Disturbance effects of weak Mode-II loading on K-based Mode-I fracture toughness test

Abstract

It is well known that making of specimens, experimental set up, fixtures and testing procedure could inevitably affect the experimental accuracy, which will actually induce the disturbance from weak Mode-II loading on the specimen in K-based Mode-I fracture toughness tests. How to quantitatively analyse the disturbance effects is quite interesting and challenging work. In present article, an energy-based modelling on multiple underlying cracks initiation from a crack tip has been suggested to capture and quantify the disturbance effects. Conventional experimental data processing will lead to higher Mode-I fracture toughness values, which would affect the accuracy of fracture assessment, and cannot truly reflect the fracture property of materials. The current investigation has revealed that three theoretical predictable values of K-based Mode-I fracture toughness may be measured in tests if weak Mode-II loading acting on the specimen is inevitable, which is helpful to identify the real value of the fracture toughness and better understand scattered experimental data.