R. Ballarini

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Natural composite materials are renowned for their mechanical strength and toughness: despite being highly mineralized, with the organic component constituting not more than a few per cent of the composite material, the fracture toughness exceeds that of single crystals of the pure mineral by two to three orders of magnitude. The judicious placement of the(More)
In the absence of a corrosive environment, brittle materials such as silicon should be immune to cyclic fatigue. However, fatigue effects are well known in micrometer-sized polycrystalline silicon (polysilicon) samples tested in air. To investigate the origins of this phenomenon in polysilicon, we developed a fixed-grip fracture mechanics microspecimen but(More)
The paper reports on the discussions at the ONR Workshop on Fracture Scaling. held at University of Maryland in June I Y9Y, under the chairmanship of Z.P. Bazant and Y.O.S. Rajapakse. The workshop dealt with size effects in structural failure and s~ale bridging in mechanics of materials. The lectures at the Workshop were published in Volume 95 of this(More)
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Geo-materials such as vuggy carbonates are known to exhibit multiple spatial scales. A common manifestation of spatial scales is the presence of (at least) two different scales of pores, which is commonly referred to as double porosity. To complicate things, the pore-network at each scale exhibits different permeability, and these networks are connected(More)
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