Journal ArticleDOI
Family of crack-tip fields characterized by a triaxiality parameter—II. Fracture applications
Noel P. O’Dowd,C. F. Shih +1 more
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In this paper, the J-dominance is used to define the size scale over which large stresses and strains develop while Q scales the near-tip stress distribution and the stress triaxiality achieved ahead of the crack.Abstract:
C entral to the J-based fracture mechanics approach is the concept of J-dominance whereby J alone sets the stress level as well as the size scale of the zone of high stresses and strains. In Part I the idea of a J Q annulus was developed. Within the annulus, the plane strain plastic near-tip fields are members of a family of solutions parameterized by Q when distances are normalized by J σ 0 , where σ0is the yield stress, J and Q have distinct roles: J sets the size scale over which large stresses and strains develop while Q scales the near-tip stress distribution and the stress triaxiality achieved ahead of the crack. Specifically, negative (positive) Q values mean that the hydrostatic stress is reduced (increased) by Qσ0 from the Q = 0 plane strain reference state. Therefore Q provides a quantitative measure of crack-tip constraint, a term widely used in the literature concerning geometry and size effects on a material's resistance to fracture. These developments are discussed further in this paper. It is shown that the J Q approach considerably extends the range of applicability of fracture mechanics for shallow-crack geometries loaded in tension and bending, and deep-crack geometries loaded in tension. The J Q theory provides a framework to organize toughness data as a function of constraint and to utilize such data in engineering applications. Two methods for estimating Q at fully yielded conditions and an interpolation scheme are discussed. The effects of crack size and specimen type on fracture toughness are addressed.read more
Citations
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An experimental and numerical investigation of ductile crack growth characteristics in surface cracked specimens under combined loading
TL;DR: In this paper, the authors compared crack growth characteristics between two types of cracks and found that the initiation of ductile crack growth along a three-dimensional crack front appears to be independent of local constraint.
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Two-parameter fracture prediction for cracked plates under bending
TL;DR: In this paper, the fracture prediction method based on two-parameter J-Ad* (J-integral and a new load-independent unified constraint parameter Ad*) with considering both in-plane and out-of-plane constraints has been investigated for semi-elliptical surface cracks in plates under bending.
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Notched M(T) specimen for plane strain studies
TL;DR: In this paper, the authors developed a specimen geometries able to isolate the plane strain state at a controlled level by introducing lateral side U-shaped and V-shaped grooves in the standard M(T) specimen.
Journal ArticleDOI
J-Q and toughness scaling model solutions for M(T), DE(T), SE(B), SE(T) and C(T) specimens
Arne S. Gullerud,Robert H. Dodds +1 more
TL;DR: In this article, J-Q trajectories and TSM curves derived from plane strain analyses of M(T), DE, SE, and C(T) specimens for a range of a/W ratios, E/σ ratios and hardening exponent (n) were provided.
Journal ArticleDOI
Evaluating J-integral and Q parameter in high-density polyethylene using a combined experimental finite element method
TL;DR: In this article, a combined experimental finite element method (FEM) was used to calculate J-integral and Q parameter for center-crack tension of high-density polyethylene specimens.
References
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Journal ArticleDOI
A Path Independent Integral and the Approximate Analysis of Strain Concentration by Notches and Cracks
TL;DR: In this paper, an integral is exhibited which has the same value for all paths surrounding a class of notches in two-dimensional deformation fields of linear or non-linear elastic materials.
Journal ArticleDOI
Plane strain deformation near a crack tip in a power-law hardening material
James R. Rice,G. F. Rosengren +1 more
TL;DR: In this paper, the authors investigated the C rack-tip strain singularities with the aid of an energy line integral exhibiting path independence for all contours surrounding a crack tip in a two-dimensional deformation field of an elastic material (or elastic/plastic material treated by a deformation theory).
Journal ArticleDOI
Singular behaviour at the end of a tensile crack in a hardening material
TL;DR: In this paper, a total deformation theory of plasticity, in conjunction with two hardening stress-strain relations, is used to determine the dominant singularity at the tip of a crack in a tension field.
Journal ArticleDOI
On the relationship between critical tensile stress and fracture toughness in mild steel
TL;DR: In this paper, the critical value of tensile stress (a) for unstable cleavage fracture to the fracture toughness (K,,) for a high-nitrogen mild steel under plane strain conditions.
Journal ArticleDOI
Family of crack-tip fields characterized by a triaxiality parameter—I. Structure of fields
Noel P. O’Dowd,C. F. Shih +1 more
TL;DR: In this article, a two-parameter fracture mechanics approach for tensile mode crack tip states in which the fracture toughness and the resistance curve depend on Q, i.e., JC(Q) and JR(Δa, Q), is proposed.
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