Mechanism for shear delamination under dynamic loading

Abstract

WE describe here a debonding mechanism for interfaces between dissimilar materials in conditions of dynamic loading, and we deal, in particular, with coated substrates that are impacted by solid or liquid projectiles. Protective coatings are commonly used to enhance the resistance of materials to impact erosion; for example, non-metallic fibre-reinforced composite materials are found to be very susceptible to impact erosion unless a suitable thin coating is applied. For these composites, certain elastomers can be successful as coating materials, even though they do not, intrinsically, possess high strength. Coatings of this type reduce the pressures that are transmitted to the substrate by presenting a lower dynamic impedance to the impacting body. The interfacial adhesion between the coating and substrate is of great importance because it enables the substrate to reinforce the coating by restricting the lateral strain, and therefore the stress, within the coating. When adhesion is lost, the coating itself becomes quickly eroded. Thus, the bond between the coating and substrate is often of great significance to the success of a coating–substrate system.