Interface fracture toughness

Fig 3.8 shows the interface shear bond strength, tb, determined from Eq. (3.7), which is not a material constant but varies substantially with embedded fiber length, L. However, to evaluate all the relevant interface properties properly, which include the interface fracture toughness, Gic, the coefficient of friction, p, and the residual clamping stress, qo, it is necessary to obtain experimental results for a full range of L and plot these characteristic fiber stresses as a function of L. More details of the... 

The interface debond criterion used in this analysis is based on the concept of fracture mechanics where the strain energy release rate against the incremental debond length is equated to the interface fracture toughness, Gk, which is considered to be a material constant... 

An upper limit to the interface fracture toughness, Gic, can thus be estimated from the work of debonding divided by the cylindrical debond area... 

Once again, the last term represents the pressure times the volume of the bulge, which is relevant to interface fracture toughness measurements conducted by injecting a fixed volume (see Section 39.4.2.2). 

Table 4.2. Values of interface fracture toughness at room temperature.

The results of the analysis can also be used to interpret data from interface fracture toughness specimens. As a simple illustration, consider the case of the... 

The final locus of failure and fracture trajectory of an adhesive bond is the result of the interactions among the material properties such as the tensile strength of all the components, quality of adhesion at the interface, fracture toughness of the bonds, and the stress state at the crack tip of existing flaws or debonds [4]. To predict the locus of failure in an adhesively bonded joint loaded in an arbitrary manner such as illustrated in Fig. 1, the mechanisms controlling the... 

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