While it is clear that myocardium responds to mechanical stimuli, it is unknown whether myocytes transduce stress or strain. It is also unknown whether myofibers maintain lateral connectivity or move freely over one another when myocardium is deformed. Due to the lack of information about the relationship between macroscopic and cellular deformations, we sought to develop an experimental method to examine myocyte deformations and to determine their degree of affinity. A set of protocols was established for specimen preparation, image acquisition, and analysis, and two experiments were performed according to these methods. Results indicate that myocyte deformations are non-affine; therefore, some cellular rearrangement must occur when myocardium is stretched.

Natural and hot isostatically pressed dolomite aggregates were experimentally deformed at effective pressures of Pe = 50 ?? 400 MPa, temperatures of 400 ?? 850??C, and strain rates of &#949;& = 1.2x10-4 s-1 to 1.2x10-7 s-1. Coarse- and fine-grained dolomite deformed at low temperature (T &#8804; 700??C for coarse-grained natural dolomite, T < 700??C for fine-grained natural and synthetic dolomite) exhibit mechanical behavior that is nearly plastic; differential stresses are insensitive to strain rate, fitted either by a power law no&#9119;&#9119;&#9120;&#9118;&#9116;&#9116;&#9117;&#9115;&#8722;=??&#963;&#963;&#949;&#949;31&& with n values that range from 12 to 49 or an exponential law ([31exp )] &#963;&#963;&#945;&#949;&#949;&#8722;=o&& with exponential law term &#945; values from 0.023 to 0.079 MPa-1. Microstructures of samples deformed at low temperatures include mechanical twins, and undulatory extinction suggesting that twin glide and dislocation slip are the predominant deformation mechanisms. At high temperatures (T &#8805; 800??C) flow strengths of coarse- and fine-grained dolomite depend more strongly on strain-rate and exhibit pronounced temperature dependencies. Microstructures of coarse-grained dolomite samples deformed at T &#8805; 800??C include undulatory extinction and fine recrystallized grains suggesting that recovery and dynamic recrystallization contribute to dislocation creep at these conditions. By comparison with lower temperature deformation, mechanical twinning is unimportant. Fine-grained synthetic dolomite deformed at high temperature (T &#8805; 700??C) exhibits nearly linear (Newtonian) viscous behavior, with n = 1.28 (??0.15) consistent with grain boundary (Coble) diffusion creep. At low temperatures (T &#8804; 700??C) coarse-grained dolomite exhibits higher strengths at higher temperatures which cannot be described by an Arrhenius relation, while fine-grained dolomite strengths show little or no temperature dependence. At high temperatures (T &#8805; 800??C), dislocation creep of coarse-grained dolomite can be described by a thermally activated power law &#9119;&#9119;&#9120;&#9118;&#9116;&#9116;&#9117;&#9115;&#8722;&#9119;&#9119;&#9120;&#9118;&#9116;&#9116;&#9117;&#9115;&#8722;=RTHno*31exp??&#963;&#963;&#949;&#949;&& with H*/n = 60 kJ/mol, or by an exponential law ()[]&#9119;&#9119;&#9120;&#9118;&#9116;&#9116;&#9117;&#9115;&#8722;&#8722;=RTHo*31expexp&#963;&#963;&#945;&#949;&#949;&& with H*/&#945; = 25447 kJ/mol. At high temperatures, diffusion creep of fine-grained synthetic dolomite can be described by &#9119;&#9119;&#9120;&#9118;&#9116;&#9116;&#9117;&#9115;&#8722;&#9119;&#9119;&#9120;&#9118;&#9116;&#9116;&#9117;&#9115;&#8722;&#9119;&#9120;&#9118;&#9116;&#9117;&#9115;&#8486;=RTHdno*313exp??&#963;&#963;&#949;&#949;&& with H* = 280 ??45 kJ/mol. Taken together, the flow laws for coarse- and fine-grained dolomites constrain the high temperature conditions over which crystal plasticity, dislocation creep, and diffusion creep dominate.

Thesis (doctoral)--Friedrich-Wilhelms-Universität zu Berlin, 1899. / Vita.

Thesis--Universität Zürich, 1941. / Lebenslauf. "Literatur": p. 64.

Thesis (doctoral)--Université de Rennes I, 2003. / Includes bibliographical references. Also available on the Internet.

No description available.

The stress state at the boundary of any underground mine opening is that of plane stress. This planar state of stress can be simulated in laboratory by subjecting a cubic rock specimen to a biaxial loading condition. Thus, research on the behaviour of biaxially loaded rock is important for better understanding of the stability of mining fronts such as crown pillar skin, drift face or shaft floor. / The objective of this research is to study the geomechanical behaviour of biaxially loaded rock. Three rock types were selected, namely limestone, granite and sandstone. / The laboratory work was conducted using a newly developed, 500-tonne biaxial loading frame, that is equipped with a servo-controlled load and displacement system. Recently patented in China, the new biaxial loading frame is spatially symmetric and equally rigid in both directions. Steel brush platens and solid platens with and without MoS2 were developed to help examine the end friction effect on biaxial strength. It is found that the biaxial strength can decrease up to 26.7% with the increase of cubic specimen size from 75 mm to 150 mm. The biaxial strength increases by 29.3% with the increase of loading rate from 1 MPa/s to 10 MPa/s, for granite. The biaxial strength of granite specimen decreases by nearly 6% when either solid platens with MoS 2 lubricant or brush platens are used. A comparison of the sigma 1-sigma2 failure envelopes reveals that the shape of the envelope and the location of the peak biaxial strength are dependent on the rock type. / Varying intensities of rock spalling generally initiate at the free faces of the specimen when sigma1 and sigma2 exceed sigma c/2. Ultimate failure occurs in the form of an out-of-plane shear failure, which splits the rock specimen into two or more wedges. / It is shown that both Mohr-Coulomb and Hoek-Brown criteria underestimate the biaxial strength of the rock. The Drucker-Prager failure criterion appears to provide poor correlation with experimental results. A new empirical biaxial rock failure criterion for intact rock is derived and another, accounting for rock mass characteristics through the Geological Strength Index (GSI), is then proposed.

Convergent continental margins are regions of intense deformation caused by the interaction of oceanic plates with continents. The spatial extent of deformation is broadly commensurate with the specific time scale of the causative phenomenon. For example, subduction-related short-term deformation is limited to <200 km from the margin, whereas long-term plate convergence cause deformation over ∼1000 km landward. Deformation is thus manifested in multiple ways, with attributes depending on the scale of measurement. In this thesis we investigate the use of two geophysical approaches in the study of deformation: 1) The analysis of potential-field anomalies to derive estimates of the elastic thickness (Te) of the lithosphere, and 2) The structural study of past and present subduction systems using seismic observations and modelling. Both approaches involve the development of appropriate methodologies for data analysis and modelling, and their application to the western Canadian landmass. Our findings are summarized as follows: 1) We develop a wavelet-based technique to map variations in Te and its anisotropy; 2) We show how a step-wise transition in Te and its anisotropy from the Cordillera to the Craton is a major factor influencing lithospheric deformation; 3) We implement a waveform modelling tool that includes the effects of structural heterogeneity and anisotropy for teleseismic applications, and use it to model the signature of a fossil subduction zone in a Paleoproterozoic terrane; 4) We use teleseismic recordings to map slab edge morphology in northern Cascadia and show how slab window tectonism and slab stretching led to the creation of the oceanic Explorer plate; 5) We use seismic signals from the subducting oceanic crust to calculate elevated Poisson’s ratio and infer high pore-fluid pressures and a low-permeability plate boundary within the forearc region of northern Cascadia.

The development of a petroleum reservoir would inevitably induce a rearrangement of the in-situ stress field. The rearrangement of the stress field would then bring about a deformation of the reservoir rock and a change of the permeability. This experimental study was carried out to investigate rock deformation and its impact on axial permeability. Triaxial compression tests were conducted on Berea sandstone, Indiana limestone, Westerly granite and tuff specimens. Axial permeability was continuously measured for Berea sandstone and Indiana limestone during triaxial compression tests. The axial permeability of fractured Westerly granite specimens was also measured during hydrostatic compression tests. Acoustic emission (AE) monitoring was performed to help improve the understanding of rock deformation. Results showed that Berea sandstone and Westerly granite were relatively brittle, while Indiana limestone and tuff were relatively ductile. Rock deformation altered pore structures and the change of pore structures considerably impacted fluid flow through rock. For porous Berea sandstone and Indiana limestone, the destruction of the pore structure by rock deformation led to a decrease in axial permeability. For tight Westerly granite, fractures created by rock deformation significantly improved the ease of fluid flow. Acoustic emission response was found to be strongly dependent on rock type. Brittle Berea sandstone and Westerly granite produced high AE rates during compression tests, while ductile Indiana limestone and tuff generated very low AE rates.

Despite real applications having complex triaxial loading, current physical test methods to predict component behaviour are mainly uniaxial. But previous work has indicated that there may be substantial differences between the rubber's uniaxial and biaxial behaviour and hence through incompressibility, its triaxial properties. In order to quantify these differences equipment was developed to assess the biaxial performance of selected rubber compounds using inflated circular diaphragms. Although allowing higher extensions than stretching a sheet in its own plane, such tests do not allow stress and strain to be measured directly, requiring careful marking of the sample, or calculation through simulation. On the grounds of perceived accuracy, the latter was chosen, requiring accurate, general, elastic constants to high extensions. In this thesis the development of this apparatus, along with the associated techniques is described, along with the development of a new elastic theory. The tests on this new apparatus indicated significant differences between the uniaxial and biaxial strength and fatigue of rubber. In a unimdal test natural rubber (NR) is much stronger than styrene butadiene rubber (SBR) below 35pphr of carbon black. In a biaxial test though the converse is true, although there is some evidence of crystallinity in NR during the biaxial test. Distinct differences were also found in fatigue between the two load cases. When plotted against extension ratio the biaxial life of SBR was found to increase, while the converse is true for NR. However if life is plotted against a function of strain energy, the biaxial life of both polymers increases for a given energy.