| 摘要 |
PURPOSE: A measuring method of crack length of delayed fracture is provided to measure delayed fracture length by using fine changes in electric resistance depending on crack length. CONSTITUTION: Various length of artificial cracks is formed at notch test pieces respectively. An electric current is fed lengthwise to the test pieces having the artificial cracks, and electric potential difference is measured at both ends of a notch. Correlation between the crack length and the measured electric potential difference is obtained. In actual test for measuring delayed fracture, an electric current is supplied lengthwise to the test pieces and electric potential difference is measured. The measured potential difference is input to the correlation. Therefore, the crack length is obtained. The changes in crack length are measured from outside exactly without stop after a load is added. Therefore, sensibility of delayed fracture is estimated.
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