The Measurement of the Fatigue Crack-Tip Displacement and Strain Fields under High Frequency Resonant Loading Applying DIC Method

Abstract:

In order to measure the displacement and strain field in the fatigue crack tip area of CT specimens under high frequency resonant loading condition in the fatigue crack propagation test, a method based on the digital image correlation (DIC) and digital high-speed photography technology are proposed in this paper. First, a series of digital speckle images of CT specimen under sinusoidal alternating load were collected by digital high-speed photography equipment, the displacement and strain fields within the region of crack tip in each image were calculated by DIC. The sinusoidal changing strain curve has been obtained by the least square sine wave fitting method, and the characteristic parameters of sinusoidal strain are calculated, such as the amplitude, frequency, phase, mean load . The images of characteristic position in one stress cycle were obtained by comparing the fitted sine curve of strain with the corresponding speckle images. Finally, the dynamic strain gauge was used to measure the strain at crack tip point during one stress cycle, and the accuracy and feasibility of DIC method were verified by the experimental results. The study result presented in this paper will supply a foundation for exploring the crack propagation law and measuring the fatigue crack growth parameters under high frequency resonant loading condition further.

• Periodical: Applied Mechanics and Materials (Volume 710)
• Pages: 83-90
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.710.83
• Online since: January 2015
• Authors: Hong Li Gao, Wei Jiang, Huan Liu*, Huan Bin Zheng, Hui Liu
• Keywords: Digital Image Correlation, Displacement Field, Fatigue Crack Tip, High Frequency Resonant Load Index, High-Speed Photography, Strain Fields

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