Initially circular delamination

Controlled circular delaminations of different diameters were introduced at the interface between the mica and the resin by using a screw that was threaded through the substrate, from the back face of the substrate to 

An example of the progressive growth, as a function of time, of wavy 

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Suppose that the film completely covers the substrate surface initially. Then, the film is cut through its thickness down to the substrate surface over a circle of radius b hf as indicated in Figure 4.25. The film material inside the circle is removed and, outside the circle of radius 6, a circular delamination front begins to grow outward. When the front is very near the film edge of radius b, the local conditions are very much like those discussed the preceding section, and the front advances spontaneously. 

The two-dimensional propagation of delaminations in isotropic plates and cross-ply laminates (0 /90°)2s was analyzed by using an interface element. The dimensions of the laminates and the material properties of each layer are the same as in the models of the previous section. Owing to the symmetry, a quarter of the plate was analyzed. Circular initial delaminations of radius 2.5 mm were situated at its center. Figure 14 shows the relationships between the applied load and the center deflection where a finite element mesh is shown. The propagation of delaminations occurred first at the center interlaminar plane where the energy... 

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