Critical analysis of adhesive layer behavior in patch-repaired carbon fiber-reinforced polymer panel involving digital image correlation

Abstract

In the present work, critical strain field in thin adhesively layer of double-sided (symmetrical) patch-repaired carbon fiber-reinforced polymer composite panel under tensile load is investigated using digital image correlation technique. Longitudinal, peel, and shear-strain distribution in adhesive layer is analyzed thoroughly in repaired panel by performing global cum local strain field analysis involving digital image correlation. Effective load/shear transfer length in repair configuration is estimated based on global strain analysis, and further, it is compared with the one predicted from finite-element analysis. Localized strain analysis using magnified optics provides higher resolution, and it is found useful in revealing complex strain field in small but critical zones responsible for failure initiation. The global and local-strain analyses are found complementary to one another, and therefore both are essential to fully characterize the strain field in thin-adhesive layer. The critical failure mechanism is also investigated and correlated with the load–displacement behavior. DIC is found to be suitable and accurate for analyzing the global and local strain field over small but critical locations and helps in predicting the damage-initiation location based on strain anomalies. Finally, the experimental results are compared with the numerical predictions, and they are found to be in good correlation.

Performance assessment and optimization of hybrid composite patch repair of aircraft structure

“…Digital image correlation (DIC) technique is widely used in laminated as well as metallic structures for damage evaluation and detects surface strain in the composite patch repair (Caminero et al , 2012, 2013; Kashfuddoja and Ramji, 2015; Pavlopoulou et al , 2016). Experimental analysis requires the involvement of sophisticated instruments such as digital image correlation and digital photoelasticity techniques for measurement of the stress intensity around the crack tip and interfacial stresses in the adhesive layer.…”

Digital Image Correlation Measuring of Strain and Stress Distributionon Mixed Adhesive Joints Bonded by Honeymoon Adhesion Using TwoTypes of Second-Generation Acrylic Adhesives of Two Components

“…M. Kashfuddoja and M. Ramji studied the critical strain field in the thin adhesive layer using DIC. Their results were compared with finite element analysis results 20) . They concluded that DIC can accurately analyze the strain field of adhesive joint specimens.…”