Search results for: flexural deformation
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 587

Search results for: flexural deformation

317 Fracture Mechanics Modeling of a Shear-Cracked RC Beams Shear-Strengthened with FRP Sheets

Authors: Shahriar Shahbazpanahi, Alaleh Kamgar

Abstract:

So far, the conventional experimental and theoretical analysis in fracture mechanics have been applied to study concrete flexural- cracked beams, which are strengthened using fiber reinforced polymer (FRP) composite sheets. However, there is still little knowledge about the shear capacity of a side face FRP- strengthened shear-cracked beam. A numerical analysis is herein presented to model the fracture mechanics of a four-point RC beam, with two inclined initial notch on the supports, which is strengthened with side face FRP sheets. In the present study, the shear crack is forced to conduct by using an initial notch in supports. The ABAQUS software is used to model crack propagation by conventional cohesive elements. It is observed that the FRP sheets play important roles in preventing the propagation of shear cracks.

Keywords: Crack, FRP, shear, strengthening.

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316 Effects of Coupling Agent on the Properties of Durian Skin Fibre Filled Polypropylene Composite

Authors: Hazleen Anuar, Nur Aimi Mohd Nasir, Yousuf El-Shekeil

Abstract:

Durian skin is a newly explores natural fibre potentially reinforced polyolefin for diverse applications. In this work, investigation on the effect of coupling agent, maleic anhydride polypropylene (MAPP) on the mechanical, morphological, and thermal properties of polypropylene (PP) reinforced with durian skin fibre (DSF) was conducted. The presence of 30 wt% DSF significantly reduced the tensile strength of PP-DSF composite. Interestingly, even though the same trend goes to PP-DSF with the presence of MAPP, the reduction is only about 4% relative to unreinforced PP and 18% higher than PP-DSF without MAPP (untreated composite or UTC). The used of MAPP in treated composite (TC) also increased the tensile modulus, flexural properties and degradation temperature. The enhanced mechanical properties are consistent with good interfacial interaction as evidenced under scanning electron microscopy.

Keywords: Durian skin fiber, coupling agent, mechanical properties, thermogravimetry analysis.

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315 Laser Forming of Titanium and Its Alloys – An Overview

Authors: Esther T. Akinlabi, Mukul Shukla, Stephen A. Akinlabi

Abstract:

Laser beam forming is a novel technique developed for the joining of metallic components. In this study, an overview of the laser beam forming process, areas of application, the basic mechanisms of the laser beam forming process, some recent research studies and the need to focus more research effort on improving the laser-material interaction of laser beam forming of titanium and its alloys are presented.

Keywords: Aerospace, Deformation, Laser forming, Mechanisms, Titanium, Titanium alloy.

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314 Pathology of Explanted Transvaginal Meshes

Authors: Vladimir V. Iakovlev, Erin T. Carey, John Steege

Abstract:

The use of polypropylene mesh devices for Pelvic Organ Prolapse (POP) spread rapidly during the last decade, yet our knowledge of the mesh-tissue interaction is far from complete. We aimed to perform a thorough pathological examination of explanted POP meshes and describe findings that may explain mechanisms of complications resulting in product excision. We report a spectrum of important findings, including nerve ingrowth, mesh deformation, involvement of detrusor muscle with neural ganglia, and polypropylene degradation. Analysis of these findings may improve and guide future treatment strategies.

Keywords: Transvaginal, mesh, nerves, polypropylene degradation.

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313 Structural Behaviour of Partially Filled Steel Grid Composite Deck

Authors: Hyun-Seop Shin, Chin-Hyung Lee, Ki-Tae Park

Abstract:

In order to apply partially filled steel grid composite deck as the horizontal supporting structure of various kinds of infrastructures, the variation of its flexural strength according to design parameters such as cross and longitudinal bars constituting the steel grid and the type of shear connection is evaluated and compared experimentally. The result shows that the design sensitivity of the deck to the spacing of the cross bars is insignificant in the case of structure with low risk of punching failure or without load distribution problem. By means of shear connection composed by transverse rebar and longitudinal bar without additional shear stud bolts, the complete interaction between steel grid and concrete slab is able to be achieved and the composite deck can develop its bending resistance capacity.

Keywords: bending strength, composite action, shear connection, steel grid composite deck

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312 Efficiency of Geocell Reinforcement for Using in Expanded Polystyrene Embankments via Numerical Analysis

Authors: S. N. Moghaddas Tafreshi, S. M. Amin Ghotbi

Abstract:

This paper presents a numerical study for investigating the effectiveness of geocell reinforcement in reducing pressure and settlement over EPS geofoam blocks in road embankments. A 3-D FEM model of soil and geofoam was created in ABAQUS, and geocell was also modeled realistically using membrane elements. The accuracy of the model was tested by comparing its results with previous works. Sensitivity analyses showed that reinforcing the soil cover with geocell has a significant influence on the reduction of imposed stresses over geofoam and consequently decreasing its deformation.

Keywords: EPS geofoam, road embankments, geocell, reinforcement, lightweight fill.

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311 Thermal and Flammability Properties of Paraffin/Nanoclay Composite Phase Change Materials Incorporated in Building Materials for Thermal Energy Storage

Authors: Awni H. Alkhazaleh, Baljinder K. Kandola

Abstract:

In this study, a form-stable composite Paraffin/Nanoclay (PA-NC) has been prepared by absorbing PA into porous particles of NC to be used for low-temperature latent heat thermal energy storage. The leakage test shows that the maximum mass fraction of PA that can be incorporated in NC without leakage is 60 wt.%. Differential scanning calorimetry (DSC) has been used to measure the thermal properties of the PA and PA-NC both before and after incorporation in plasterboard (PL). The mechanical performance of the samples has been evaluated in flexural mode. The thermal energy storage performance has been studied using a small test chamber (100 mm × 100 mm × 100 mm) made from 10 mm thick PL and measuring the temperatures using thermocouples. The flammability of the PL+PL-NC has been discussed using a cone calorimeter. The results indicate that the form composite PA has good potential for use as thermal energy storage materials in building applications.

Keywords: Flammability, paraffin, plasterboard, thermal energy storage.

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310 Modeling of Titanium Alloy Implant for Fractured Distal Femur

Authors: Abhishek Soni, Bhagat Singh

Abstract:

In the present work, reverse engineering (RE) approach has been used to create a 3D model of a fractured femur bone using the computed tomography (CT) scan data. Thereafter, counter fit fixation plates of Titanium alloy (Ti6Al4V) have been designed and analyzed considering physiological static loading conditions. From the analysis, it has been inferred that the stresses and deformation developed are quite low. It implies that these designed customized fixation plates are able to provide stable fixation resulting in improved fracture union.

Keywords: Biomechanical evaluations, customized implant, reverse engineering, titanium alloy.

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309 Lateral Torsional Buckling of Steel Thin-Walled Beams with Lateral Restraints

Authors: Ivan Balázs, Jindřich Melcher

Abstract:

Metal thin-walled members have been widely used in building industry. Usually they are utilized as purlins, girts or ceiling beams. Due to slenderness of thin-walled cross-sections these structural members are prone to stability problems (e.g. flexural buckling, lateral torsional buckling). If buckling is not constructionally prevented their resistance is limited by buckling strength. In practice planar members of roof or wall cladding can be attached to thin-walled members. These elements reduce displacement of thin-walled members and therefore increase their buckling strength. If this effect is taken into static assessment more economical sections of thin-walled members might be utilized and certain savings of material might be achieved. This paper focuses on problem of determination of critical load of steel thin-walled beams with lateral continuous restraint which is crucial for lateral torsional buckling assessment.

Keywords: Beam, buckling, numerical analysis, stability, steel.

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308 Enhanced Dimensional Stability of Rigid PVC Foams Using Glass Fibers

Authors: Nidal H. Abu-Zahra, Murtatha M. Jamel, Parisa Khoshnoud, Subhashini Gunashekar

Abstract:

Two types of glass fibers having different lengths (1/16" and 1/32") were added into rigid PVC foams to enhance the dimensional stability of extruded rigid Polyvinyl Chloride (PVC) foam at different concentrations (0-20 phr) using a single screw profile extruder. PVC foam-glass fiber composites (PVC-GF) were characterized for their dimensional stability, structural, thermal, and mechanical properties. Experimental results show that the dimensional stability, heat resistance, and storage modulus were enhanced without compromising the tensile and flexural strengths of the composites. Overall, foam composites which were prepared with longer glass fibers exhibit better mechanical and thermal properties than those prepared with shorter glass fibers due to higher interlocking between the fibers and the foam cells, which result in better load distribution in the matrix.

Keywords: Polyvinyl Chloride, PVC Foam, PVC Composites, Glass Fiber Composites.

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307 On the Fatigue Behavior of a Triphasic Composite

Authors: G. Minak, D. Ghelli, A. Zucchelli

Abstract:

This paper presents the results of an experimental characterization of a glass fibre-epoxy composite. The behavior of the traditional two-phase composite has been compared with the one of a new three-phase composite where the epoxy matrix was modified by addition of a 3% weight fraction of montmorillonite nano-particles. Two different types of nano-clays, Cloisite® 30B and RXG7000, produced by Southern Clay Products Inc., have been considered. Three-point bending tests, both monotonic and cyclic, were carried out. A strong reduction of the ultimate flexural strength upon nano-modification has been observed in quasi-static tests. Fatigue tests yielded a smaller strength loss. In both quasi-static and fatigue tests a more pronounced tendency to delamination has been noticed in three-phase composites, especially in the case of 30B nano-clay, with respect to the standard two-phase glass fiber composite.

Keywords: Bending fatigue, epoxy resin, glass fiber, montmorillonite.

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306 Calculation of the Thermal Stresses in an Elastoplastic Plate Heated by Local Heat Source

Authors: M. Khaing, A. V. Tkacheva

Abstract:

The work is devoted to solving the problem of temperature stresses, caused by the heating point of the round plate. The plate is made of elastoplastic material, so the Prandtl-Reis model is used. A piecewise-linear condition of the Ishlinsky-Ivlev flow is taken as the loading surface, in which the yield stress depends on the temperature. Piecewise-linear conditions (Treska or Ishlinsky-Ivlev), in contrast to the Mises condition, make it possible to obtain solutions of the equilibrium equation in an analytical form. In the problem under consideration, using the conditions of Tresca, it is impossible to obtain a solution. This is due to the fact that the equation of equilibrium ceases to be satisfied when the two Tresca conditions are fulfilled at once. Using the conditions of plastic flow Ishlinsky-Ivlev allows one to solve the problem. At the same time, there are also no solutions on the edge of the Ishlinsky-Ivlev hexagon in the plane-stressed state. Therefore, the authors of the article propose to jump from the edge to the edge of the mine edge, which gives an opportunity to obtain an analytical solution. At the same time, there is also no solution on the edge of the Ishlinsky-Ivlev hexagon in a plane stressed state; therefore, in this paper, the authors of the article propose to jump from the side to the side of the mine edge, which gives an opportunity to receive an analytical solution. The paper compares solutions of the problem of plate thermal deformation. One of the solutions was obtained under the condition that the elastic moduli (Young's modulus, Poisson's ratio) which depend on temperature. The yield point is assumed to be parabolically temperature dependent. The main results of the comparisons are that the region of irreversible deformation is larger in the calculations obtained for solving the problem with constant elastic moduli. There is no repeated plastic flow in the solution of the problem with elastic moduli depending on temperature. The absolute value of the irreversible deformations is higher for the solution of the problem in which the elastic moduli are constant; there are also insignificant differences in the distribution of the residual stresses.

Keywords: Temperature stresses, elasticity, plasticity, Ishlinsky-Ivlev condition, plate, annular heating, elastic moduli.

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305 In-situ Observations Using SEM-EBSD for Bending Deformation in Single-Crystal Materials

Authors: Yuko Matayoshi, Takashi Sakai, Ying-jun Jin, Jun-ichi Koyama

Abstract:

To elucidate the material characteristics of single crystals of pure aluminum and copper, the respective relations between crystallographic orientations and microstructures were examined, along with bending and mechanical properties. The texture distribution was also analysed. Bending tests were performed in a SEM apparatus while its behaviors were observed. Some analytical results related to crystal direction maps, inverse pole figures, and textures were obtained from electron backscatter diffraction (EBSD) analyses.

Keywords: Pure aluminum, Pure copper, Single crystal, Bending, SEM-EBSD analysis, Texture, Microstructure.

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304 FEM Study of Different Methods of Fiber Reinforcement Polymer Strengthening of a High Strength Concrete Beam-Column Connection

Authors: Talebi Aliasghar, Ebrahimpour Komeleh Hooman, Maghsoudi Ali Akbar

Abstract:

In reinforced concrete (RC) structures, beam-column connection region has a considerable effect on the behavior of structures. Using fiber reinforcement polymer (FRP) for the strengthening of connections in RC structures can be one of the solutions to retrofitting this zone which result in the enhanced behavior of structure. In this paper, these changes in behavior by using FRP for high strength concrete beam-column connection have been studied by finite element modeling. The concrete damage plasticity (CDP) model has been used to analyze the RC. The results illustrated a considerable development in load-bearing capacity but also a noticeable reduction in ductility. The study also assesses these qualities for several modes of strengthening and suggests the most effective mode of strengthening. Using FRP in flexural zone and FRP with 45-degree oriented fibers in shear zone of joint showed the most significant change in behavior.

Keywords: High strength concrete, beam-column connection, FRP, FEM.

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303 A Self-Consistent Scheme for Elastic-Plastic Asperity Contact

Authors: Xu Jianguo

Abstract:

In this paper, a generalized self-consistent scheme, or “three phase model", is used to set up a micro-mechanics model for rough surface contact with randomly distributed asperities. The dimensionless average real pressure p is obtained as function of the ratio of the real contact area to the apparent contact area, 0 A / A r . Both elastic and plastic materials are considered, and the influence of the plasticity of material on p is discussed. Both two-dimensional and three-dimensional rough surface contact problems are considered.

Keywords: Contact mechanics, plastic deformation, self-consistent scheme.

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302 Static Study of Piezoelectric Bimorph Beams with Delamination Zone

Authors: A. Zemirline, M. Ouali, A. Mahieddine

Abstract:

The FOSDT (the First Order Shear Deformation Theory) is taking into consideration to study the static behavior of a bimorph beam, with a delamination zone between the upper and the lower layer. The effect of limit conditions and lengths of the delamination zone are presented in this paper, with a PVDF piezoelectric material application. A FEM “Finite Element Method” is used to discretize the beam. In the axial displacement, a displacement field appears in the debonded zone with inverse effect between the upper and the lower layer was observed.

Keywords: Beam, Delamination, Piezoelectricity, Static.

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301 Comparative Finite Element Simulation of Nonlinear Vibrations and Sensor Output Voltage of Smart Piezolaminated Structures

Authors: Ruediger Schmidt, Thang Duy Vu

Abstract:

Two geometrically nonlinear plate theories, based either on first- or third-order transverse shear deformation theory are used for finite element modeling and simulation of the transient response of smart structures incorporating piezoelectric layers. In particular the time histories of nonlinear vibrations and sensor voltage output of a thin beam with a piezoelectric patch bonded to the surface due to an applied step force are studied.

Keywords: Nonlinear vibrations, piezoelectric patches, sensor voltage output, smart structures.

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300 Studies on the Blended Concrete Prepared with Tannery Effluent

Authors: K. Nirmalkumar

Abstract:

There is a acute water problem especially in the dry season in and around Perundurai (Erode district, Tamil Nadu, India) where there are more number of tannery units. Hence an attempt was made to use the waste water from tannery industry for construction purpose. The mechanical properties such as compressive strength, tensile strength, flexural strength etc were studied by casting various concrete specimens in form of cube, cylinders and beams etc and were found to be satisfactory. Hence some special properties such as chloride attack, sulphate attack and chemical attack are considered and comparatively studied with the conventional potable water. In this experimental study the results of specimens prepared by using treated and untreated tannery effluent were compared with the concrete specimens prepared by using potable water. It was observed that the concrete had some reduction in strength while subjected to chloride attack, sulphate attack and chemical attack. So admixtures were selected and optimized in suitable proportion to counter act the adverse effects and the results were found to be satisfactory.

Keywords: Calcium nitrite, concrete, fly ash.

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299 Effects of Adding Fibre on Strength and Permeability of Recycled Aggregate Concrete Containing Treated Coarse RCA

Authors: Sallehan Ismail, Mahyuddin Ramli

Abstract:

This paper presents the experiment results of investigating the effects of adding various types and proportions of fibre on mechanical strength and permeability characteristics of recycled aggregate concrete (RAC), which was produced with treated coarse recycled concrete aggregate (RCA). Two types of synthetic fibres (i.e., barchip and polypropylene fibre) with various volume fractions were added to the RAC, which was calculated by the weight of the cement. The hardened RAC properties such as compressive strength, flexural strength, ultrasonic pulse velocity, water absorption and total porosity at the curing ages of 7 and 28 days were evaluated and compared with the properties of the control specimens. Results indicate that the treated coarse RCA enhances the mechanical strength and permeability properties of RAC and adding barchip fibre further optimises the results. Adding 1.2% barchip fibre has the best effect on the mechanical strength performance of the RAC.

Keywords: Barchip fibre, polypropylene fibre, recycled aggregate concrete.

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298 Fabrication of Al/Cu Clad Sheet by Shear Extrusion

Authors: Joon Ho Kim, Duck Su Kim, Tae Kwon Ha

Abstract:

Aluminum/Copper clad sheet has been fabricated using asymmetric extrusion method, which caused severe shear deformation between Al and Cu plate to easily bond to each other. Interfacial microstructure and mechanical properties of Al/Cu clad were studied by scanning electron microscope equipped with energy dispersive X-ray detector, micro-hardness, and tension tests. The asymmetric extrusion bonding was very effective to provide a good interface for atoms diffusion during subsequent annealing. The strength of bonding was higher with the increasing extrusion ratio.

Keywords: Aluminum/Copper clad sheet, Asymmetric extrusion, Interfacial microstructure, Annealing, Tensile test.

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297 Structural Cost of Optimized Reinforced Concrete Isolated Footing

Authors: Mohammed S. Al-Ansari

Abstract:

This paper presents an analytical model to estimate the cost of an optimized design of reinforced concrete isolated footing base on structural safety. Flexural and optimized formulas for square and rectangular footingare derived base on ACI building code of design, material cost and optimization. The optimization constraints consist of upper and lower limits of depth and area of steel. Footing depth and area of reinforcing steel are to be minimized to yield the optimal footing dimensions. Optimized footing materials cost of concrete, reinforcing steel and formwork of the designed sections are computed. Total cost factor TCF and other cost factors are developed to generalize and simplify the calculations of footing material cost. Numerical examples are presented to illustrate the model capability of estimating the material cost of the footing for a desired axial load.

Keywords: Footing, Depth, Concrete, Steel, Formwork, Optimization, Material cost, Cost Factors.

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296 Trispectral Analysis of Voiced Sounds Defective Audition and Tracheotomisian Cases

Authors: H. Maalem, F. Marir

Abstract:

This paper presents the cepstral and trispectral analysis of a speech signal produced by normal men, men with defective audition (deaf, deep deaf) and others affected by tracheotomy, the trispectral analysis based on parametric methods (Autoregressive AR) using the fourth order cumulant. These analyses are used to detect and compare the pitches and the formants of corresponding voiced sounds (vowel \a\, \i\ and \u\). The first results appear promising, since- it seems after several experimentsthere is no deformation of the spectrum as one could have supposed it at the beginning, however these pathologies influenced the two characteristics: The defective audition influences to the formants contrary to the tracheotomy, which influences the fundamental frequency (pitch).

Keywords: Cepstrum, cumulant, defective audition, tracheotomisy, trispectrum.

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295 Preparation and Some Mechanical Properties of Composite Materials Made from Sawdust, Cassava Starch and Natural Rubber Latex

Authors: Apusraporn Prompunjai, Waranyou Sridach

Abstract:

The composite materials were prepared by sawdust, cassava starch and natural rubber latex (NR). The mixtures of 15%w/v gelatinized cassava starch and 15%w/v PVOH were used as the binder of these composite materials. The concentrated rubber latex was added to the mixtures. They were mixed rigorously to the treated sawdust in the ratio of 70:30 until achive uniform dispersion. The batters were subjected to the hot compression moulding at the temperature of 160°C and 3,000 psi pressure for 5 min. The experimental results showed that the mechanical properties of composite materials, which contained the gelatinized cassava starch and PVOH in the ratio of 2:1, 20% NR latex by weight of the dry starch and treated sawdust with 5%NaOH or 1% BPO, were the best. It contributed the maximal compression strength (341.10 + 26.11 N), puncture resistance (8.79 + 0.98 N/mm2) and flexural strength (3.99 + 0.72N/mm2). It is also found that the physicochemical and mechanical properties of composites strongly depends on the interface quality of sawdust, cassava starch and NR latex.

Keywords: Composites, sawdust, cassava starch, natural rubber (NR) latex, surface chemical treatments.

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294 Modeling of Cobalt-Chromium-Molybdenum Alloy Implant for Fractured Distal Femur

Authors: Abhishek Soni, Bhagat Singh

Abstract:

Distal femur fractures are the cause of abnormal gloomy. Several types of surgical treatments have been adopted by the practitioners to restore the fractured region of distal femur. Still within this domain of study, unstable fixation remains a challenge for orthopedists. In the present study, a fixation implant is designed and analyzed under physiological loading conditions for cobalt-chromium-molybdenum alloy (Co-Cr-Mo). It has been found that the stresses and deformation developed are quite low. It means that customized fixation plates will provide stable fixation resulting in improved fracture union.

Keywords: Biomechanical evaluations, customized implant, Co-Cr-Mo alloy, reverse engineering.

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293 Mathematical Modeling of SISO based Timoshenko Structures – A Case Study

Authors: T.C. Manjunath, Student Member, B. Bandyopadhyay

Abstract:

This paper features the mathematical modeling of a single input single output based Timoshenko smart beam. Further, this mathematical model is used to design a multirate output feedback based discrete sliding mode controller using Bartoszewicz law to suppress the flexural vibrations. The first 2 dominant vibratory modes is retained. Here, an application of the discrete sliding mode control in smart systems is presented. The algorithm uses a fast output sampling based sliding mode control strategy that would avoid the use of switching in the control input and hence avoids chattering. This method does not need the measurement of the system states for feedback as it makes use of only the output samples for designing the controller. Thus, this methodology is more practical and easy to implement.

Keywords: Smart structure, Timoshenko beam theory, Discretesliding mode control, Bartoszewicz law, Finite Element Method, State space model, Vibration control, Mathematical model, SISO.

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292 Grooving Method to Postpone Debonding of FRP Sheets Used for Shear Strengthening

Authors: Davood Mostofinejad, Seyed Amirali Mostafavizadeh, Amirhomayoon Tabatabaei Kashani

Abstract:

One of the most common practices for strengthening the reinforced concrete structures is the application of FRP (Fiber Reinforce Plastic) sheets to increase the flexural and shear strengths of the member. The elastic modulus of FRP is considerably higher than that of concrete. This will result in debonding between the FRP sheets and concrete surface. With conventional surface preparation of concrete, the ultimate capacity of the FRP sheets can hardly be achieved. New methods for preparation of the bonding surface have shown improvements in reducing the premature debonding of FRP sheets from concrete surface. The present experimental study focuses on the application of grooving method to postpone debonding of the FRP sheets attached to the side faces of concrete beams for shear strengthening. Comparison has also been made with conventional surface preparation method. This study clearly shows the efficiency of grooving method compared to surface preparation method, in preventing the debonding phenomenon and in increasing the load carrying capacity of FRP.

Keywords: FRP composite, grooving, rehabilitation, reinforced concrete, shear strengthening, surface preparation.

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291 Mechanical Behaviour Analysis of Polyester Polymer Mortars Modified with Recycled GFRP Waste Materials

Authors: M.C.S. Ribeiro, J.P. Meixedo, A. Fiúza, M.L. Dinis, Ana C. Meira Castro, F.J.G. Silva, C. Costa, F. Ferreira, M.R. Alvim

Abstract:

In this study the effect of incorporation of recycled glass-fibre reinforced polymer (GFRP) waste materials, obtained by means of milling processes, on mechanical behaviour of polyester polymer mortars was assessed. For this purpose, different contents of recycled GFRP waste powder and fibres, with distinct size gradings, were incorporated into polyester based mortars as sand aggregates and filler replacements. Flexural and compressive loading capacities were evaluated and found better than unmodified polymer mortars. GFRP modified polyester based mortars also show a less brittle behaviour, with retention of some loading capacity after peak load. Obtained results highlight the high potential of recycled GFRP waste materials as efficient and sustainable reinforcement and admixture for polymer concrete and mortars composites, constituting an emergent waste management solution.

Keywords: GFRP waste, Mechanical behaviour, Polymer mortars, Recyclability.

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290 Mechanical and Thermal Properties Characterisation of Vinyl Ester Matrix Nanocomposites Based On Layered Silicate: Effect of Processing Parameters

Authors: A. I. Alateyah, H. N. Dhakal, Z. Y. Zhang

Abstract:

The mechanical properties including flexural and tensile of neat vinyl ester and polymer based on layered silicate nanocomposite materials of two different methodologies are discussed. Methodology 1 revealed that the addition of layered silicate into the polymer matrix increased the mechanical and thermal properties up to 1 wt.% clay loading. The incorporation of more clay resulted in decreasing the properties which was traced to the existence of aggregation layers. The aggregation layers imparted a negative impact on the overall mechanical and thermal properties. On the other hand, methodology 2 increased the mechanical and thermal properties up to 4 wt.% clay loading. The different amounts of improvements were assigned to the various preparation parameters. Wide Angle X-ray Diffraction, Scanning Electron Microscopy and Transmission Electron Microscopy were utilized in order to characterize the interlamellar structure of nanocomposites.

Keywords: Vinyl ester, nanocomposites, layered silicate, mechanical properties, thermal analysis.

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289 Lamb Waves in Plates Subjected to Uniaxial Stresses

Authors: Munawwar Mohabuth, Andrei Kotousov, Ching-Tai Ng

Abstract:

On the basis of the theory of nonlinear elasticity, the effect of homogeneous stress on the propagation of Lamb waves in an initially isotropic hyperelastic plate is analysed. The equations governing the propagation of small amplitude waves in the prestressed plate are derived using the theory of small deformations superimposed on large deformations. By enforcing traction free boundary conditions at the upper and lower surfaces of the plate, acoustoelastic dispersion equations for Lamb wave propagation are obtained, which are solved numerically. Results are given for an aluminum plate subjected to a range of applied stresses.

Keywords: Acoustoelasticity, dispersion, finite deformation, lamb waves.

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288 Experimental Investigation of Cold-Formed Steel-Timber Board Composite Floor Systems

Authors: Samar Raffoul, Martin Heywood, Dimitrios Moutaftsis, Michael Rowell

Abstract:

This paper comprises an experimental investigation into the structural performance of cold formed steel (CFS) and timber board composite floor systems. The tests include a series of small-scale pushout tests and full-scale bending tests carried out using a refined loading system to simulate uniformly distributed constant load. The influence of connection details (screw spacing and adhesives) on floor performance was investigated. The results are then compared to predictions from relevant existing models for composite floor systems. The results of this research demonstrate the significant benefits of considering the composite action of the boards in floor design. Depending on connection detail, an increase in flexural stiffness of up to 40% was observed in the floor system, when compared to designing joists individually.

Keywords: Cold formed steel joists, composite action, flooring systems, shear connection.

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