Strain and Deflection Assessment of SFRC Using Digital Image Correlation

The two-dimensional Digital Image Correlation (DIC) technique is a recognized and widely utilized method in the field of experimental mechanics. It is a valuable and accurate way to measure the in-plane deformation of an object's surface. This technology is used in many industries, including engineering and medical imaging. It allows for highly accurate remote deformation assessment. The present methodology identifies the correspondence between images in their pre-deformed state (i.e., reference image) and post-deformed state (i.e., degraded image). The measurement of Strain and deflection is a fundamental component of the material testing process. Several contact-based units are available for strain and deflection estimation, including strain gauges, extensometers, LVDTs, dial gauges, seismic waves, and acoustic emission techniques. Nonetheless, these techniques have some problems, such as sensitivity concerns, external noise susceptibility, and breakage. The present study showcases the outcomes of implementing the DIC approach to measure the deflection and Strain of Steel Fiber Reinforced Concrete (SFRC) specimens under loading conditions. The study employs cost-effective cameras, such as the Nikon D3400 DSLR and mobile phone (iPhone 13 Pro Max) cameras, to implement DIC. The results demonstrate the capability of DIC in measuring the deflection of the sample under loading, with a Root Mean Square (RMS) error value of 0.03 compared to dial gauges, and a maximum discrepancy of 0.266 in deflection at peak load between DIC and Dial Gauge measurements. The DIC approach showed exceptional efficacy in calculating the modulus of elasticity of SFRC gained from cameras, achieving an absolute percentage error between 0% and 8.5%.