A Complex Review of the Possibilities of Residual Stress Analysis Using Moving 2D and 3D Digital Image Correlation System

Abstract

Understanding the levels of residual stresses in the material is very important in predicting the service life of structural elements. One of the most widely used techniques to quantify them is the drilling method, where a small hole is milled in the structure. If the residual stresses are present, stress redistribution will occur, resulting in deformation of the hole surroundings. Nowadays, there is an effort to replace the conventionally used strain gauges, i.e. special strain gauge rosettes, with full-field optical experimental techniques. This paper deals with analysing the possibilities of measuring the relieved strains/stresses with a unique drilling/measuring device, which, unlike other non-commercial measuring systems, uses the moving digital image correlation (DIC) system. Since correlation systems do not tend to move during operation, an analysis was performed describing the effect of changing the position of the single and stereo camera correlation systems on the quality of the results of the strain/stress analysis performed in the vicinity of the milled hole. The conclusion from the analyses performed is that there is no significant accumulation of correlation errors during measurement. Therefore, the information on the magnitudes of the strains/stresses relieved obtained by the moving DIC system can be used to quantify the residual stresses with an expected error corresponding to the sensitivity of this full-field optical experimental technique.

Keywords

• residual stress
• hole drilling
• drilling device
• positioning
• digital image correlation