Effects of the surface crack shape on J values along the front of an elliptical crack

Abstract

Surface cracks are one of common forms of flaws in thin-walled structures such as pressure vessels, oil, and gas pipelines. Accurate evaluation of the growth driving force of such surface cracks is important for integrity analyses of these structures. In this study, the combined effect of the depth and the length of a given surface crack under tension was analyzed using combined elastoplastic finite element analysis (EPFEA) and crack propagation experiments with selected crack shapes. Based on the consideration of the distribution profile of the J integral as the crack growth driving force along crack front, the crack growth stability with different crack shapes was analyzed.Finite element analysis (FEA) results showed that the growth from partial to through-wall penetration is affected by the shape of the initial crack. As shown by the distribution profile of the J integral along the crack front, the location(s) of the maximum J, that is, the highest crack driving force, is (are) found to vary with the crack shape and development.crack growth, elastoplastic finite element analysis (EPFEA), J integral, surface crack | INTRODUCTIONPressurized components for storage or transportation of static or circulating fluids are commonly used in the industry, such as the nuclear, chemical, oil, and gas sector. 1 These critical components are sometimes utilized up to their design capacity during services. Operators may also look into potentials to extend the service life of ageing installations. The structural integrity assessment of these components is thus required to ensure adequate safety margins can be maintained at all time.

Numerical Investigation of the Influence of Ultimate-Strength Heterogeneity on Crack Propagation and Fracture Toughness in Welded Joints

“…The critical failure displacement load was used as the boundary condition to calculate the J-integral under the critical load state of the welded joint. The J-integral is the critical fracture resistance of the material in fracture and forward propagation [ 37 ], which is used as the critical fracture toughness, J 1c . This process is cycled until the displacement load reaches the set maximum value, disp max .…”

Effect of specimen thickness on fatigue crack shape evolution for aluminum alloy

“…In recent years, the evolution of fatigue crack shapes has emerged as a topic of considerable interest. Numerous research studies have been undertaken to investigate crack shapes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], and the collective findings suggest that finite thickness specimens exhibit a phenomenon known as the "tunneling effect." Specifically, in specimens with an initially straight crack that eventually penetrates, the central crack front advances ahead of all others as the loading cycles progress.…”