Search results for "Shake"

Shakedown of elastic—plastic solids with frictionless unilateral contact boundary conditions

1997

Abstract Elastic perfectly plastic solids (or structures) in frictionless unilateral contact with a rigid obstacle and subjected to quasi-statically variable loads within a given domain are considered. In the hypothesis that the structure undergoes small displacements and complies with a d -stability requisite herein introduced, a Melantype shakedown theorem is presented. This theorem is conceptually similar to the classical one; namely, it requires that the unilateral-contact elastic stress response to the loads and to some initial plastic strains be plastically admissible everywhere in the body and for all load conditions. A method for evaluating the shakedown load boundary is also discus…

Shakedown of Structures Accounting for Damage Effects

2002

Shakedown theory for elastic-plastic-damage materials is exposed. Two kinds of shakedown are considered: i) Enlarged shakedown (or simply shakedown), in which both plastic deformations and damage eventually cease, after which the structural response is purely elastic; ii) Weak-form shakedown, in which plastic deformations eventually cease together with their consequences (including ductile damage), not necessarily damage from other sources (which are however escluded by assumption). An (enlarged) shakedown static-type theorem is given for a class of D-stable structures. Sufficient theorems of weak-form shakedown are provided, i.e. a static-type one (quite similar to that of Hachemi and Weic…

MACRO-ZONES SGBEM APPROACH FOR STATIC SHAKEDOWN ANALYSIS AS CONVEX OPTIMIZATION

2013

A new strategy utilizing the Multidomain SGBEM for rapidly performing shakedown analysis as a convex optimization problem has been shown in this paper. The present multidomain approach, called displacement method, makes it possible to consider step-wise physically and geometrically nonhomogeneous materials and to obtain a self-equilibrium stress equation regarding all the bem-elements of the structure. Since this equation includes influence coefficients, which characterize the input of the quadratic constraints, it provides a nonlinear optimization problem solved as a convex optimization problem. Furthermore, the strategy makes it possible to introduce a domain discretization exclusively of…

Freedom and Necessity in The Winter’s Tale

2014

From the first expository scene, The Winter’s Tale exhibits a concern with necessity, either through the use of the word itself, its derivatives (necessities, necessary), and their synonyms (needful, required) or through the notion of what “must” happen, what “cannot but” happen. The recurrence of such terms conveys a sense that this is a world where no one is free, and every action is dictated by force of circumstance. This is reinforced by the widespread use of the traditional imagery of fate. Yet the characters of the play are reluctant to submit to necessity. Some even fantasize states of absolute freedom, including freedom from the laws of nature. The play itself, notwithstanding the o…

Computational procedures for plastic shakedown design of structures

2004

The minimum volume design problem of elastic perfectly plastic finite element structures subjected to a combination of fixed and perfect cyclic loads is studied. The design problem is formulated in such a way that incremental collapse is certainly prevented. The search for the structural design with the required limit behaviour is effected following two different formulations, both developed on the grounds of a statical approach: the first one operates below the elastic shakedown limit and is able to provide a suboptimal design; the second one operates above the elastic shakedown limit and is able to provide the/an optimal design. The Kuhn–Tucker conditions of the two problems provide usefu…

Bounds on plastic strains for elastic plastic structures in plastic shakedown conditions

2007

The problem related to the computation of bounds on plastic deformations for structures in plastic shakedown condition (alternating plasticity) is studied. In particular, reference is made to structures discretized by finite elements constituted by elastic perfectly plastic material and subjected to a special combination of fixed and cyclic loads. The load history is known during the steady-state phase, but it is unknown during the previous transient phase; so, as a consequence, it is not possible to know the complete elastic plastic structural response. The interest is therefore focused on the computation of bounds on suitable measures of the plastic strain which characterizes just the fir…

Risk Assessment of Hand-Arm Vibration in Different Types of Portable Shakers for Olives Harvesting

2010

"Mens sana in corpore sano": The Rhetoric of the Body in Shakespeare’s Roman and Late Plays

2010

Dynamic shakedown design of structures under repeated seismic loads

2013

The paper is devoted to the formulation of an optimal design (minimum volume) problem of elastic perfectly plastic structures subjected to suitable combinations of static (fixed) and dynamic (seismic) loads. The structure is constrained to simultaneously respect two different safety criteria; actually, it must exhibit an elastic shakedown behaviour for the combination of loads characterizing the serviceability conditions and it must prevent the instantaneous collapse for the highest expected load condition (combination of loads characterized by the presence of fixed loads and maximum expected intensity of seismic action). The shakedown limit behaviour for the optimal structure will be impos…

Comparison between unrestricted dynamic shakedown design and a new probabilistic approach for structures under seismic loadings

2014

The paper concerns a study related to the comparison between two different approaches utilized for the formulation of an optimal shakedown design problem for elastic plastic frame structures subjected to a combination of fixed and seismic loading. The first formulation utilizes the unrestricted dynamic shakedown theory, while the second one is based on a new probabilistic approach. The comparison is effected in terms of mathematical formulations, in terms of adopted loading models and in terms of numerical results. The performed applications are related to plane steel frames.