Abstract
The effects of rubber modification and adhesive thickness on the fatigue-fractured surfaces of epoxy adhesives under mode I cyclic loading were examined using fractals. When the energy release rate range, ΔGI, is higher than 100 J/m2, the fractal dimension of fractured surfaces becomes high due to rubber modification. The fractal dimension decreases with increasing fatigue crack growth rate, da/dN. The following equation shows the relationship between parameter S(=da/dN·ΔGI)and fractal dimension D for unmodified and rubber-modified adhesives. log S=log(da/dN·ΔGI)=α4·D+β4 Here, α4 and β4 are experimental constants. Regardless of whether the adhesives contain rubber particles or not, the fractal dimension as well as the da/dN-ΔGI relation is little affected by adhesive thickness.
