Tunneling cracks in the adhesive layer of an orthotropic sandwich structure

A tunneling crack confined in the orthotropic adhesive layer bonded to orthotropic substrates under steady state conditions was examined. The problem was formulated using the modified Stroh formalism and orthotropy rescaling technique. The energy release rate for the crack in the sandwich structure was obtained from a solution of the transformed sandwich structure composed of an orthotropic adhesive layer and isotropic substrates. The dimensionless energy release rate for the transformed sandwich problem depends only on four material parameters. Finite element analysis was performed to determine the changes in energy release rate on the four material parameters. The effects of the material parameters on the energy release rate are discussed for various combinations. Periodic tunneling cracks were also considered to examine the effect of the crack spacing on the energy release rate.