Simple-extension test specimen

Figure 7.7 Adhesive joint geometries used for evaluating Gc for flexible joints, (a) Peel test specimen before and after peeling by an eunount, a. (b) Simple-extension test specimen, (c) Pure shear test specimen, (d) Blister test specimen.

Figure 7.9 Applied strain energy density, L dc, at onset of crack growth versus reciprocal of the crack length, from simple-extension test specimens [103]. (a) Cross-linked SBR/fluorocarbon copolymer tested at 100 °C. (b) Crosslinked SBR/poly(ethylene terephthalate) tested at 50 °C. 

W.F. Deans, and C.E. Richards, A Simple and Sensitive Method of Monitoring Crack Extension and Load in Compact Fracture Mechanics Specimens Using Strain Gages, J. Testing and Eval., Vol. 7, No. 3, 147 154 (1979). 

A generic term for measures of resistance to extension of a crack. The term is sometimes restricted to results of fracture mechanics tests, which are directly applicable in fracture control. However, the term commonly includes results from simple tests of notched or precracked specimens not based on fracture mechanics analysis. Results from test of the latter type are often useful for fracture control, based on either service experience or empirical correlations with fracture mechanics tests. 

In their extensive review work, Baranya et al. [8] attested to the growing usage of the EWF concepts for polymers, related blends and composites because of the ease of specimen preparation, easy testing and the simple data reduction procedure. EWF is typically used for mode-I type loading, however, it has been reported to have been successfully adopted for mode-II and mode-IH type deformations. 

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