Cálculo de propriedades de fraturamento do concreto reforçado por fibras de aço utilizando correlação de imagens digitais e mecânica da fratura linear elástica

Abstract

The great demand for mechanical tests in engineering induces the usage and development of several alternative measurement methods. In this context, digital image correlation (DIC) is a practical, accurate and inexpensive technique for measuring surface displacement in a nonintrusive way. DIC consists in correlating pairs of images taken from the surface of the specimen under stress in distinct stages of loading, resulting in the displacement fields. By using the concepts from linear elastic fracture mechanics (LEFM), the displacement fields can be applied to evaluate some fracture properties of the material. The strategy addressed in this work uses images taken from a number of three-point bending tests (3PBT) of steel fiber reinforced concrete (SFRC) specimens as input data and measures the displacement field by DIC using the opensource software NCorr. This displacement field is used to create virtual extensometers in order to study the crack opening. The fracture properties are then computed from LEFM equations with the displacement previously calculated. The proposed strategy is a robust alternative and it can be a powerful mechanism to analyze and validate the material properties used in several engineering problems.