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Engineering Review
Faculty of engineering university of Rijeka
Engineering Review

Faculty of engineering university of Rijeka

1330-9587

Engineering Review/Journal Engineering ReviewESCI
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    FRACTURE ANALYSIS OF A NONHOMOGENEOUS BEAM WITH TWO CONCENTRIC CYLINDRICAL LONGITUDINAL CRACKS

    Rizov, Victor
    19页
    查看更多>>摘要：This paper is concerned with the analysis of the fracture behaviour of a nohomogeneous cantilever beam with two concentric longitudinal cracks. The beam has a circular cross-section with linearly varying radius along the beam length. Moreover, the beam exhibits continuously varying material inhomogeneity in the radial direction. The fracture is analyzed in terms of strain energy release rate assuming nonlinear mechanical behaviour of the material. For this purpose, solutions for the strain energy release rate are derived by considering the energy balance. Two cantilever beam configurations with different lengths of longitudinal cracks are analysed. Moreover, the two cracks are arranged arbitrarily in the radial direction. The longitudinal fracture behaviour of the beam is also analysed by considering the complementary strain energy for verification. The strain energy release rate solutions are used to investigate the influence of varying radius of the cross section along the length of the beam on the longitudinal fracture behaviour. The effects of crack lengths and the location of the two concentric cracks in the radial direction on fracture are also studied. The influences of the loading conditions of the beam and the inhomogeneity of the material in the radial direction on the fracture behaviour are also evaluated.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    DEVELOPMENT AND TRIBOLOGICAL CHARACTERIZATION OF FLY ASH REINFORCED IRON BASED FUNCTIONALLY GRADIENT FRICTION MATERIALS

    Kannan, Kasi RajeshVignesh, Ramalingam VairaKalyan, Kota PavanGovindaraju, Myilsamy...
    9页
    查看更多>>摘要：The tribological and thermal properties enable iron based sintered materials with hard phase ceramic reinforcements as promising friction material for heavy-duty wind turbines. In wind turbines, the braking system consists of aerodynamic and mechanical braking systems. During application of mechanical brakes, the friction materials are pressed against the rotating low-speed shaft. The desired braking efficiency is achieved by utilizing a number of friction materials, which in turn are joined in a steel backing plate. Though this arrangement increases the braking efficiency, the hard phase ceramic reinforcement particles reduces the bonding strength between the friction material and steel backing plate. The joint failure leads to catastrophic failure of wind turbine. Therefore, the need of the hour is to develop friction materials with functional gradients that have high wear resistance (contact area) and high bond strength (interface). In this study, an attempt is made to fabricate and characterize a friction material with gradient profile of composition along the cross section to provide functional gradient property. The functional gradient friction material is synthesized by gradient deposition of Fe, Cu, Cg, SiC and fly ash powders which is then compacted and sintered. The prepared functional gradient friction material was characterized in terms of microstructure and microhardness. The tribological performance (wear rate and coefficient of friction) of the developed functionally gradient friction material was investigated at various loads using pin-on disc apparatus. The results show that as the load increases, the wear rate decreases and at the same time the COF tends to increase at higher loads. The predominant wear mechanism was deduced from the morphology of the worn surface.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    RHEOLOGICAL BEHAVIOUR OF CLAYS IN PLASTIC STATE

    Camacho Tauta, JavierJavier Reyes-Ortiz, OscarFredy Rincon-Morantes, Jhon
    13页
    查看更多>>摘要：Clayey soils exhibit viscoelastic behaviour in the plastic state, implying simultaneous retentive and dissipative mechanical properties as well as strain rate dependent properties. Such response is partially captured by the so-called Atterberg plastic limits. A more comprehensive evaluation of the mechanical response of this type of soils in the plastic state can be obtained by testing in a dynamic shear rheometer. Clayey soils consisting of different proportions of kaolin and bentonite and different water contents were subjected to dynamic shear tests to measure their rheological properties. All tests were performed with a constant strain amplitude of 10%, a fixed range frequency sweep (0.1 Hz to 100 Hz) and a constant temperature of 20 degrees C. The results show that the complex shear modulus has an inverse relationship with the soil water content and a direct relationship with the plasticity index. Moreover, the phase angle increases slightly and then decreases suddenly as the frequency increases. The complex shear moduli obtained by dynamic tests were compared with the oedometric moduli estimated by correlations and showed satisfactory trends between them. The study contributed to the understanding of the complex behaviour of soils in the plastic state. Although the mechanical response of these materials is affected by some factors, the plasticity limits were consistent with the complex moduli under analogous conditions of strain and frequency.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    REAL-TIME FRICTION TORQUE ESTIMATION ON A DIESEL ENGINE USING THE CRANKSHAFT SPEED FLUCTUATION

    Mohammed, SeddakAmina, Lakhdari A.
    17页
    查看更多>>摘要：Under the pressure of stricter regulations on pollutant emissions and the desire of users for lower fuel consumption and more comfortable driving, engine control based on torque has been developed. To provide an accurate estimate of effective torque, friction losses must be modeled. The details of a model that predicts the total instantaneous friction torque for compression ignition engines are described. The model is based on a combination of the dynamic model of the crankshaft and the thermodynamic model. The total instantaneous friction torque is determined using the instantaneous measurements or numerical predictions of the gas pressure in the combustion chamber, the rotational speed of the crankshaft and the load torque. The experimental data and the numerical simulation results were compared. The comparison between the different variables shows a good agreement between the simulation and the experimental results.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    THE ANALYSIS OF MATERIAL REMOVAL RATE OF WEDM MINIATURE GEARS

    Goyal, AshishSingh, VyomPatel, Abhishek
    6页
    查看更多>>摘要：Gear fabrication in wire electrical discharge machining (WEDM) plays an important role in manufacturing industries. This paper describes the analysis and optimization of process parameters for the fabrication of spur gear on brass spur gear on brass workpiece (10cmx15cmx6mm) material by wire EDM process. The experiments were performed by using the design of experiment (DoE) approach and the material removal rate (MRR) was analyzed by response surface methodology technique. The effect of input parameters i.e. pulse on time, pulse off time and feed rate on MRR has been investigated. The surface geometry of the gears has been analysed by the Scanning Electron Microscopy (SEM). This study found that 0.4 mu s for pulse on time, 60 mu s for pulse-off time and 6 mm/min for feed rate provides improved material removal rate. The analysis of variance shows that pulse on time and feed rate are the significant parameters for the wire EDM process. The SEM image exhibits the capability of WEDM to machined miniature gear with a uniform distribution of regular-shaped craters and defect-free flank surface.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    A COMPUTATIONAL APPROACH TO FORECASTING AND MINIMIZING ELECTRICITY COSTS IN THE SHORT-TERM MARKET FOR DISTRIBUTORS IN BRAZIL

    Bezerra, Francisco E.Santos Jr, Luis C.Dias, Cleber G.Pereira, Fabio H....
    11页
    查看更多>>摘要：In Brazil, the electric power distributors must buy electricity on auctions one, three and five years ahead. If there is inefficiency in the contracting of electric energy, the chamber of Commercialization of Electric Energy, which enables the commercialization, can apply penalties. Thus, this paper proposes a computational approach to forecasting electricity by the class of the consumer using a multi-layer perceptron artificial neural network with a backpropagation algorithm and a prediction using time series techniques through the Bayesian and Akaike selection criteria. The forecast of electricity consumption can serve as support in the purchase of electricity in auctions in the regulated contracting environment and in the process of settlement of differences and for energy management, customer service, and distributor billing. The results show that a multilayer network with a backpropagation algorithm is able to learn the behavior of the data that influences the electric energy consumed by consumption class and can be used to follow the evolution in the demand of each class of consumption and, consequently, to help distributors in the process of contracting of electricity, reduce losses like fines, and reduce the costs of the energy distributor.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    PRACTICAL REALIZATION OF ELECTRONICALLY ADJUSTABLE UNIVERSAL FILTER USING COMMERCIALLY AVAILABLE IC-BASED VDBA

    Roongmuanpha, NatchanaiPukkalanun, TattayaTangsrirat, Worapong
    10页
    查看更多>>摘要：This paper describes the practical realization of electronically adjustable voltage-mode universal filter with three inputs and single output (TISO) using the commercially available integrated circuit (IC)-based voltage differencing buffered amplifiers (VDBAs). The realization is resistor-less and contains only two VDBAs and two capacitors. The described filter structure can realize all the five standard biquadratic filter functions from the same configuration without needing any component matching criterions. It also exhibits low-output impedance, which enables for easy cascading in voltage-mode operation. Owing to practical VDBA realization, the filter circuit can be easily made electronically tunable with orthogonal omega(o)-Q tuning. The effects of the VDBA non-idealities on the filter performance have been analyzed in detail. To prove the theoretical finding, the performance of the studied circuit was also experimentally measured using the operational transconductance amplifier CA3080 and the operational amplifier LF356 ICs.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    THERMOCHEMICAL CONVERSION OF PLANT BIOMASS IN THE ENERGOTECHNOLOGICAL COMPLEX WITH HEAT RECOVERY

    Zablodskiy, MykolaZhyltsov, AndriiRadko, IvanTrokhaniak, Viktor...
    12页
    查看更多>>摘要：Basic performance principles of the energotechnological complex used for thermochemical conversion of plant biomass with the influence of a magnetic field and high recovery of spent heat carrier energy have been developed. The concurrent saturation of a spent heat carrier in a loading bunker with the steam from humid biomass aimed at using a certain part of a spent heat carrier, which is clear from oxygen and nitrogen oxide, and moisture in thermochemical recovery has been considered as an important aspect of recuperation processes. A mathematical model has been developed and the results of numerical simulation have been presented for determining the distribution of temperature, velocity and pressure fields in a loading bunker. Prospective assessment of the engineering solutions developed for heat energy recovery of a double flow spent heat carrier has been conducted.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    A SIX-CHANNEL MICROSTRIP DIPLEXER FOR MULTI- SERVICE WIRELESS COMMUNICATION SYSTEMS

    Fouladi, FarhadRezaei, Abbas
    8页
    查看更多>>摘要：In this paper, a six-channel microstrip diplexer is designed and fabricated. It operates at 0.75/0.85/1/1.25/1.6/1.8 GHz for multi-service wireless communication systems. It consists of two stub-loaded resonators, which are integrated by coupled lines. The channels are close together, which makes the proposed diplexer suitable for frequency division duplex (FDD) schemes. The proposed structure has a compact size of 0.025 lambda(2)(g) where lambda(g) is the guided wavelength calculated at 0.75 GHz. The other advantages of the introduced multi-channel diplexer are the low insertion losses of 1.62/1.27/0.43/0.53/1.26 and 1 dB, as well as good return losses of 26/26/25/25/21.7 and 22 dB at 0.75/0.85/1/1.25/1.6/1.8 GHz respectively. A good isolation of less than 22 dB is obtained between the channels. In order to design the presented diplexer a designing technique is used which is based on the proposing of an equivalent approximated LC model and calculating the inductors and capacitors. To confirm the simulation results, the introduced diplexer is fabricated and measured.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering

    ROLLING OF A SINGLE-CAVITY HYPERBOLOID OF ROTATION ON A HELICOID ON WHICH IT BENDS

    Kresan, TetianaPylypaka, SerhiiRuzhylo, ZynoviiRogovskii, Ivan...
    9页
    查看更多>>摘要：The bending of a single-cavity hyperboloid with rotation while maintaining the rectilinear generator is considered. The resulting bending surfaces are a plural of open skew helicoids, including partial cases of oblique closed and open ordinary helicoid s. The parametric equations for the continuous bending of these surfaces are established by changing the angle between the straight line and its axis. The possibility of pure unrolling of a hyperboloid along a helicoid from the set of its bends with linear contact along a common rectilinear generator of both surfaces is shown. Using the obtained equations, the surfaces are constructed and the images of hyperboloid and helicoid with the common rectilinear generator of their contact are shown.
      原文链接:
    • NSTL
    • Univ Rijeka, Fac Engineering