An ESPI experimental study on the phenomenon of fracture in glass. Is it brittle or plastic?

Ferretti, Daniele; Rossi, Marco; Royer-Carfagni, Gianni

doi:10.1016/j.jmps.2011.04.008

Cited by 18 publications

(6 citation statements)

References 32 publications

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“…The boost mechanism demonstrated here on PMMA is expected to hold in this whole class of materials. Note that a similar effect has also been invoked (Prades et al, 2005) in oxide glasses under stress corrosion, where ultra-slow crack propagation (down to few tenths of nanometers per second) was found to involves "nano"cracks forming ahead of the main crack tip (Célarié et al, 2003;Celarié et al, 2003;Bonamy et al, 2006;Ferretti et al, 2011). This yields us to conjecture that failures with anomalously high apparent velocities measured at continuum-level scale may arise in all situations involving propagation-triggered microcracks, including e.g.…”

Section: Discussionmentioning

confidence: 59%

Damage mechanisms in the dynamic fracture of nominally brittle polymers

et al. 2013

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Linear Elastic Fracture Mechanics (LEFM) provides a consistent framework to evaluate quantitatively the energy flux released to the tip of a growing crack. Still, the way in which the crack selects its velocity in response to this energy flux remains far from completely understood. To uncover the underlying mechanisms, we experimentally studied damage and dissipation processes that develop during the dynamic failure of polymethylmethacrylate (PMMA), classically considered as the archetype of brittle amorphous materials. We evidenced a well-defined critical velocity along which failure switches from nominally-brittle to quasibrittle, where crack propagation goes hand in hand with the nucleation and growth of microcracks. Via postmortem analysis of the fracture surfaces, we were able to reconstruct the complete spatiotemporal microcracking dynamics with micrometer/nanosecond resolution. We demonstrated that the true local propagation speed of individual crack fronts is limited to a fairly low value, which can be much smaller than the apparent speed at the continuum-level scale. By coalescing with the main front, microcracks boost the macroscale velocity through an acceleration factor of geometrical origin. We discuss the key role of damage-related internal variables in the selection of macroscale fracture dynamics.

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Section: Discussionmentioning

confidence: 59%

Damage mechanisms in the dynamic fracture of nominally brittle polymers

et al. 2013

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“…However, the deduction of displacement field from the fringe pattern is not straightforward, since it requires to count the full fringes (representing the locus of points characterized by the same displacements) of each image and multiply them for a coefficient depending on the ESPI setup. Automatic methods for this procedure, called unwrapping, could be otherwise performed [19]. Anyway, in this work ESPI images have been qualitatively read so as to determine cracking onset and crack depth h w , while crack width w has been deduced just on the basis of clip-gauge measurements.…”

Section: Experimental Evaluation Of Aac Fracture Energymentioning

confidence: 99%

Cracking in autoclaved aerated concrete: Experimental investigation and XFEM modeling

Ferretti

Michelini

Rosati

2015

Cement and Concrete Research

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“…Whereas the cause for exhibiting such high stress intensity factor has been discussed in previous study [24], it is still unclear. The measured stress intensity factor may exhibit higher value than the actual stress intensity factor at the crack tip because of the existence of the enclave and the process zone [29], or the plastic zone [30] which show the nonlinear material behavior and cause the relaxation effect of the stress. However, only the macroscopic stress field and the stress intensity factor are dis- cussed in this paper from the viewpoint of the results of the experimental stress analysis.…”

Section: Measurement and Analysismentioning

confidence: 99%