A comparison of models for ductile fracture prediction in forging processes

• Autorzy: Zheng C. , Cesar de Sa J. M. A. , Pires F.

Warianty tytułu

PL

Porównanie modeli zniszczenia dla przewidywania plastycznego pękania w procesach kucia

• Języki publikacji: EN

Abstrakty

EN

The possibility of predicting ductile fracture plays an important role in the design of components by forging processes. Experimental observations showed that the nucleation, growth and coalescence of voids are the mechanisms that control the initiation and propagation of fracture and that these mechanisms are influenced in different ways by factors like the hydrostatic stress, the equivalent stress or by the maximal principal stress. Many ductile fracture indicators, based on some or all of those factors, are available and used in many practical situations in the design of those components. In this work a comparative work of many of those criteria was undertaken. Different criteria were chosen amongst the more popular ones and from different groups, in which they may be classified, namely those based on micromechanics and those based on the geometry of voids or their growth mechanisms. The criteria based on the Continuous Damage Mechanics, in which a coupling between plastic deformation and material degradation is taken into account and that include different damage evolution descriptions for traction or compressive stress states give a more correct and clear localization for the fracture initiation site.

PL

Możliwość przewidywania plastycznego pękania odgrywa ważną rolę w projektowaniu wyrobów kutych. Badania doświadczalne pokazują, że zarodkowanie, wzrost i łączenie się pustek są mechanizmami kontrolującymi powstawanie i rozprzestrzenianie się pęknięć. Na te mechanizmy oddziałują w różnym stopniu, takie parametry jak ciśnienie hydrostatyczne , intensywność naprężenia i maksymalne naprężenie główne. Znanych i używanych w praktyce jest wiele kryteriów pękania plastycznego opartych na tych parametrach. W niniejszej pracy te kryteria są porównywane. Spośród najbardziej popularnych wybrano kryteria pękania przynależne do różnych grup, klasyfikowane według podstaw danego kryterium, a więc kryteria oparte na mikrostrukturze materiału, kształcie pustek lub me chanizmie ich wzrostu. Kryteria oparte na mechanizmie kontinuum pękania, w których bierze się pod uwagę sprzężenie między odkształceniem plastycznym i degradacją materiału poprzez analizę różnych możliwości rozwoju zniszczenia dla rozciągającego i ściskającego stanu naprężenia, dają bardziej poprawną lokalizację obszarów, w których następuje inicjacja pęknięcia.

Słowa kluczowe

EN

Ductile fracture indicators; forging processes

• Wydawca: Wydawnictwa AGH
• Czasopismo: Computer Methods in Materials Science
• Rocznik: 2007
• Tom: Vol. 7, No. 4
• Strony: 389--396
• Opis fizyczny: Bibliogr. 31 poz., rys.

Twórcy

autor

Zheng C.

autor

Cesar de Sa J. M. A.

autor

Pires F.

• IDMEC-Institute for Mechanical Engineering, Faculty of Engineering, University of Porto Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal,

Bibliografia

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