On the Equilibrium Conditions of Nonstationary Mechanical Systems

1999 ◽  
Vol 66 (4) ◽  
pp. 937-939
Author(s):  
M. Kazic ◽  
R. Bulatovic
Keyword(s):  
Equilibrium Problem ◽  
Virtual Work ◽  
Mechanical Systems ◽  
Principle Of Virtual Work ◽  
Equilibrium Conditions ◽  
New Approach ◽  
Starting Point ◽  
Stationary Problems ◽  
Nonstationary Systems

The equilibrium problem of nonstationary systems is studied. The starting point is the principle of virtual work (PVW). Contrary to stationary problems, some additional conditions (along with PVW) should be satisfied. Proof of Gantmacher’s postulate is derived. A new approach is given, and some results of other authors are discussed.

On the Mechanical Behavior of the Orthotropic Cord-Rubber Composite

1976 ◽  
Vol 4 (4) ◽  
pp. 219-232 ◽  
Author(s):  
Ö. Pósfalvi
Keyword(s):  
Mechanical Behavior ◽  
Uniaxial Tension ◽  
Elastic Properties ◽  
Large Deformations ◽  
Virtual Work ◽  
Poisson's Ratio ◽  
Principle Of Virtual Work ◽  
Effective Elastic Properties ◽  
Rubber Composite ◽  
Mooney Equation

Abstract The effective elastic properties of the cord-rubber composite are deduced from the principle of virtual work. Such a composite must be compliant in the noncord directions and therefore undergo large deformations. The Rivlin-Mooney equation is used to derive the effective Poisson's ratio and Young's modulus of the composite and as a basis for their measurement in uniaxial tension.

scholarly journals Discrete element model for general polyhedra

2021 ◽  
Author(s):  
Alfredo Gay Neto ◽  
Peter Wriggers
Keyword(s):  
Frictional Contact ◽  
Virtual Work ◽  
Particle Surface ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Element Model ◽  
Principle Of Virtual Work ◽  
Dynamics Model ◽  
Railway Ballast ◽  
Multibody Dynamics Model

AbstractWe present a version of the Discrete Element Method considering the particles as rigid polyhedra. The Principle of Virtual Work is employed as basis for a multibody dynamics model. Each particle surface is split into sub-regions, which are tracked for contact with other sub-regions of neighboring particles. Contact interactions are modeled pointwise, considering vertex-face, edge-edge, vertex-edge and vertex-vertex interactions. General polyhedra with triangular faces are considered as particles, permitting multiple pointwise interactions which are automatically detected along the model evolution. We propose a combined interface law composed of a penalty and a barrier approach, to fulfill the contact constraints. Numerical examples demonstrate that the model can handle normal and frictional contact effects in a robust manner. These include simulations of convex and non-convex particles, showing the potential of applicability to materials with complex shaped particles such as sand and railway ballast.

scholarly journals Reconciling Loss Aversion and Gain Seeking in Judged Emotions

2021 ◽  
pp. 096372142199204
Author(s):  
Barbara A. Mellers ◽  
Siyuan Yin ◽  
Jonathan Z. Berman
Keyword(s):  
Loss Aversion ◽  
Reference Point ◽  
Emotional Reactions ◽  
Status Quo ◽  
New Approach ◽  
Negative Change ◽  
Starting Point ◽  
The Status ◽  
Positive Feelings ◽  
Negative Feelings

Is the pain of a loss greater in magnitude than the pleasure of a comparable gain? Studies that compare positive feelings about a gain with negative feelings about a comparable loss have found mixed answers to this question. The pain of a loss can be greater than, less than, or equal to the pleasure of a comparable gain. We offer a new approach to test hedonic loss aversion. This method uses emotional reactions to the reference point, a positive change, and a negative change. When we manipulated the reference point (i.e., pleasurable and painful), two distinct patterns emerged. Pain surpassed pleasure (loss aversion) when the reference point was positive, and pleasure exceeded pain (gain seeking) when the reference point was negative. A reference-dependent version of prospect theory accounts for the results. If the carriers of utility are changes from a reference point—not necessarily the status quo—both loss aversion and gain seeking are predicted. Loss aversion and gain seeking can be reconciled if you take the starting point into account.

Analytical Modelling of the Dynamics of the Four-Bar Mechanism: A Comparison of Some Methods

2018 ◽  
Author(s):  
J. P. Meijaard ◽  
V. van der Wijk
Keyword(s):  
Virtual Work ◽  
Equations Of Motion ◽  
Differential Algebraic Equations ◽  
Force Balance ◽  
Dynamic Force ◽  
Algebraic Equations ◽  
Principle Of Virtual Work ◽  
Principal Vector ◽  
Reaction Forces ◽  
Principal Points

Some thoughts about different ways of formulating the equations of motion of a four-bar mechanism are communicated. Four analytic methods to derive the equations of motion are compared. In the first method, Lagrange’s equations in the traditional form are used, and in a second method, the principle of virtual work is used, which leads to equivalent equations. In the third method, the loop is opened, principal points and a principal vector linkage are introduced, and the equations are formulated in terms of these principal vectors, which leads, with the introduced reaction forces, to a system of differential-algebraic equations. In the fourth method, equivalent masses are introduced, which leads to a simpler system of principal points and principal vectors. By considering the links as pseudorigid bodies that can have a uniform planar dilatation, a compact form of the equations of motion is obtained. The conditions for dynamic force balance become almost trivial. Also the equations for the resulting reaction moment are considered for all four methods.

Static analysis of spatial parallel manipulators by means of the principle of virtual work

2012 ◽  
Vol 28 (3) ◽  
pp. 385-401 ◽  
Author(s):  
J. Jesús Cervantes-Sánchez ◽  
José M. Rico-Martínez ◽  
Salvador Pacheco-Gutiérrez ◽  
Gustavo Cerda-Villafaña
Keyword(s):  
Static Analysis ◽  
Virtual Work ◽  
Parallel Manipulators ◽  
Principle Of Virtual Work

scholarly journals Calculating Value Added of Prostitution with Multiple Data: A New Approach for Belgium

2017 ◽  
Vol 47 (1) ◽  
pp. 58-86 ◽  
Author(s):  
Stef Adriaenssens ◽  
Jef Hendrickx
Keyword(s):  
Sex Workers ◽  
Relative Size ◽  
Value Added ◽  
Added Value ◽  
Standard Errors ◽  
New Approach ◽  
Economic Output ◽  
Multiple Data ◽  
Innovative Methodology ◽  
Starting Point

Economic output implies that underground sectors such as prostitution are taken into account. This article presents an innovative methodology to measure turnover and added value in prostitution based on a combination of observational and Internet data. The method is applied to Belgium. Turnover is broken down in transactions and price per segment. The starting point is an observation-based measure of turnover in one locational and visible segment of the market: window prostitution. Fundamental differences between segments make linear generalizations from one segment invalid. Therefore, we estimate the relative size of transactions in other segments (such as brothels or escort) with Internet data. In combination with measures of average price per transaction, a consolidated estimate of turnover in prostitution in Belgium is measured. Estimates of nonresident production are based on data on sex workers’ country of origin. Several bootstrap replications allow for robustness checks of the delta-based standard errors.

Optimal Design of Bi- and Multi-Stable Compliant Cellular Structures

2018 ◽  
Author(s):  
Quantian Luo ◽  
Liyong Tong
Keyword(s):  
Optimal Design ◽  
Virtual Work ◽  
Reaction Force ◽  
Nonlinear Finite Element ◽  
Cellular Structures ◽  
Stress And Strain ◽  
Principle Of Virtual Work ◽  
Stable States ◽  
Threshold Method ◽  
Element Analysis

This paper presents optimal design for nonlinear compliant cellular structures with bi- and multi-stable states via topology optimization. Based on the principle of virtual work, formulations for displacements and forces are derived and expressed in terms of stress and strain in all load steps in nonlinear finite element analysis. Optimization for compliant structures with bi-stable states is then formulated as: 1) to maximize the displacement under specified force larger than its critical one; and 2) to minimize the reaction force for the prescribed displacement larger than its critical one. Algorithms are developed using the present formulations and the moving iso-surface threshold method. Optimal design for a unit cell with bi-stable states is studied first, and then designs of multi-stable compliant cellular structures are discussed.

On the Sufficiency of the Principle of Virtual Work for Mechanical Equilibrium: A Critical Reexamination

1989 ◽  
Vol 56 (3) ◽  
pp. 704-707 ◽  
Author(s):  
John G. Papastavridis
Keyword(s):  
Virtual Work ◽  
Mechanical Equilibrium ◽  
Principle Of Virtual Work ◽  
Holonomic Constraints ◽  
Kinetic Principle ◽  
Sufficiency Conditions

Starting from the general kinetic principle of d’Alembert/Lagrange, an energetic proof of the sufficiency conditions for equilibrium (known as Principle of Virtual Work) is presented. It is clearly demonstrated why to maintain equilibrium requires that, in addition to the familiar vanishing of the virtual work of the impressed forces on the originally motionless system, its geometrical (holonomic) constraints be explicitly time independent (stationary) and its nonintegrable kinematical (nonholonomic) ones be linear and homogeneous in the generalized velocities (catastatic).

scholarly journals Decision making in reverse logistics using system dynamics

2004 ◽  
Vol 14 (2) ◽  
pp. 259-272 ◽  
Author(s):  
P. Georgiadis ◽  
D. Vlachos
Keyword(s):  
Decision Making ◽  
System Dynamics ◽  
Reverse Logistics ◽  
Closed Loop ◽  
System Modeling ◽  
New Approach ◽  
Helpful Tool ◽  
Starting Point ◽  
Decision Making Tool

Reverse logistics is a modern field of consideration, research and study, providing helpful information on the operation of the closed-loop supply chain. Although the starting point of this field is traced back to the early 90?s, no standard method has been suggested, neither prevailed. The purpose of this paper is to introduce a new approach on the study of reverse logistics. It is actually a review on how System Dynamics (SD) can be a helpful tool when it is used in the reverse logistics field. The paper explains the basic theory of the system modeling and next it utilizes the reverse logistics model. Finally, an illustrative example shows how SD modeling can be used to produce a powerful long-term decision-making tool.

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