Double cantilever beam test piece

To summarise, the choice of the particular fracture test determines a, and defines a critical length, for example the width of the beam in the double cantilever beam test piece or the plastic zone size at general yield of a notched bar. The fracture transition then occurs... 

Figure 12.4). Alternatively, test pieces of standard geometry can be used, for which the compliance is known as a function of crack length. For example, the relationship between the extension A (usually termed the deflection in this case) and the load P for a double cantilever beam specimen of thickness B (see Figure 12.5) is given by...

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