Abstract
In this paper, fatigue life circular cross-section elastic bar under pure fatigue axial loading is studied through principles of linear elastic fracture mechanics (LEFM) coupled with the three-dimensional finite element technique for determination of critical crack size and residual lifetime. Three different initial notch depths are discussed. The relations between aspect ratio (b/c) and relative crack depth (b/D) are obtained, and it is shown that there is great difference in the growth of cracks with different front shapes and initial notch depths.
Highlights
In many cases, the lifetime of structures and components depends on the behavior of cracks, especially under cyclic loading so called fatigue [1]
Paris and Erdogan have constructed a quantitative framework of fatigue fracture mechanics, which correlates the fatigue crack growth rate to the range of stress intensity factor as follows [3]: da= C (∆K )m where the stress-intensity factors (SIF) range, ∆K, is related to the crack geometry and the applied load, whilst constants C and m account for stress ratio R, the material and environmental effects
The estimate of fatigue life can be made by integrating Equation (1), if the stress intensity factor (SIF) range is known
Summary
The lifetime of structures and components depends on the behavior of cracks, especially under cyclic loading so called fatigue [1]. Cracks may develop and lead to catastrophic failure of the whole structure at the stresses even far below static strength limits. A published for part circular, part-elliptical, or straight fronted cracks in a bar. Analysis is carried out to determine the stress-intensity factors (SIF) along the front of an edge flaw [2]-[4]. The problem is very complex since a three-dimensional computation is necessary to obtain the values of the stress intensity factors along the crack front. An actual surface crack may usually be replaced by an equivalent circular arc or an elliptical-arc edge flaw [5]. The stress-intensity factors have been published for part circular, part-elliptical, or straight fronted cracks in a bar [6].
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