Crack Propagation Measurement Based on Digital Image Correlation Technology

The commonly used methods for measuring fracture toughness of pipeline steels include Charpy impact test (CVN), drop weight tear test (DWTT), crack tip opening displacement (CTOD) test, crack tip opening angle (CTOA) test and double-sample method. The test results of the double-sample method for low-toughness materials are more accurate than those for high-toughness materials. For the fracture toughness of high-toughness pipeline steel materials, the CVN and DWTT methods are affected by energy dissipation that is not related to ductile fracture propagation. CTOA is considered by many scholars that the measurement results are highly accurate and easy to use, and it is a convenient crack arrest criterion. Based on the systematic analysis of various testing methods of metal crack propagation, the steady crack propagation resistance measurement technique based on digital image correlation method was studied. A high precision fast measuring hardware and software processing system was developed. The practical application proved the practicability and reliability of the system.