The 2 GPa tensile strength of corundum has not been confirmed by anyone else, either. So I will assume that the tensile strength of sapphire monocrystal is 400 MPa. I have further questions: 1) if sapphire is subjected to essentially constant tension of e.g. 350 MPa, does it experience fatigue? 2) Can you make a sapphire plate, whose width is given by a given Gaussian function (maximum e.g. 40 mm in the center) , thickness about 1 mm, and length about 200 mm?

1) What causes fatigue? Movement of grain boundaries. Sapphire is a single crystal material with no grain boundaries. It has two states under tension, not moving, or moving catastrophically (break point). The only thing close to fatique is if it has strain due to grinding or thermal processing.

2) Unfortunately, we have not the machines which could cut the sapphire using Gaussian function.

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