This paper evaluates the effect of two experimental parameters, namely microvise blade geometry and blade separation, on the scatter in measured interfacial strength in microbond experiments, with the help of two-dimensional (2D) and three-dimensional (3D) finite element models. The 3D model better captures the ‘exact’ loading nature of the problem as compared to the 2D model but it is computationally intensive. Stress distributions obtained by finite element analysis are compared with those from the shear-lag model often used to analyze microbond experiments. This comparison determines the effectiveness of using shear-lag analysis in microbond experiments and for explaining the reasons for commonly observed data scatter.

Carbon fiber composites have witnessed an increased application in aerospace and other civil structures due to their excellent structural properties such as specific strength and stiffness. However, unlike other structural materials, carbon fiber composites have not been as widely studied. Hence, their increased application is also accompanied with a serious concern about their long‐term durability. Many of these applications are exposed to multiple environments such as moisture, temperature, and UV radiation. Composites based on conventional epoxies readily absorb moisture. However, recently synthesized fluorinated epoxies show reduced moisture absorption and hence potentially better long‐term durability. The aim of this project is to study the effect of moisture absorption on fluorinated‐epoxy‐based carbon fiber composites and their comparison with conventional epoxy carbon fiber‐based composites. Microbond tests are performed on fluorinated and nonfluorinated epoxy‐based single fiber samples before and after boiling water degradation. It is found that fluorinated epoxy‐based single fiber coupons showed relatively reduced degradation of interface when compared with the nonfluorinated epoxy single fiber coupons. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers