Research On Fracture Behaviors Of Slightly Curved Extension Crack

In this article, the distributing state of normal and shear stresses on the boundaries of plasticity area of curved extension crack tip has been worked over theoretically and accurately. Plasticity area at the tip of the curved extension crack has been studied and analyzed. Elasticity-plasticity curved extension crack tip opening displacement are calculated as a practical application of the second order perturbation method,theorem of surname KA. Elasticity-plasticity curved extension crack tip J integral are calculated making use of the boundary curve of splinter strip plasticity area of original curved extension crack tip as an integral loop,where the effects of static applied stresses,normal and shear stresses on the boundaries of plasticity area of curved extension crack tip are taken into considerations.Amplitude of stress intensity factors is analyzed for a slightly curved crack by using a second order perturbation method. This method is extended to obtain an approximate representation of the amplitude of stress intensity factors at the tip of slightly curved extension crack under cyclic loading. Having examined the near tip asymptotic stress field,effects of the remote boundary conditions are taken into account in the sense of a matched asymptotic expansion. Amplitude of an energy release rate due to the crack growth can be calculated by using Irwin's formula. Prediction of crack extension in materials with inhomogeneous fracture toughness is considered. Paths of brittle crack propagation along a welded joint are predicted as an application of the method, where the effects of cyclic loading, residual stresses, and material deterioration due to welding are considered.In this article, the distributing state of cyclic normal stresses and cyclic shear stresses on the boundaries of plasticity area at fatigue curved extension crack tip has been worked over theoretically and accurately. Plasticity area at the tip of fatigue curved extension crack has been studied and analyzed. Maximum and amplitude of fatigue curved extension crack tip opening displacement are calculated as a practical application of the second order perturbation method,theorem of surname KA. Maximum and amplitude of fatigue curved extension crack tip J integral are calculated using the boundary curve of plasticity area of original curved extension crack tip as an integral loop,where the effects of cyclic applied stresses, cyclic normal stresses and cyclic shear stresses on the boundaries of plasticity area at fatigue curved extension crack tip are taken into considerations.Dynamic stress intensity factors are analyzed for slightly curved extension crack by means of a second order perturbation method. The method is extended to obtain an approximate representation of dynamic stress intensity factors at the tip of slightly curved extension crack. Having examined the near tip asymptotic stress field,the effects of far field boundary conditions are taken into account in the sense of a matched asymptotic expansion. An dynamic energy release rate due to curved extension crack growth can be calculated by using Irwin's formula. Considerations are made for growth of curved extension crack in materials with inhomogeneous fracture toughness. Paths of brittle cracks propagating along a welded joint are predicted as a practical application of the present method, where the effects of dynamic applied stresses, residual stresses, and material deterioration due to welding are taken into considerations.In this article, plasticity area at the tip of curved extension crack tip and the distributing state of dynamic normal stresses and dynamic shear stresses on the boundaries of it has been worked over theoretically and accurately. Function expression concerning time of elasticity-plasticity curved extension crack tip opening displacement under dynamic loads are deduced as a practical application of the second order perturbation method,theorem of surname KA;Dynamic J integral of elasticity-plasticity curved extension crack tip under dynamic loads are studied using the boundary curve of plasticity area of original curved extension crack tip as an integral loop,where the effects of dynamic applied stresses,dynamic normal stresses and dynamic shear stresses on the boundaries of plasticity area of curved extension crack tip are taken into considerations.