Acta Optica Sinica, Volume. 40, Issue 11, 1112001(2020)

Regularized Global Digital Image Correlation Method for Crack Tip Deformation Field Measurement

Jianxin Du, Jiaqing Zhao*, Haitao Wang, Libin Sun, and Xinxin Wu
Author Affiliations
  • The Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
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    Crack tip deformation field measurements are crucial for the quantitative study of material fracture characteristics and behavior. Subset-based digital image correlation (DIC) is commonly used for this purpose; however, results obtained across the crack are meaningless and are faced with under-match problems in measuring complex deformation fields around the crack. To solve these problems, we propose the Hermite-element based regularized global DIC (HRGDIC) method for deformation field measurements around the crack. HRGDIC uses the high order Hermite element function to construct each finite element in global DIC, and it establishes an iteration method that simultaneously considers the gray-scale error and the displacement field smoothness. During each iteration, the generalized cross-validation method is used to obtain the optimum regularization parameter. Therefore, the proposed HRGDIC method can not only handle the complex high-gradient deformation around the crack tips but also produce smoothed displacement and strain fields at the end of the iterations. Simulations and experimental results of crack tip deformation images show that compared with the traditional local DIC, the proposed HRGDIC has higher measurement accuracy, and it is an effective method for solving the high-gradient deformation field measurement problems around crack tips.

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    Jianxin Du, Jiaqing Zhao, Haitao Wang, Libin Sun, Xinxin Wu. Regularized Global Digital Image Correlation Method for Crack Tip Deformation Field Measurement[J]. Acta Optica Sinica, 2020, 40(11): 1112001

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    Paper Information

    Category: Instrumentation, Measurement and Metrology

    Received: Dec. 23, 2019

    Accepted: Mar. 2, 2020

    Published Online: Jun. 10, 2020

    The Author Email: Zhao Jiaqing (jqzhao@mail.tsinghua.edn.cn)

    DOI:10.3788/AOS202040.1112001

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