Desenvolvimento de algoritmo para cálculo de campos de deslocamento e deformação por correlação digital de imagem

Abstract

Digital Image Correlation (DIC) is a technique that aims to calculate displacement and deformations of different materials without contact and presents itself as an alternative to conventional strain gauge techniques. This work aims to develop an algorithm for the determination of deformations of specimens through the DIC method in Matlab, for this purpose specimens were used in aluminum, epoxy and polyester polymers and composites with red mud and with jute and mauve fibers, on which textures were applied in the useful area for tracking the points of interest, being then subjected to tensile tests, according to ABNT NBR 7549, ASTM D3039 and ASTM D638 standards. During the tests, strain gauges and strain gauges were used in the longitudinal and transverse directions, in order to allow the comparison of the deformation results obtained by conventional strain gauge techniques and those obtained through DIC. The results showed that in the aluminum specimens, the displacement fields presented very good results, represented in a wide field by the DIC, presenting underestimated and overestimated values, respectively, on average, equal to 8.43% and 4.35%. The composite samples showed values underestimated by an average of 16.05% for the longitudinal strain, and another set of composite samples showed values of overestimated longitudinal strain by 10.75%. The results also showed that the increase in the precision of the measurements of deformations by DIC depends fundamentally on the increase of the resolution of the images generated during the test for a better evaluation through the DIC algorithms produced.