切欠き底が二軸応力状態の切欠き材の変形挙動と強度

抄録

Longitudinal and transverse strain distributions at the notch root were examined up to the maximum tensile load for three types of aluminum specimens, i. e., two rectangular ones notched on either two or four sides and a circumferentially notched cylindrical one. All of them possess the biaxial state of stress at the notch root.
For the rectangular specimen notched on two sides the maximum longitudinal strain occurred at the center of the notch root and the longitudinal strain distribution was a convex one, whereas for the retangular specimen notched on four sides the maximum longitudinal strain occurred at the end of the notch root and the distribution was a concave one. These patterns of strain distribution hold from the elastic range up to the maximum load. In the same way as in the elastic range, a high strain concentration existed up to maximum load and the state of stress in the vicinity of the notch root was biaxial tension at least near the maximum load.
The longitudinal strain at the notch root at the maximum load, which corresponds to the beginning of unstable deformation of the notched specimen, was remarkably greater than the uniform elongation of the unnotched specimen. It is considered that this phenomenon is closely related to the notch strengthening.