Fractured surfaces of epoxy adhesives and fractals under mode I loading (1st report, static crack growth properties and fractal dimensions)

Fractured surfaces of epoxy adhesives under mode I loading have fractal characteristics. The fractal dimensions of fractured surfaces can quantitatively characterize the fractured surface topology. The effects of rubber modification, adhesive thickness and cross-head speed on the static fractured surfaces of epoxy adhesives were examined using the fractal dimensions. The fractal dimensions become high due to rubber modification. The fractal dimensions are related to the static crack growth properties for both rubber-modified and unmodified adhesives. The following equation gives the relationship between the crack extension resistance, G, and the fractal dimension, D:log G = a · D + b, where a and b are experimental constants. Regardless of whether the adhesives contained rubber particles, fractal dimensions were not affected by adhesive thickness and cross-head speed.