Our recent atomic force microscopy studies of surfaces of several advanced reinforcing fibers have revealed their self-similar fractal properties over a scale range from nanometres to micrometres. The fractal nature of fiber surfaces implies a fractal morphology for the interfaces in composites. Fiber composites with fractal interfaces and transitional layers between the fibers and matrix are addressed. Simple models for the effective elastic, viscoelastic, and thermal properties of a unidirectional composite in axial and transverse directions are developed. A general scaling relationship for effective properties is derived with the thickness of an interlayer as a scale parameter. Variation of elastic and transport properties, expansion coefficients, viscoelastic loss and creep factors with the thickness of the transitional layer are analysed for different fractal dimensions of the interface. Strong effects of the fractal dimension on mechanical properties are observed. The importance of fractal characterization and design of interface regions in composites is emphasized.
- Fibrous composites
- Fractal interface
- Thermo-visco-elastic properties
ASJC Scopus subject areas
- Ceramics and Composites