Methods for interface toughness measurement

Once the performance of the interface bond was established by the previous delamination (durability) tests, contoured double cantilever beam (CDCB) specimens were designed to conduct mode-I fracture tests. In this study, bilayer CDCB specimens (see Fig. 6) were designed by the Rayleigh-Ritz method [8] and used for fracture toughness tests on bonded FRP wood interfaces under both dry and wet conditions. The critical strain energy release rate, G/c, which is a measure of the fracture toughness, is given as ... 

In order to obtain a clear, concise, and accurate picture of the surface tmder investigation, there will almost certainly be the need to resort to more than one of the methods described in this chapter. The choice will be influenced by the nature of the material, the type of investigation, and other variables. In adhesive bonding research one thread that runs through virtually all work, be it quality assurance, development, or research, is to relate surface characteristics to a performance measure of the bonded structure. This may he joint strength or toughness but more usually, and particularly for structural adhesive honding, attempts will be made to correlate the surface and interface characteristics with joint durahihty. 

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