© 2016, European Conference on Composite Materials, ECCM. All rights reserved.This study presents a measurement technique of interfacial strength between fiber and matrix based on non-rigid bonding modeled as a cohesive surface. By focusing on the stress concentration near a fiber crack obtained from a single-fiber fragmentation test, the stress contour in matrix visualized by photoelasitic experiment was utilized to characterize the interfacial strength. The primary advantage of this measurement technique is that only a single fiber crack is required, whereas the conventional analysis is based on saturated fiber fragmentation, which is usually obtained in the range of plastic deformation. The stress contours near cracks of as-received and acetone-soaked fibers were observed by photoelasticity. Utilizing polychromatic light, the color values defined in hue, saturated, and value (HSV) system were automatically extracted from each pixel of observed omage by developing simple application software. The results successfully visualized contours of the principal stress difference along the interface, which was generated by a shear traction between fiber and matrix due to fiber crack. Based on the observed stress contour in matrix, maximum value of the traction i.e. interfacial strength was clearly quantified and the decrease in interfacial strength due to acetone treatment was reasonably detected.

Cohesive surface,Fragmentation,Interfacial strength,Measurement techniques,Polychromatic lights,Principal stress,Single fiber fragmentation test,Stress transfer

Fragmentation,Interfacial strength,Photoelasticity,Stress concentrations,Stress transfer