Mode I Stress-Intensity Factor Measurements by the Electrical Strain Gage

Abstract

This paper describes the method of determining the Mode I stress-intensity factor (K_I) by using the electrical strain gage. When fracture mechanics is applied to engineering, The stress-intensity factor near the crack tip must be accurately determined by way of a convenient measuring method of the strain. Usually, electrical strain gages are used for the strain measurement of the structure material. Thus the strain gage is used in this study. The type of strain gage used in this study is the chain strain gage consisting of 5 measuring grids. It is used in the experiments which examine the center-cracked test specimens (CCT) and single-edge-cracked plate tension specimens (SECT) as well as the compact-type specimens (CT). The accuracy of the stress-intensity factor (K_I) determined by the experiments is within ±10 percent, compared to the analytical value.