Determination of Fracture Toughness Characteristics of Small- Size Chevron-Notched Specimens

Abstract

A new method is proposed to determine fracture toughness of structural materials according to the test data of non-standard small-size chevron-notched specimens. During the tests, loading diagrams and photographic images of the specimens taken in time intervals are obtained. The crack length is measured in the process of its initiation and propagation. The analytical expressions are obtained being based and derived from the constitutive equations of engineering fracture mechanics to determine the crack-driving force (specific fracture energy) and the stress intensity factor. The method allows us to exclude the periodic unloading of the specimen applied under standard test conditions to determine the change in specimen compliance, which is taken into account in constitutive equations at crack length increase. All necessary calculation parameters are determined according to the experimental data. The method allows us to certify fracture toughness of the material without restrictions regarding the amount of plastic deformation and in front of the crack tip and in the specimen as a whole. The examples are given to calculate the fracture toughness criteria for a number of structural materials characterized by the ability to plastic deformation and by the Young's modulus value.

Osobennosti razvitiya treshchiny v keramicheskikh obraztsakh ZrO2 s shevronnym nadrezom

“…Таким образом установлено, что нелинейная стадия диаграммы нагружения керамики ZrO2 связана с развитием трещины в зоне шевронного надреза. В работе [4]…”