Deformation Anomalies Accompanying Tsunami Origination

Basing on the analysis of data on variations of deformations in the Earth’s crust, which were obtained with a laser strainmeter, we found that deformation anomalies (deformation jumps) occurred at the time of tsunami generation. Deformation jumps recorded by the laser strainmeter were apparently caused by bottom displacements, leading to tsunami formation. According to the data for the many recorded tsunamigenic earthquakes, we calculated the damping ratios of the identified deformation anomalies for three regions of the planet. We proved the obtained experimental results by applying the sine-Gordon equation, the one-kink and two-kink solutions of which allowed us to describe the observed deformation anomalies. We also formulated the direction of a theoretical deformation jump occurrence—a kink (bore)—during an underwater landslide causing a tsunami.

Cоотношение Холла-Петча для размеров скачков деформации металлов

The paper presents an attempt to use the Hall–Petch relationship to relate the yield strength of copper and titanium in three different states (initial, annealed, and after equal-channel angular pressing) to the sizes of nano- and micrometer deformation jumps measured using a precision interferometric technique. It is shown that, upon a compression strain near the yield point, one can observe six levels of deformation with three nano- and three micrometer sizes of deformation jumps from 1–2 nm to 20–35 μm. Each of the six structural states of metals is characterized by its own set of deformation jump sizes. Dependences of the yield strengths of copper and titanium on the jump sizes L ^–1/2 are constructed, and the general regularities and features of deformation jumps for each of the metals in different structural states are discussed.

Разрушение алюминий-магниевого сплава при воздействии импульсного лазерного излучения в условиях ползучести

—Using high-speed video recording, the stages of predestruction and development of a main crack initiated by pulsed infrared laser radiation on the surface of the AlMg6 aluminum–magnesium alloy deformed by the uniaxial tensile testing under creep conditions are studied. The role of macroscopic bands of plastic strain in the development of the last deformation jump with an amplitude of about 10%, and the generation and propagation of the main crack is revealed. A possible mechanism of fracture is discussed.

Размеры скачков и уровни деформации металлов

It is proposed to characterize levels of deformation by a size of its jumps, which can be observed when the strain rate is accurately measured in experiments with load that is constant or defined according a certain law. At the micro- and nanometer scales, the strain rate was measured and the deformation jumps were computed for copper, lead, and tin using a precision interferometric method. A correlation of the size of jumps with the Burgers vector of dislocations in metals was shown, and hypotheses about ensembles of dislocations participating in the formation of a deformation jump are made.

Discountinuity of Plastic Flow Controlled by Magnetic Field in NaCl:Eu Crystals

An influence of a constant magnetic field (MF) with induction up to 15 T upon macroscopic plastic deformation of diamagnetic NaCl single crystals containing paramagnetic Eu impurity was observed. Effects of MF on instability of plastic flow (on the Portevin-Le Chatelier effect) in quenched NaCl:Eu crystals were found. The MF results in a decrease of the yield stress, a decrease of the probability of the instability appearance, and a decrease of the averaged magnitude of the deformation jumps, as well as in a chaotization of the distribution of the deformation jump magnitudes. The latter can be explained by partial plastic relaxation of internal stresses under MF that was confirmed by dislocations displacement induced by internal stresses in MF. The averaged amount of shear bands observed on the surface of the investigated crystals deformed under MF is half of that in reference specimens.

A Numerical Study of Pillar Failure Based on a Cusp-Type Catastrophe Model

Based on cusp-type catastrophe theory, a sample rock-rock (hypocenter surrounding the rock) model for studying the pillar rockburst mechanism is presented in this paper. It is expounded theoretically that the stiffness ratio, K, of the roof and floor to the pillar plays an important role in the outbreak of instability. Using a newly developed numerical code, RFPA2D, the progressive failure process and associated microseismic behavior of the twin rock samples are simulated. The numerically simulated results also confirm that a soft roof and floor promotes an unstable failure or collapse of pillars. Additionally, the simulated results reproduced the deformation jump and the energy release that occur during a pillar rockburst. It is demonstrated that the proposed model properly simulates the pillar failure process.