Modelling of a Magnetorheological Fluid Knee in a Prosthetic Leg

2016 ◽  
Author(s):  
The Nguyen ◽  
Saurabh Bapat ◽  
Xinli Wang
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Theoretical Model ◽  
Theoretical Data ◽  
Magnetorheological Fluid ◽  
Theoretical Modelling ◽  
Gap Size ◽  
Applied Current ◽  
Prosthetic Knee ◽  
Braking Torque

The purpose of the study is to theoretically model a prosthetic knee. A knee similar to magnetorheological fluid (MRF) brake is designed and the study focuses on modelling the MRF knee, predict the torque and compare it with the experimental data. The torque generated by the MRF knee is highly dependent on the gap size, angle, and the applied current. Here, the MRF knee features a non-circular rotor which results in a variable gap size for the MR fluid, between the stator and the rotor. Therefore, the gap size varies with the angle of the knee. When the current is applied and MR knee is subjected to a magnetic field, the yield stress produces the shear friction due to which the braking torque is generated. This derives the braking torque as a function of angle and applied current. A torque equation is derived from the theoretical data to yield the predicted results. In addition to the theoretical modelling and derived torque equations, the torque for the MRF fluid is also calculated experimentally. For the validation of the theoretical model and the derived torque equations, they were compared with the experimental results.

Design and Experimental Analysis of a Biomedical Prosthetic Knee With Magnetorheological Fluid

2015 ◽  
Author(s):  
The Nguyen ◽  
Alan Suarez ◽  
Saurabh Bapat
Keyword(s):  
Smart Materials ◽  
Theoretical Models ◽  
Magnetorheological Fluid ◽  
Gap Size ◽  
Electric Motors ◽  
Mr Fluid ◽  
Prosthetic Knee ◽  
The Family ◽  
Braking Torque ◽  
Improved Design

Current prosthetic legs rely on technology that is inefficient. Electric motors used today require high amounts of current to operate. Prostheses utilizing smart materials, including magnetorheological fluid (MRF), require less power to operate effectively. In this study, the MR fluid knee was designed for above the knee amputees. The design was in the family of MR fluid brake/clutch as it provides simple design and good MR fluid uniformity. However, this MR knee design is different from any existing MR brake, featuring a novel non-circular rotor. Three fourths of the rotor, considered circular, has the same radius, and the remaining quarter has a varying radius to provide a variable gap size between the rotor and stator. This feature allows the MR fluid to experience a stronger magnetic field as the knee rotates, resulting in a variable braking torque. At this stage of research, the first working prototype of the proposed MR fluid knee was built and tested to determine the braking torque profile. Corresponding theoretical models were also created. The calculated torque was used to predict the performance of the MRF knee. The experiments has been conducted to examine the MRF knee performance and to compare with the theoretical model. The knee was expected to use less power to operate and provided the necessary braking torque required by an average male human body. An improved design was planned for weight reduction and optimization to allow the commercialization of the MRF knee.

Influence of Permanent Magnets Installation Approach on the Torque of а Magneto-Rheological Disk Brake

2021 ◽  
Vol 105 ◽  
pp. 184-193
Author(s):  
Ilya Aleksandrovich Frolov ◽  
Andrei Aleksandrovich Vorotnikov ◽  
Semyon Viktorovich Bushuev ◽  
Elena Alekseevna Melnichenko ◽  
Yuri Viktorovich Poduraev
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Materials ◽  
Permanent Magnets ◽  
Magnetorheological Fluid ◽  
Simulation Modelling ◽  
Disc Brake ◽  
Large Area ◽  
Braking Torque ◽  
The Magnetic Field

Magnetorheological braking devices function due to the organization of domain structures between liquid and solid magnetic materials under the action of an electromagnetic or magnetic field. The disc is most widely used as a rotating braking element that made of a solid magnetic material due to the large area of contact with a magnetorheological fluid. Many factors affect the braking characteristics of the magnetorheological disc brake. Specifically, the value of the magnetic field and how the field is distributed across the work element is significantly affected at the braking torque. There are different ways to generate a magnetic field. In this study, the method of installation of permanent magnets into the construction, allowing to increase the braking torque of the magnetorheological disc brake is proposed. Simulation modelling showing the distribution of the magnetic field across the disk depending on the installation of permanent magnets with different pole orientations were carried out. The model takes into account the possibility of increasing the gap between solid magnetic materials of the structure, inside them which the magnetorheological fluid is placed. Comparative estimation of the distribution of the magnetic fields depending on the chosen method of installation of permanent magnets with different orientations of their poles is carried out. Further research is planned to focus on a comparative assessment of the distribution of magnetic fields depending on the selected material of the braking chamber.

Validation of a method for odor sampling on solid area sources

2012 ◽  
Vol 66 (8) ◽  
pp. 1607-1613 ◽  
Author(s):  
L. Capelli ◽  
S. Sironi ◽  
R. Barczak ◽  
M. Il Grande ◽  
R. Del Rosso
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Wind Tunnel ◽  
Solid Surface ◽  
Laboratory Tests ◽  
Theoretical Data ◽  
Experimental Setup ◽  
Good Correspondence ◽  
Adopted Model ◽  
Solid Area

The aim of this paper is the study and the validation of a method for odor sampling on solid area sources. This aim is achieved by considering a suitable theoretical model that accounts for all the variables involved in the volatilization process of odorous compounds from solids into the atmosphere. The simulation of the emission of odors from a solid surface was achieved by designing a suitable experimental setup and a specific wind tunnel for laboratory tests. The results of the tests show a good correspondence between the theoretical data derived from the adopted model and the experimental data. The verification of the possibility of describing the wind tunnel functioning with a theoretical volatilization model proves the applicability of this device for sampling on solid area sources.

EFFECT OF MAGNETIC FIELD ON PROPERTIES OF MR FLUIDS

2005 ◽  
Vol 19 (01n03) ◽  
pp. 597-601 ◽  
Author(s):  
J. HUANG ◽  
J. Q. ZHANG ◽  
J. N. LIU
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Theoretical Model ◽  
Yield Stress ◽  
Applied Magnetic Field ◽  
Mr Fluids ◽  
Magnetic Chain ◽  
Viscoplastic Properties

The yield stress is one of the most important parameters that characterize viscoplastic properties of magnetorheological (MR) fluids. Based on the microstructure of magnetic-chain a theoretical model is developed to analyze the effect of the applied magnetic field on the yield stress. It has been shown that the values of the yield stress calculated by the model agree well with the experimental data.

scholarly journals Research on a mechanical model of magnetorheological fluid different diameter particles

2021 ◽  
Vol 11 (1) ◽  
pp. 158-166
Author(s):  
Jun Qiu ◽  
Yiping Luo ◽  
Yuqing Li ◽  
Jiao Luo ◽  
Zhibin Su ◽  
...  
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Mechanical Model ◽  
Volume Fraction ◽  
Silicone Oil ◽  
Theoretical Data ◽  
Magnetorheological Fluid ◽  
Average Error ◽  
Shear Strain Rate ◽  
Particle Volume

Abstract In this paper, the chain structure of magnetorheological fluid (MRF) magnetic particles was studied and analyzed, the mechanical model of MRF with different diameter ferromagnetic particles was established, silicone oil-based MRF with different particle volume fractions was prepared, the shear properties of the MRF were tested, and the theoretical and experimental data were compared. The experimental results show that the shear stress is stable with the increase of shear strain rate under the action of the magnetic field, and it has a shear thinning effect. The shear stress increases linearly with the increase of particle volume fraction. The shear stress increases with the increase of magnetic induction intensity. After data analysis and in the case of control variables, the average error of improved theoretical data and experimental data is lower than that of previous theoretical data and experimental data, which verifies that the improved theory (mechanical model) has a certain accuracy.

scholarly journals Underplatform Dampers for Turbine Blades: Theoretical Modelling, Analysis and Comparison With Experimental Data

1999 ◽  
Author(s):  
Kenan Y. Sanliturk ◽  
David J. Ewins ◽  
Anthony B. Stanbridge
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Normal Load ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Hysteresis Loops ◽  
Theoretical Modelling ◽  
Contact Behaviour ◽  
Modes Of Vibration ◽  
Opening And Closing

This paper describes a theoretical model for analysing the dynamic characteristics of wedge-shaped underplatform dampers for turbine blades, with the objective that this model can be used to minimise the need for conducting expensive experiments for optimising such dampers. The theoretical model presented in the paper has several distinct features to achieve this objective including: (i) it makes use of experimentally-measured contact characteristics (hysteresis loops) for description of the basic contact behaviour of a given material combination with representative surface finish, (ii) the damper motion between the blade platform locations is determined according to the motion of the platforms, (iii) three-dimensional damper motion is included in the model, and (iv) normal load variation across the contact surfaces during vibration is included, thereby accommodating contact opening and closing during vibration. A dedicated non-linear vibration analysis program has been developed for this study and predictions have been verified against experimental data obtained from two test rigs. Two cantilever beams were used to simulate turbine blades with real underplatform dampers in the first experiment. The second experiment comprised real turbine blades with real underplatform damper. Correlation of the predictions and the experimental results revealed that the analysis can predict (i) the optimum damping condition, (ii) the amount of response reduction and (iii) the natural frequency shift caused by friction dampers, all with acceptable accuracy. It has also been shown that the most commonly-used underplatform dampers in practice are prone to rolling motion, an effect which reduces the damping in certain modes of vibration usually described as the lower nodal diameter bladed-disc modes.

SMALL HYSTERESIS LOOPS INVESTIGATIONS ON HIGH Tc OXIDE SUPERCONDUCTORS

1991 ◽  
Vol 05 (18) ◽  
pp. 1237-1248
Author(s):  
J. SOSNOWSKI ◽  
J. RAABE ◽  
E. BOBRYK ◽  
A. GILEWSKI ◽  
J. WARCHULSKA
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
High Temperature ◽  
Theoretical Model ◽  
Magnetic Field Dependence ◽  
Numerical Approximation ◽  
Hysteresis Loops ◽  
Oxide Superconductors ◽  
High Tc ◽  
Fitting Procedure

Results of investigations on small hysteresis loops of yttrium-based high temperature ceramical compounds are presented. A proposed theoretical model describing the magnetic induction profile in a sample has been used for numerical approximation of the experimental data. The results of this fitting procedure then allow one to obtain detailed information on the pinning force's magnetic field dependence as well as the critical current of ceramical compounds.

scholarly journals A Magneto-Active Elastomer Crawler with Peristaltic and Caterpillar Locomotion Patterns

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 74
Author(s):  
Tsam Lung You ◽  
Hemma Philamore ◽  
Fumitoshi Matsuno
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
External Magnetic Field ◽  
Mathematical Models ◽  
Confined Spaces ◽  
Low Mass ◽  
Structural Simplicity

In this work we present a soft crawler fabricated using a magneto-active elastomer. The crawler is controlled by an external magnetic field to produce two locomotion patterns: peristaltic and caterpillar crawling. Due to its structural simplicity, low mass, wirelessly controlled actuation and compliant body the design of this crawler has the potential to address the key challenges faced by existing crawling robots. Experimental data were gathered to evaluate the performance of the crawler locomotion in a pipe. The results validated the mathematical models proposed to estimate the distance traveled by the crawler. The crawler shows potential for use in exploration of confined spaces.

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