We consider crack propagation in brittle non-linear elastic materials in the context of quasi-static evolutions of energetic type. Given a sequence of self-similar domains nΩ on which the imposed boundary conditions scale according to Bažant’s law, we show, in agreement with several experimental data, that the corresponding sequence of evolutions converges (for n → ∞) to the evolution of a crac...

Shape memory materials are a class of smart materials able to convert heat into mechanical strain (or strain into heat) by virtue of a martensitic phase transformation. Some brittle materials such as intermetallics and ceramics exhibit a martensitic transformation but fail by cracking at low strains and after only a few applied strain cycles. Here we show that such failure can be suppressed in ...

In this paper we investigate, both experimentally and theoretically, the competition between different failure mechanisms (stretching, bending and curvature l ocalization) in freestanding submicron thin films commonly used in micro-electromechanical systems. Micro structures made of elastic -brittle materials such as ultrananocrystalline diamond, diamond like carbon and silicon nitride, as well...

Highly mineralized natural materials such as teeth or mollusk shells boast unusual combinations of stiffness, strength and toughness currently unmatched by engineering materials. While high mineral contents provide stiffness and hardness, these materials also contain weaker interfaces with intricate architectures, which can channel propagating cracks into toughening configurations. Here we repo...

The fracture toughness and strength of ceramics can be improved with respect to monolithic ceramics by developing graded materials as laminates composed of periodic alternating layers of one material separated by layers of a second material. The second layer must contain residual compressive stresses which are induced during densification because of differential thermal contraction of the layer...

Traditional strengthening ways, such as strain, precipitation, and solid-solution, come into effect by pinning the motion of dislocation. Here, through first-principles calculations we report on an extra-electron induced covalent strengthening mechanism, which alters chemical bonding upon the introduction of extra-valence electrons in the matrix of parent materials. It is responsible for the br...

Recent ideas on the mechanisms controlling the initial stages of plastic flow at cracks in intrinsically brittle materials, at the ductile-brittle transition, are reviewed. New experiments on precracked specimens of Si are reported, which confirm earlier work that the ductile-brittle transition is controlled by dislocation velocity. A model has been developed in which at the ductile-brittle tra...