فهرست مطالب

Scientia Iranica - Volume:26 Issue: 6, 2019
  • Volume:26 Issue: 6, 2019
  • Transactions on Mechanical Engineering (B)
  • تاریخ انتشار: 1398/09/29
  • تعداد عناوین: 12
|
  • Mojtaba Delkhosh, Mahmoud Saadat Foumani * Pages 3245-3254
    This paper proposes a new power management strategy (PMS) for parallel hybrid electric vehicles equipped with continuously variable transmission (CVT). The proposed PMS is established on the basis of electric assist control strategy (EACS) and equivalent consumption minimization strategy (ECMS). This control approach is based on maintaining the battery energy within a recommended range, considering the CVT efficiency in selecting the engine operating point, and finding the best power split between the engine and electric motor at certain moments of the driving. In order to evaluate the effectiveness of this scheme, it is compared with EACS, a modified version of EACS and ECMS. It is shown that, in all of the studied driving cycles, the proposed PMS is superior to the considered rival strategies in terms of the fuel consumption and also HC and CO emissions.
    Keywords: Hybrid electric vehicle, continuously variable transmission, fuel consumption, emissions, speed ratio control, electric assist control strategy, equivalent consumption minimization strategy
  • Ali Bolatturk, Osman Ipek, Karani̇ Kurtulus *, Mehmet KAN Pages 3255-3261
    Shorter cycle times, better product quality and less product outage can be possible with faster cooling. But mold cooling channels can only be made in linear directions and limited forms via classical manufacturing methods. Therefore, it limits that performance of mold cooling. Developed in recent years additive manufacturing technologies are capable of building complex geometries and monoblock 3D products. With this technology it is possible to produce metal molds with conformal cooling channels in different forms and capable of qualified cooling. In this study, conformal cooling channels were designed in order to achieve optimum cooling in monoblock permanent mold. In this study, CFD (Computational Fluid Dynamic) analyses are performed to steady stead conditions for designed conformal cooling channels and classical cooling channel mold. Pressure drops, cooling channel outlet temperatures and exergy destructions are calculated depending on the flow velocity rate in channels. The numerical investigations of the cooling process have shown that approximately 5% higher cooling performance can be achieved with conformal cooling channels. However, the pressure drop in the conformal cooling is observed to be higher than classical cooling channel. In addition, exergy destruction in the conformal cooling channel is approximately 12% greater than the classical cooling channel.
    Keywords: Metal Mold, Exergy Destruction, Cooling Channel Design
  • Z Matin, Mahdi Moghimi Zand *, M Tehrani Pages 3262-3270
    Predicting the nonlinear response of biological tissues is challenging issue, due to strain rate- (short term) and time-dependent (long-term) nature of its response. While many of the tissue properties have already been extensively examined, some are left unnoticed, such as dependence of the stress-relaxation behavior on the strain levels. In this paper, a hyperviscoelastic constitutive model is derived within the integral form presented by Pipkin and Rogers model to remove this limitation. In the suggested model, the hyperelastic and short-term viscous parts are represented by the suitable strain energy function. The long-term viscous function includes the deformation history, which is expressed through a tensorial-relaxation function and has not been considered elsewhere. The constitutive model involves a number of material parameters. The values of those are identified from experimental data for Adiprene-L100 as a tissue-equivalent material. Parameters appearing in constitutive law are estimated by fitting the model with the experimental data. It is assumed that the tissue phantom is slightly compressible, isotropic and homogenous. The obtained results indicate that the presented model can describe the nonlinearity, strain rate- (short-term) and time-dependent (long-term) effects of materials. The validation of the model is investigated and shows very good agreement with the experimental data.
    Keywords: Hyperviscoelastic, modeling, Tissue-equivalent material, Strain-dependent, Stress-relaxation behavior
  • Mohammad Ali Modaresi, E. Shirani *, Mahmood Charmiyan, Fethi Aloui, Amine Koched, Michel Pavageau Pages 3271-3282
    In the present study, impinging of vertical twin jet against a horizontal plate is numerically and experimentally investigated. Four two equation RANS based turbulence models are used and their capabilities to simulate such complicated turbulent flow were examined. The two fluid jets are separated by a thin membrane. The inlet jet hydraulic diameters are the same and the Reynolds number of external flows of jets is 13500. The ratio of width of nozzles (e) to nozzle-to-plate distance (H) considered as 1:10. The turbulent models used in this work are k-ε, k-ε RNG, k-ω and k-ω SST. The results obtained by the models were compared with each other as well as two-dimensional PIV data to evaluate the capabilities of such models for this kind of flows. By comparing the numerical and experimental results, it is concluded that all of the models can predict acceptable results in the free jet area, but in the near wall region none of the models can predict flow characteristics with reasonable accuracy. It was observed that, at low nozzle-to-plate distances, the prediction results of the turbulence models are approximately in accordance with the experimental data, particularly for a zone near the midline separating the two jets.
    Keywords: Impinging jets, Twin-jet, RANS, Turbulence models, PIV
  • Hamed Akhtari *, Iraj Mirzaee, Nader Pourmahmoud Pages 3283-3292
    In the present article, Lattice Boltzmann method is utilized to simulate two-dimensional incompressible viscous flow in an open and closed microchannel (vessel). The main focus of the present research is to study physical parameters of blood flow in a vessel. To find the effect of oscillatory flow inside the vessel, we take account of the Reynolds number from 0.05 to 1.5 for numerical computation in the present manuscript in an open straight vessel. In addition, the accuracy of Poiseuille Law is investigated for blood flow in open vessel too. For this purpose, the effect of the vessel diameter and blood viscosity on the blood flow is studied numerically. As extra results, the effect of blood injection to a coronary bifurcation with two closed ends are studied. The blood pressure drop is high at the beginning of the vessel (pressure variation is high between the adjacent points along the vessel), but after the path along the vessel, the speed of dropping pressure decreases and the pressure difference between the adjoining points decreases along the vessel. Finally, the present results have been compared with the available experimental and numerical results that show good agreements.
    Keywords: Lattice Boltzmann method, Blood flow, Poiseuille law, Reynolds number
  • Abil Muratov, Assemkhan Kainarbekov, Suleimen Sultangazinov *, Тaizhan Sarzhanov, Aspan Kazhigulov, Abdiashim Shalkarov, Gulmira Mussaeva, Kanagat Bekmambet, Bekture Yessengarayev, Amangeldi Tanirbergenov Pages 3293-3303
    This work offers a new chassis design, namely the wheel-track, represents a mathematical model of this chassis, and also proves the advantage of the proposed design when driving the vehicle on arbitrary terrain - rough off-road. The proposed approach can find application in the design of unmanned research mechanisms for other planets (Mars Rovers, Lunar Rovers etc.), also for design of robots and transport of rescuers at liquidation of consequences of natural or technological disasters. The article presents the analysis of the requirements for the chassis of extraterrestrial research unmanned mechanism demonstrated high compliance of the proposed approach. The analysis of the requirements for the chassis of extraterrestrial research unmanned mechanism demonstrated high compliance of the proposed approach. We proposed and investigated a mathematical model of wheel-track, demonstrated the optimization of the proposed mathematical model to machine computing, demonstrated the flexibility and scalability of the mathematical model. The proposed design is an attempt to combine the advantages of a walking and wheel types of travel in one mechanism.
    Keywords: drivers, chassis, transport of rescuers, unmanned research mechanisms, wheel-track
  • Cagatay Teke *, Murat Colak, Alper Kiraz, Mumtaz Ipek Pages 3304-3312
    Casting simulation programs are the computer programs that digitally model the casting of an alloy in the sand, shell or permanent mold and then the cooling and solidification processes. However, obtaining consistent results from the casting modeling depends on providing many parameters and boundary conditions accurately. Critical fraction of solid (CFS), which is one of the most important of these parameters, is defined as the point where the solid dendrites do not allow any flow of the liquid metal in the mushy zone. Since the CFS value varies depending on many factors, inconsistent results can be experienced in the modeling applications. In this study, the CFS value obtained during the solidification of various commercial aluminum alloys' casting process carried out using low pressure die casting method, is predicted by using artificial neural network (ANN) method based on alloy type, grain refiner and modifier additions, initial mold temperature, pressure level parameters. In the scope of the study, 162 experiments are conducted. The results obtained from the low pressure die casting experiments using a special model designed for the study are validated by using SOLIDCast casting simulation. The CFS values obtained from this validation range from 33% to 61%.
    Keywords: Critical fraction of solid, artificial neural network, low pressure die casting, casting simulation
  • Karim Alilakbari *, Mohammad Imanparast, Reza Masoudi Nejad Pages 3313-3324
    The main goal of this research is the experimental and numerical study on the fatigue function and failure of the crankshaft of diesel engine of a heavy truck. To do this, a crankshaft of the diesel engine of a heavy truck that has gone under failure after traveling 955000 km, has been used. To examine the sources of this failure, several experimental studies have been carried out including chemical composition, the strength of the material, determining the hardness and the microstructure of the material. Besides, using an elastic–plastic three dimensional finite element method (FEM) model, the location of the maximum stress in the crankshaft was determined using the ‘‘complete crankshaft model’’ and ‘‘one crank model’’. Using the results of stress analysis, was a basis for the three-dimensional crack growth model and fatigue life estimation to determine the stress intensity factor and fatigue life considering the related parameters and boundary conditions method. At the final stage, using the results gotten from the given model for the fatigue crack growth, comparing it with experimental results, and examining the whole process, it was concluded that the scratches in crankpin region, was the main reason for the fatigue failure got from bending-torsional load-combination.
    Keywords: Fatigue crack growth, Fractography, Crankshaft, Finite Element, Fracture mechanics
  • Osman İPEK, Ali BOLATTURK, Mehmet KAN *, Karani̇ Kurtuluş Pages 3325-3333
    The cooling process in metal molds is one of the important factors in the solidification process of molten metal. Molding defects such as hot spot defects and warping occur in cast products when the cooling is not uniform. However, qualified and faster cooling affects product quality positively. Molding is one of the important processes both in terms of cycle time and product quality, with permanent mold casting, high quality liquid metal casting, and quality product. Selective Laser Melting (SLM) method has been used to design metal mold cores with unique cooling channels to be compactly produced. The effects of the designed cooling channels, heat transfer and solidification of the molten metal are studied in transient numerical terms. The temperature distributions for 1, 3 and 5 seconds after casting were obtained and the solidification processes were investigated according to the standard cooling channels of the original cooling channels. According to the results obtained, it has been observed that solidification is better in originally designed cooling channels.
    Keywords: Metal Mold, SLM, Conformal Cooling Channels
  • Abdullah Demir *, Ali Oz Pages 3334-3355
    In this study, two pairs of OEM brake disc-pads have been used. One of these discs belongs to a passenger car, and the other one belongs to a light commercial vehicle. The disc-pad pair of the passenger car (PC) has been subjected to global brake effectiveness test by full scale inertia dynamometer according to SAE J2522 test standard; and the other one has been subjected to the tests by full-scale inertia dynamometer according to FIAT 7-H4020 and 7-H2000 standards. During these tests, 13 variables for passenger car disc-pad pair and 11 variables for light commercial vehicle disc-pad pair have been measured and recorded. Interrelation of the parameters has been analyzed with multiple regression method and importance levels have been determined. In this study, dependent variables in multiple regression method are selected as braking time, friction coefficient, disc final temperature, brake speed and brake pressure for each braking pair. In multiple regression analysis for PC, for each unit increase in deceleration and friction coefficient, braking time decreases with 7.3 and 60.9 units, respectively. Also, for each unit increase in brake pressure and friction coefficient for LCV, braking time increases with 1.267 and 91.887 units, respectively.
    Keywords: Braking parameters, braking performance, brake disc-pad pair, brake fade, multiple regression method, dummy variable
  • Halil Zeybek *, S. Battal Gazi Karakoc Pages 3356-3368

    In this article, a collocation algorithm based on quintic B-splines is proposed for the numerical solution of the non-linear generalized regularized long wave (GRLW) equation. Also, to analyse the linear stability of the numerical scheme, the von-Neumann technique is used. The numerical approach is discussed on three test examples consisting of a single solitary wave, the collision of two solitary waves and the growth of an undular bore. The accuracy of the method is demonstrated by calculating the error in the L2 and L¥ norms and the conservative quantities I1, I2 and I3. The findings are compared with those of previously reported in the literature. Finally, the motion of solitary waves is graphically plotted according to different parameters.

    Keywords: GRLW equation, Finite element scheme, Quintic B-spline, Solitons, Undular bore
  • Ahmed J.R ALMUSAWI *, Lale Canan DULGER, S. KAPUCU Pages 3369-3374

    Two case studies are performed in this study; one with 4-dof robotic system, the other 6-dof industrial robot arm . Both robot arms are actually operated in Mechatronics Laboratory, Gaziantep University. Different motion trajectories are designed, and implemented for training, medical tasks and surgical operations base. Simulations are built by using VR Toolbox in Matlab. Virtual reality environment is achieved through Simulink with real time examples . The motions and trajectories necessary for training and surgical applications are directly seen. This enables the surgeons training with many benefits; greater control during tasks reduced training periods, possibility of error free tasks for example.

    Keywords: robotic surgery (RS), robotic training (RT), virtual reality (VR)