observed that the magnetic steel and low carbon steel piston head provided maximum magnetic flux density. Eventually the higher damping force can be observed for same case.

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