科研之友
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摘要
J-integral is an important fracture parameter which quantitatively describes the stress and strain fields near a crack tip. Accurate and efficient measurement of J-integral is of great significance for the evaluation of crack stability and propagation in mechanical equipment. This paper proposes a new method for J-integral measurement by using digital image correlation technique. The displacement and strain fields on the surface of a pre-cracked compact tension specimen were firstly measured and calculated by digital image correlation technique under different loads. A MATLAB program was then developed to calculate the J-integral by selecting a rectangular integral path around the crack tip. The calculated results were compared with those obtained from the US Electric Power Research Institute (EPRI) estimation method and finite element method. The proposed method can produce similar results compared with other methods. It also has advantages of non-contact, high-precision, simple optical path, and less sensitive to the environment. The proposed method for J-integral measurement has potential to be applied to the crack evaluation for large in service mechanical equipment.
