Search results for "SHEAR"
showing 10 items of 804 documents
Intrusion mechanisms in a turbidite sequence; the Voetspoor and Doros plutons in NW Namibia
2007
Abstract Two syntectonic plutons of Cambrian age intruded Neoproterozoic metaturbidites in Namibia at the junction of the NS trending Kaoko and EW trending Damara belts. Sinistral transpression in the Kaoko Belt produced km-scale upright D1 folds overprinted by minor D2 folds. D3 is associated with N–S shortening in the Damara Belt. The plutons show two main pulses of intrusion: hornblende syenite intruded late during D1 or during D2 and biotite granite during D3. Each tectonic event produced a strain shadow defined by the shape of folds and the foliation trend around the plutons. The internal igneous fabric and the arrangement of wall rock xenoliths that locally make up 50% of the intrusio…
Physico-chemical and mechanical characterization of in-situ forming xyloglucan gels incorporating a growth factor to promote cartilage reconstruction
2016
Abstract The development of growth factors is very promising in the field of tissue regeneration but specifically designed formulations have to be developed in order to enable such new biological entities (NBEs). In particular, the range of therapeutic concentrations is usually very low compared to other active proteins and the confinement in the target site can be of crucial importance. In-situ forming scaffolds are very promising solutions for minimally invasive intervention in cartilage reconstruction and targeting of NBEs. In this work injectable, in-situ forming gels of a temperature responsive partially degalactosylated xyloglucan (Deg-XG) incorporating the growth factor FGF-18 are fo…
Analysis of local shear effects in brick masonry infilled RC frames
2013
Masonry infills panels placed among framed structures meshes have a relevant influence in presence seismic actions in terms of strength stiffness and global displacement capacity. In the case of RC structures, the modifications of internal forces due to infill-frame interaction may be not compatible with surrounding frame members strength especially considering additional shear forces arising at the ends of beams and columns in contact with the panel under lateral actions. Such effects may be in many cases the cause of unexpected brittle collapse mechanisms which compromise the safety of the entire structure. In this paper by means of a double (micromodeling and macromodeling) procedure reg…
Un élément fini mixte tridimensionnel pour le calcul des contraintes d'interface
1999
ABSTRACT In this paper we present an interfacial finite element designed for analysing planar interfaces in a three-dimensional approach. The element is derived from Hellinger-Reissner's mixed variational principle and takes into account the continuity of the displacement and of the transverse stress components through the interface. Stress analysis of a sandwich plate is made to assess the validity and the effectiveness of the element models, with comparisons to closed-form and numerical solutions.
Apparent interfacial shear strength of short-flax-fiber/starch acetate composites
2016
Abstract The paper deals with an indirect industry-friendly method for identification of the interfacial shear strength (IFSS) in a fully bio-based composite. The IFSS of flax fiber/starch acetate is evaluated by a modified Bowyer and Bader method based on an analysis of the stress–strain curve of a short-fiber-reinforced composite in tension. A shear lag model is developed for the tensile stress–strain response of short-fiber-reinforced composites allowing for an elastic-perfectly plastic stress transfer. Composites with different fiber volume fractions and a variable content of plasticizer have been analyzed. The apparent IFSS of flax/starch acetate is within the range of 5.5–20.5 MPa, de…
Influence of the anisotropy of sisal fibers on the mechanical properties of high performance unidirectional biocomposite lamina and micromechanical m…
2021
Abstract High performance biocomposites reinforced by sisal fibers, are between the most promising materials that could be used in various fields, from automotive to civil constructions, thanks to their good mechanical performance, as well as to the low cost and the great availability of the fiber. Nevertheless, at present their practical use is prevented by the limited knowledge of their mechanical performance. The results of the present study have shown that the intimate fibrillar structure of the sisal fiber is associated with a high anisotropy involving not only the elastic parameters, but also the damage processes with typical fiber splitting phenomena, that influence noticeably the bi…
Comparison among three boundary element methods for torsion problems: CPM, CVBEM, LEM
2011
This paper provides solutions for De Saint-Venant torsion problem on a beam with arbitrary and uniform cross-section. In particular three methods framed into complex analysis have been considered: Complex Polynomial Method (CPM), Complex Variable Boundary Element Method (CVBEM) and Line Element-less Method (LEM), recently proposed. CPM involves the expansion of a complex potential in Taylor series, computing the unknown coefficients by means of collocation points on the boundary. CVBEM takes advantage of Cauchy’s integral formula that returns the solution of Laplace equation when mixed boundary conditions on both real and imaginary parts of the complex potential are known. LEM introduces th…
The Latomiae of Syracuse: A Geotechnical Mapping Through Rock Reflectivity
2014
The archeological site of the Latomia del Paradiso (Syracuse) is endangered by severe instability phenomena due to the shape of walls and underground excava-tion related with the poor mechanical characteristics of the weathered and wet rock. The failure of huge blocks from the ceiling of the underground areas and the detaching of rock "flakes" from the walls surface make the geotechnical zon-ing particularly complex. the zoning is based on the characteristics of the rock wall surface that, in first approximation, can be distinguished in regularized sur-faces because of mining , and in irregular surfaces characterized by fracture prop-agation. The elaboration of reflectivity values obtained …
Evaluation of viscoelastic constants of metallic materials by laser-ultrasonics at elevating temperature
2002
The main objective of this study is the determination of elastic moduli and viscosity coefficients of metals at elevating temperature up to melting point. More specifically, it involves the analysis of the propagation of acoustic waves generated and detected simultaneously by laser-ultrasonic for the measurement of longitudinal and shear velocities. This preliminary work primarily concerns Tin (Sn) metal known for its low melting point and attenuation coefficient.
Shear heating induced lithospheric-scale localization: Does it result in subduction?
2012
Abstract Even though it is a well-established fact that the Earth is currently in a plate-tectonics mode, the question on how to “break” lithospheric plates and initiate subduction remains a matter of debate. Here we focus on shear heating as a potential mechanism to cause lithospheric shear localization and subsequent subduction initiation in oceanic plates. It is shown that shear heating under some conditions (i) facilitates the formation of a lithospheric-scale shear zone and (ii) is capable of stabilizing a lithospheric-scale shear zone, thus creating the necessary condition for subduction initiation to occur. Furthermore, we demonstrate that not only the localization process is of impo…