Dynamic Modeling and Fluid-Structure Interactive Analysis of an Innovative Self-Tuning Shock Absorber for the Prosthesis Knee Joint

2010 ◽  
Author(s):  
Yen-Chieh Mao ◽  
Wei-Chih Chang
Keyword(s):  
Knee Joint ◽  
Shock Absorber ◽  
Knee Prosthesis ◽  
Element Model ◽  
Heel Strike ◽  
Design Parameters ◽  
Fluid Structure ◽  
Shock Absorbers ◽  
Damper Design ◽  
The Impact

The above-knee prosthesis, as a supplement of the lost biological leg, is supposed to provide equivalent or enhanced shock absorption capability and reduce the shock waves on the amputee body when walking and running. Prosthesis knee joint with a shock absorber is a feasible solution that efficiently absorbs the impact loads during each heel-strike. Conventional shock absorbers consist of springs and dampers with constant coefficients produce excessive rigid reactions when encountering impact forces, while unreasonable weak responses for gentle loads. This study proposes an innovative viscous damper design for the prosthesis knee joint which automatically and smoothly tunes the damping coefficient without any electronic components according to the input force velocities. High order differential system of the shock absorber is constructed and simulates the system dynamics during cyclic loads. The fluid-structure interactive finite element model for key components in the absorber is established in this study. Design parameters of the damper system under certain absorbing performance requirements are determined in this paper.

NONLINEAR MODELING WITH CAVITATION PHENOMENON OF A NOVEL SHOCK ABSORBER FOR ABOVE-KNEE PROSTHESIS

2010 ◽  
Vol 07 (03) ◽  
pp. 243-257 ◽  
Author(s):  
Y. C. MAO
Keyword(s):  
Shock Wave ◽  
Ground Reaction Force ◽  
Shock Absorber ◽  
Knee Prosthesis ◽  
Reaction Force ◽  
Damping Coefficient ◽  
Heel Strike ◽  
Cavitation Phenomenon ◽  
Wide Range ◽  
The Impact

The shock wave of ground reaction forces during walking and running is suggested as a primary etiological agent in some conditions, such as degenerative joint disease, prosthetic joint loosening, plantar fasciitis or muscle tears. This study proposes a novel shock absorber design with an adjustable automatic smooth tuning range of the damping coefficient and rapid rebounds after impact loads, equipped in the above-knee prosthesis tibia section without any electronic devices. This absorber is also capable of automatic locking-out and releasing for stance and heel-strike phases without manual switching. It absorbs the impact load of the ground reaction force at each heel strike and adapts itself to the input force speed, feasible for patients to tolerate a wide range of athletic and inert situations. This study constructs a high order nonlinear dynamic model for its pressure-sensitive plunger and check valve systems and considers the cavitation phenomenon during speedy fluid flows. Simulation results show that both the damper resistant force and the damping coefficient reduce as the ground reaction force velocity increases, providing a desirable tendency of diminishing shock wave influences on the biological musculoskeletal system.

scholarly journals Analysis of Water Flow Pressure on Bridge Piers considering the Impact Effect

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Yin-hui Wang ◽  
Yi-song Zou ◽  
Lue-qin Xu ◽  
Zheng Luo
Keyword(s):  
Water Flow ◽  
Coupling Effect ◽  
Highway Bridges ◽  
Element Model ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Water Current ◽  
Fluid Structure ◽  
Impact Effect ◽  
The Impact

In order to investigate the effects of water current impact and fluid-structure interaction on the bridge piers, the mechanism of water flow impact on the bridge pier is firstly studied. Then a finite element model of a bridge pier is established including the effects of water flow impact as well as the water circumferential motion around the pier. Comparative study is conducted between the results of water impact effect, fluid-structure coupling effect, theoretical analysis, and also the results derived using the formulas specified in the design codes home and abroad. The results show that the water flow force calculated using the formulas provided by the codes should be multiplied by an impact amplifier to account for the effect of flood impact on the bridge pier. When the flood flows around the pier, the fluid-structure coupling effect on the bridge pier can be neglected. The method specified in the China guidelines ofGeneral Code for Design of Highway Bridges and Culvertstends to provide a larger result of the water flow force.

Fatigue Crack Propagation Simulation of Rubber Shock Absorbers

2011 ◽  
Vol 415-417 ◽  
pp. 2298-2303
Author(s):  
Jing Yu Zhai ◽  
Ying Yang ◽  
Qing Kai Han
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Crack ◽  
Crack Growth ◽  
Shock Absorber ◽  
Three Dimensional ◽  
Element Model ◽  
Initial Crack ◽  
Shock Absorbers ◽  
Element Method

Rubber shock absorbers are the key parts to isolate vibrations of the machinery and equipment. In this paper, a three dimensional finite element model of a rubber shock absorber is established; then the computation of three dimensional fatigue crack growth rates are discussed by using the nonlinear finite element method. The stress distribution which can determine the initial crack location and the possible risk surface under dynamic loads is obtained. The three dimensional crack growth is simulated by using finite element method and linear elastic fracture mechanics. A brittle fracture process of the rubber shock absorber along the dangerous surface is simulated by using the cohesive element of ABAQUS.

Damping force characteristics of electrorheological shock absorbers with different electrode designs

2010 ◽  
Vol 224 (2) ◽  
pp. 293-304 ◽  
Author(s):  
Y-M Han ◽  
M-S Seong ◽  
S-B Choi ◽  
N M Wereley
Keyword(s):  
Shock Absorber ◽  
Equations Of Motion ◽  
Design Parameters ◽  
Damping Force ◽  
Passenger Vehicles ◽  
Shock Absorbers ◽  
Car Suspension ◽  
Field Dependent ◽  
The Time Domain ◽  
Er Fluid

This article presents the effect of electrode design parameters on the damping force of an electrorheological (ER) shock absorber for passenger vehicles. As a first step, an ER fluid is synthesized by dispersing arabic gum particles into non-conducting oil, and its field-dependent Bingham characteristics are experimentally evaluated. The Bingham model of the ER fluid is then formulated and incorporated with the governing equations of motion of the ER shock absorber. Subsequently, several ER shock absorbers are designed and manufactured with various electrode designs, which have three different electrode gaps, lengths, and materials, respectively. The field-dependent damping force of the manufactured shock absorbers is demonstrated in the time domain and compared with simulation results. In addition, the vibration control performance of a quarter-car suspension system is presented and compared with different electrode gaps and lengths.

Mechanical Motion Rectifier Based Energy-Harvesting Shock Absorber

2012 ◽  
Author(s):  
Zhongjie Li ◽  
Lei Zuo ◽  
Jian Kuang ◽  
George Luhrs
Keyword(s):  
Energy Harvesting ◽  
Shock Absorber ◽  
Mechanical Motion ◽  
Vibration Energy Harvesting ◽  
Innovative Design ◽  
Shock Absorbers ◽  
Impact Forces ◽  
Road Roughness ◽  
Energy Harvesting Efficiency ◽  
The Impact

Energy-harvesting shock absorber is able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppress the vibration induced by road roughness. It can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called “mechanical motion rectifier (MMR)”, to convert the suspension’s oscillatory vibration into unidirectional rotation of the generator. An implementation of motion rectifier based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than the conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to verify the feasibility of the MMR shock absorber, in which more than 15 Watts’ electricity is harvested while driving at 15 mph. The motion rectifier based design can also be used for other applications of electromagnetic vibration energy harvesting.

Optimization of a Hydraulic Damper Performance with the Use of Fluid-Structure Simulation

2012 ◽  
Vol 452-453 ◽  
pp. 1356-1360
Author(s):  
Dawid Jakubowski ◽  
Jacek Gnilka ◽  
Grzegorz Wszołek ◽  
Piotr Czop
Keyword(s):  
Shock Absorber ◽  
Flow Paths ◽  
Fluid Structure ◽  
Hydraulic Damper ◽  
Shock Absorbers ◽  
Cavitation Effect ◽  
Structure Simulation ◽  
Key Steps ◽  
Disc Spring ◽  
Structure Domain

The aim of this paper is to develop a method for optimizing the design of a spring valve system by reducing the aeration and cavitation effect which negatively influences the performance of a shock absorber. A fluid-structure interaction (FSI) model is used in order to modify the geometry of the valve interior and, in turn, to achieve better performance in shock absorbers. The paper analyzes the pressure distribution along the flow paths inside the valve cavity to reduce the risk of aeration and cavitation, while other important engineering aspects are omitted, e.g. durability of disc-spring valve systems as discussed in [1]. The objective of this work is to show key steps of the simulation process focusing on interactions between fluid and structure domain and to review relevant simulation results.

The influence of selected operating parameters on assessment of technical condition of shock absorber at EUSAMA station

2018 ◽  
Vol 123 ◽  
pp. 55-61
Author(s):  
Łukasz Konieczny ◽  
Zdzisław Niedziela ◽  
Jan Łukowski ◽  
Marcin Stańczyk
Keyword(s):  
Shock Absorber ◽  
Test Bench ◽  
Operating Parameter ◽  
Technical Condition ◽  
Technical State ◽  
Operating Parameters ◽  
Tabular Form ◽  
Shock Absorbers ◽  
Vehicle Inspection ◽  
The Impact

The article presents the results of the technical state of shock absorbers on the stand with harmonic Eusam type kinematic forcing applied at vehicle inspection stations. As operating parameter, the pressure in the tires was assumed (assumed a reduced value in relation to the recommended nominal value) and the impact of this parameter on the values obtained during testing on the test bench was determined. The measurements were carried out several times. The results are summarized in tabular form and in the form of a graph and based on them final conclusions were formulated.

Parameter Sensitivity and Reliability Analysis for Construction Control of Cable-Net Structure Supporting the Reflector of FAST

2013 ◽  
Vol 671-674 ◽  
pp. 529-533
Author(s):  
Xu Kong ◽  
Qi Ming Wang ◽  
Chuan Jia Liu ◽  
Zhong Yi Zhu
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Structural Parameters ◽  
Element Model ◽  
Parameter Sensitivity ◽  
Tension Force ◽  
Design Parameters ◽  
Structural Parameter ◽  
Global Sensitivity ◽  
The Impact

Five-hundred-meter Aperture Spherical radio Telescope (FAST) is supported by cable-net structure, which enables its surface to form a paraboloid in real time under active control. FAST is now entering project construction and implement stage, however there are always a considerable amount of errors existed in practice which would result in the deviation of the structure from its ideal model. Therefore, structural parameter sensitivity analysis was indispensable discussed. In the paper, the variation ranges of structural parameters were rationally determined. Base on local sensitivity analysis and global sensitivity analysis method, Using the finite element model investigated the influence of different structural parameters change on the static behavior, gets the conclusions that the impact of several key design parameters on the tension force of cable-net is large. The results indicate that of all types of the structural parameters, the error of the length of cable plays the most important role, and the global sensitivity analysis indicates that the tension force range of cable-net is -18% to 27%.

scholarly journals Shock Absorber Applications

2019 ◽  
Vol 4 (1) ◽  
pp. 37-41
Author(s):  
Shaun Spiteri
Keyword(s):  
Everyday Life ◽  
Shock Absorber ◽  
Shock Absorbers ◽  
Different Types ◽  
Specific Shape ◽  
The Impact ◽  
High Winds

Shock Absorbers are a part of everyday life and have many different applications and uses.  They are used for bridges, highways, buildings and cars to absorb the impact from the bumps, earthquakes and high winds.  Different applications require different types of shocks and different materials.  A rubber shock absorber cannot be used on a vehicle while a cylindrical shock absorber cannot be used on a highway.  All the situations require a specific shape and type of shocks to be used for the required tasks.

scholarly journals Contribution to the development of methodology for assessing the impact of bus suspension system on fuel consumption and CO2 emission

2020 ◽  
pp. 168-168
Author(s):  
Dragan Sekulic ◽  
Ivan Ivkovic ◽  
Dusan Mladenovic ◽  
Davor Vujanovic
Keyword(s):  
Fuel Consumption ◽  
Co2 Emission ◽  
Degrees Of Freedom ◽  
Shock Absorber ◽  
Ride Comfort ◽  
Suspension System ◽  
Vertical Acceleration ◽  
Shock Absorbers ◽  
Parameter Values ◽  
The Impact

This paper analyzes the effects of intercity bus suspension system oscillatory parameters on driver's ride comfort and road damage. The analysis has been carried out through simulation by means of validated in-plane bus model with six degrees of freedom excited by real road roughness signal. Low root-mean-square values of the weighted vertical acceleration (less than 0.315 m/s2) have been achieved by shock-absorbers with lower damping coefficient and softer suspension system springs. Low values of dynamic load coefficient provide low shock-absorber damping and softer springs. However, low crest factor values for both axles are accomplished for high shock-absorber damping and softer springs in bus suspension system. Results from this analysis could be used as reference for selecting proper oscillatory parameter values when designing road-friendly bus suspension system which in turn would increase vehicle energy efficiency. Presented methods, results and analyzes are the part of wider methodology for assessing the impact of bus suspension system on fuel consumption and CO2 emission.

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