Phase angle of local stress state at interface

3 Phase angle of local stress state at interface 

For any particular material system, the delamination resistance of the interface is characterized by a fracture energy F(V ) per unit area which depends on the phase V of the stress state acting on the interface immediately in 

As noted in the preceding chapter, available data for such processes suggest a phenomenological expression for fracture energy of the form 

Section 4.1, both an and am can be expected to be negative. On physical grounds, it can also be anticipated that aim 0 and aum 0. 

In terms of the stress intensity factors K and Kn, the energy release rate is given by 

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