Anti-plane analysis of orthotropic strips with defects and imperfect FGM coating

Stress analysis is carried out in a medium composed of an orthotropic substrate weakened by defects and reinforced by an orthotropic functionally graded coating utilizing the distributed dislocation technique. The medium is under anti-plane shear deformation. Imperfect bonding of substrate and coating is allowed and imperfection is quantified by means of the well-known linear spring model. The solution to a screw dislocation located in the orthotropic layer of the medium is obtained. Furthermore, stress fields are derived in the medium under self-equilibrating anti-plane point forces. These solutions are Cauchy singular at the location of dislocations and the point of application of forces. The dislocation solution is utilized to perform integral equations in the medium weakened by multiple defects. The integral equations are solved numerically to determine stress intensity factor for cracks and hoop stress on cavities. The effects of interfacial imperfection between the layers and mechanical properties of coating on stress fields in the vicinity of defects are studied.