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A new methodology to introduce sharp through-thickness defects in brittle materials is described in this
work. A sandwich, composed by the notched specimen and two bars of different material is loaded in
three-point-bending. The stress intensity factor, varies with crack length in such a way that stable growth
of the defect is possible. The defects obtained with this technique are ideal to measure the fracture
toughness: they are geometrically defined and easily measurable; in addition they are not associated to
residual stress field. Cracks of different length can also be produced, allowing the evaluation of possible
R-curve effect.