Strain energy release rate analysis of adhesive-bounded composite laminate joints with a cohesive crack

Abstract

Fiber-reinforced composites have been widely used in the aviation industry due to their light weight and high corrosion resistance. In many applications, bolted joints have been replaced by adhesive-bonded joints because of the weight penalty and corrosion problems associated with bolted joints. This paper presents an analytical model to determine the strain energy release rate of an adhesive-bonded single-lap composite joint with a prescribed cohesive crack within the bond line at the edge of the joint subjected to axial tension. A stress model is derived to determine the stress/strain distribution within the joint. In the stress model, the governing equations of displacements within the adherends are formulated using the first-order laminated plate theory. Based on the adhesive stress distributions, the equivalent crack tip forces are obtained and the strain energy release rate due to the crack extension is determined by using the virtual crack closure technique (VCCT). The modified specimen geometry from ASTM D3165 standard test is used in the derivation. The system of second-order differential equations is solved to provide the adherend and adhesive stresses using the symbolic computational tool, Maple 9. Experiments are conducted to obtain the joint strength. The predicted joint strengths are compared with the experimental joint strengths to show the application of the developed analytical model.