Automatic edge detection of ply cracks in glass fiber composite laminates under quasi-static and fatigue loading using multi-scale Digital Image Correlation

2020 ◽  
Vol 200 ◽  
pp. 108401 ◽  
Author(s):  
I. Miskdjian ◽  
M. Hajikazemi ◽  
W. Van Paepegem
2015 ◽  
Vol 99 ◽  
pp. 353-360 ◽  
Author(s):  
Bataxi ◽  
Xi Chen ◽  
Zhefeng Yu ◽  
Hai Wang ◽  
Cees Bil

2018 ◽  
Vol 8 (12) ◽  
pp. 2541 ◽  
Author(s):  
Liang-Chia Chen ◽  
Ching-Wen Liang

Digital image correlation (DIC) has emerged as a popular full-field surface profiling technique for analyzing both in-plane and out-of-plane dynamic structures. However, conventional DIC-based surface 3D profilometry often yields erroneous contours along surface edges. Boundary edge detection remains one of the key issues in DIC because a discontinuous surface edge cannot be detected due to optical diffraction and height ambiguity. To resolve the ambiguity of edge measurement in optical surface profilometry, this study develops a novel edge detection approach that incorporates a new algorithm using both the boundary subset and corner subset for accurate edge reconstruction. A pre-calibrated gauge block and a circle target were reconstructed to prove the feasibility of the proposed approach. Experiments on industrial objects with various surface reflective characteristics were also conducted. The results showed that the developed method achieved a 15-fold improvement in detection accuracy, with measurement error controlled within 1%.


Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 400 ◽  
Author(s):  
Ivo Campione ◽  
Tommaso Maria Brugo ◽  
Giangiacomo Minak ◽  
Jelena Janković Tomić ◽  
Nebojša Bogojević ◽  
...  

This work investigates the fracture behavior of maraging steel specimens manufactured by the selective laser sintering (SLS) technology, in which a crack-like notch (sharp notch) was directly produced during the additive manufacturing (AM) process. For the evaluation of the fracture toughness, the inclined asymmetrical semi-circular specimen subjected to three points loading (IASCB) was used, allowing to cover a wide variety of Mode I and II combinations. The effectiveness of manufacturing crack-like notches via the SLS technique in metals was evaluated by comparing the obtained experimental results with the ones obtained with pre-cracks induced by fatigue loading. The investigation was carried out by using the digital image correlation (DIC) technique, that allowed the evaluation of the full displacement fields around the crack tip. The displacement field was then used to compute the stress intensity factors (SIFs) for various combinations of Mode I and II, via a fitting technique which relies on the Williams’ model for the displacement. The SIFs obtained in this way were compared to the results obtained with the conventional critical load method. The results showed that the discrepancy between the two methods reduces by ranging from Mode I to Mode II loading condition. Finally, the experimental SIFs obtained by the two methods were described by the mixed mode local stress criterium.


2019 ◽  
Vol 18 (5-6) ◽  
pp. 1686-1697 ◽  
Author(s):  
Wen-zheng Zhao ◽  
Wei Zhou

Understanding the damage and failure of carbon/glass epoxy hybrid woven composites under tensile loading based on acoustic emission signals is a challenging task in their practical uses. In this study, an approach based on fuzzy c-means algorithm is proposed to process the acoustic emission signals from tensile loading of composites monitored by combining acoustic emission technology and digital image correlation method. The results show that the acoustic emission signals from tensile loading can be divided into three clusters. The three clusters correspond to three kinds of damage modes including matrix cracking, fiber/matrix debonding, delamination, and fiber breakage. By comparing the acoustic characteristics of these classes, a correlation procedure between the clusters and the damage mechanisms observed is proposed. Meanwhile, it can be found that debonding and fiber break signals for glass fiber correspond to a lower frequency range than that for carbon fiber. Moreover, the method combining acoustic emission and digital image correlation can effectively monitor the damage process of the specimen both on the inside and outside, which can provide a reference for the health monitoring of composite structure.


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