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Static and free vibration analysis of four-parameter continuous grading elliptical sandwich plates

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Applied mathematics and mechanics(English Edition) 2022年第4期43卷 523-536页

作者： m.h.YAS F.AKhLAGhI S.KAmARIAN A.h.YAS Department of mechanical Engineering Razi UniversityKermanshah ***Iran Department of mechanical Engineering Ilam BranchIslamic Azad UniversityIlam ***Iran Department of mechanical Engineering Amir-Kabir University of TechnologyTehran 158754413Iran

In the present study,the static and dynamic analyses of elliptical functionally graded sandwich(FGS)plates are *** constituent materials of the sandwich plates are ceramic and metal so that the core is made of pure metal,while the face sheets consist of a combination of metal and ceramic according to a four-parameter power-law *** material profiles such as classic,symmetric,and asymmetric can be obtained using the applied generalized power-law distribution *** analysis is performed based on the classical laminated plate theory(CLPT)and the Ritz *** effects of four parameters in the material distribution relation as well as different geometric parameters on the deflection and natural frequencies of elliptical FGS plates are *** results of this study show that with a proper distribution of materials,the optimal static and dynamic behavior can be *** results also indicate that the generalized power-law distribution has significant effects on the natural frequencies of elliptical FGS *** example,although the frequency parameter of a plate with ceramic face sheets is more than the one with metal face sheets,the use of larger amounts of ceramic does not necessarily increase the natural frequency of the structure.

关键词： elliptical plate sandwich plate four-parameter power-law distribution static analysis free vibration analysis Ritz method

An extended cell-based smoothed discrete shear gap method （XCS-FEm-DSG3） for free vibration analysis of cracked Reissner-mindlin shells

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Frontiers of Structural and Civil Engineering 2015年第4期9卷 341-358页

作者： m. h. NGUYEN-ThOI Division of Computational mathematics and Engineering (CmE) Institute for Computational Science (INCOS) Ton Duc ThangUniversity Hochiminh city Vietnam Faculty of Civil Engineering Ton Duc Thang University Hochiminh city Vietnam

A cell-based smoothed discrete shear gap method (CS-FEm-DSG3) was recently proposed and proven to be robust for free vibration analyses of Reissner-mindlin shell. The method improves significantly the accuracy of the solution due to softening effect of the cell-based strain smoothing technique. In addition, due to using only three-node triangular elements generated automatically, the CS-FEm-DSG3 can be applied flexibly for arbitrary complicated geometric domains. however so far, the CS-FEm-DSG3 has been only developed for analyzing intact structures without possessing internal cracks. The paper hence tries to extend the CS-FEm-DSG3 for free vibration analysis of cracked Reissner-mindlin shells by integrating the original CS-FEm-DSG3 with discontinuous and crack–tip singular enrichment functions of the extended finite element method (XFEm) to give a so-called extended cell-based smoothed discrete shear gap method (XCS-FEm-DSG3). The accuracy and reliability of the novel XCS-FEm-DSG3 for free vibration analysis of cracked Reissner-mindlin shells are investigated through solving three numerical examples and comparing with commercial software ANSYS.

关键词： cracked Reissner-mindlin shell free vibration analysis cell-based smoothed discrete shear gap method (CS-FEm-DSG3) extended cell-based smoothed discrete shear gap method (XCS-FEm-DSG3) smoothed finite element methods (SFEm)

Performance enhancement of water bath heater at natural gas city gate station using twisted tubes

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Chinese Journal of Chemical Engineering 2020年第1期28卷 165-179页

作者： P.Soleimani m.Khoshvaght-Aliabadi h.Rashidi h.Bahmanpour Department of Chemical Engineering Shahrood BranchIslamic Azad UniversityShahroodIran Department of Environment Shahrood BranchIslamic Azad UniversityShahroodIran

Natural gas is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is reduced in city gate stations(CGSs). Before the pressure reduction process, the temperature of natural gas is increased usually by using a water bath heater,which burns natural gas as fuel, to protect against freezing of natural gas. These types of heat exchangers have a low efficiency and consume a lot of fuel to generate the required heat. In the current study, the twisted configuration of the heating coil is proposed and investigated to enhance the heat transfer through a water bath heater with a nominal capacity of 1000 m^3·h^-1. Firstly, the implementation procedure is validated with data collected from the CGS of Qaleh-Jiq(located in Golestan province of Iran). A very good agreement is achieved between the obtained results and the real data. Then, three different twist ratios are considered to examine the twisting effects. The proposed technique is evaluated in the terms of velocity, temperature, and pressure variations, and the results are compared with the conventional case, i.e. straight configuration. It is found that both the heat transfer rate and the pressure drop augment as the twist ratio is raised. Finally, it is concluded that the twisted tubes can reduce the length of the gas coil by about 12.5% for the model with low twist ratio, 18.75% for the model with medium twist ratio, and 25% for the model with high twist ratio as compared to the straight configuration.

关键词： Natural gas city gate station Water bath heater heat transfer enhancement Twisted tube

Spectroscopic Study of a Radio-Frequency Atmospheric Pressure Dielectric Barrier Discharge with Anodic Alumina as the Dielectric

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Plasma Science and Technology 2013年第9期15卷 900-903页

作者： h.I.A.QAZI m.ShARIF S.hUSSAIN m.A.BADAR h.AFZAL Department of Physics University of SargodhaSargodha 40100Pakistan Department of Physics GC UniversityFaisalabad 38000Pakistan

This paper presents the fabrication and a spectroscopic study of a stable radio- frequency dielectric barrier discharge （RF DBD） in Ar with a novel dielectric, anodic alumina, at atmospheric pressure. Dielectric electrodes are fabricated from commercially available low cost impure aluminum strips by a two-step anodization process in 0.3 m solution of oxalic acid. The discharge is found to be stable with excellent spatial uniformity for the RF input power range of 30～80 W. Excitation and rotational temperatures measured in the experiment range of 1472～3255 K and 434～484 K, respectively, as the input power changes from 30 W to 80 W. These temperature ranges are suitable for surface modification applications.

关键词： radio frequency atmospheric pressure glow discharge dielectric barrier dis-charge anodic alumina dielectric

Nonlinear elastic constitutive relations of residually stressed composites with stiff curved fibres

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Applied mathematics and mechanics(English Edition) 2022年第10期43卷 1515-1530页

作者： m.h.B.m.Shariff J.merodio R.Bustamante Department of mathematics Khalifa University of Science and TechnologyAbu Dhabi127788United Arab Emirates Departamento de matemática Aplicada a las TIC ETS de Ingeniería de Sistemas InformaticosUniversidad Politecnica de MadridMadrid28031Spain Departamento de Ingeniería mecánica Universidad de ChileBeauchef 851Santiago CentroSantiago8370448Chile

mechanical models of residually stressed fibre-reinforced solids,which do not resist bending,have been developed in the ***,in some residually stressed fibre-reinforced elastic solids,resistance to fibre bending is significant,and the mechanical behavior of such solids should be ***,in this paper,we model the mechanical aspect of residually stressed elastic solids with bending stiffness due to fibre curvature,which up to the authors’knowledge has not been mechanically modeled in the *** proposed constitutive equation involves a nonsymmetric stress and a couple-stress *** invariants are used in the constitutive equation,where each spectral invariant has an intelligible physical meaning,and hence they are useful in experiment and analysis.A prototype strain energy function is ***,we use this prototype to give results for some cylindrical boundary value problems.

关键词： fibre-reinforced solid residual stress bending stiffness spectral invariant second gradient finite elasticity

Efficiency enhancement of building multi-layer solar collector with SiO2–TiO2 hybrid nanofluids

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Building Simulation 2023年第10期16卷 1851-1862页

作者： N.N.m.Zawawi W.h.Azmi Z.A.A.majid R.A.Rahim h.m.Ali Lebuhraya Tun Razak Centre for Research in Advanced Fluid and Processes26300GambangKuantanPahangMalaysia Faculty of mechanical and Automotive Engineering Technology Universiti Malaysia PahangPekanPahang26600Malaysia Kulliyyah of Allied health Sciences International Islamic University of MalaysiaBandar Indera Mahkota25200KuantanPahangMalaysia ECE Department Kulliyyah of EngineeringInternational Islamic University MalaysiaJalan GombakKuala LumpurMalaysia mechanical Engineering Department King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia Interdisciplinary Research Center for Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia

Due to the depletion of conventional energy sources and its limitless resources,solar energy is currently being considered as a viable alternative,especially for water heating *** thermal performance of multilayer solar collectors for water heating systems can be improved further by introducing hybrid nanofluids as advanced *** study demonstrates the utilisation of hybrid nanofluids in heating systems by employing a multilayer absorber solar *** SiO2–TiO2 hybrid nanofluids at volume concentrations up to 2.0%were tested at various flow rates(1.7 to 3.7 LPm)and solar radiation intensities(250 to 1000 W/m2).The thermal performance of the solar collector was assessed by measuring the temperature variation,heat loss,and overall efficiency of the *** the optimal volume concentration,the temperature difference for solar collectors employing SiO2–TiO2 hybrid nanofluids increased *** optimal volume concentration of 1.5%yields a maximum temperature difference of 9.5°*** addition,the efficiency and fluid temperature of the solar collector containing hybrid nanofluids have been enhanced by 22%and 37%,*** SiO2–TiO2 hybrid nanofluids with the optimal volume concentration of 1.5%were therefore recommended for maximum efficiency in the solar collector.

关键词： solar collector hybrid nanofluids solar water heating system solar simulator thermal efficiency

Thickness-dependent mechanical properties of nacre in Cristaria plicata shell:Critical role of interfaces

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Journal of materials Science & Technology 2020年第9期44卷 1-8页

作者： S.m.Liang h.m.Ji X.W.Li Department of materials Physics and Chemistry School of Materials Science and EngineeringKey Laboratory for Anisotropy and Texture of MaterialsMinistry of EducationNortheastern UniversityShenyang110819China

The thickness dependence of mechanical properties of nacre in Cristaria plicata shell was studied under three-point bending *** results show that the mechanical behavior of nacre exhibits a strong thickness *** bending strength firstly increases with the increase of specimen thickness and then becomes roughly constant as the thickness reaches a certain value of∼***,the mean value of work per unit volume increases constantly with increasing specimen thickness;meanwhile,the cracking mode changes from penetration into the platelets to deflection along the *** theoretical analyses indicate that the thickness-dependent mechanical properties of nacre are mainly caused by the variation in the number of inter-lamellar *** more the number of inter-lamellar interfaces is,the higher the strength and work of fracture of nacre under bending tests will ***,as the number of inter-lamellar interfaces reaches a certain value(e.g.,in the present specimen with 2.5mm thickness),the strength tends to remain constant,while the work of fracture still ***,the present research findings are expected to provide a valuable guidance for the interfacial design of nacre-like materials with high strength and toughness.

关键词： Cristaria plicata shell Nacre mechanical property Thickness Interface

manipulation of Crawling Growth for the Formation of Sub-millimeter Long ZnO Nanowalls

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Journal of materials Science & Technology 2008年第4期24卷 589-593页

作者： h.J.FAN m.Zacharias Department of Earth Sciences University of Cambridge U.K. Faculty of Applied Science Albert-Ludwigs-University Freiburg Germany Formerly at： max Planck Institute of microstructure Physics Halle Germany

Vapor-phase growth of ZnO nanowires based on gold catalyst is usually accompanied with lateral crawling growth on the substrate surface. We present results from our systematic experiments where the growth temperature and catalyst size are controlled. The data corroborate that it is possible to obtain clean vertical nanowire arrays while avoiding the crawling growth. 0% the other hand, crawling growth can be manipulated to obtain root-interconnected nanowire arrays, which could be useful for certain applications. Our results also imply that the previously suggested growth mechanism for the wire-on-wall hybridstructure might be incorrect. Finally, we show the formation of sub-millimeter long, straight ZnO nanowalls by combining a gold-catalyzed epitaxial growth of vertical nanowires and their mergence due to a confined crawling growth. These unconventional nanostructures might have unique electric or optical transport properties.

关键词： Nanowire Nanowall ZnO Crawling growth

Novel synthesis of stabilized Bi_(1-x-y)Gd_(x)Dy_(y)O_(1.5) solid electrolytes with enhanced conductivity for intermediate temperature solid oxide fuel cells(SOFCs)

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Journal of Rare Earths 2024年第10期42卷 1903-1911页

作者： Ahmed h.Ibrahim Yehia m.Abbas h.A.Ayoub marwa h.Ali mustafa Aldoori materials Science Laboratory Physics DepartmentFaculty of ScienceSuez Canal University41522IsmailiaEgypt ministry of higher Education and Scientific Research Aliraqia University10011BaghdadIraq

herein,we report the synthesis of a Dy-Gd co-doped cubic phase-stabilized Bi_(2)O_(3) solid electrolyte system via solid-state processing under atmospheric *** with Dy^(3+) and Gd^(3+) has been observed to significantly enhance the densification process during sintering for stabilization purposes,thereby improving the electrical properties of δ-Bi_(2)O_(3)-type *** synthesized ceramics were characterized using X-ray diffraction(XRD),field emission scanning electron microscopy-energy dispersive X-ray spectroscopy(FESEm-EDX),thermal gravimetry/differential thermal analysis(TG/DTA),and the four-point probe technique(4PPT).XRD analysis reveals that the samples Bi_(1-x-y)Gd_(x)Dy_(y)O_(1.5)(y=0.05/x=0.05,0.10,0,15,and 0.20,and x=0.05/y=0.10,0.15,and 0.20) exhibit a stable face-centered cubic δ-phase and a mixed-phase crystallographic *** XRD analysis of the stabilized δ-phase suggests that the prepared oxides show a face-centered cubic(FCC) structure with a space group of *** micrographs reveal that the composition Bi_(0.90)Gd_(0.05)Dy_(0.05)O_(1.5) has no significant ***,an evident increase in the pore formation is observed as the amount of Gd_(2)O_(3) increases until it reaches 20%.This finding suggests that dense pellets are formed during the sintering process at 900-1000℃.The DTA analyses were performed to verify the phase stability,which agrees with the XRD *** electrochemical performance of the synthesized Dy-Gd co-doped Bi_(2)O_(3)solid electrolyte system was evaluated and analyzed in detail by using the electrochemical impedance spectroscopy(EIS) technique,Based on EIS and conductivity measurements,Bi_(0.75)Gd_(0.20)Dy_(0.05)O_(1.5) exhibits the lowest activation energy of 0.519 eV and the highest conductivity value of 0.398 S/cm at 627℃compared to the other samples;this composition can be used as a solid electrolyte for intermediatetemperature solid oxide fuel cells(SOFCs).

关键词： Solid oxide fuel cells(SOFCs) Rare earths Solid-state processing Rietveld Fast Fourier transform(FFT) Electrochemical impedance spectroscopy(EIS)