Assessment of local strain field in adhesive layer of an unsymmetrically repaired CFRP panel using digital image correlation

Kashfuddoja, M and M, Ramji (2015) Assessment of local strain field in adhesive layer of an unsymmetrically repaired CFRP panel using digital image correlation. International Journal of Adhesion and Adhesives, 57. pp. 57-69. ISSN 0143-7496

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The present study focuses on experimental investigation of through the thickness displacement and strain field in thin adhesive layer in single sided (unsymmetrical) patch repaired CFRP (carbon fiber reinforced polymer) panel under tensile load. Digital image correlation (DIC) technique is employed to acquire the displacement and strain (longitudinal, peel and shear) field. Experimental determination of shear transfer length based on shear strain field obtained from DIC is introduced to estimate the optimum overlap length which is an essential parameter in patch design for the repair of CFRP structures. Further, DIC experiment with magnified optics is performed to get an insight into complex and localized strain field over thin adhesive layer especially at critical zones leading to damage initiation. The failure mechanism, load displacement behavior, damage initiation and propagation are closely monitored using DIC. The influence of patch edge tapering on strain distribution in adhesive layer is also investigated. The DIC successfully captures the global and localized strain field at critical zones over thin adhesive layer and further helps in monitoring the damage based on strain anomalies. Strains are found to have maximum magnitude at the patch overlap edge and the shear strain level in adhesive layer is higher than the peel strain. Normal tapering increases the peel strain and has negligible influence on shear strain level in adhesive layer. The recommended overlap length is found to be consistent with the recommendation in the literature. Whole field strain pattern and the overlap length obtained from experiment are further compared with the finite element analysis results and they appear to be in good coherence.

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IITH Creators:
IITH CreatorsORCiD
Item Type: Article
Uncontrolled Keywords: Adhesive strain; Carbon/Epoxy composite; Digital image correlation; Debonding; Load transfer/shear transfer length; Longitudinal; Peel and shear strain; Repair
Subjects: Others > Space research
Materials Engineering > Materials engineering
Divisions: Department of Physics
Depositing User: Team Library
Date Deposited: 27 May 2015 08:35
Last Modified: 24 Sep 2015 06:12
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