| CPC G01N 3/068 (2013.01) [G06F 17/11 (2013.01)] | 10 Claims |
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1. A stress measuring method that measures a stress generated in a sample when external force is applied to the sample, the sample having a surface formed with a first stress luminescent film, the stress measuring method comprising:
creating a calibration curve representing a relationship between a luminescence intensity of stress luminescence and a stress; and
measuring a stress generated in the sample on the basis of a luminescence intensity of the first stress luminescent film under application of the external force to the sample,
wherein the creating the calibration curve including
forming a second stress luminescent film having the same configuration as the first stress luminescent film, on a surface of a test piece,
applying external force to the test piece,
detecting the external force to be applied to the test piece,
photographing the test piece under application of the external force,
creating a luminescence intensity-stress curve, which represents a relationship between a luminescence intensity of stress luminescence and a stress on the basis of a photographed luminescent image of the second stress luminescent film and a detection value of external force obtained by the detecting the external force,
creating a regression equation consisting of a fourth or higher degree polynomial representing a regression relationship of the stress with respect to the luminescence intensity by polynomial regression analysis of the luminescence intensity-stress curve, and
storing the regression equation as the calibration curve, and
wherein the measuring the stress generated in the sample including
applying external force to the sample,
photographing the sample under application of the external force, and
measuring the stress generated in the sample on the basis of the luminescence intensity of the first stress luminescent film, using the calibration curve.
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