Assessment of stable tearing on fatigue fracture surfaces

Predictive models for stable tearing crack growth due to overloading in fatigue

“…The theoretical plastic zone size due to each overload was sufficiently small in comparison with the specimen thickness and the distance from the crack to any free surface edges of the specimen, to ensure that linear elastic fracture mechanics (LEFM) was applicable in this study. The small‐scale yielding conditions are also studied by using the finite element (FE) method on a CT specimen model under elastic–plastic condition 16 . The plastic strain is contained within the ligament area.…”

“…Several stable tearing analytical models have been proposed in the literature; 9,10 these are all based on the two‐dimensional (2D) analysis. In aluminium alloys, these models assumed that the first onset of stable tearing under either constant–amplitude or variable–amplitude fatigue loading occurs when the stress intensity factor K of the fatigue crack front exceeds a critical K ‐value that is comparable to the material's plane strain fracture toughness K Ic 11,12 .…”

Structural overloading evaluation based on the identification of subcritical crack increments

“…The tearing at the overloading cycle occurs at the corresponding stress intensity factor value close to the fracture toughness [15]. Crack advance caused by tearing is similar to the final unstable fracture from a macroscopic view, but with the difference being that it is stable [18]. The loading level, which corresponds to the stress intensity factor K I of the present crack being close to value of the fracture toughness K IC , indicates a near-critical loading condition of the structure component.…”

“…References to stable tearing are found in the literature in theoretical analyses [21][22][23] and empirical analyses as well [15,[23][24][25][26]30]. Sih [27] stated that the crack growth conditions of stable tearing are similar to the total of critical strain energy density and its process is assumed to be similar to ductile fracture under static loading.…”

“…Forming such zone of ductile fracture is mostly referred to stable tearing. However, other descriptive terms are used in the literature, such as brittle crack growth, tensile crack jumping, quasi-cleavage, tongue-shaped crack extension, ductile tearing rupture, and mixed fatigue-tensile crack growth [18].…”