Applying the Integrated Digital Image Correlation Method to Detect Stress Measurements in Precision Drilling

Abstract

Drilling is a precision machining method, and stress measurement in situ can be used to evaluate its machining efficiency. The most used technique for measuring the stress state of the tested object is the drilling method or the blind hole method. By measuring the relative deformation before and after drilling using deformation measurement techniques, the stress tensor before drilling can be derived. The traditional digital image correlation (DIC) method has a large stress recognition error and faces problems such as rigid body displacement and image scaling that can affect accuracy. This study proposes a new experimental method that incorporates rigid body displacement parameters into the Nelson–integrated DIC identification parameters, with the aim of perfecting both rigid body displacement and stress recognition accuracy. The results show that the images identified by this method exhibit a high degree of agreement, confirming the convergence and applicability of the displacement field in the wired limited-scale specimens. The compensation method for false strain proposed in this study has been experimentally verified to be highly dependable. The results of the current stress measurement are in good agreement with the predrilling stress measured by DIC, with a main stress measurement error of only 1.57 % of the reference stress. This method can improve the accuracy of image measurement methods and become a low-cost, high-precision, and highly mobile current stress measurement technology.