A damage mechanics based on the constitutive model for strain-softening rocks July Simulating time-dependent quasi-brittle failures based on a multilinear releasing mechanism of viscous force VF fields July Fracture investigation of the shape memory alloy using GTN model July Combined effects of steel fibers and water to cementitious materials ratio on the fracture behavior and brittleness of high strength concrete July A mode III Dugdale crack interacting with a non-elliptical inhomogeneity with internal uniform stresses July On through-thickness distribution of stress intensity factors and energy release rates in the vicinity of crack fronts July Influence of micro-modulus functions on peridynamics simulation of crack propagation and branching in brittle materials July Analysis of load-induced top-down cracking initiation in asphalt pavements using a two-dimensional microstructure-based multiscale finite element method July Hybrid image processing approach for autonomous crack area detection and tracking using local digital image correlation results applied to single-fiber interfacial debonding July An alternative bilinear peridynamic model to simulate the damage process in quasi-brittle materials July Observations of compression and fracture in polymer networks subjected to impact loading July Fatigue crack growth simulations of plastically graded materials using XFEM and J-integral decomposition approach July Stiffness degradation of composite laminates due to matrix cracking and induced delamination during tension-tension fatigue July Discrete meso-scale modeling and simulation of shear response of scaled glass FRP reinforced concrete beams without stirrups July Experiments and numerical simulations with the H-specimen on damage and fracture of ductile metals under non-proportional loading paths Available online 9 July Adaptive modeling of rock crack mechanism during drilling operation based on modified peridynamics Available online 8 July Electrochemical hydrogen charging to simulate hydrogen flaking in pressure vessel steels Available online 8 July The quantitative analysis of the crack propagation on the fatigue properties of dual-phase approximate equiaxial nanocrystalline AgCu alloy Available online 8 July Applicability of mode II interlaminar fracture toughness testing methods for characterization of thermoplastic laminates with woven fabric reinforcements Available online 2 July Wavelet analysis of acoustic emissions Associated with cracking in Rocks Available online 29 June The synergistic action and interplay of hydrogen embrittlement mechanisms in steels and iron: Localized plasticity and decohesion Available online 28 June Mechanical and morphological characterization of spherical cell porous structures manufactured using FDM process Available online 27 June Mesoscale analysis of the transverse cracking kinetics in woven composite laminates using a phase-field fracture theory Available online 27 June Damage tolerance reliability analysis combining Kriging regression and support vector machine classification Available online 26 June Verification of stress-intensity factor and compliance relations for a single edge notch specimen under tension-compression loading Available online 25 June Revisit of antiplane shear problems for an interface crack Does the stress intensity factor for the interface Mode III crack depend on the bimaterial modulus?
Available online 21 June Temperature dependence of vacancy concentration and void growth mechanism in Al with constant hydrogen concentration: A first-principles study Available online 21 June Unification of hydrogen-enhanced damage understanding through strain-life experiments for modeling Available online 20 June Study of rock dynamic fracture toughness and crack propagation parameters of four brittle materials under blasting Available online 20 June Reexamination of the edge crack torsion test for determining the mode III delamination toughness of laminated composites 15 June Ductile fracture prediction based on J-integral and unified constraint parameters for cracked pipes 15 June Figure 1.
The crack growth rate is obtained by taking the slope of the crack growth curve at the crack length, a, as shown in Figure 2.
Figure 2. A cyclic plastic zone forms at the crack tip, and the growing crack leaves behind a plastic wake. If the plastic zone is sufficiently small that it is embedded within an elastic singularity zone, the stress intensity factor may still give a good indication of the stress environment at the crack tip.
Linear Elastic Fracture Mechanics and Fatigue Crack Growth — Residual Stress Effects
If two different cracks have the same stress environment i. This curve may be divided into three regions, which are discussed in the following sections. Figure 3.
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Due to the sensitivity of the fatigue threshold to the environment and load history, the best method to determine the threshold value is through testing under conditions that simulate actual service conditions. Although this would ensure a low probability of fatigue failure, this is often impractical for design conditions due to either the low level of operating stress or the small crack size required.
The threshold value may be useful when a component is subjected to low stress levels and a very large number of cycles. An example would be power trains that operate at very high speeds. Most structures operate in this region.
Most of the current applications of linear elastic fracture mechanics LEFM concepts used to describe fatigue crack growth behavior are associated with Region II. Region II is generally the largest region of the fatigue crack growth rate curve and many curve fits for this region have been suggested. Values of the exponent n can range from 2.
Since the stress intensity factor uses a correction factor, , that is usually a function of the crack length, the Paris Equation must often be integrated numerically. Thus, the Paris Equation can be solved in closed form.
Large changes in af result in small changes in the calculated fatigue life. The Stress Intensity Factor module can be used to calculate values of.
Fracture mechanics - Wikipedia
Region III At high stress intensities, crack growth rates are extremely high and little fatigue life is involved. Region III is characterized by rapid, unstable crack growth.
The crack growth rate accelerates as the maximum stress intensity factor approaches the fracture toughness of the material. In many practical engineering situations this region may be ignored because it does not affect the total crack propagation life.
The point of transition from Region II and Region III behavior is dependent on the yield strength of the material, stress intensity factor, and stress ratio.