Elastoplastic Analysis of Space Framework: Initial Force Schemes

1975 ◽  
Vol 97 (2) ◽  
pp. 90-94 ◽  
Author(s):  
K. N. Lee
Keyword(s):  
Initial Stress ◽  
Limit Analysis ◽  
Classical Limit ◽  
Iterative Scheme ◽  
Yield Criterion ◽  
The Other ◽  
Elastoplastic Behavior ◽  
Quadratic Equations ◽  
Internal Forces ◽  
Initial Force

Based upon the Morris and Fenves yield criterion for space frameworks, two initial force schemes are presented to analyze the elastoplastic behavior of space frameworks. One is the initial force iterative scheme, which follows the initial stress scheme proposed by Zienkiewicz, et al. The other is a self-equilibrating force scheme, which predicts the next yielding sections and determines the corresponding load increments, deflection and internal forces of the system by solving a set of quadratic equations. Several sample problems are presented. The results show that the load deflection curves obtained by using either scheme are identical. Note that for plane frameworks, element forces and load parameters corresponding to the subsequent yielding sections are identical to those obtained by using the classical limit analysis.

A Yield Criterion of Porous Materials With Anisotropy Caused by Geometry or Distribution of Pores

1991 ◽  
Vol 113 (4) ◽  
pp. 425-429 ◽  
Author(s):  
T. Hisatsune ◽  
T. Tabata ◽  
S. Masaki
Keyword(s):  
Velocity Field ◽  
Porous Materials ◽  
Upper Bound ◽  
Volume Fraction ◽  
Yield Criterion ◽  
Longitudinal Direction ◽  
Axisymmetric Deformation ◽  
The Other ◽  
The Matrix ◽  
Spherical Cells

Axisymmetric deformation of anisotropic porous materials caused by geometry of pores or by distribution of pores is analyzed. Two models of the materials are proposed: one consists of spherical cells each of which has a concentric ellipsoidal pore; and the other consists of ellipsoidal cells each of which has a concentric spherical pore. The velocity field in the matrix is assumed and the upper bound approach is attempted. Yield criteria are expressed as ellipses on the σm σ3 plane which are longer in longitudinal direction with increasing anisotropy and smaller with increasing volume fraction of the pore. Furthermore, the axes rotate about the origin at an angle α from the σm-axis, while the axis for isotropic porous materials is on the σm-axis.

Repairing the damage: wishful, defensive, or restorative?

2021 ◽  
Vol 21 (1) ◽  
pp. 28-39
Author(s):  
Susan Long
Keyword(s):  
Climate Change ◽  
Economic Recession ◽  
The Other ◽  
Hostile Environment ◽  
Racial Inequalities ◽  
Internal Forces ◽  
System Restoration ◽  
Large Groups ◽  
Malicious Intent ◽  
Social Level

Damage, physically and to the psyche is inevitable. This is whether it is caused unconsciously, through consciously malicious intent, thoughtlessness, as collateral or just through a hostile environment or the warring of internal forces. At the group or social level, the last few years have seen much damage in terms of economic recession, climate change, racial inequalities, and domestic violence. The desire to repair follows such damage. The psychoanalytic focus on reparation sees the process as an attempt by a person to repair perceived damage to another or, more precisely, to an internal image of the other—a loved other. Large groups such as organisations and societies also do damage and sometimes acknowledge this and make attempts to repair—perhaps defensively, simply to restore their own reputation, but perhaps from guilt and remorse. This article will invite readers to think about reparation in terms of either fantasied wishfulness, or defensiveness, or its possible restorative capacity. My exploration rests on the premise that damage is always to the system and that both that which damages and that which is damaged suffer. It is in system restoration that hope re-emerges.

Plastic Collapse of Orthotropic Plates

1982 ◽  
Vol 26 (04) ◽  
pp. 286-295
Author(s):  
John C. Christodoulides ◽  
Joao G. de Oliveira
Keyword(s):  
Limit Analysis ◽  
Lateral Pressure ◽  
Yield Criterion ◽  
Plastic Collapse ◽  
Orthotropic Plates ◽  
Perfectly Plastic ◽  
Technical Theory ◽  
Orthotropic Shells ◽  
Theory Of Shells

A yield criterion for thin orthotropic shells expressed in terms of generalized stresses is first derived. This yield criterion is based on the yield criterion proposed by Hill for anisotropic continua and it is consistent with all the assumptions usually adopted in the technical theory of shells. As an example of application of this criterion the collapse of perfectly plastic rectangular orthotropic plates subjected to a uniform lateral pressure is studied using the Theorems of Limit Analysis.

Plastic Collapse of a Thin Annular Disk Subject to Thermomechanical Loading

2013 ◽  
Vol 80 (5) ◽  
Author(s):  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Yeau-Ren Jeng
Keyword(s):  
Analytic Solution ◽  
Hydrostatic Stress ◽  
Yield Criterion ◽  
The Other ◽  
Collapse Mechanism ◽  
Plastic Collapse ◽  
Thermomechanical Loading ◽  
Annular Disk ◽  
Collapse Mechanisms ◽  
Inner Radius

A semi-analytic solution for plastic collapse of a thin annular disk subject to thermomechanical loading is presented. It is assumed that the yield criterion depends on the hydrostatic stress. A distinguished feature of the boundary value problem considered is that there are two loading parameters. One of these parameters is temperature and the other is pressure over the inner radius of the disk. The general qualitative structure of the solution at plastic collapse is discussed in detail. It is shown that two different plastic collapse mechanisms are possible. One of these mechanisms is characterized by strain localization at the inner radius of the disk. The entire disk becomes plastic according to the other plastic collapse mechanism. In addition, two special regimes of plastic collapse are identified. According to one of these regimes, plastic collapse occurs when the entire disk is elastic, except its inner radius. According to the other regime, the entire disk becomes plastic at the same values of the loading parameters at which plastic yielding starts to develop.

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