Ceramics are hard and strong, yet they break suddenly with almost no deformation. In ①, compare how metal and ceramic specimens stretch and fail in a tensile test; in ②, see how stress concentrates at holes and crack tips, along with the Griffith energy balance. In ③, use a schematic of the atoms to confirm that in metals, where dislocations can move, the crack tip blunts, whereas in ceramics, where they cannot, bonds break and the material cracks, and find the tolerable crack size for each material. In ④, break specimens one at a time to see that the scatter in strength follows a Weibull distribution; in ⑤, see how strength depends on volume and test method. In ⑥, press a diamond indenter in with the testing machine, measure the diagonals of the remaining impression yourself and calculate the Vickers hardness, and check your answer against the automatic measurement. In ⑦, see the temperature and stress distributions that arise inside a sample under thermal shock.
Mochizuki Research Group, Tokyo University of Science | The figures and numbers are computed on the fly in your browser (the material constants are rough values for teaching, and the pictures of atoms and cracks are schematic). In ⑥, “(tentative)” or “(tent.)” in the material categories marks entries whose sources for the manufacturing method have not been verified. For detailed explanations and sources, see the explanation page (in Japanese): The Theory of Fracture — Deriving the Theoretical Strength, Griffith’s Equation, Fracture Toughness, and Weibull Statistics.