Q#1. A fully stabilized, cubic polycrystalline ZrO2 sample has a fracture toughness of Kic=3.8 MPa – /m when tested on a four-point bend test. (5 points) (a) If the sample fails at a stress of 450 MPa, what isthe size of the largest surface flaw? Assume Y = Vn. (b) The same test is performed with a partially stabilized ZrO2 specimen. This material is transformation-toughened and has a Kic = 12.5MPa-Vm. If this material has the same flaw distribution as the fully stabilized sample, what stress must be applied to cause failure?

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