| 摘要 |
PURPOSE:To detect the crack generation of a test piece easily with high accuracy by detecting the point of inflection of load-strain loop in the load removing process of test by means of a load detector and a strain detector. CONSTITUTION:The outputs of a load detector 5 detecting the load acting upon a test piece 4 and a strain detector 6 detecting the strain of the test piece are inputted to a scanner 7. The scanner 7 samples load strains at constant time intervals and applies outputs thereof to an arithmetic device 8. The device 8 compares the load values at the 3 points measured at constant time interdvals in a load removing process, determines the curvature of a curve and determines the times of crack generation by the repetitive number at which the curvature shifts from positive to negative. When the device 8 decides the generation of cracks, it emits a signal to a times measuring device 9, and records the current repetitive number that the device 9 is measuring in a recorder 10. At this same instant, the recorder 10 feeds the siganl for the end of the test to the scanner 7, thereby stopping the sampling of data. |
