Variations of stress intensity factor of a semi-elliptical surface crack subjected to mixed mode loading |
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Authors: | Nao-Aki Noda Toshiaki Kihara Daisuke Beppu |
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Affiliation: | (1) Department of Mechanical Engineering, Kyushu Institute of Technology, 1-1, Sensui-cho, Tobata, Kitakyushu 804-8550, Japan |
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Abstract: | Maximum stress intensity factors of a surface crack usually appear at the deepest point of the crack, or a certain point along
crack front near the free surface depending on the aspect ratio of the crack. However, generally it has been difficult to
obtain smooth distributions of stress intensity factors along the crack front accurately due to the effect of corner point
singularity. It is known that the stress singularity at a corner point where the front of 3 D cracks intersect free surface
is depend on Poisson's ratio and different from the one of ordinary crack. In this paper, a singular integral equation method
is applied to calculate the stress intensity factor along crack front of a 3-D semi-elliptical surface crack in a semi-infinite
body under mixed mode loading. The body force method is used to formulate the problem as a system of singular integral equations
with singularities of the form r
−3 using the stress field induced by a force doublet in a semi-infinite body as fundamental solution. In the numerical calculation,
unknown body force densities are approximated by using fundamental density functions and polynomials. The results show that
the present method yields smooth variations of mixed modes stress intensity factors along the crack front accurately. Distributions
of stress intensity factors are indicated in tables and figures with varying the elliptical shape and Poisson's ratio. |
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Keywords: | Body force method elasticity fundamental density numerical analysis semi-elliptical surface crack singular integral equation stress intensity factor |
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