Search results for "Shear"
showing 10 items of 804 documents
Temperature, fluid content and rheology of localized ductile shear zones in subsolidus cooling plutons
2020
Temperature and fluid content are critical parameters that control rock rheology and strain localization in the continental crust. Here, we determine by thermodynamic modelling the urn:x-wiley:02634929:media:jmg12553:jmg12553-math-0004 of localized ductile shearing during cooling of three different granitoid plutons: the Rieserferner and the Adamello plutons in the Italian Alps, and the Lake Edison pluton in the Sierra Nevada—USA. Shear zones exploited precursor joints, associated veins and alteration zones. urn:x-wiley:02634929:media:jmg12553:jmg12553-math-0005 and P−T phase diagram sections were computed with Perple_X in the system MnO−Na2O−CaO −K2O−FeO−MgO−Al2O3−SiO2−H2O−Fe2O3. The phase…
Non-uniformity of displacement and strain within the Achilles tendon is affected by joint angle configuration and differential muscle loading.
2020
Although the Achilles tendon (AT) has been studied for more than a century, a complete understanding of the mechanical and functional consequences of AT structural organization is currently lacking. The aim of this study was to assess how joint angle configuration affects subtendon displacement and strain of soleus (SOL) and lateral gastrocnemius (LG) muscles. Knots sutured onto SOL and LG subtendons of 12 Wistar rats, were videotaped to quantify displacements and the ankle torque was assessed for different isometric activation conditions (i.e., individual and simultaneous) of the triceps surae muscles. Changing ankle and knee joint angle affected the magnitude of displacement, relative dis…
Benchmark study of undrained triaxial testing of Opalinus Clay shale: Results and implications for robust testing
2021
Triaxial testing of argillaceous rocks and shales is significantly more challenging than conventional rock mechanical testing. The challenges are mainly related to the very low permeability of these geomaterials, and their sensitivity to exposure of atmosphere and brines, which induces variations of water content, suction and effective stress. There are currently no international standards to guide service laboratories for robust testing procedures for shales. A benchmark study of undrained triaxial testing was therefore initiated with three leading service laboratories in shale testing, performing 13 tests and using two different methods of establishing sample saturation prior to deformati…
Fracture Shape and Orientation Contributions to P-Wave Velocity and Anisotropy of Alpine Fault Mylonites
2021
P-wave anisotropy is significant in the mylonitic Alpine Fault shear zone. Mineral- and texture-induced anisotropy are dominant in these rocks but further complicated by the presence of fractures. Electron back-scattered diffraction and synchrotron X-ray microtomography (micro-CT) data are acquired on exhumed schist, protomylonite, mylonite and ultramylonite samples to quantify mineral phases, crystal preferred orientations, microfractures and porosity. The samples are composed of quartz, plagioclase, mica and accessory garnet, and contain 3-5% porosity. Based on the micro-CT data, the representative pore shape has an aspect ratio of 5:2:1. Two numerical models are compared to calculate the…
Stability of Embankments Resting on Foundation Soils with A Weak Layer
2021
The presence of weak layers in geotechnical systems, including soil or rock masses, both natural and man-made, is more frequent than is normally believed. Weak layers can affect both failure mechanisms, in drained and in undrained conditions, as well as in static and seismic conditions, and the safety factor. In the present study, conducted numerically using the finite-element method (FEM) Plaxis 2D code, the influence of a horizontal thin weak layer on stress and strain distribution, on failure mechanisms and on the overall stability of an embankment was evaluated. The results obtained prove that when the weak layer is located at a significant depth from the foundation plane, the failure m…
Characterisation of Fibre Glass Panels for Naval Use
2004
This work examines the characteristic of fiber glass composite panels constructed by Cantieri Arturo Stabile in Trapani (Italy): composite materials are very used in the naval applications, where high stiffness and resistance are required with reduced weight. Experimental tests are executed following ASTM or UNI EN rules, in particular the shear test is executed using a rig constructed to the purpose, designed following the rule ASTM D 4255-83. Besides the tests were simulated by analytical methods, by means of Cadec software and numerically by FEM software as Altair Hyperworks and Ansys, to evidence the error range of the experimental test and to obtain the configuration that can give suit…
Analysis of thin film cracking and buckling on compliant substrate by fragmentation test
2007
Application of coating fragmentation test for determination of coating properties is considered. A probabilistic model of coating fragmentation under uniaxial tensile loading is applied for coating and interface property identification of thin brittle coating/polymer substrate system. A finite element model is developed to simulate the process of buckle formation in coating strips during fragmentation test. The measured buckle geometry parameters and buckle density evolution as a function of the applied strain is used to estimate the interface toughness.
On the shear influence on the free vibration behavior of magneto-electro-elastic beam
2009
A magneto-electro-elastic Timoshenko beam model is presented and employed to study the effect of the shear strain on the free vibration behavior of the beam. Once the differential governing equation for Timoshenko magneto-electro-elastic beam is derived, the Euler-Bernoulli model is obtained by letting be zero some of the governing equation coefficients. Results for the Timoshenko and Euler- Bernoulli beam are presented in comparison with two-dimensional finite element computation.
Intrusion within a transtensional tectonic domain: the Čistá granodiorite (Bohemian Massif)—structure and rheological modelling
2000
Abstract The Cista granodiorite stock, which intrudes the Tis granite laccolith, and their Neoproterozoic country rocks of the Tepla–Barrandian zone were studied by means of structural analysis and anisotropy of magnetic susceptibility. The rocks were dated by the Pb–Pb evaporation on zircons, determining the age of the Cista granodiorite and Tis granite at 373 Ma and 504 Ma, respectively. The structures in the country rocks are characterised by an axial cleavage dipping to the northwest and overprinting the folded bedding. S1 cleavage bears NE–SW-trending mineral lineations, which plunge to the northeast or southwest at shallow angles. The cleavage is deformed by D2 kink-bands, which indic…
Intrusion age of Pan-African augen gneisses in the southern Menderes Massif and the age of cooling after Alpine ductile extensional deformation
1996
AbstractPb–Pb single zircon ages of 546.2 ± 1.2 Ma demonstrate that the augen gneisses in the southern Menderes Massif were generated from Pan-African intrusions. During the Alpine orogenic evolution of the Menderes Massif these granites were metamorphosed and transformed into augen gneiss in an extensional top-to-the-south shear zone, located between augen gneisses and overlying schists. Quartz fabrics suggest a pronounced static recrystallization that post-dates the ductile deformation in the shear zone. Ar–Ar muscovite ages of 43–37 Ma from augen gneisses and schists suggest that ductile deformation and subsequent cooling occurred in the Eocene. These results contradict previous models t…