scholarly journals Theoretical Analysis and Optimization of a Gloved Hand-arm System

2021 ◽  
Author(s):  
Oreoluwa Alabi ◽  
Sunit Kumar Gupta ◽  
Oumar Barry
Keyword(s):  
Harmonic Balance ◽  
Equations Of Motion ◽  
Biomechanical Model ◽  
Lumped Parameter Model ◽  
Human Hand ◽  
Governing Equations ◽  
Lumped Parameter ◽  
Hand Tool ◽  
Modeling Techniques ◽  
Linear Spring

Abstract Studies have shown that isolators in the form of anti-vibration gloves effectively reduce the transmission of unwanted vibration from vibrating equipment to the human hand. However, as most of these studies are based on experimental or modeling techniques, the level of effectiveness and optimum glove properties for better performance remains unclear. To fill this gap, hand-arm system dynamics with and without gloves are studied analytically in this work. In the current work, we use a lumped parameter model of the hand-arm system, with hand-tool interaction modeled as a linear spring-damper system. The resulting governing equations of motion are solved analytically using the method of harmonic balance. Parametric analysisis performed on the biomechanical model of the hand-armsystem with and without a glove to identify key design pa-rameters. It is observed that the effect of glove parameters on its performance is not repetitive and changes in the studied different frequency ranges. This observation further motivates us to optimize the glove parameters to minimize the overall transmissibility in different frequency ranges.

Mitigation of Biodynamic Response to Shock Loads Using Semi-Active Vertically Stroking Crew Seats

2010 ◽  
Author(s):  
Harinder J. Singh ◽  
Norman M. Wereley
Keyword(s):  
Human Body ◽  
Control Algorithm ◽  
Equations Of Motion ◽  
Comprehensive Analysis ◽  
Lumped Parameter Model ◽  
Force Model ◽  
Body Parts ◽  
Governing Equations ◽  
Lumped Parameter ◽  
Yield Force

This study addresses mitigation of biodynamic response due to an initial velocity impact of a vertically stroking crew seat using an adaptive magnetorheological energy absorber. Under consideration is a multiple degree-of-freedom detailed lumped parameter model of a human body falling with prescribed initial crash velocity (sink rate). The lumped parameter model of the human body consisted of four main parts: pelvis, upper torso, viscera and head. The governing equations of motion of a vertically stroking crew seat incorporating a human body were derived using parameters such as available damper stroke as well as MR yield force. The control algorithm for smooth landing of a rigid occupant was examined for compliant occupant and was modified accordingly. Four MR yield force models were analyzed to shape decelerations experienced by human body and an appropriate model was selected for comprehensive analysis. The simulated responses were analyzed with selected MR yield force model for a crew seat with an occupant corresponding to 90th percentile male at sink rates varying from 8 to 12 m/s. In addition, the mitigation of injuries to the human body parts due to load transmissions corresponding to crash velocities was also evaluated for the selected MR yield force model along with terminal conditions necessary for smooth landing.

Segmental vibration transmissibility of seated occupant from lumped parameter models

2011 ◽  
Vol 18 (11) ◽  
pp. 1683-1689 ◽  
Author(s):  
Masilamany Santha Alphin ◽  
Krishnaswamy Sankaranarayanasamy ◽  
Suthangathan Paramashivan Sivapirakasam
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Biomechanical Model ◽  
Dynamic Parameter ◽  
Experimental Results ◽  
Lumped Parameter Model ◽  
Whole Body ◽  
Driving Frequency ◽  
Lumped Parameter ◽  
Lumped Parameter Models

One of the important parameters for the comfort of a seated occupant of a vehicle is the dynamic parameter. The effects of vibration depend on biomechanical characteristics, transmissibility (TR) and apparent mass. The range of input vibration at the seat and TR at the driving frequency will decide the magnitude of the displacement at any point of the human occupant. The most preferred form of biomechanical model for unidirectional whole body vibration is the lumped parameter model. Lumped parameter models are formulated by number of masses depending on the number of degrees-of-freedom (d.f.). The objective of this work is to study the vibration TR by developing the equations of motion (EOM) for different d.f. models for the seated occupant. Then the generated equations of motion for lumped parameter models are solved using the frequency domain technique. In this paper two, four, seven and 11 d.f. models are considered. The TR values are determined by solving the derived parameters using the MATLAB program. The maximum seats to head TR in the case of two, four, seven and 11 d.f. are obtained at the frequency of 2 Hz, 2.5 Hz, 3.15 Hz, and 4 Hz respectively. The TR obtained from models is compared with real time experimental results. The comparison shows a better fit for the TR obtained from the four and seven d.f. models. There is a wide deviation from the TR observed with two and 11 degrees of models when compared with experimental results of the past literature.

On the Modeling and Optimization of Anti-Vibration Gloves for Hand-Arm Vibration Control

2019 ◽  
Author(s):  
Sunit K. Gupta ◽  
Oreoluwa Alabi ◽  
Paul-Camille Kakou ◽  
Oumar Barry
Keyword(s):  
Mechanical Model ◽  
Harmonic Balance ◽  
Parametric Analysis ◽  
Harmonic Balance Method ◽  
Analytical Models ◽  
Human Hand ◽  
Frequency Range ◽  
Hand Tools ◽  
Hand Tool ◽  
Linear Spring

Abstract Various studies in hand-arm vibrations have shown that isolators in the form of anti-vibration (AV) gloves are effective to reduce unwanted vibrations, transmitted to the human hand, from machines and hand tools. However, most of these studies are based on experimental or numerical analysis and hence, the level of effectiveness and optimum values of the glove’s properties remain unclear. In this work, we analytically study the dynamics of hand-arm vibrations with and without a glove using the harmonic balance method. The considered analytical models for the hand-arm vibration comprise of lumped multi-degree of freedom system. The hand-tool interactions are modeled as linear spring and damper system for simplicity and accordingly, we obtain the equations governing the dynamics of the human-hand system. We perform parametric analysis using this bio-mechanical model of the hand-arm vibrations with and without a glove. The parametric analysis on the relative transmissibility (i.e., the ratio of transmissibilities with glove to without glove) shows the dependence of the transmissibility on the glove parameters. We observe that the effect of glove parameters on the relative transmissibility is not monotonous for the studied frequency range. This observation further motivates us to perform optimization of the glove parameters to minimize the overall transmissibility.

scholarly journals A Novel Elastic Metamaterial with Multiple Resonators for Vibration Suppression

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Saman Ahmadi Nooraldinvand ◽  
Hamid M. Sedighi ◽  
Amin Yaghootian
Keyword(s):  
Vibration Suppression ◽  
Equations Of Motion ◽  
Small Mass ◽  
The Other ◽  
Governing Equations ◽  
System Parameters ◽  
Rectangular Frame ◽  
Adams Software ◽  
Linear Spring ◽  
Base Structure

In this paper, two models of elastic metamaterial containing one and two resonators are proposed to obtain the bandgaps with the aim of providing broadband vibration suppression. The model with one DOF is built by assembling several unite cells in which each unite cell consists of a rectangular frame as the base structure and a rack-and-pinion mechanism that is joined to the frame with a linear spring on both sides. In the second model with two DOF, a small mass is added while its center is attached to the center of the pinion on one side and the other side is connected to the rectangular frame via a linear spring. In the first mechanism, the pinion is considered as the single resonator, and in the 2DOF model, on the other hand, the pinion and small mass acted as multiple resonators. By obtaining the governing equations of motion for a single cell in each model, the dynamic behavior of two metastructures is thoroughly investigated. Therefore, the equations of motion for the two models are written in matrix form, and then, the dispersion relations are presented to analyze the influences of system parameters on the bandgaps’ starting/ending frequencies. Finally, two models are successfully compared and then numerically simulated via MATLAB-SIMULINK and MSC-ADAMS software. With the aid of closed-form expressions for starting/ending frequencies, the correlation between the system parameters and bandgap intervals can be readily recognized.

A Discrete Lumped-Parameter Dynamic Model for a Planetary Gear Set with Flexible Ring Gear

2011 ◽  
Vol 86 ◽  
pp. 756-761 ◽  
Author(s):  
Jun Zhang ◽  
Yi Min Song ◽  
Jin You Xu
Keyword(s):  
Individual Component ◽  
Natural Frequencies ◽  
Equations Of Motion ◽  
Planetary Gear ◽  
Lumped Parameter Model ◽  
Vibration Modes ◽  
Ring Gear ◽  
Lumped Parameter ◽  
Planetary Gear System ◽  
Flexible Ring

A discrete lumped-parameter model for a general planetary gear set is proposed, which models the continuous flexible ring gear as discrete rigid ring gear segments connected with each other through virtual springs. The ring-planet mesh is analyzed to derive equations of motion of ring segments and planet. By assembling equations of motion of each individual component, the governing equations of planetary gear system are obtained. The solution for eigenvalue problem yields to natural frequencies and corresponding vibration modes. The simulations of example system reveal that the ring gear flexibility decreases system lower natural frequencies and the vibration modes can be classified into rotational, translational, planet and ring modes.

Vibration Modes of Helical Planetary Gears

2009 ◽  
Author(s):  
Tugan Eritenel ◽  
Robert G. Parker
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Rigid Bodies ◽  
Three Dimensions ◽  
Lumped Parameter Model ◽  
Vibration Modes ◽  
Planetary Gears ◽  
Gear Mesh ◽  
Modal Properties ◽  
Lumped Parameter

This paper examines the vibration modes of single stage helical planetary gears in three dimensions with equally spaced planets. A lumped-parameter model is formulated to obtain the equations of motion. The gears and shafts are modeled as rigid bodies with compliant bearings at arbitrary axial locations on the shafts. A translational and a tilting stiffness account for the force and moment transmission at the gear mesh interface. The modal properties generalize those of two-dimensional spur planetary gears; there are twice as many degrees of freedom and natural frequencies due to the added tilting and axial motion. All vibration modes are categorized as planet, rotational-axial, and translational-tilting modes. The modal properties are shown to hold even for configurations that are not symmetric about the gear plane, due to, for example, shaft bearings not being equidistant from the gear plane. Computational modal analysis are performed to numerically verify the findings.

Optimized Biodynamic Shock Attenuation Performance Using an Adaptive Seat Suspension

2011 ◽  
Author(s):  
Harinder J. Singh ◽  
Norman M. Wereley
Keyword(s):  
Equations Of Motion ◽  
Lumped Parameter Model ◽  
Local Optimum ◽  
Shock Attenuation ◽  
Energy Absorber ◽  
Seat Suspension ◽  
Lumped Parameter ◽  
Cubic Polynomial ◽  
Yield Force ◽  
Vertical Impact

Design optimization-based techniques are presented for the minimization of biodynamic loads of a seated occupant subjected to a shock due to an initial velocity vertical impact. A 95th percentile male occupant was modeled using a multiple degree-of-freedom biodynamic lumped parameter model (BLPM) seated on a vertically stroking adaptive seat suspension with a semi-active magnetorheological energy absorber (MREA). The governing equations of motion of the adaptive MREA-based seat suspension with biodynamic lumped parameter model were developed. The variation of magnetorheological yield force with respect to the energy absorber stroke was shaped using cubic polynomial for the maximum shock attenuation. Three cost functions were devised with a common goal of minimizing biodynamic decelerations. Constraints were established based on limitation of MREA stroke and, yield force as well as stroking load. The MREA yield force and damper stroke were crucial parameters for improved biodynamic response mitigation to shock loads. A globally optimized biodynamic response was analyzed among several local optimum responses for better shock attenuation.

Non-Linear Constraints and Stiffness Representations in Simple Flexible-Body Dynamic Beam Formulations

2003 ◽  
Vol 9 (8) ◽  
pp. 911-929 ◽  
Author(s):  
William Haering
Keyword(s):  
Linear Constraint ◽  
Linear Constraints ◽  
Model Verification ◽  
Lumped Parameter Model ◽  
Flexible Body ◽  
Flexible Beam ◽  
Lumped Parameter ◽  
Non Linear ◽  
Linear Spring ◽  
Insight Into

Abstract: A simple discrete four-degree-of-freedom (lumped parameter) model representing a flexible beam undergoing large overall planar prescribed motion has been developed. It serves as a simple tool to investigate two previously studied problems involving flexible-body beam dynamics, namely those involving bending and membrane stiffness dominated behavior. The tool is used to investigate the requirements to accurately solve these problems using non-linear constraints and a non-linear spring representation. The validity of this model is demonstrated by comparing results to those previously published for continuous flexible-body beam formulations. One of these continuous representations is modified to include a non-linear tether spring representation. This allows additional model verification as well as insight into the non-linear constraint and stiffness representations. Taken in its entirety, this investigation demonstrates the utility of these simple lumped parameter models, by showing their ability to provide rapid insight into the behavior of the more complicated continuous models, as well as the system in general.

Elastic System Moving on an Elastically Supported Beam

1984 ◽  
Vol 106 (2) ◽  
pp. 292-297 ◽  
Author(s):  
T. C. Huang ◽  
V. N. Shah
Keyword(s):  
Elastic System ◽  
Equations Of Motion ◽  
Variable Coefficients ◽  
Structural Members ◽  
Governing Equations ◽  
Linear Spring ◽  
Inertia Properties ◽  
Elastically Supported ◽  
Predictor Corrector ◽  
Unsprung Mass

The problem of a two-dimensional elastic system moving on a beam is considered. The moving elastic system or vehicle is represented by the structural members with distributed stiffness, damping, and inertia properties, and it is supported by the suspension units. Each suspension unit consists of a linear spring, a viscous damper, and an unsprung mass. The beam is supported at discrete points along its length, and/or by an elastic foundation. The deformations of the moving system and the beam are represented by their corresponding eigenfunction series. The resulting governing equations are represented by the coupled, ordinary differential equations with variable coefficients. The equations of motion for an elastic platform moving with constant velocity on a beam are derived and solved by the Hamming’s predictor-corrector method. Numerical examples are presented.

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