Interfacial measurements and fracture characteristics of 2D microcomposites using remote laser Raman microscopy

The micromechanics of two-dimensional carbon fibre/epoxy microcomposites incorporating seven equally spaced fibres, has been investigated. The fibre stress at each level was monitored with the technique of remote laser Raman microscopy (ReRaM). The ineffective or transfer lengths (L(t)) for reinforcement and the corresponding positively affected lengths (PALs) were measured for various interfibre distances. Finally, the interfacial shear stress distribution along the fibre was derived through a balance of forces analysis. The 'large' interfibre distance microcomposite showed no stress redistribution at the vicinity of a fibre break. In contrast, composites of 'zero' interfibre distance showed a distinct redistribution of stresses in fibres adjacent to fibre breaks. A stress concentration value of the order of 1.5 was measured at the vicinity of two adjacent fibre fractures.