| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1987: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1986: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Research Abstract |
Development of a compute-aided x-ray analysis system of the fracture surface was investigated. Fatigue fracture surfaces of steels, which were obtained under a wide rang of stress ratid some enviromental conditions, were examined to find the correlation between the residual stress on and under the furacture surface and the stress intensity factor(SIF) under fracture surface had formed. The results are summerised as follows.
1) The residual stress could be measured even on the fracture surface on which the exide on the corrosive products were induced. The residual stress, however, was not useful as an input information for the quantitative analysis of fracture, since is was much influenced by surface parameters such as toughness.
2) The residual stress under the fracture surface, which was obrained by successive removal of the thin layer from original fracture surface, counld be used as a useful information for the quanitative analsys of freacture.
3) It was found that the residual stress under the fatigue fracture surface was less influenced by the stress ratio, unless the stress tratio increased beyond a higher value of 0.5. The estimation of K_<max>, the maximum value of SIF, could be made on the basis of this residual stress under the fracture surface, which <delta>K, the range of SIF, could not be estimated.
4) A new method of estimating K_<max> was proposed. A-master curve in the residual stress distribution under ther fracture surface was produced from the experimetal data. The proposed method was formulated by using th emaster curve. The valus K_<max> could be estimated by the method from two values of the residual stress at two different depths. The proposed method was successfully applicable to the fatrigur fracture surface under corrosive environment.
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