Effect of fracture toughness and tensile strength on fracture based on boundary effect theory

Based on the Boundary Effect Theory, the effect of fracture toughness and tensile strength on fracture of material and structure were studied. The equivalent crack ae is introduced in Boundary Effect Model (BEM), by which two separate boundary measurements are effectively combined into a single and unified boundary measurement. Based on the ratio of equivalent crack to characteristic crack a_e/a^* _∞, the fracture control mode such as strength criteria, fracture criteria and quasi-brittle fracture, can be determined. BEM can be applied in LEFM and elastic-plastic fracture analysis, and the limit scope of application of ASTM standard and RILEM standard has been solved by BEM. Given that ASTM strict limitations to determine fracture toughness such as initial crack length and specimen size and others, a method for determining fracture toughness and tensile strength according to small specimen of RILEM was proposed. The reasonability and applicability of the proposed method has been confirmed by test results analysis.