Crack growth mechanism on SGA adhesive joints

The fracture toughness and fracture process of second generation acrylic (SGA) adhesive joints were investigated in detail using tapered double cantilever beam (TDCB) tests. The distribution of granular elastomer with a size of ca. 150 nm in the bulk specimen by transmission electron microscopy (TEM) observation was similar to the distribution of cavitation determined by scanning electron microscopy (SEM) observation of the fracture surface. A mechanism was proposed for the role of the elastomer and acrylic phase in the cohesive failure process of SGA. A dimple, which is evidence of ductile fracture, was observed on the fracture surface. The relationships between the size of dimples, their number and energy release rate were clarified. An understanding of the proposed failure mechanisms is useful for constructing a numerical model for stress analysis and explaining the fracture phenomenon.