IRT and DIC Synchronous Detection of Stress Intensity Factors and Plastic Zone Ranges

Abstract

To achieve non-contact in situ detection of stress intensity factors (SIF), this paper innovatively adopts the advanced IRT and DIC synchronous detecting system to measure SIFs as using plastic zone range to assist in determining the state of stress fields. Though this synchronous detecting method has been applied to analyze thermomechanical coupling effects of materials, it has never been used to detect SIFs, which requires a high accuracy of point stress state detection. Thus, to testify its feasibility and accuracy in SIF detection, three engineering materials were subjected to various loading conditions to provide sufficient verification. Firstly, the coefficients of volumetric strain and temperature change of different materials were calibrated by thermocouple and infrared thermography. Then, the compact tensile specimens were subjected to high-speed loading, of which the SIFs and plastic zone ranges were computed by taking several measurement points on infrared and deformation images. Compared with the theoretical values, the errors of the SIF and K-dominated range measured by this experimental method are all within 5%. It demonstrates that the synchronous detecting method has a wide application prospect in high-accurate crack tip strain field and crack development analysis.