Alma Amad Alhussaini
Dhahran Schools, Khobar, SAUDI ARABIA
In the field of Mechanical Engineering, displacement of material can be used in identification of mechanical properties. When heterogeneous materials are subject to loads, they deform and their mechanical properties can be understood when local displacements are measured. In this research study, the main goal was to optimize a process called Digital Image Correlation which measures local displacements by comparing images of a specimen before and after loading. Recently, Digital Image Correlation has become a popular method because of the low cost of imaging devices. It is considered as a new method which, in comparison to standard methods such as the cross-head and strain gauge displacement method, can give full-field measurements. Optimization of DIC is essential in order to improve the accuracy of the data obtained when compared to the strain gauge method. In this study, the speckle pattern and subset sizes are parameters that were tuned in order to optimize the DIC process based on a specific testing apparatus. The three specimens tested: epoxy, aluminum, and steel were speckle patterned and displaced using the microstrain machine. Images taken via the CCD camera were later used for numerical comparison before and after displacement. When graphed, the larger subset size was closest to the ideal line obtained from Finite Element Method which suggests improved accuracy. It has been concluded that using a larger subset size and applying a speckle pattern from a greater distance leads to more accurate displacement estimation than the cross-head displacement and strain gauge methods. Findings show that using DIC methodology will assist in identification of material properties using inverse methods. Awards won at the 2013 ISEF Second Award of $1,500 - Society for Experimental Mechanics, Inc.