Characterization of tensile failure behaviour of magnesia refractory materials by a modified dog-bone shape direct tensile method and splitting tests

Abstract

A novel modified dog-bone shape direct tensile test is proposed and compared with the wedge splitting test as well as Brazilian test. The acoustic emission and digital image correlation techniques are adopted for monitoring the entire fracture process. The tensile strength determined by Brazilian test and wedge splitting test are higher than that evaluated by the direct tensile test. For direct tensile test, the specimens lost their integrity immediately after reaching the tensile strength and its predominant fracture mode is tensile nature cracking. The wedge splitting test enables the stable crack propagation because of the development of remarkable fracture process zone, which contributes to the presence of intensive shear cracking. The fracture behaviour of Brazilian test has the material brittleness dependence. For brittleness reduced refractories, the quasi-stable failure process is noticed. The deviations of the tensile strength, fracture process and failure mode for the three Mode I tensile tests are attributed to the different mechanical principles, the geometry/size effect and heterogeneity effect.