Search results for "shear"
showing 10 items of 804 documents
Investigation of the hemodynamic flow conditions and blood-induced stresses inside an abdominal aortic aneurysm by means of a SPH numerical model.
2019
The estimation of blood flow-induced loads occurring on the artery wall is affected by uncertainties hidden in the complex interaction of the pulsatile flow, the mechanical parameters of the artery, and the external support conditions. To circumvent these difficulties, a specific tool is developed by combining the aorta displacements measured by an electrocardiogram-gated-computed tomography angiography, with the blood velocity field computed by a smoothed particle hydrodynamics (SPH) numerical model. In the present work, the SPH model has been specifically adapted to the solution of the 3D Navier-Stokes equations inside a domain with boundaries of prescribed motion. Images of the abdominal…
On the hydro-mechanical behaviour of a lime-treated embankment during wetting and drying cycles
2018
Abstract The paper presents some experimental results obtained on samples extracted from a full-scale embankment obtained by compacting a lime-treated clayey soil. A comprehensive test programme was carried out in order to highlight the improvement of mechanical behaviour induced by lime treatment as well as to assess the durability of the improved material, which may be affected by severe seasonal wetting and drying cycles. Direct shear tests, triaxial compression tests, swelling potential measurement and oedometric tests were performed on samples cured in controlled environmental conditions for at least 18 months. Wetting and drying cycles were applied in a very wide range of suction valu…
Fibre break processes in unidirectional composites
2014
International audience; A model to predict the effects of the accumulation of fibre breakages in unidirectional carbon fibre composites has been developed that takes into account several physical phenomena controlling fibre failure, including the stochastic nature of fibre strength, stress transfer between fibres due to the shear of the matrix, interfacial debonding and viscosity of the matrix. The damage processes leading up to failure are discussed and quantified, first in terms of fibre breaks for the case of monotonically increasing tensile loading, then for sustained loading and finally the implications for more complex loads and structures are discussed. It is clearly shown that the f…
Simple equations for strength and deformability verification of tubular steel wind turbine towers
2021
Abstract Simple analytical expressions for a preliminary design of tubular steel wind turbine towers under flexure and shear are proposed. Expressions derived included local buckling effects, shear to moment interaction, ovalization of cross-section and inelastic rotation of foundation. A finite-element analysis with ABAQUS program was also conducted for examination of the ovalization effects and for the whole response of steel tube in flexure. Numerical and analytical results were compared with the experimental results of recent studies available in the literature, showing good agreement. The range of variable investigated refers to medium and large size steel wind tower with cylindrical s…
Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets
2014
Objectives: 1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. Study Design: A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in each of the first four groups while the last one (group V) was used as the control. Groups (I-V) were subjected to shear force within half an hour until the brackets debond. SBS was measured and the me…
Orthogonal and Oblique Cutting Mechanics
2008
This chapter provides the engineering knowledge and modelling techniques applied in description of the material behaviour in the cutting zone resulting in chip formation and its separation from the bulk material. Geometrical and kinematical characteristics of orthogonal and oblique cutting models are classified and specified. Forces acting on the cutting tools and their measurement methods for several machining operations, such as turning, milling, drilling, boring and grooving, are presented. Moreover, forces acting in the cutting zone and their resolution on the shear plane and the rake and flank faces, along with stress distributions, are presented. The chapter highlights how components …
Practical Model for Load-Carrying Capacity of Eccentrically Loaded Square Column Footings
2018
In this paper, a practical calculus model based on the strut-and-tie approach for prediction of the load-carrying capacity of eccentrically loaded RC column footings with square cross sections is presented. Existing models based on beam or slab models with flexural and two-way slab punching shear failure are presented and discussed. Several subgrade contact pressure distributions for column footings are considered. A parametric analysis of the effects of footing and column dimensions (depth, width), longitudinal ratio of longitudinal steel, and strength of concrete and steel is made for all models examined. Available experimental data are utilized to verify the model in comparison with exis…
EXPERIMENTAL AND NUMERICAL EVALUATION OF THE MECHANICAL BEHAVIOUR OF GFRP SANDWICH PANELS
2007
This work deals with the analysis of the mechanical behaviour of a class of sandwich structures widely employed in marine constructions, constituted by fiber-glass laminate skins over PVC foam or polyester mat cores. In detail, a systematic experimental study and numerical simulations have shown that the theoretical prediction of the strength and the actual failure mechanism of these sandwich structures can be affected by significant errors, specially in the presence of prevalent shear loading. Moreover, because of the low shear stiffness and the elastic constants mismatch of the skins and core material, failure modes and strength are strongly influenced by eventual stresses orthogonal to t…
Analytical modelling of force transmission in axially loaded RC columns with indirectly loaded jackets
2019
Abstract Concrete and steel jacketing are common strengthening techniques for reinforced concrete (RC) columns subjected to axial loads. In the most of cases the external jacket is made leaving gaps between the strengthening layer and the slabs, avoiding to carry directly a portion of the load. In this way, the external jacket induces a confinement pressure on the inner column, and its beneficial effect is due to the increase of strength and ductility. However, shear stresses develop on the interface between the column and consequently, the external jacket can be considered indirectly loaded. It sustains a portion of the axial load, which depends by the value of the axial shortening, relati…
Behaviour of concrete deep beams with openings and low shear span-to-depth ratio
2012
Abstract The goal of this study is to experimentally and analytically evaluate the influence of circular openings in reinforced concrete deep beams with low shear span-to-depth ratio. Twenty reinforced concrete small-scale deep beams with or without openings were tested in flexure under four-point loading. The beams had a small shear span-to-depth ratio in order to stress the shear behavior. The specimens had different reinforcement arrangements and opening positions. The load was transmitted to the specimen with bearing plates having the same side length as the beam. Two LVDT’s were arranged to record the transverse and axial strain of the theoretical struts forming in the beam. Additional…