Topological Reaction Force Analysis

1979 ◽  
Vol 101 (2) ◽  
pp. 192-198 ◽  
Author(s):  
J. R. Milner ◽  
D. A. Smith
Keyword(s):  
Reaction Force ◽  
Mechanical Systems ◽  
Computational Approach ◽  
Alternative Methods ◽  
Force Analysis ◽  
Dynamic Mechanical ◽  
Reaction Forces ◽  
Linear Graphs

A method of using directed linear graphs for the determination of reaction forces in dynamic mechanical systems is developed. The method is compatible with other more classical techniques for calculating reaction forces and results in a more efficient computational approach than alternative methods. Example problems are discussed and analyzed using these topological techniques.

Repelling-Screw Based Force Analysis of Origami Mechanisms

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Chen Qiu ◽  
Ketao Zhang ◽  
Jian S. Dai
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Reaction Force ◽  
Theoretical Background ◽  
Force Analysis ◽  
Modeling Approach ◽  
Reaction Forces ◽  
Redundantly Actuated

This paper provides an approach to model the reaction force of origami mechanisms when they are deformed. In this approach, an origami structure is taken as an equivalent redundantly actuated mechanism, making it possible to apply the forward-force analysis to calculating the reaction force of the origami structure. Theoretical background is provided in the framework of screw theory, where the repelling screw is introduced to integrate the resistive torques of folded creases into the reaction-force of the whole origami mechanism. Two representative origami structures are then selected to implement the developed modeling approach, as the widely used waterbomb base and the waterbomb-based integrated parallel mechanism. With the proposed kinematic equivalent, their reaction forces are obtained and validated, presenting a ground for force analysis of origami-inspired mechanisms.

Determination of Gait Events Using an Externally Mounted Shank Accelerometer

2013 ◽  
Vol 29 (1) ◽  
pp. 118-122 ◽  
Author(s):  
Jonathan Sinclair ◽  
Sarah J. Hobbs ◽  
Laurence Protheroe ◽  
Christopher J. Edmundson ◽  
Andrew Greenhalgh
Keyword(s):  
Distal Tibia ◽  
Force Platform ◽  
Biomechanical Analysis ◽  
Alternative Methods ◽  
Heel Strike ◽  
Strong Correlations ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Vertical Ground Reaction Forces

Biomechanical analysis requires the determination of specific foot contact events. This is typically achieved using force platform information; however, when force platforms are unavailable, alternative methods are necessary. A method was developed for the determination of gait events using an accelerometer mounted to the distal tibia, measuring axial accelerations. The aim of the investigation was to determine the efficacy of this method. Sixteen participants ran at 4.0 m/s ±5%. Synchronized tibial accelerations and vertical ground reaction forces were sampled at 1000 Hz as participants struck a force platform with their dominant foot. Events determined using the accelerometer, were compared with the corresponding events determined using the force platform. Mean errors of 1.68 and 5.46 ms for average and absolute errors were observed for heel strike and of –3.59 and 5.00 ms for toe-off. Mean and absolute errors of 5.18 and 11.47 ms were also found for the duration of the stance phase. Strong correlations (r= .96) were also observed between duration of stance obtained using the two different methods. The error values compare favorably to other alternative methods of predicting gait events. This suggests that shank-mounted accelerometers can be used to accurately and reliably detect gait events.

Reaction Force Analysis in Generalized Machine Systems

1973 ◽  
Vol 95 (2) ◽  
pp. 617-623 ◽  
Author(s):  
D. A. Smith
Keyword(s):  
Dynamic Systems ◽  
Virtual Work ◽  
Reaction Force ◽  
Inertial Forces ◽  
Force Analysis ◽  
Lagrange’S Equation ◽  
Reaction Forces ◽  
Applied Forces ◽  
Machine Systems ◽  
Centers Of Mass

A method is developed which reduces the calculation of reaction forces for multi-degree-of-freedom, constrained, mechanical, dynamic systems to a process of accumulating a sum of terms representing inertial forces, applied forces, and Lagrange multiplier forces. This method results in an approach to reaction force calculations which is computationally more efficient than either virtual work or equilibrium when these methods are applied in conventional ways. The method is based on selecting a tree for the network being simulated in which the chords of the network correspond to revolute pairs (for two-dimensional systems). When such a tree is determined, Lagrange’s equation with constraint is used to represent the mechanical system. If the paths to the centers of mass and the paths associated with applied forces are developed from tree branches, the Lagrange multipliers are directly interpretable in terms of the total reaction forces at the chords of the network. These multipliers are obtained in the process of determining the system motion. The remaining reaction forces and torques are determined by a sequence of additions.

Generalized and Actual Constraint Forces in the Inverse Dynamic Analysis of Spatial Flexible Mechanical Systems

1991 ◽  
Author(s):  
D. C. Chen ◽  
A. A. Shabana ◽  
J. Rismantab-Sany
Keyword(s):  
Mechanical Systems ◽  
Constraint Forces ◽  
Actual System ◽  
Inverse Dynamic ◽  
Joint Torques ◽  
Elastic Bodies ◽  
Elastic Mechanism ◽  
Reaction Forces ◽  
Multi Body

Abstract In this investigation, a procedure is developed for the determination of the actual system of constraint forces in spatial flexible mechanical systems. Expressions for the generalized reaction forces in terms of the constraint Jacobian matrices of the joints are presented. The effect of the elastic deformation on the actual reaction forces is also examined numerically using the spatial flexible multi-body RSSR mechanism that consists of a set of interconnected rigid and elastic bodies. The procedure described in this investigation can also be used to determine the joint torques in kinematically driven spatial elastic mechanism and manipulator systems.

Ground reaction force analysis for assessing the efficacy of focused and radial shockwaves in the treatment of symptomatic plantar heel spur

2020 ◽  
pp. 1-9
Author(s):  
Piotr Król ◽  
Andrzej Franek ◽  
Tomasz Król ◽  
Arkadiusz Stanula ◽  
Paweł Dolibog ◽  
...  
Keyword(s):  
Shock Wave ◽  
Reaction Force ◽  
Extracorporeal Shock Wave Therapy ◽  
Therapeutic Effects ◽  
Force Analysis ◽  
Heel Spur ◽  
Temporal Parameters ◽  
Extracorporeal Shock Wave ◽  
Reaction Forces ◽  
Foot Function

BACKGROUND: Extracorporeal shock wave therapy is among the conservative treatments for symptomatic heel spur. OBJECTIVE: The purpose of this trial is to evaluate and compare the therapeutic effects of radial shock wave (RSWT) and focused shock wave (FSWT) applied in the treatment of symptomatic heel spur. METHODS: Fifty-five participants were randomly divided into two comparative groups that were administered FSWT and RSWT, respectively. The severity of dysfunction (Foot Function Index, FFI), ground reaction forces (GRF) and walking temporal parameters were measured in all patients at baseline and at weeks 1, 3, 6, 12 and 24 after treatment. RESULTS: In both groups, a gradual decrease in the FFI values occurred after treatment. The percentage reduction in the FFI was comparable for both groups. Statistically significant changes were only noted between some measurements of GRF and walking temporal parameters. The percentage changes in the values of the force and temporal parameters were similar between the groups. CONCLUSIONS: Both FSWT and RSWT are efficacious in the treatment of symptomatic heel spur and their therapeutic effects are comparable. Objective data registered by force platforms during walking are not useful for tracing the progress of treatment applied to patients with symptomatic heel spur between consecutive procedures.

Intramolecular Proton Transfer in the Isomerization of Hydroxyacetone: A Detailed Characterization Based on Reaction Force Analysis and the Bond Fragility Spectrum

2020 ◽  
Author(s):  
Wallace Derricotte ◽  
Huiet Joseph
Keyword(s):  
Chemical Potential ◽  
Reaction Force ◽  
Intramolecular Proton Transfer ◽  
Intermediate Energy ◽  
Force Analysis ◽  
Activation Energy Barrier ◽  
Detailed Characterization ◽  
Proton Transfers ◽  
Reaction Force Constant

The mechanism of isomerization of hydroxyacetone to 2-hydroxypropanal is studied within the framework of reaction force analysis at the M06-2X/6-311++G(d,p) level of theory. Three unique pathways are considered: (i) a step-wise mechanism that proceeds through formation of the Z-isomer of their shared enediol intermediate, (ii) a step-wise mechanism that forms the E-isomer of the enediol, and (iii) a concerted pathway that bypasses the enediol intermediate. Energy calculations show that the concerted pathway has the lowest activation energy barrier at 45.7 kcal mol<sup>-1</sup>. The reaction force, chemical potential, and reaction electronic flux are calculated for each reaction to characterize electronic changes throughout the mechanism. The reaction force constant is calculated in order to investigate the synchronous/asynchronous nature of the concerted intramolecular proton transfers involved. Additional characterization of synchronicity is provided by calculating the bond fragility spectrum for each mechanism.

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