by Janeiro, Raymond P.; Einstein, Herbert H.

This paper presents the results of an experimental investigation on the cracking behavior of brittle heterogeneous materials. Unconfined, uniaxial compression tests were conducted on prismatic gypsum specimens containing either one, or two, inclusions. These inclusions were of different strengths, stiffnesses shapes, and sizes. Emphasis was placed on crack coalescence processes associated with specimens containing an inclusion pair, as this was the primary objective of the research. Some observations reported in this study compare well with those of other researchers as the overall cracking sequences are similar. On the other hand, the amount of debonding observed in this study at the inclusion interface is significantly less than what was previously observed. Moreover,

by Stoll, Anke; Wilkinson, Angus J.

A dislocation model for simulating two-dimensional quasi-static crack propagation is presented. The crack and plastic flow along slip planes are described using dislocation dipoles. A stationary crack can be modeled as well as a propagating crack along a straight line inclined at an arbitrary angle to a free surface of a semi-infinite medium. Cracks are also allowed to kink. A superdipole algorithm is introduced to save simulation time without loosing important information and necessary geometric details. It reduces the number of dislocation dipoles on slip planes in the plastic wake. The paper gives results on crack shapes for stationary and advancing cracks as well as it describes how the size of the

by Anandakumar, Ganesh; Kim, Jeong-Ho

This paper addresses mixed-mode crack growth in two-dimensional functionally graded solids under thermomechanical loads, and investigates the effect of mechanical and thermal loads as well as the T-stress on their crack growth behavior. A novel residual strain-based formulation in the interaction integral method is developed and used for the accurate evaluation of mixed-mode stress intensity factors and/or the T-stress. Simulation of mixed-mode crack propagation in functionally graded materials including solid oxide fuel cells under thermomechanical loads is performed by means of the finite element method and the generalized interaction integrals in conjunction with a remeshing algorithm. An iterative procedure is used for crack growth simulation including the calculation of mixed-mode stress intensity factors

by Nara, Yoshitaka; Takada, Masafumi; Mori, Daisuke; Owada, Hitoshi; Yoneda, Tetsuro; Kaneko, Katsuhiko

High-strength and ultra low-permeability concrete (HSULPC) is a strong candidate for a radioactive waste package containing transuranic radionuclides (TRU waste) for geological disposal. Knowledge of the time-dependent fracturing of HSULPC and surrounding rock mass is essential to assess the long-term stability of such underground repositories. We have measured crack velocity in andesite and HSULPC both in air and water to examine subcritical crack growth by the Double-Torsion method. In air, the crack velocity in andesite increased when the temperature and relative humidity increased. On the other hand, the temperature and relative humidity had little effect on the crack velocity in HSULPC in air. In water,

by Nikolić, Ružica R.; Djoković, Jelena M.; Mićunović, Milan V.

The problem analyzed is of the crack kinking away from the interface between the two different anisotropic materials. The attention is concentrated on the initiation of the crack kinking and the condition that the length of the crack segment that is leaving the interface is small in comparison to the crack segment that remains along the interface. The emphasis is placed to the application of the fracture mechanics concept for the interfacial crack that propagates dynamically between the two orthotropic materials. The simulations and calculations were done by application of the Mathematica

by Harding, Steven; Kotousov, Andrei; Lazzarin, Paolo; Berto, Filippo

The concept of a stress singularity is a cornerstone of modern fracture mechanics. A new mode of stress singularity, the out-of-plane singular mode or K

O
mode, was recently identified for V-shaped notches subjected to in-plane loading. This new mode is coupled with the

by Carpinteri, Alberto; Corrado, Mauro; Paggi, Marco

In the present paper, a new fracture-mechanics based model is proposed for the analysis of reinforced concrete beams in bending describing both cracking and crushing growths taking place during the loading process by means of the concept of strain localization. In particular, the nonlinear behaviour of concrete in compression is modelled by the Overlapping Crack Model, which considers a material interpenetration when the elastic limit is overcome, in close analogy with the Cohesive Crack Model, routinely adopted for modelling the tensile behaviour of concrete. On the basis of different nonlinear contributions due to concrete and steel, a numerical finite element algorithm is proposed. According to this approach, the flexural behaviour of

by Moutou Pitti, Rostand; Dubois, Frédéric; Petit, Christophe

This paper deals with the generalization of T-integral to crack growth process in viscoelastic materials. In order to implement this expression in a finite element software, a modelling form of this integral, called Aθ, is developed. The analytical formulation is based on conservative law, independent path integral, and a combination of real, virtual displacement fields, and real, virtual thermal fields introducing, in the same time, a bilinear form of free energy density F. According to the generalization of Noether’s method, the application of Gauss Ostrogradski’s theorem combined with curvilinear cracked contour, T

by Chen, Y. Z.; Lin, X. Y.

This paper investigates the T-stress in the branch crack problem. The problem is modeled by a continuous distribution of dislocation along branches, and the relevant singular integral equation is obtained accordingly. After discretization of the singular integral equation, the balance for the number of equations and unknowns is well designed. After the singular integral equation is solved, the equation for evaluating the T-stress is derived. The merit of present study is to provide necessary equation for evaluating T-stress, rather than to provide the integral equation. Many computed results for T-stress under different conditions for branch crack are presented. It is found from the computed results that the interaction for T-stress among