The strength and durability of adhesively bonded sandwich structures often depend on the mechanisms of fracture, which in turn depend on the properties of the adhesive and the microstructures of the interface. When the thin adhesive layer is ductile, cavitation either within the layer or along the interface is often the dominant failure mechanism. In the present paper, fracture due to cavity growth in a thin ductile layer is analyzed. A new method utilizing fluid mechanics solutions is developed. Solutions of fluid flow field are used to approximate the plastic deformation field in the corresponding solid body with a cavity. The equilibrium condition is satisfied by using the principle of virtual work rate. Stress-separation curves due to cavitation in the thin layer can thus be obtained. The method is validated by reevaluating the one-dimensional problem of cavity growth in a sphere—a problem for which an exact, analytical solution exists. A two-dimensional plane strain cavitation problem is analyzed using the new method. The stress-separation curves and the fracture resistance due to this mechanism are obtained. The results show that both the stress-separation curves and the fracture resistance are sensitive to the strain-hardening exponent and the initial void size, but not the yield strength of the material. The new method has clear advantages over numerical methods, such as the finite element method, when parametric studies are performed.
Modeling the Fracture of a Sandwich Structure due to Cavitation in a Ductile Adhesive Layer
