Fracture mechanics experimental considerations

The experimental results described above can be explained within the basic fracture mechanism map after detailed consideration of the processes necessary to generate a craze at the interface. The criterion lfb > ocmze is a necessary condition for the formation of stable craze fibrils. However, it is not sufficient for the formation of a craze at an interface. Craze initiation is believed to occur by a meniscus instability process that happens within a yield zone (an active zone) at a... 

Background and Overaii Considerations. Many aspects of FCP including both experimental approach and theory evolve from concepts well established in the area of fracture mechanics. Many treatments dealing with both the theory (59-63) as well as associated treatments to pol5mieric materials (2,5,64,65) have been published. The basic tenent of fracture mechanics is that the strength of most real solids is governed by the presence of flaws. Many theories have been... 

The problem of secondary flexure in axial tensile tests is considered in view of the tension-softening process. The procedures aimed at elimination of that parasite effect were studied by Akita et al. (2001) and Novak et al. (2006) who have shown possibilities of nonlinear fracture mechanics simulation in analysis of the experimental data, including post-peak descending branch of the load-displacement curves, taking into consideration material imperfections and heterogeneities. 

Background and Overall Considerations. Many aspects of FCP including both experimental approach and theory evolve from concepts well established in the area of fracture mechanics. Many treatments dealing with both the... 

Application of fracture mechanics to characterize toughness at high loading rates deserves special attention because of dynamic effects inherent in the test. With polymers at speeds around 1 m/s these effects can be contained or circumvented, and Kic and Gic can be determined with sufficient accuracy. The protocol developed within ESIS TC4 has been validated by a large amount of experimental data and thus has now been submitted to ISO for consideration as an international standard [77]. 

The discussion to this point has dealt only with the mechanical properties of SFRC. However, the durability of SFRC is at least as important, and there have been a number of studies in this area. Atfirst glance, itwould appear that steel fibres would be susceptible to severe corrosion, particularly near the surface of the concrete, where the cover is quite small. Since the diameter of the fibre is effectively reduced by corrosion, any substantial corrosion of the relatively thin fibre would lead to a considerable decrease in both the strength and the toughness of the SFRC, as has been confirmed experimentally by Kosa and Naaman [127]. They also found that the mode of failure could change from fibre pull-out to fibre fracture, which... 

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