Cylinder Of Material Research Articles

Effects of Fiber Diameter and Tribotest Conditions on Nonlubricated Frictional Behavior of a Microsized Metal Fiber

ABSTRACTExperimental determination of the frictional properties of a microsized fiber wrapped around a cylinder has been of long-standing interest to the academic community. The purpose of the current experiments was to explore the diameter dependence of such microsized fibers in nonlubricated friction using a highly accurate tribometer. For this work, NbTi superconducting material was used for the fibers and polyvinyl chloride (PVC) was used as the cylinder material. Significant effects were observed in the kinetic friction coefficient for different fiber diameters, normal forces, and sliding speeds. Moreover, the effects of fiber diameter on the frictional stability were measured. Smaller fiber diameters and low sliding speeds both produced poor frictional stability. The most likely explanation for the observed stick–slip phenomena is hypothesized to be a combination of creep mechanics and plastic deformation of the junctions on the contacting surfaces.

Influence of different treatments of the ceramic surface and thermal cycling on the bond strength of brackets to ceramic

Abstract Objective To evaluate in vitro the effect of different treatments of the ceramic surface and thermal cycling on the shear bond strength (SBS) of metallic brackets bonded to feldspathic ceramic. Material and method Ceramic cylinders were divided into four groups (n=4) according to the treatment of ceramic surface: G1-Clearfil Ceramic Primer silane and Transbond XT (CCPT); G2-etched with 10% hydrofluoric acid (HFA) for 60 s, CCP and Transbond XT (ACCPT); G3-etched with 10% HFA for 60 s, Ambar Adhesive and Transbond XT (AAAT); and, G4 - etched with 10% HFA for 60 s, RelyX Ceramic Primer silane -RCP, adhesive primer Transbond and Transbond XT (ACPPT). Brackets were bonded to the cylinders with Transbond XT and light-activated for 40 s with LED Radii Plus. All specimens were stored in deionized water at 37 °C for 24 h, and two cylinders from each group were subject to 7,000 thermal cycles in a thermal cycler (5 °C/55 °C). After storage and thermal cycling, the SBS test was performed at a crosshead speed of 1 mm/min. Data were subjected to two-way ANOVA and Tukey’s post hoc test (α=0.05). Result The SBS of ACCPT was significantly higher than the other groups (p<0.05). The specimens submitted to thermal cycling showed significantly lower SBS than those without thermal cycling (p<0.05), regardless the ceramic surface treatment. The ARI showed predominance of score 0 for all groups. Conclusion Acid etching, CCP silane and Transbond XT method obtained the best results for bracket bonding. Thermal cycling reduced SBS for all groups. Score 0 was predominant for ARI in all groups.

Evaluation of metal artefact reduction in cone-beam computed tomography images of different dental materials.

The aim of this study is to evaluate the efficacy of metal artefact reduction (MAR) in different dental materials with Picasso Trio cone-beam computed tomography (CBCT) scanner. Three imaging phantoms were custom-made of acrylic resin. Each phantom presented three cylinders of the same material: dental amalgam alloy, gutta-percha or aluminium-copper alloy. CBCT scans were performed on Picasso Trio unit with and without MAR, and artefact expression (standard deviation of grey values) was obtained and compared by Kruskal-Wallis and Student-Newman-Keuls (post hoc) (α=0.05). Significant reduction of artefact expression (p<0.05) was observed with MAR on areas around dental alloys. No significant difference (p>0.05) was observed with or without MAR when gutta-percha was scanned. MAR was effective in reducing artefacts arising from dental alloys on CBCT images. Dental materials of high atomic number and density are widely used in dentistry and can produce artefact that compromise CBCT image. The present study demonstrated that metal artefact reduction algorithm is an effective tool to improve image quality.

A singular integral equation for the current density of a conformal microstrip dipole on a dielectric cylinder

The problem of current-density distribution over the surface of a microstrip dipole antenna conformally arranged on a dielectric cylinder is reduced to a singular integral equation with a Cauchy kernel. Patterns of current distribution on the antenna surface for various values of dielectric permittivity of the cylinder material are presented.

Evaluation of the efficacy of a metal artifact reduction algorithm in different cone beam computed tomography scanning parameters

The aim of this study was to evaluate the efficacy of a metal artifact reduction (MAR) algorithm in cone beam computed tomography (CBCT) images of dental materials obtained with different field-of-view (FOV) and voxel sizes. Two imaging phantoms were custom-made of acrylic resin. Each phantom had 3 cylinders made of the same dental material: dental amalgam or copper-aluminum alloy. CBCT scans were obtained separately for each of the imaging phantoms using the Picasso-Trio CBCT (Vatech, Hwaseong, Republic of Korea) unit at 4 FOV sizes and 2 voxel sizes. Each imaging phantom was scanned with and without MAR. All images were evaluated in the OnDemand3D software (Cybermed, Seoul, Republic of Korea) and image noise (gray value variability) was calculated as the standard deviation (SD) of the gray values of regions of interest around the dental material cylinders. Data were compared by the Friedman test and Dunn test (α=0.05). Intraclass correlation coefficient (ICC) was calculated to assess intraobserver reliability. MAR significantly reduced (P<.05) image noise around the dental materials, irrespective of FOV and voxel sizes, with an ICC of 0.997. The efficacy of MAR was similar for the different FOV and voxel sizes studied. Hence, imaging protocols and the use of MAR algorithm should be based on the selection criteria.

Development of novel symmetrical electrode metal-core piezoelectric fibers for an application as airflow sensors

Crickets and many other orthopteran insects can detect an impinging airflow using mechanosensory hairs located on their cerci. Inspired by these filiform mechanosensory hairs, a new symmetrical electrodes metal-core piezoelectric fiber (SMPF) was designed and fabricated as a building block for future airflow sensors. This novel type of airflow sensor was produced utilizing the extrusion method and high-temperature sintering. A metal core was basically located at the center of the fiber and surrounded by a hollow cylinder of ceramic material. Two thin metal films were spray-coated symmetrically on the surface of the fiber on opposite sides. After successful polarization, the two surface metal layers could be used as sensor electrodes. This way, a cantilevered SMPF was able to detect the strength and direction of an impinging airflow. A theoretical model of the SMPF airflow sensor was established and validated by the experimental results. The results further showed that the electric charge generated on the electrodes of a cantilevered SMPF grows exponentially with the airflow strength, and that it is proportional to the cosine of the airflow direction.

Effect of Annealing Process on the Performance of Pressure of the φ3.5mm×8.75mm Cylindrical Copper Cylinder

By using different annealing processes to anneal the pressure-measuring cylindrical copper cylinder, playing some static experiments on different copper cylinders, the difference of pressure measuring performance of copper cylinder was analyzed. Results show that, by using current annealing processes all can achieve the purpose of full softening the material of the copper cylinder and the deformation of copper is not significantly affected by the different temperatures. Some copper cylinders which use short holding time have poor linear sensitivity, but their measurement deviation is better than those which use longer holding time. So, in the actual production of copper, we should use shorter annealing time to improve their measuring accuracy.

Optimisation of monotube magnetorheological damper under shear mode

Magnetorheological dampers (MR) are one of the semi active devices, which has the capability of providing variable damping force for the variable input current. Induced force is directly dependent on the amount of magnetic flux density developed in effective fluid flow gap of the MR damper. In the present work, influence of material properties on the magnetic flux is investigated by considering magnetic and nonmagnetic material for the outer cylinder of shear mode type MR damper. Magnetostatic analysis is carried out to obtain magnetic flux density for the initial configuration of the MR damper. From the analysis, it is found that usage of magnetic material cylinder which is insulated with nonmagnetic material provided higher value of magnetic flux and damping force. The geometric optimisation of MR damper is carried out to obtain the maximum flux density in the fluid flow gap. The objective function of the optimisation includes the maximum magnetic flux density and minimising fluid flow gap. Design variables considered are fluid flow gap, number of turns in the electromagnetic coil, length of the flange and DC current input. The optimisation is performed through response surface method using finite element analysis software (ANSYS). The best optimal design parameters are obtained by choosing the appropriate value of objective function. The best configuration of the design parameters, which induce the maximum magnetic flux density, is identified. The force induced in the MR damper is estimated analytically and a comparative study of the optimised and non-optimised results was carried out.

An experimental and numerical study on the volume change of particle-filled elastomers in various loading modes

Laboratory tests show that there is a pronounced difference in the volumetric response between uniaxial tension and confined axial compression loading for commercial particle-filled hydrogenated nitrile butadiene rubber (HNBR) and fluoroelastomer (FKM) compounds. In uniaxial tension (UT), a volume increase of 5% and 20% for the HNBR and FKM respectively was present for a hydrostatic stress of less than 6 MPa, in addition, both compounds showed a clear hysteresis loop in the hydrostatic stress - volume ratio space. For confined axial compression (CAC) tests, on the other hand, the materials reached a 6–7% volume change for a hydrostatic stress of 140 MPa, and an elastic behavior was seen. This loading mode dependence of the volumetric response has severe implications for the constitutive representation of the materials. It is demonstrated that existing elastomer models, whereof many assume incompressible volumetric response, are unable to capture the behavior in both loading modes. To gain an increased understanding of the macroscopically obtained results, a tension in situ scanning electron microscopy study was performed. Matrix–particle debonding was observed to occur at the external surface of the materials, rendering a possible explanation for the loading mode dependent volumetric behavior. Finite element simulations of a single-particle model, incorporating a cylinder of matrix material with a spherical particle in its center, showed that the observed debonding can explain the experimental response of the materials in a qualitative manner.

Thermal Analysis of cylinder block with fins for different materials using ANSYS

In internal combustion engines cylinder part is the heart of the engine and this cylinder block forms the walls of a combustion chamber where air fuel mixture burns. Due to this continues combustion process the cylinder walls subjected combustion zone and heat transfer takes place through the cylinder material. If the heat is not dissipated properly then it causes to development of detonation and it finally decreases the working efficiency of the engine, hence the heat removal rate from the cylinder is one of the important and interesting task. Mostly the heat transfer rate through the material is depends on the thermal conductivity of the material. Hence in this paper an attempt has been made to find out the thermal analysis of cylinder block with fins for different materials by using ANSYS, and the results has been analyzed to find out the best material that gives the better heat transfer rate and consists of light weight.

TRIBOLOGICAL PERFORMANCE OF REFINED, BLEACHED AND DEODORISED PALM OLEIN BLENDS BIO-LUBRICANTS

Vegetable oils have been investigated to replace petroleum lubricants due to their environmental-friendly characteristics and have become a vital source of bio-lubricants. In the investigation of the tribological characteristics of palm oil as the vegetable oil, using in its neat form or as partial bio-lubricants, a reciprocating machine was employed. Initially, refined, bleached and deodorised (RBD) palm olein with mineral oil blends were optimised using the design of experiments procedure from the outcomes of the four ball tribotester. The optimised blend was found to have characteristics that were better or at par with mineral oil. Then, a reciprocating machine was used for verifying the blend. In the investigation of the optimised blend, the sample was tested for a total of 60 hr in intermittent operation. Other than having similar viscosity for the ISO requirements, the optimised blend demonstrates decreased in the values of material weight loss and cylinder temperatures as compared with mineral oil. Finally, it is concluded that the RBD palm olein blend (E53.11/RB46.89) could be a potential partial bio-lubricant due to having no negative impact on wear and decent performance as a bio-lubricator.

Investigation of stress intensity factor for internal cracks in FG cylinders under static and dynamic loading

This paper investigates the variations of mode I stress intensity factor (KI) for inner penny-shaped and circumferential cracks in functionally graded solid and hollow thick walled cylinders, respectively with the changes of crack geometry, material gradation and loading conditions. The functionally graded material of cylinders consists of epoxy and glass. It is assumed that the mechanical properties vary with a power law in the radial direction of cylinders. Micromechanical models for conventional composites are used to estimate the material properties of functionally graded cylinders. The equations of motion obtained from the extended finite element discretization are solved by the Newmark method in the time domain. The interaction integral method is employed to calculate the mode I stress intensity factor (KI). The MATLAB programming environment was implemented to solve the problem.

Analytical modelling of bond stress at steel concrete interface due to corrosion

AbstractAn analytical model is proposed for bond stresses at the corroded steel‐concrete interface in reinforced concrete. The concrete around the corroded bar is modelled as a thick‐walled cylinder – consisting of an inner cylinder of an anisotropic material and an outer cylinder made of an isotropic material – subjected to internal pressure exerted by the growth of corrosion products on the concrete wall at the interface. A frictional model is used to combine the action of confining pressure due to radial pressure produced by principal bar ribs and the pressure resulting from expansion of corrosion products. The analysis results using the proposed model show good agreement with the experimental results of several researchers.

Smoothed particle hydrodynamics modeling of granular column collapse

The Smoothed Particle Hydrodynamics (SPH) is a particle-based, Lagrangian method for fluid-flow simulations. In this work, fundamental concepts of this method are first briefly recalled. Then, the ability to accurately model granular materials using an introduced visco-plastic constitutive rheological model is studied. For this purpose sets of numerical calculations (2D and 3D) of the fundamental problem of the collapse of initially vertical cylinders of granular materials are performed. The results of modeling of columns with different aspect ratios and different angles of internal friction are presented. The numerical outcomes are assessed not only with respect to the reference experimental data but also with respect to other numerical methods, namely the Distinct Element Method and the Finite Element Method. In order to improve the numerical efficiency of the method, the Graphics Processing Units implementation is presented and some related issues are discussed. It is believed that this study corresponds to a new application of SPH approaches for simulations of granular media and results reveal the interest of this method to capture fine details of processes of such complex problems as waves–seabed interactions.

Numerical Investigation and Nondimensional Analysis of the Dynamic Performance of a Thermal Energy Storage System Containing Phase Change Materials and Liquid Water

The dynamic performance of a thermal energy storage tank containing phase change material (PCM) cylinders is investigated computationally. Water flowing along the length of the cylinders is used as the heat transfer fluid. A numerical model based on the enthalpy-porosity method is developed and validated against experimental data from the literature. The performance of this hybrid PCM/water system was assessed based on the gain in energy storage capacity compared to a sensible only system. Gains can reach as high as 179% by using 50% packing ratio and 10 °C operating temperature range in water tanks. Gains are highly affected by the choice of PCM module diameter; they are almost halved as diameter increases four times. They are also affected by the mass flow rate nonlinearly. A nondimensional analysis of the energy storage capacity gains as a function of the key nondimensional parameters (Stefan, Fourier, and Reynolds numbers) as well as PCM melting temperature was performed. The simulations covered ranges of 0.1 &lt; Stẽ &lt; 0.4, 0 &lt; Fo &lt; 600, 20 &lt; Re &lt; 4000, 0.2&lt;(ρCP)*&lt;0.8, and 0.2&lt;θm&lt;0.8.

Wave propagation and transient response of a fluid-filled FGM cylinder with rigid core using the inverse Laplace transform

Abstract This paper studies the wave propagation and transient response of a fluid-filled functionally graded material (FGM) cylinder with rigid core using the Laplace transform. The mechanical properties of the FGM are assumed to vary smoothly and continuously with the change of volume concentrations of the constituting materials across the thickness of the structure according to a specific grading pattern. The FGM cylinder is approximated by a laminate model, for which the solution is expected to gradually approach the exact one as the number of layers' increases. For each layer of the cylinder, equations of motion are extracted based on elasticity theory. The equations of motion are derived in the form of plane strain according to the problem definition. Then, transfer matrix method, which includes a global transfer matrix that composed as the product of the local transfer matrices by applying continuity of the displacement and stress components at the interfaces of neighboring layers, is employed. This problem is solved in the Laplace domain and the Durbin's numerical Laplace transform inversion is employed to convert the obtained results into the time domain. Finally, the effects of various radius of rigid core on hydrodynamic field of fluid and transient response of the FGM cylinder subjected to impulsive loads are examined in detail. The numerical results show that von-misses stress considerably decreased by increasing the radius of rigid core.

Wear Characteristics of Hybrid Al 6063 Matrix Composites Reinforced with Graphite and Fly Ash Particulates

As auto manufacturers strive to meet imposed fuel economy and emissions regulations while producing vehicles with the quality and features that consumer expect, the industry needs to rely on advancements made in the field of metal matrix composites. The efforts of combining or replacing metals with the use of advanced metal matrix composites (MMCs) not only reduce weight, but can also improve safety, reliability and efficiency. A hybrid MMC was developed for the cylinder liner of advanced diesel engines. Composites of Al-6063 aluminium alloy reinforced with, fly ash particulate containing 10% and graphite particulate containing 5, 10 and 15 % were produced by stir casting. The wear and frictional properties of the casted hybrid metal matrix composites were investigated by performing dry sliding wear test using a pin-on-disc wear tester. The investigation was done to find the influence of applied load, sliding speed and sliding distance on wear rate, as well as the coefficient of friction during wearing process. From the investigation, it is evident that wear resistance of Al-6063 is increased while adding the fly ash and graphite reinforcement content. The results were compared with the existing liner material. From this comparative study the Al-6063/fly ash/graphite hybrid metal matrix composite can be the considered as an alternative material for existing cylinder material.

Disintegration process and performance of a coaxial porous injector

In order to understand the breakup performance of coaxial porous injectors, the sprays of coaxial porous injectors with two different porous material cylinder lengths were compared with those of conventional shear coaxial injectors. To allow comparison, the wall injection lengths were designed to be equivalent to the value of the recess depth. Cold flow sprays were visualized using back-lit photography methods and analyzed quantitatively with a laser diffraction apparatus, in order to study the effects of the momentum flux ratio and Weber number on the breakup for each type of injector. In case of the shear coaxial injector, the large liquid core was observed in low air mass flow rate condition. However, the destabilization of the liquid jet from the coaxial porous injector is almost complete within the inner region, near the injector face plate. Additionally, better breakup performance in low gas flow rate condition was obtained when the porous cylinder length decreased, while the shear coaxial injectors showed better breakup efficiency when the recess length increased. In conclusion, the different breakup process caused by the radial momentum in the inner region of the porous injector disintegrated the liquid core.

Electromagnetic scattering from cylinders of infinite length immersed in a complex conjugate medium

Electromagnetic wave scattering from cylinders of different materials immersed in complex conjugate medium (CCM) is studied. CCM is a non-dissipative medium through which electromagnetic wave can travel without attenuation. Lengths of cylinders are infinite and CCM is also taken as infinite. Chiral, perfect electromagnetic conductor (PEMC), nihility and dielectric cylinders have been considered for the analysis. TM polarization is considered for the normally incident plane wave on the cylinder. Scattered fields are then formulated in terms of unknown coefficients. It is a boundary value problem. Boundary conditions are used according to the material of the cylinder to find the unknown coefficients. Once the scattered fields are known, far fields approximations are used to find the scattering widths for the co and cross polarized components. Numerical results are shown to give a comparison between the cylinders of different materials immersed in the same material. Comparison of work found in good agreement with already published work.

Validation of material constitutive parameters for the AISI 1010 steel from Taylor impact tests

Numerical simulations of high strain-rate events require robust characterization of constitutive material parameters in order to predict accurately the deformation process. Historically, this characterization has been performed using non-standardized techniques such as the Taylor impact test, where specimen's final deformed geometry is used to determine the material constitutive parameters by inverse analysis. However, validation of material parameters found in this way, in terms of internal plastic strains, is an open research problem. In this work, material constitutive parameters of steel AISI 1010 found by inverse analysis from Taylor tests at ~5×103s−1 were validated. This was done by comparing the Vickers hardness profile along the axis of a deformed specimen against the numerically calculated hardness from a finite element model of the Taylor impact, which used the constitutive parameters found by inverse analysis. To map the simulated effective plastic strains found in the model into Vickers hardness, an experimentally-derived analytical relation between compressive quasi-static plastic strains and Vickers hardness on cylinders of the same material was used. It was found that the material constitutive parameters of steel AISI 1010 characterized by inverse analysis, from silhouettes of deformed Taylor tests, are capable to predict the plastic-strain distribution inside the deformed material.