Deformation of a thin film after contact loss with a cylindrical base axial delamination

The paper deals with the problem of a coating section delaminated from a cylindrical base due to compressive stresses. It has been studied using the theory of cylindrical shells with boundary conditions of the type of generalized elastic clumping. We obtained distributions of the components of the coating displacements and the energy release rate for the delamination growth along the rectilinear and curvilinear boundaries. We compared the values of the energy release rate and components of the displacement calculated with and without the influence of transverse forces. The dependences of the energy release rate, mode I of the stress intensity factor, the angle of rotation at the clamping point, and the coating displacement components on the relative compliance of the substrate and its curvature have been studied. It is shown that with an increase in the compliance of the substrate, the magnitude of the delamination buckling and the energy release rate increase significantly. The positive curvature also leads to an increase in the energy release rate. Several reasons have been identified, according to which the delamination stops developing along its rectilinear boundary and the tunneling effect occurs. It is shown that for sufficiently compliant substrates there is a certain critical width of a delamination, at which the development in the axial direction becomes energetically more favorable. Besides, it follows from the presented data, that positive curvature and an increase in the compliance of the substrate lead to a decrease in this critical width. According to the analysis of the results for the angle of rotation at the clamping point and the separation mode of the stress intensity factor, the observed effect of tunneling can be caused not only by the difference in the energy release rates during the propagation of delamination due to expansion and elongation (tunneling), but also by the prohibition of overlapping of the coating and substrate faces.