Search results for "SHEAR"
showing 10 items of 804 documents
On the history of torsional stress concentrations in shafts: From electrical analogies to numerical methods
2014
This article proposes a retrospective on experimental and numerical methods developed throughout the past century to solve the torsion problem in shafts, with particular emphasis on the determination of shear stress concentration factors in discontinuities of typical use in shaft design. This article, in particular, presents the theory and related solutions distinguishing between two classes of geometries: shafts with constant cross section and axisymmetric shafts with variable diameter. Emphasis is given to approaches based on physical analog methods and, in particular, those based on electrical analogies proposed since about 1925. Experimental methods based on structural physical models …
A smeared seismicity constitutive model
2004
The classical application of rate and state dependent frictional constitutive laws has involved the instabilities developed between two sliding surfaces. In such a situation, the behaviour and evolution of asperities is the controlling mechanism of velocity weakening. However, most faults have a substantial thickness and it would appear that it is the bulk behaviour of the fault gouge, at whatever scale, that is important. The purpose of this paper is to explore how bulk frictional sliding behaviour may be described. We explore here the consequences of applying the rate and state framework initially developed to describe the frictional behaviour at the interface between two interacting slid…
Just another drip: Re-analysis of a proposed Mesoarchean suture from the Barberton Mountain Land, South Africa
2014
Abstract Structural analysis of a proposed Mesoarchean suture located immediately to the southwest of the Barberton Greenstone Belt, South Africa – known as the Inyoni Shear Zone (ISZ) – reveals that the main, steeply dipping, NNE-striking fabric is distributed across only 1 km width, is late (D3), and clearly overprints two earlier sets of fabric elements (D1, D2) that were originally oriented at right angles to the direction of proposed collision. Dating of a S2 foliated meta-trondhjemite is interpreted to indicate that D2 deformation was at, or younger than, 3238.2 ± 0.9 Ma. The D3 high strain fabric of the ISZ is localised around tightly folded, kilometre-scale supracrustal rafts, but d…
Contrasting metamorphic evolution of metasedimentary rocks from the Çine and Selimiye nappes in the Anatolide belt, western Turkey
2003
P-T conditions, mineral isograds, the relation of the latter to foliation planes and kinematic indicators are used to elucidate the tectonic nature and evolution of a shear zone in an orogen exhumed from mid- crustal depths in western Turkey. Furthermore, we discuss whether simple monometamorphic fabrics of rock units from different nappes result from one single orogeny or are related to different orogenies. Metasedimentary rocks from the Cine and Selimiye nappes at the southern rim of the Anatolide belt of western Turkey record different metamorphic evolutions. The Eocene Selimiye shear zone separates both nappes. Metasedimentary rocks from the Cine nappe underneath the Selimiye shear zone…
The influence of strain localisation on the rotation behaviour of rigid objects in experimental shear zones
2002
Abstract Mica fish and tourmaline fish from natural mylonites were analysed in thin section to determine their orientation distribution. They are oriented with their long axes tilted with respect to the mylonitic foliation, and fish with a small aspect ratio exhibit a slightly larger angle than fish with a large aspect ratio. This orientation seems to be a stable orientation for the mica and tourmaline fish. Analogue experiments with two rheologically different matrix materials were performed to explain the data. One material was PDMS, a linear viscous polymer. The other was tapioca pearls, a granular material with low cohesion and Mohr–Coulomb type behaviour. In contrast to a fairly homoge…
Growth and anisotropic ripening in twinned colloidal crystals
2008
The heterogeneous crystallization of colloidal suspensions of Yukawa particles on a wall was observed by Bragg microscopy. The growth velocity ν 110 of the fluid-crystal interface can be very well described by a Wilson-Frenkel growth law, while the limiting velocity is found to be lower than in previous investigations. Twinned bcc domains in lateral direction (parallel to the wall) and their ripening behavior are for the first time investigated systematically. A strong anisotropic growth behavior is found: in the direction of the shear flow, which shear melts the suspension prior to the crystallization process, the extension of the domains is much larger than perpendicular to that. The incr…
Ferroelastic transition in Kbr:Kcn studied by neutrons, x-rays and ultrasonic
1986
The ferroelastic phase transition of (KBr) 0 27 (KNC) 0.73 has been studied by X-ray diffraction, ultrasonics and inelastic neutron scattering. It is the first example of a cubic crystal where the elastic shear constant C 44 softens completely corresponding to the m = 2 universality class. C 44 and the Bragg intensities show a non-classical critical behaviour.
Experimental Studies Regarding the Mechanical Behaviour of Silicon-Coated and Uncoated P.A. 6.6 Fabrics
2014
These paper aims to present an experimental study for determining the mechanical properties of woven fabrics used for airbags manufacturing. In order to realise the study, there were chosen two types of fabric, one that is coated with silicon and one that is uncoated. The experimental tests that were carried out were uniaxial tension tests for samples extracted on the warp and on the weft direction, the Bias test, a test specific for shear loads and the dome test, a test specific for biaxial loads. For the uniaxial tension test the force-displacement curve was obtained and the maximum values of the loads and the displacement. For the last two tests (bias test and dome test) there have been …
Magneto-elastic oscillations and the damping of crustal shear modes in magnetars
2010
In a realistic model of magneto-elastic oscillations in magnetars, we find that crustal shear oscillations, often invoked as an explanation of quasi-periodic oscillations (QPOs) seen after giant flares in soft gamma-ray repeaters (SGRs), are damped by resonant absorption on timescales of at most 0.2s, for a lower limit on the dipole magnetic field strength of 5 10 13 G. At higher magnetic field strengths (typical in magnetars) the damping timescale is even shorter, as anticipated by earlier toy-models. We have investigated a range of equations of state and masses and if magnetars are dominated by a dipole magnetic field, our findings exclude torsional shear oscillations of the crust from ex…
Healon®5: A New Viscoadaptive Formulation
2000
To relate the practical relevance of our study results, specific requirement profiles for individual procedures have been correlated to the desired physicochemical characteristics. Healon®5 demonstrated the statistically significant highest zero shear viscosity of all OVD and a long relaxation time (Dick et al., 2000). It therefore most effectively creates and maintains a deep anterior chamber in order to facilitate safe surgical maneuvers (e.g., in case of vitreous pressure). Additionally, the high viscosity of Healon®5 exhibits a dynamic frequency dependence, which has not been observed in any pure hyaluronic acid formulation before. Healon®5’s properties change in response to surgical ma…