Combined Macroscopic And Microscopic Investigation On The Fracture Process Of Materials

Combined macroscopic and microscopic investigation on the fracture process of materials becomes a recent research trend. In the present thesis, the crack tip atom motion is analyzed to explore the origin of fracture, and the crack path is studied to evaluate the influence of microstructures on the local mechanical atmosphere.Many new materials have nanoscale structures. Combined atom /continuum calculations are performed to study the metal/ceramics interfaces. The toughening mechanisms of nanocomposite ceramics are analyzed. The results are in good agreement with the experiment.Fracto-emissions and chaos accompanying fracture processes are observed in experiments. Nonlinear motions of crack tip atoms are studied. Many phenomena related to fracto-emissions are explored. The chaotic motions of the crack tip atoms during fracture are characterized which explains the heat generation in fracture.The innovations of this thesis are: the description of the parameters characterizing nonlinear behavior of the crack tip atoms, the realization of the combined atom/continuum simulations, and the proposal of four toughening mechanisms of nanocomposite ceramics.Tan Honglai (Solid Mechanics) Directed by Professor Yang Wei...