A unified method to estimate J-resistance curve of thin-walled metallic tube containing axial cracks

Abstract

Fracture toughness of thin-walled metallic tubes is an important mechanical property index to ensure their safety in service. Because of the particularity of geometric structure, the fracture toughness test of thin-walled metallic tubes cannot be carried out using traditional standard specimens. In this work, the expressions of load–displacement relationship and J-integral of thin-walled tube specimens containing bilateral axial cracks are proposed based on the energy density equivalence principle, in which the effect of material and specimen geometry has been considered. Through three-dimensional finite element simulation analysis, the relevant parameters of the expression are obtained and validated, and then a fracture toughness test method for thin-walled metallic tubes is established. The method is applicable to the fracture toughness measurement of thin-walled metallic tubes with different sizes and materials. Finally, the fracture toughness tests of two thin-walled alloy tubes were completed by the new method, and the J-resistance curves were obtained.