Nonlinear Wheelset Forces in Flange Contact—Part 2: Measurements Using Dynamically Scaled Models

1979 ◽  
Vol 101 (3) ◽  
pp. 247-255 ◽  
Author(s):  
L. M. Sweet ◽  
J. A. Sivak ◽  
W. F. Putman
Keyword(s):  
Lateral Force ◽  
Contact Forces ◽  
Scale Model ◽  
Rail Vehicle Dynamics ◽  
Curving Performance ◽  
Lateral Displacements ◽  
Scaled Models ◽  
Force Displacement ◽  
Yaw Moment ◽  
Contact Part

This paper presents new experimental methods for the study of rail vehicle dynamics through the use of scaled models on tangent track, and the application of these techniques to the measurement of nonlinear wheelset force/displacement relations in steady-state. These relations are important to the analysis of wheelset response to track inputs, curving performance of trucks, and wheelclimb derailment. A one-fifth scale model instrumented wheelset with new wheel profiles is used, with similitude scaling of the contact forces achieved through use of a polycarbonate resin for the contact surfaces. Data are presented for wheelset lateral force and yaw moment for the nonlinear range of wheelset lateral displacements and yaw angles, including flange contact. The measured data validate the analytical model presented in Part 1 of this paper, based on nonlinear wheel/rail contact geometry, creep forces with adhesion limits, and wheelset kinematics. A criterion for wheelclimb derailment is presented and verified experimentally.

Nonlinear Wheelset Forces in Flange Contact—Part 1: Steady State Analysis and Numerical Results

1979 ◽  
Vol 101 (3) ◽  
pp. 238-246 ◽  
Author(s):  
L. M. Sweet ◽  
J. A. Sivak
Keyword(s):  
Steady State ◽  
Contact Point ◽  
Lateral Force ◽  
Lateral Position ◽  
Geometric Constraints ◽  
Curving Performance ◽  
Yaw Angle ◽  
Nonlinear Geometric ◽  
Force Displacement ◽  
Yaw Moment

A theoretical model for steady-state wheelset force/displacement relations in tread and flange contact is presented. The analysis includes nonlinear geometric constraints that characterize wheel/rail contact, creep forces in the contact plane due to wheel/rail differential velocities, limits on adhesion at each contact point, and equilibrium conditions applied to the wheelset body forces. Results are summarized as the resultant lateral force and yaw moment acting on the wheelset as functions of lateral position and yaw angle. The results of this analysis, verified experimentally in Part 2 of this paper, are important to the analysis of wheelset response to track inputs, curving performance, and wheelclimb derailment.

scholarly journals Seismic Behavior and Force-Displacement Characterization of Neotype Column-Slab High Piers

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
YanQun Zhou ◽  
YeZhi Zhang ◽  
MeiXin Ye ◽  
MengSi Zhan
Keyword(s):  
Seismic Behavior ◽  
Large Scale ◽  
Scale Model ◽  
Test Results ◽  
Lateral Displacements ◽  
High Pier ◽  
Experimental Values ◽  
Large Scale Tests ◽  
Force Displacement

The seismic behavior and plasticity spreading of a neotype column-slab high pier are researched in this paper. Four scale model tests of a web slab with two boundary columns are carried out under cyclic inelastic lateral displacements simulating seismic response. The test results show that the neotype column-slab high pier has strong and stable bearing capacity, good ductility, and energy dissipation capacity. The experimental values pertaining to the spread of plasticity are derived. An approach for deriving the spread of plasticity analytically is deduced and applied to the four tests. This method accurately assesses a pier’s spread of plasticity for most ductility levels. At nearly all ductility levels, the mean difference between analytical assessments of the spread of plasticity and results from 4 large-scale tests is 12% with a 9% coefficient of variation.

Contact force analysis on two-fingered robot grasping

2020 ◽  
pp. 146441932096402
Author(s):  
Jiun-Ru Chen ◽  
Wei-En Chen ◽  
CH Liu ◽  
Yin-Tien Wang ◽  
CB Lin ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Contact Force ◽  
Numerical Procedure ◽  
Spherical Body ◽  
Solution Procedure ◽  
The Body ◽  
Contact Forces ◽  
Grasping Forces ◽  
Robot Grasping ◽  
Force Displacement

A procedure for inverse kinetic analysis on two hard fingers grasping a hard sphere is proposed in this study. Contact forces may be found for given linear and angular accelerations of a spherical body. Elastic force-displacement relations predicted by Hertz contact theory are used to remove the indeterminancy produced by rigid body modelling. Two types of inverse kinetic analysis may be dealt with. Firstly, as the fingers impose a given tightening displacement on the body, and carry it to move with known accelerations, corresponding grasping forces may be determined by a numerical procedure. In this procedure one contact force may be chosen as the principal unknown, and all other contact forces are expressed in terms of this force. The numerical procedure is hence very efficient since it deals with a problem with only one unknown. The solution procedure eliminates slipping thus only nonslip solutions, if they exist, are found. Secondly, when the body is moving with known accelerations, if the grasping direction of the two fingers is also known, then the minimum tightening displacement required for non-sliding grasping may be obtained in closed form. In short, the proposed technique deals with a grasping system that has accelerations, and in this study the authors show that indeterminancy may be used to reduce the complexity of the problem.

Application of the MCC Model on 2-D Finite Element Analyses for the Assessment of Pipe-Soil Lateral Response

2019 ◽  
Author(s):  
Tianna Bloise Thomaz ◽  
Daniel Carneiro ◽  
Gilberto Bruno Ellwanger ◽  
Leonardo Sant’Anna do Nascimento
Keyword(s):  
Finite Element ◽  
Simulation Models ◽  
Lateral Force ◽  
Soil Behavior ◽  
Soil Plasticity ◽  
Lateral Response ◽  
Modified Cam Clay ◽  
Full Scale Tests ◽  
Subsea Pipelines ◽  
Force Displacement

Abstract The assessment of the pipe-soil interaction is an area of continuous research, either by the application of small- and full-scale tests in the attempt to reproduce accurately the interaction of the pipelines and the soil, or by the development of sophisticated numerical simulation models accounting for different sources of nonlinearities. Motivated to investigate the interaction between subsea pipelines and the soil, with focus in the response under lateral loading, 2-D finite element numerical simulations have been developed applying soil plasticity mechanisms through the extended maximum distortion strain energy criteria [1] and critical state concept [2]. The modified-cam-clay MCC model has been adopted to simulate the soil behavior in large deformations, aiming to numerically reproduce site conditions for selected pipelines ranging from 12 in to 18 in. The results are presented in terms of the lateral force-displacement curves for numerically representative drained and undrained cases. For the simulations investigated in this work, the agreement of the numerical results with the analytical breakout lateral resistances obtained from the SAFEBUCK guideline [3] formulations have been confirmed for cases where the ratio of initial pipe embedment and pipe diameter is below 0.4.

Optimization of Quadriceps Force Distribution for Minimization of Patellofemoral Contact Pressure During a Squat

2007 ◽  
Author(s):  
Aarthi S. Shankar ◽  
Trent M. Guess
Keyword(s):  
Contact Pressure ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Strong Relationship ◽  
Lateral Force ◽  
Quadriceps Muscle ◽  
Contact Forces ◽  
In Vivo Studies ◽  
Muscle Forces

Patellofemoral Pain (PFP) syndrome is a very common knee disorder. A possible cause may be excessive lateral force applied by the quadriceps and the patellar tendon producing an abnormal distribution of force and pressure within the patellofemoral joint [1]. EMG and in-vivo studies have been conducted to understand the function of the quadriceps and its relationship with PFP [2,3]. These studies suggest a strong relationship between muscle forces and PFP which originates from high lateral retropatellar contact forces. A dynamic computational model of the knee was developed which includes the quadriceps muscles Rectus Femoris (RF), Vastus Intermedius (VI), Vastus Lateralis (VL), and Vastus Medialis (VM) represented as force vectors. The model can predict retro-patellar contact pressures and the action of the individual quadriceps muscles based on the predicted pressures. The objective of this study was to develop a control system which could optimize the distribution of quadriceps muscle forces to minimize contact pressure between the patella and the femur of the knee during a squat.

Analysis of Experimental Data in the Context of Safety against Derailment of a Railway Vehicle, Using the Energy Method

2012 ◽  
Vol 518 ◽  
pp. 16-23 ◽  
Author(s):  
Michał Opala
Keyword(s):  
Experimental Data ◽  
Monitoring System ◽  
Condition Monitoring ◽  
Energy Method ◽  
Lateral Force ◽  
Contact Forces ◽  
Railway Vehicle ◽  
Interaction Forces ◽  
Condition Monitoring System

This article describes an example analysis of safety against derailment of a railway vehicle. The analysis is based on the experimental data recorded during measurement of the wheel-rail interaction forces and lateral accelerations. The data is used for the calculation of two safety against derailment indicators and then the indicators are compared to each other. The first indicator is the ratio of the lateral to vertical wheel-rail forces Y/Q, based on the Nadal criteria. The second indicator is given in the energy description. In this description, the derailment of a railway vehicle depends on the amount of the work that has been done by the total lateral force acting on the single wheelset. The second indicator can be particularly convenient for a railway vehicle condition monitoring system, because it does not require the measurement of the contact forces.

Contact Force Analysis in Static Two-Fingered Robot Grasping

2013 ◽  
Author(s):  
I Cheng ◽  
C. H. Liu ◽  
Yin-Tien Wang
Keyword(s):  
Rigid Bodies ◽  
The Body ◽  
Contact Forces ◽  
Contact Theory ◽  
Force Analysis ◽  
Equilibrium Solutions ◽  
Spherical Object ◽  
Closed Form Solutions ◽  
Robot Grasping ◽  
Force Displacement

Static grasping of a spherical object by two robot fingers is studied in this paper. The fingers may be rigid bodies or elastic beams, they may grasp the body with various orientation angles, and the tightening displacements may be linear or angular. Closed-form solutions for normal and tangential contact forces due to tightening displacements are obtained by solving compatibility equations, force-displacement relations based on Hertz contact theory, and equations of equilibrium. Solutions show that relations between contact forces and tightening displacements depend upon the orientation of the fingers, the elastic constants of the materials, and area moments of inertia of the beams.

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