Contribution à l'étude des deformations finies dans les matériaux ecrouissables PDF Download

Author: Maurice Boivin
Publisher:
ISBN:
Category :
Languages : fr
Pages : 149

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Author: Maurice Boivin (spécialiste en mécanique).)
Publisher:
ISBN:
Category :
Languages : fr
Pages : 149

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Author: Marie-Jeanne Philippe
Publisher:
ISBN:
Category :
Languages : fr
Pages : 512

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Author: Jean-Luc Hanus
Publisher:
ISBN:
Category :
Languages : fr
Pages : 18

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LE PROBLEME DE L'APPARITION D'UN MODE DE DEFORMATION LOCALISE DANS DES MATERIAUX ET STRUCTURES EST ABORDE DANS CETTE ETUDE. PLUS PRECISEMENT, LA MODELISATION DE LA LOCALISATION DES DEFORMATIONS DANS DES MATERIAUX A COMPORTEMENT DEPENDANT DU TEMPS ET POUR DES CHARGEMENTS LENTS EST ENTREPRISE. NOTRE ATTENTION SE PORTE TANT SUR LE PROBLEME THEORIQUE - DEFINITION D'UN CRITERE DE LOCALISATION - QUE SUR LE PROBLEME NUMERIQUE - EXPLICATION DE LA SENSIBILITE DE LA REPONSE NUMERIQUE AU MAILLAGE. UNE ANALYSE DE RESULTATS EXPERIMENTAUX RECENTS - OBTENUS A L'ECHELLE MESOSCOPIQUE ET METTANT EN EVIDENCE DES EFFETS D'ACCELERATION LOCAUX A LA LOCALISATION - NOUS CONDUIT A SUPPOSER QUE LA LOCALISATION DES DEFORMATIONS EST UN PHENOMENE ESSENTIELLEMENT DYNAMIQUE ET CE MEME POUR DES CHARGEMENTS LENTS. EN CONSEQUENCE, UN CRITERE DE PERTE DE QUASI-STATICITE / LOCALISATION EST ETABLI. A LA VERIFICATION DE CE DERNIER, LE CALCUL NE DOIT PLUS ETRE CONDUIT STATIQUEMENT MAIS POURSUIVI DE MANIERE DYNAMIQUE. DIVERSES SIMULATIONS NUMERIQUES, TANT SUR UN ELEMENT DE VOLUME QUE SUR UNE STRUCTURE (ELEMENTS FINIS), PERMETTENT D'ILLUSTRER ET DE DISCUTER LA DEMARCHE THEORIQUE PROPOSEE.

Author: Bernard Jaoul
Publisher:
ISBN:
Category : Deformations (Mechanics)
Languages : fr
Pages :

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Author: Dieter Weichert
Publisher: Springer Science & Business Media
ISBN: 9781402003820
Category : Technology & Engineering
Languages : en
Pages : 400

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The question whether a structure or a machine component can carry the applied loads, and with which margin of safety, or whether it will become unserviceable due to collapse or excessive inelastic deformations, has always been a major concern for civil and mechanical engineers. The development of methods to answer this technologically crucial question without analysing the evolution of the system under varying loads, has a long tradition that can be traced back even to the times of emerging mechanical sciences in the early 17th century. However, the scientific foundations of the theories underlying these methods, nowadays frequently called "direct", were established sporadically in the Thirties of the 20th century and systematically and rigorously in the Fifties. Further motivations for the development of direct analysis techniques in applied mechanics of solids and structures arise from the circumstance that in many engineering situations the external actions fluctuate according to time histories not a priori known except for some essential features, e.g. variation intervals. In such situations the critical events (or "limit states") to consider, besides plastic collapse, are incremental collapse (or "ratchetting") and alternating plastic yielding, namely lack of "shakedown". Non evolutionary, direct methods for ultimate limit state analysis of structures subjected to variably-repeated external actions are the objectives of most papers collected in this book, which also contains a few contributions on related topics.

Author: Zenon Mróz
Publisher: Springer Science & Business Media
ISBN: 9401102716
Category : Technology & Engineering
Languages : en
Pages : 501

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This collection of papers is a state of the art presentation of theories and methods related to the problem of the behaviour of mechanical structures under variable loads beyond their elastic limit In particular, the problems of shakedown, ratchetting, transient and asymptotic cyclic states are addressed. The volume is composed of four chapters devoted to material modelling for cyclic loading conditions; general theory of accommodated states of structures; effects of changes of the geometry on the inelastic structural response; and numerical techniques with applications to particular engineering problems. It was aimed to provide a unified approach in order to understand both inelastic material and structural response under variable loading conditions. The attempt to extend the classical shakedown theory of Melan and Koiter to geometrically non-linear problems is presented in several papers. The industrial application of cyclic plasticity to the analysis and the design of pressure bellows, compensators, turbine disks, or flange connections under thermal and pressure cycles illustrates the great potential of the numerical techniques developed for this purpose using mostly min-max approaches. The treatment of railway problems and the analysis and optimisation of pavements are further examples of important areas of applications. Emphasis was laid on approaches that take into account the fact that loading histories are often not precisely known Therefore, the center of interest lies in other than step by step calculation methods.

Author: Konstantinos Spiliopoulos
Publisher: Springer Science & Business Media
ISBN: 9400768273
Category : Technology & Engineering
Languages : en
Pages : 281

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Book Description
Knowing the safety factor for limit states such as plastic collapse, low cycle fatigue or ratcheting is always a major design consideration for civil and mechanical engineering structures that are subjected to loads. Direct methods of limit or shakedown analysis that proceed to directly find the limit states offer a better alternative than exact time-stepping calculations as, on one hand, an exact loading history is scarcely known, and on the other they are much less time-consuming. This book presents the state of the art on various topics concerning these methods, such as theoretical advances in limit and shakedown analysis, the development of relevant algorithms and computational procedures, sophisticated modeling of inelastic material behavior like hardening, non-associated flow rules, material damage and fatigue, contact and friction, homogenization and composites.