Experimental and Analytical Study of Pantograph Dynamics

1991 ◽  
Vol 113 (2) ◽  
pp. 242-247 ◽  
Author(s):  
W. Seering ◽  
K. Armbruster ◽  
C. Vesely ◽  
D. Wormley
Keyword(s):  
Experimental Data ◽  
Dynamic Response ◽  
Coulomb Friction ◽  
Close Agreement ◽  
Analytical Study ◽  
Model Performance ◽  
Nonlinear Effects ◽  
Variable Stiffness ◽  
Response Data ◽  
Lumped Parameter

A nonlinear, lumped parameter pantograph model including geometric and coulomb friction nonlinearities and variable stiffness has been developed. The model performance has been compared with experimental dynamic response data measured on a prototype pantograph. Responses of the model and the experimental data including subharmonic and harmonic resonances are in close agreement for motions excited by comparable forcing functions for input frequencies of 0 to 12 Hz. The model has been used to identify the primary parameters and nonlinear effects which influence dynamic pantograph performance.

Effects of Bearing Radial Internal Clearance on Dynamic Behavior and Bifurcations in Planetary Gears

2011 ◽  
Author(s):  
Yi Guo ◽  
Robert G. Parker
Keyword(s):  
Dynamic Response ◽  
Harmonic Balance Method ◽  
Nonlinear Behavior ◽  
Nonlinear Effects ◽  
Lumped Parameter Model ◽  
Solution Stability ◽  
Planetary Gears ◽  
Gear Mesh ◽  
Bearing Clearance ◽  
Lumped Parameter

This study investigates the dynamics of planetary gears where nonlinearity is induced by bearing clearance. Lumped-parameter and finite element models of planetary gears with bearing clearance, tooth separation, and gear mesh stiffness variation are developed. The harmonic balance method with arc-length continuation is used to obtain the dynamic response of the lumped-parameter model. Solution stability is analyzed using Floquet theory. Rich nonlinear behavior is exhibited in the dynamic response, consisting of nonlinear jumps and a hardening effect induced by the transition from no bearing contact to contact. The bearings of the central members (sun, ring, and carrier) impact against the bearing races near resonance, which leads to coexisting solutions in wide speed ranges, grazing bifurcation, and chaos. Secondary Hopf bifurcation is the route to chaos. Input torque can significantly suppress the nonlinear effects caused by bearing clearance.

The Determination of Squeeze Film Dynamic Coefficients From Transient Two-Dimensional Experimental Data

1990 ◽  
Vol 112 (2) ◽  
pp. 288-296 ◽  
Author(s):  
J. B. Roberts ◽  
J. Ellis ◽  
A. Hosseini Sianaki
Keyword(s):  
Experimental Data ◽  
Simulated Data ◽  
Degree Of Freedom ◽  
Squeeze Film ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
Response Data ◽  
Lumped Parameter ◽  
Experimental Trials ◽  
State Variable Filter

A state variable filter (SVF) method of identifying parameters in lumped-parameter systems is extended to accommodate multi-degree-of-freedom problems. The method is computationally efficient and can be used with both transient and forced squeeze-film response data. In this paper the method is successfully applied to the analysis of transient simulated data both with and without signal noise. Finally the method is shown applied in the analysis of two-dimensional transient experimental data from a squeeze-film bearing rig. The identified results for the dynamic film coefficients compare well with results from earlier single-degree-of-freedom experimental trials.

Analytical Study of Hydro-Pneumatic Processes for Gorlov's Power System

1994 ◽  
Vol 208 (1) ◽  
pp. 67-70
Author(s):  
A I Ryazanov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Power System ◽  
Analytical Study ◽  
Model Tests ◽  
Air Pressure ◽  
Pneumatic Power ◽  
Time Required ◽  
The Mathematical Model

This paper describes the aerohydrodvnamics of processes in chambers of Gorlov's hydro-pneumatic power system. The mathematical model is developed to determine the main parameters of the processes: water and air velocities, air pressure in the chamber, the periods of time required to fill and empty the chambers and the output of energy during the cycle. The results obtained are in agreement with experimental data and model tests.

Impact Simulation of a Crashworthy Composite Fuselage Section with Energy-Absorbing Floor

2014 ◽  
Vol 529 ◽  
pp. 102-107
Author(s):  
Hai Bo Luo ◽  
Ying Yan ◽  
Xiang Ji Meng ◽  
Tao Tao Zhang ◽  
Zu Dian Liang
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Dynamic Response ◽  
Relative Error ◽  
High Strength ◽  
Computer Code ◽  
Impact Simulation ◽  
Average Acceleration ◽  
Simulation Results ◽  
Energy Absorbing

A 7.8m/s vertical drop simulate of a full composite fuselage section was conducted with energy-absorbing floor to evaluate the crashworthiness features of the fuselage section and to predict its dynamic response to dummies in future. The 1.52m diameter fuselage section consists of a high strength upper fuselage frame, one stiff structural floor and an energy-absorbing subfloor constructed of Rohacell foam blocks. The experimental data from literature [6] were analyzed and correlated with predictions from an impact simulation developed using the nonlinear explicit transient dynamic computer code MSC.Dytran. The simulated average acceleration did not exceed 13g, by contrast with experimental results, whose relative error is less than 11%. The numerical simulation results agree with experiments well.

TEMPERATURE DEPENDENCE OF THERMODYNAMIC PROPERTIES OF IONIC SOLIDS

2009 ◽  
Vol 23 (11) ◽  
pp. 2503-2509 ◽  
Author(s):  
S. K. SHARMA
Keyword(s):  
Experimental Data ◽  
Temperature Dependence ◽  
Volume Expansion ◽  
Close Agreement ◽  
Present Model ◽  
Expansion Ratio ◽  
Thermal Expansivity ◽  
Temperature Derivative ◽  
Computing Model ◽  
Ionic Solids

The present paper proposes a computing model for temperature dependence of volume thermal expansivity, volume expansion ratio and second order temperature derivative of volume based on the assumption that the product αKT remains constant at high temperatures and zero pressure. We have taken NaCl and KCl to testify the validity of the present model. A fairly close agreement between the calculated results and experimental data strongly supports the present model.

scholarly journals A reduced order computational model of a semi-active variable-stiffness foot prosthesis

2020 ◽  
Author(s):  
Michael McGeehan ◽  
Peter Adamczyk ◽  
Kieran Nichols ◽  
Michael Hahn
Keyword(s):  
Body Weight ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Variable Stiffness ◽  
Performance Standard ◽  
Design Parameters ◽  
Compression Tests ◽  
Static Compression ◽  
Lumped Parameter ◽  
Contact Models

INTRODUCTION: Passive energy storage and return (ESR) feet are the current performance standard in lower limb prostheses. A recently developed semi-active variable-stiffness foot (VSF) prosthesis balances the simplicity of a passive ESR device with the adaptability of a powered design. The purpose of this study was to model and simulate the ESR properties of the VSF prosthesis. METHODS: The ESR properties of the VSF were modeled as a lumped parameter overhung beam. The overhung length is variable, allowing the model to exhibit variable ESR stiffness. Foot-ground contact was modeled using sphere-to-plane contact models. Contact parameters were optimized to represent the geometry and dynamics of the VSF and its foam base. Static compression tests and gait were simulated. Simulation outcomes were compared to corresponding experimental data. RESULTS: Stiffness of the model matched that of the physical VSF (R2: 0.98, RMSE: 1.37 N/mm). Model-predicted resultant ground reaction force (GRFR) matched well under optimized parameter conditions (R2: 0.98, RMSE: 5.3% body weight,) and unoptimized parameter conditions (R2: 0.90, mean RMSE: 13% body weight). Anterior-posterior center of pressure matched well with R2 > 0.94 and RMSE < 9.5% foot length in all conditions. CONCLUSIONS: The ESR properties of the VSF were accurately simulated under benchtop testing and dynamic gait conditions. These methods may be useful for predicting GRFR arising from gait with novel prostheses. Such data are useful to optimize prosthesis design parameters on a user-specific basis.

scholarly journals Analytical Study on Dynamic Response of RC Buildings Retrofitted by Compressive CFT Braces

2011 ◽  
Vol 22 (2) ◽  
pp. 2_1-2_10
Author(s):  
Hiroyuki Nakahara ◽  
Yuichi Nishida ◽  
Kenji Sakino ◽  
Koichiro Kitajima
Keyword(s):  
Dynamic Response ◽  
Analytical Study ◽  
Rc Buildings
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