Search results for "T method"
showing 10 items of 1254 documents
In vivo morphological and clinical effects of a desensitizing agent
2010
Objectives: This study evaluated the in vivo effectiveness of Universal Dentin Sealant (UDS), a new resin-based material, as dentinal desensitizing agent on dentin morphology and clinical symptoms. Materials and methods: Thirty premolars, exhibiting non-carious cervical lesions, and scheduled for extraction for periodontal reasons, were selected for the ultrastructural study. These samples were randomly divided into three groups ( n = 10): group 1, brushing with UDS; group 2, brushing with Flor-Opal ® Varnish (FOV); and group 3, untreated control. After 7 days, teeth were extracted and samples processed for SEM and TEM comparative observations. The in vivo study was carried out on 90 teeth …
Solid-fluid interaction in a pillar-based phononic crystal
2016
In this paper, we investigate the wave dispersion of two dimensional pillar-based phononic crystal surrounded in liquid medium. An unit cell structure with reduced pillar height (hp/a)=0.5 and reduced radius (rp/a)=0.3 is simulated using Finite Element Method. The geometrical parameter is chosen to demonstrate a local resonance mechanism that allow the confinement of elastic energy at the interface between the solid and the fluid. In order to identify the energy distribution, we represent the eigenmode at high symmetry (point X) in the first Brillouin zone. The decreasing trend of frequency is also boosted with the increase of pillar height. From the total displacement, the energy is mostly…
Numerical Procedure For Residual Stresses Prediction In Friction Stir Welding
2011
The prediction of residual stresses is a relevant and, under many points of view, still open issue for a proper welding process design. In the present paper a 3D FE model, with general validity for different joint configurations, was used to simulate the Friction Stir Welding (FSW) process of butt joints through a single block approach. The model is able to predict the residual stresses by considering thermal actions only, thanks to a new time efficient approach. A good agreement between calculated and experimentally measured data was found; the effectiveness of the presented numerical procedure was evaluated by comparing the calculation times of the proposed method with the ones of already…
Influence of laser beam profile on the generation of ultrasonic waves
2011
The different ultrasonic fields generated in metallic materials by a laser beam with flat and Gaussian profile are investigated experimentally and using the finite element method (FEM). A high power laser beam irradiating a solid surface produces elastic waves with a mechanics that depends on many parameters, including the profile of the laser beam. The influence of the beam profile is investigated with the FEM analysis, considering the temperature dependence of material properties.
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…
Experimental Investigation and Finite Element Analysis of Dynamic Behavior and Damage of Glass/Epoxy Tubular Structures
2011
This paper presents finite element analysis (FEA) of static and dynamic tests of thick filament wound glass/epoxy tubes. The first part involves the validation of elastic properties and identification of damage initiation and its development in dynamic tests. The results of FEA of the dynamic tests without damage appeared satisfactory. An impact model, including material property degradation, is used for damage prediction. The simulated damage is compared with that obtained experimentally. The sizes of projected and cumulated surfaces are of the same order of magnitude as in the experimental measurements.
Approximate Solution on Large Deflection of Glass Panels Subjected to Uniform Pressure
2015
The estimation of the deflection of glass panels under wind pressure is important in designing external facades of buildings. A direct method to compute the large deflections of glass panels under uniform loads such as wind pressure is presented. The model allows for derivation of the load-deflection response of square or rectangular multilayered glass panels subject to uniform loads. The boundary conditions examined are those of four-point discontinuous supports or continuous supports along the four sides. With some assumptions on bending and membrane action of flat glasses, simple analytical expressions were derived from the elastic theory. Viscoelastic effects for multilayered glass pane…
A Multiscale Approach to Polycrystalline Materials Damage and Failure
2014
A two-scale three-dimensional approach for degradation and failure in polycrystalline materials is presented. The method involves the component level and the grain scale. The damage-induced softening at the macroscale is modelled employing an initial stress boundary element approach. The microscopic degradation is explicitly modelled associating Representative Volume Elements (RVEs) to relevant points of the macro continuum and employing a cohesive-frictional 3D grain-boundary formulation to simulate intergranular degradation and failure in the Voronoi morphology. Macro-strains are downscaled as RVEs' periodic boundary conditions, while overall macro-stresses are obtained upscaling the micr…
Experimental and Numerical Analysis on FSWed Magnesium Alloy Thin Sheets Obtained Using “Pin” and “Pinless” Tool
2012
The present investigation aims at studying the effect of different tool geometries and process parameters on FSW of thin sheets in AZ31 magnesium alloy. In particular two properly designed tools, with shoulder diameters equal to 8 and 19 mm, were used; each of them was manufactured both in pin and pinless configurations. The effect of the different tool configurations and sizes, and welding parameters on mechanical properties of FSWed joints were analyzed in detail. The results were compared with those obtained on the base material. It was shown that FSWed joints are characterized by strength and ductility values lower than those of base material. Furthermore, the pin tool configuration, wi…