An empirical stress intensity factor set of equations for a semi-elliptical crack in a semi-infinite body subjected to a polynomial stress distribution.

An engineering set of equations for the stress intensity factor of mode I s urface cracks subjected to a complex stress field is provided here. Stress intensity factors for a semi-elliptical surface crack under various stress distribution were analysed by the body force method (Nisitani H, Murakami Y . Stress intensity factors of an elliptical crack or a semi-elliptical crac k subject to tension. International Journal of Fracture 1974,10:353-368). A semi-elliptical crack is assumed on the y-z plane in a semi-infinite body. Various stress fields, on the y-z plane, are assumed, such as constant, li near and parabolic, etc.., in the y- and z- direction. The numerical result s are arranged in a set of equations as a function of parametric angle, cra ck depth, crack length, y- order and z-order of the monomials. From that se t of empirical equations, the stress intensity factor of a surface crack su bjected to a sum of monomials can be easily calculated. A practical example is given. (C) 1999 Elsevier Science Ltd. All rights reserved.