Date of Graduation
We use dynamical Monte Carlo simulations to investigate instabilities of solids in the presence of externally applied stresses or strains. One of the instabilities is the classical Euler buckling instability of compressed rods. We address, for the first time, the dynamical aspects of this instability, that is, we study how an initially straight flexible chain reaches the final buckled configuration at long times. We find that this process has much in common with coarsening phenomena such as the spinodal decomposition or unstable mound growth in molecular beam epitaxy. Evolving chain's profile is like a wave with a wavelength which grows, via coarsening, as a power of time. The evolving chain is a rough object with transversal roughness growing as a power of time. The second class of instabilities studied in this dissertation is the fracture nucleation in stressed solids. By dynamical Monte Carlo simulations, we show that this process has primarily the character of microcavity nucleation rather than micro-crack nucleation. We find that microcavities much smaller than the Griffith length can still grow and fracture the solid. We investigate fracture nucleation also in more complex situations involving grain boundaries and environmental effects, such as oxide formation, via Monte Carlo simulations incorporating also chemical dynamics of oxidation. At small oxidation rates, our simulations reveal an interesting embrittlement mechanism related to inhomogeneous internal stresses produced by a nonuniform oxide production.
Peredera, Anatoli M., "Monte Carlo studies of instabilities in solids under external strains and stresses." (1997). Graduate Theses, Dissertations, and Problem Reports. 9572.