Experimental Calibration of Computational Constants for Hole Drilling Method

Abstract

The hole drilling strain-gage method measures residual stresses near the surface of the material. The method involves attaching strain gage rosette to the surface, drilling a hole in the vicinity of the gages and measuring the relieved strains. The measured strains are then related to relieved principal stresses through a series of equations using dimensionless constants a, b. This method is a basic of ASTM E837 [1] standard for residual stress measurement, which involves the constants a, b obtained by FEA calculations, In presented work, the experimental set-up is described for calibration of these constants for uniform stress field; their verification on non-uniform linear stress field and given results of measurements is discussed. The constants are derived using proposed method for several strain gage rosettes and are compared with those, obtained using FEA model and those, given in ASTM standard. One example of using the hole drilling method for uniform and non-uniform stress field is given to show the limits of ASTM standard. As an alternative, the results evaluated from integral method [1] and one own developed method are presented and discussed, focused especially on separation of surface machining stresses.