| 摘要 |
Method and apparatus for determining a point of inflection in a evaluating maximum prior stresses to which a sample has been subject is accomplished by acoustical emission response from the sample versus the applied stress to the sample. The method comprises applying a compressive force to the sample in a manner which gradually and uniformly increases stress on the sample. Stress as applied to the sample is measured and simultaneously, cumulatively acoustic emission pulses are counted in response to the gradually increasing applied stress to the sample. In an X-Y co-ordinate system, the measured stress is plotted along one co-ordinate and the cumulative acoustic emission count supplied along the other co-ordinate to develop a curve having a recognizable point of inflection to indicate maximum prior stresses to which the sample had been previously subjected.
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