Towards a Digital Image Correlation Based Strain Sensor

A need exists for a non-contact two-dimensional strain measurement system,which could provide information for field monitoring and greatly enhance theaccuracy of structural models through the development of larger data sets for model calibration. This paper introduces a potential technique for measuring displacement with a high degree of accuracy, which is required for a two-dimensional strain sensor, using relatively inexpensive digital cameras using the digital image correlation technique and a software package called GeoPIV. The basics of the digital image correlation technique are presented. The paper focuses on the importance of image texture in achieving accurate displacement measurements. As an illustration of this, compression tests on textured and untextured concrete cylinders are presented. Using a full displacement field analysis region, it was found that the cylinders with artificially added texture produced more accurate results than those without. These results are discussed to highlight the impact of image texture on the digital image correlation technique.