In this paper, the characteristics of the stress field near a corner of jointed dissimilar materials are studied as a plane problem. It is found that the order of singularity is dependent not only on the elastic constants of materials and the local geometry of corner, but also on the deformation mode. The dependence of the order of singularity was established for the case of mode I and the case of mode II. An explicit closed-form expression is given for the singular stress field at the close vicinity of the corner, in which the stress field is expressed as a sum of the symmetric state with a stress singularity of 1/r1-λ1 and the skew symmetric state with a stress singularity of 1/r1-λ2. When both λ1 and λ2 are real the singular stress field around the point singularity is defined in terms of two constants K1, λ1, K11, λ2, as in the case of crack problems.

A B S T R A C T This paper is concerned with the analysis of stress intensity factors of a semi-infinite body with an elliptical or a semielliptical crack subject to tension.Analysis is based on the body force method [1] which has been applied to the various plane stress problems. In this paper the method is extended to three-dimensional problems. The numerical calculations are performed for various shapes and configurations of ellipses and the results are in agreement with the two-dimensional cases by M. Isida as b/a~O. The stress intensity factor of a semi-elliptical crack in a plate of finite width is also discussed.

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Based on the S-shaped unloading hysteresis curve a new method for determining the crack closure has been developed in which the plastic deformation near the crack tip is taken into consideration. The crack growth rate can be expressed uniquely by the effective stress intensity range, ΔKeffop = Kmax − Kop or ΔKeffcl = Kmax − Kcl, which is independent of the stress ratio and the loading history. The tip of a nonpropagating crack does not open even under the maximum tensile load during one loading cycle. The measured values of the crack opening ratios Uop(ΔKeffop/Kmax) and Ucl(ΔKeffcl/Kmax) of a steadily propagating crack are mainly controlled by Kmax and the stress ratio R.