We study theoretically the yielding of sheared amorphous materials as a function of increasing le... more We study theoretically the yielding of sheared amorphous materials as a function of increasing levels of initial sample annealing prior to shear, in two widely used constitutive models and three widely studied annealing protocols. In each case we demonstrate a gradual progression, with increasing annealing, from smoothly "ductile" yielding, in which the sample remains homogeneous, to abruptly "brittle" yielding, in which the sample becomes strongly shear banded. We show that this arises from an increase with annealing in the size of an overshoot in the underlying stress-strain curve for homogeneous shear. This in turn causes a shear banding instability that becomes ever more severe with increasing annealing. "Ductile" and "brittle" yielding thereby emerge as two limiting cases of a continuum of yielding transitions, from smoothly gradual to abruptly catastrophic.
We study theoretically the yielding of sheared amorphous materials as a function of increasing le... more We study theoretically the yielding of sheared amorphous materials as a function of increasing levels of initial sample annealing prior to shear, in two widely used constitutive models and three widely studied annealing protocols. In each case we demonstrate a gradual progression, with increasing annealing, from smoothly "ductile" yielding, in which the sample remains homogeneous, to abruptly "brittle" yielding, in which the sample becomes strongly shear banded. We show that this arises from an increase with annealing in the size of an overshoot in the underlying stress-strain curve for homogeneous shear. This in turn causes a shear banding instability that becomes ever more severe with increasing annealing. "Ductile" and "brittle" yielding thereby emerge as two limiting cases of a continuum of yielding transitions, from smoothly gradual to abruptly catastrophic.
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Papers by Hugh Barlow