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Plastic stresses at the tip of a crack impinging perpendicularly the interface of two different elastic-plastic materials

100%

Espapragoza J. E.

International Journal of Applied Mechanics and Engineering

2005

tom Vol. 10, no 2

207-216

The problem of stresses at the tip of a crack impinging the interface of two different elastic-perfectly plastic materials is considered. The mathematical model is based on the assumption that both solids are incompressible elastic-perfectly plastic materials obeying the Huber-Von Misses yielding criterion under conditions of plane strain. It is shown that the problem of local stresses near the crack tip has two possible solutions, one of which is continuous and the other discontinuous. For the inhomogeneous case it was found that the discontinuous solution is the only feasible. In the limiting case of a homogeneous elastic-perfectly plastic material, the continuous solution coincides with that of Prandtl (1920), and the discontinuous solution with that of Cherepanov (1997). Some reasons for preferring the discontinuous solutions are provided since it is evident that both solutions cannot exist simultaneously.

Charakterystyka pól naprężeń przed wierzchołkiem pęknięcia dla kwadratowej płyty poddanej dwuosiowemu rozciąganiu

84%

Grabania M.

2015

tom R. 22, nr 12

585--592, CD

W artykule przedstawiona została charakterystyka pól naprężeń przed wierzchołkiem pęknięcia dla kwadratowej płyty zawierającej centralne pęknięcie, poddanej dwuosiowemu rozciąganiu. Praca prezentuje szczegóły obliczeń numerycznych, a także porównania stanów naprężeń dla płyt poddanych jednoosiowemu rozciąganiu oraz płyt poddawanych dwuosiowemu rozciąganiu. Analiza numeryczna prowadzona jest dla szeregu modeli materiałów sprężysto-plastycznych oraz różnych względnych długości pęknięcia. Dyskusja dotyczy wpływu geometrii, poziomu i rodzaju obciążenia zewnętrznego oraz charakterystyki materiałowej na pole naprężeń przed wierzchołkiem pęknięcia.

In the paper the stress field near front of crack for center cracked square plate in biaxial tension was pre-sented. The paper presents the details of numerical calculations, and also the comparison of states of stress for plates subjected to uniaxial tensile and plates to be in biaxial tension. The influence of the crack length, material characteristic and the level or type of external load were discussed.

A Model for Fatigue Crack Growth in the Paris Regime under the Variability of Cyclic Hardening and Elastic Properties

84%

Kebir T. , Benguediab M. , Imad A.

Fatigue of Aircraft Structures

2017

tom Iss. 9

117--135

Over the last 60 years, several models have been developed governing different zones of fatigue crack growth from the threshold zone to final failure. The best known model is the Paris law and a number of its based on mechanical, metallurgical and loading parameters governing the propagation of cracks. This paper presents an analytical model developed to predict the fatigue crack propagation rate in the Paris regime, for different material properties, yield strength (σy), Young’s modulus (E) and cyclic hardening parameters (K’, n’) and their influence by variability. The cyclic plastic deformation at a crack tip or any other cyclic hardening rule may be used to reach this objective, for to investigate this influence, these properties of the model are calibrated using available experimental data in the literature. This FCGR model was validated on Al-alloys specimens under constant amplitude load and shows good agreement with the experimental results.

Influence of the variability of the elastics properties on plastic zone and fatigue crack growth

67%

Kebir T. , Benguediab M. , Imad A.

Mechanics and Mechanical Engineering

2017

tom Vol. 21, nr 4

919--934

Several theoretical models have been proposed to predict the fatigue crack growth range (FCGR) process using solid mechanics, based theoretical tools and basic or fundamental mechanical properties. Moreover crack growth is linked to the existence of a plastic zone at the crack tip when the formation and intensification are accompanied by dissipation of energy. The overall objective of the present research is to develop, verify, and extend the computational efficiency of the model for fatigue crack growth range (FCGR) function by elastic properties, cyclic hardening and celebrated Paris law. The influence of the variability to elastic properties (Young’s modulus E, tensile strength e and cyclic hardening exponent n’) is a necessary analysis in this work. The predictions of the proposed model were compared with experimental data obtained by [1].