Experimental Proof that Stress does not Cause Cracking of Adhesive Joints

EXPERIMENTAL PROOF THAT STRESS DOES NOT CAUSE CRACKING OF ADHESIVE JOINTS 

It is clear from the peel equation F=Wb that stress in the elastic material can be altered while the crack criterion does not change. For example, as a film is 

CONSISTENCY OF THE BROWNIAN MECHANISM WITH FRACTURE MECHANICS 

The Brownian mechanism is an atomistic model, describing molecular bonds which are in rapid thermal motion, with local fluctuations and statistics of adhering molecules which interact with intermolecular potentials, hi contrast, the fracture mechanics is a global continuum model which satisfies the conservation of energy principle and the particular equation of state of the material at large scales. 

There is no way that we can model every atom or molecule in a block of material. It is far better to understand the overall macroscopic behavior of a material in terms of the continuum mechanics of elasticity theory, for example. However, it is equally evident that such continuum theories must fail as we approach molecular dimensions where adhesive failure is occurring. It is far too simplistic to suggest that a single variable in the equation of state (e.g. stress or pressure) should dictate adhesion. This might have worked for the Magdeburg hemispheres but does not work for molecular forces. Instead, consider the situation deincted in Fig. 7.14. This shows that, at large scales we should treat 

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