Journal of Materials and Engineering Structures
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Numerical investigation of damage protective oxide mechanisms in thermal barrier system for aeronautical turbine blade.
Get PDFThe choice of a material for a given application requires insuring a good durability in its conditions of employment, in particular environmental. It is especially true for the systems destined to work in corrosive hot atmospheres. For it, the knowledge and the understanding of the corrosion phenomena, oxidization, ageing and damage are indispensable in order to anticipate the life period of the structures and to propose the adapted protective solutions. The study of the corrosion in high temperature is therefore a greatly interdisciplinary topic, into the interface of the physico-chemistry, metallic and ceramic materials and mechanics.We propose in this work a finite element method for the simulation of EBPVD TBCs spallation. Our studies concern one of several systems that we call thermal barrier coatings, which are a Composite materials deposited in layers on the hot components to isolate them chemically and thermally at high temperatures. This is the last operational technology adapted on aircraft engines but it is still studied and not fully exploited.This comprehensive article describes the systems currently used and the problem of interaction between mechanical and environment in the turbine.
Evaluation of response reduction factor and ductility factorfor RC braced frame
Get PDFResponse reduction factor is the factor by which the actual base shear force should be reduced, to obtain the design lateral force during design basic earthquake (DBE) shaking. The response reduction factor (R) is basically depends on Over strength (Rs), Ductility (Rµ), Redundancy (RR). So there is a need to come up with realistic R factors for different structural systems used in various countries. In the present study efforts are made to evaluate the response reduction factor and ductility of RC braced frame using nonlinear static pushover analysis. The types of the frame considered in this study are RC frame with X bracing at centre bay, RC frame with X bracing at alternate bays, shear wall at canter and alternate bays. The result of this study shows that R factor and lateral strength of RC frames are considerably affected by the types and arrangement of the bracing system
Effects of opening in shear walls of 30- storey building
Get PDFTall towers and multi-storey buildings have fascinated mankind from the beginning of civilization, their construction being initially for defense and subsequently for ecclesiastical purposes. These tall buildings because of its height, is affected by lateral forces due to wind or earthquake actions tends to snap the building in shear and push it over in bending. In general, the rigidity (i.e. Resistance to lateral deflection) and stability (i.e. Resistance to overturning moments) requirement become more important. Shear walls (Structural walls) contribute significant lateral stiffness, strength, and overall ductility and energy dissipation capacity. In many structural walls a regular pattern of openings has to be provided due to various functional requirements such as to accommodate doors, windows and service ducts. Such type of openings reduces the stiffness of the shear wall to some extent depending on the shape and size of the opening. In the present parametric study, efforts are made to investigate and critically assess the effects of various size of openings in shear walls on the responses and behaviors of multi-storey buildings. The 30 storey Prototype buildings with different types of openings in shear wall with and without incorporating the volume of shear wall reduced in the boundary elements are analyzed using software E-TABS using Response spectrum method (1893(Part-1)-2002) and Time history method
Buckling analysis of thick plates using refined trigonometric shear deformation theory
Get PDFIn this paper, a refined trigonometric shear deformation plate theory is applied for the buckling analysis of thick isotropic square and rectangular plates. The theory involves only two unknowns, as against three in first order shear deformation theory and other higher order theories. The theory involves sinusoidal function in the in-plane displacement. The transverse displacement involves bending and shear components. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. A simply supported isotropic rectangular plate subjected to uniaxial and biaxial compression is considered for the detailed numerical study. Results of critical buckling load for simply supported isotropic rectangular plates are compared with those of other refined theories
Effect of waste synthetic bag pieces on the CBR value of expansive Soil
Get PDFExpansive soils such as black cotton soil which are widely distributed in India have a tendency for volume changes due to change in moisture content. Also exhibits very low bearing capacity and high compressibility. Stabilization of such soil by admixture is used commonly now days. But no mix is suitable to improve all the types of soil. But it is obvious that depending on type of soil type of admixture the optimum mix can be designed. In this paper a mix has been designed to improve the bearing capacity of soil by using fly ash and lime mixture, reinforced with waste synthetic bag pieces. Various tests are carried out to determine the CBR value and other soil properties with and without using any admixture and reinforcement. The maximum value of CBR was found to be23.82% for 2.5 mm penetration and 22.21% for 5 mm penetration, when waste synthetic bag pieces of size 2 cm * 2 cm were used at a proportion of 0.1%
Flexural Fatigue Analysis of Concrete made with 100% Recycled Concrete Aggregates
Get PDFThe paper presents results of an investigation to study the flexural fatigue performance of concrete beams made with 100% Coarse Recycled Concrete Aggregates (RCA). Experimental investigation has been carried out to obtain the flexural fatigue lives of concrete beam specimens of size 100 × 100 × 500 mm at various stress levels under four point flexural fatigue loading. The test data is used to plot the S-N curves and a simple regression analysis is used to propose an equation to estimate the flexural fatigue strength of concrete made with 100% RCA. The flexural fatigue performance of concrete made with 100% RCA has been assessed in terms of its mean and design fatigue lives. Two million cycles fatigue strength/endurance limit has also been estimated and compared with the previous studies available on Natural Aggregates (NA).
Comparison Study of Axial Behavior of RPC-CFRP Short Columns
Get PDFIn this paper, the axial behaviors of reactive powder concrete (RPC) short columns confined with carbon fiber reinforced polymer (CFRP) were investigated. All the specimens have square cross section of 100 mm × 100 mm and length of 400 mm with aspect ratio 4. The experimental work consists of three groups. The first group consists of six specimens of RPC with 2% micro steel fiber, without ordinary reinforcing steel and confining by zero, one and two layer of CFRP respectively. The second group consists of six specimens of RPC with 2% micro steel fiber and minimum ordinary reinforcing steel and confining by zero, one and two layers of CFRP respectively. The third group consists of four specimens of RPC without micro steel fiber and ordinary reinforcing steel and confining by one and two layers of CFRP respectively. Experimental data for strength, longitudinal and lateral displacement and failure mode were obtained for each test. The toughness (area under the curve) for each test was obtained by using numerical integration. The RPC columns confined with CFRP showed stiffer behavior compared with RPC columns without CFRP. The ultimate load of the RPC columns with 2% micro steel fiber + two layers of CFRP + minimum ordinary reinforcement were more than that of the RPC columns with 2% micro steel fiber + minimum ordinary reinforcement and without CFRP by about 1.333.
Evaluation of Shear Wall-RC Frame Interaction of High-Rise Buildings using 2-D model Approach
Get PDFThe usefulness of structural walls in the framing of buildings has long been recognized. It is generally preferred to use shear wall in combination with moment resisting frame. In the present study, an effort is also made to investigate the shear wall-RC frame interaction using 2-D modeling of 20, 30 and 35 storey RC frame building with shear wall. In equivalent simplified 2-D model, two exterior frames with shear wall modeled as single frame with double stiffness, strength and weight. The interior frames without shear wall are modeled as a single frame with equivalent stiffness, strength and weight. The modeled frames are connected with rigid link at each floor level. Using 2-D plane frame model the lateral force distribution between Exterior frame with shear wall and Interior frame without shear wall is investigated. From the analysis, it is observed that up to bottom seven/eight storey more than 50% load is taken by frame with shear wall and the lower most three storeys take about 75% of total storey shear
Etude d’une console en matériaux piézo-thermo-élastique
Get PDFIn the first part of this work, analytical expressions were determined for the stresses through the thickness of a composite beam submitted to electrical excitation. In the second part of this study we are interested in the theory of elasticity, which is used to obtain exact solutions of piezo-thermo-elastic consoles gradually coupled evaluated under different loads. These solutions are used to identify the piezoelectric parameter and thermal coefficients of the materials. In addition, numerical results are obtained for the analysis of the loaded console by two different types of loading. In this study we show also that changing the linear thermal parameters of the material does not affect the distribution of the stress and the induction of the beam. However it affetcs the components of the deformation, electric field, the displacement and the electric potential of the console. Dans la première partie de ce travail, des expressions analytiques ont été déterminées pour les contraintes à travers l'épaisseur d'une poutre composite soumise à une excitation électrique. Dans la deuxième partie de cette étude, on s’intéresse à la théorie de l'élasticité qui est utilisée pour obtenir des solutions exactes des consoles piezo-thermo-élastique graduellement évaluée sous différents chargements couplés. Ces solutions sont utilisées pour identifier le paramètre piézoélectrique et les coefficients thermiques des matériaux. En outre, des résultats numériques sont obtenus pour l’analyse de la console chargée par deux différents types de chargement. Dans cette partie d’étude on montre aussi que le changement linéaire des paramètres thermiques du matériau n’influe pas sur la distribution de la contrainte et l'induction de la poutre. Cependant il influe sur les composants de la déformation, champ électrique, le déplacement et le potentiel électrique de la console. Dans la première partie de ce travail, des expressions analytiques ont été déterminées pour les contraintes à travers l'épaisseur d'une poutre composite soumise à une excitation électrique. Dans la deuxième partie de cette étude, on s’intéresse à la théorie de l'élasticité qui est utilisée pour obtenir des solutions exactes des consoles piezo-thermo-élastique graduellement évaluée sous différents chargements couplés. Ces solutions sont utilisées pour identifier le paramètre piézoélectrique et les coefficients thermiques des matériaux. En outre, des résultats numériques sont obtenus pour l’analyse de la console chargée par deux différents types de chargement. Dans cette partie d’étude on montre aussi que le changement linéaire des paramètres thermiques du matériau n’influe pas sur la distribution de la contrainte et l'induction de la poutre. Cependant il influe sur les composants de la déformation, champ électrique, le déplacement et le potentiel électrique de la console
A refined shear deformation theory for bending analysis of isotropic and orthotropic plates under various loading conditions
Get PDFIn this paper, a refined trigonometric shear deformation theory is applied for the bending analysis of isotropic and orthotropic plates under the various loading conditions. The two unknown variables are involved in the present theory. The present theory satisfies the shear stress free condition at top and bottom surface of the plates without using shear correction factors. The governing equations and boundary conditions are obtained by using the principle of virtual work. A closed form solution is obtained using Navier Solution Scheme. A simply supported isotropic and orthotropic plate subjected to sinusoidally distributed, uniformly distributed and linearly varying loads are considered for the detailed numerical study. The results obtained using present theory are compared with previously published results.