فهرست مطالب

Scientia Iranica - Volume:27 Issue: 4, 2020
  • Volume:27 Issue: 4, 2020
  • Transactions on Mechanical Engineering (B)
  • تاریخ انتشار: 1399/05/14
  • تعداد عناوین: 12
|
  • Javad Afshari *, Mohammad Haghpanahi, Reza Kalantarinejad, Abel Rouboa Pages 1867-1877
    Traumatic brain injury (TBI) is one of the most important causes of death and disability. The objective of this study is to develop new head injury criteria which can predict the greatest principal strain and shear stress in the brain considering the impact directions and magnitudes. So, 150 head impact simulations were performed for 3 magnitudes and 50 directions of impact using head finite element model (FEM). Simulations were performed in order to assess the strain and shear stress created in the brain tissues due to different impact directions and magnitudes. Next, new head injury criteria were developed through performing statistical analysis. The simulation results showed that TBI risks in the sagittal and frontal planes were higher than those with impacts in transverse plane. Furthermore, new brain injury indices were developed to predict maximum principal strain and shear stress in the brain, which had correlation coefficients of 0.85 and 0.89 with head FEM responses, respectively. However, finding of present research showed the effects of impact directions on TBI risks. They also demonstrate that impact magnitude, direction, and duration should be used to develop a brain injury index.
    Keywords: Brain injury, Computational modeling, Finite Element Method, Injury Criteria, Safety
  • Dhananjay Mishra *, Hrishi Jain, Nishant Kumar, M.S. Sodha Pages 1878-1885
    This paper presents an experimental evaluation of portable modified conventional buckets of 10 l capacity. Out of ten modified portable storage, best three cases (viz. Non-insulated open plastic bucket (OPB), Non insulated plastic bucket top surface covered with a transparent cover (CPB), and Insulated plastic bucket closed with a transparent cover (ICPB)) are discussed. Maximum temperature rise after two hour time duration OPB, CPB, and ICPB are 29.82%, 47.36%, and 21.49% respectively as compared with the initial value the temperatures (22.8 ℃). At 14:45 hour CPB temperature reaches 35.6 °C which is 17.88 and 23.61% higher values as compared to the OPB and ICPB units. Net saving due to utilization solar energy in CPB for a range of 35-50°C is net saving increased by 12.34%, 25.76%, 40.73%, 57.93%, 76.45%, and 97.18% from 2017 to 2022 as compared with the saving in 2016.
    Keywords: Solar water heater, Heat, mass transfer, Modified conventional bucket
  • S. P. Jena *, D. R. Parhi Pages 1886-1896
    The current work is based on the development of an indirect approach in the domain of Recurrent Neural Networks (RNNs) to identify and quantify cracks on a multi-cracked cantilever beam structure subjected to transit mass. At first, the responses of the multi-cracked structure subjected to transit load are determined using fourth order Runge-Kutta numerical method and finite element analysis (FEA) has been executed using ANSYS software to authenticate the employed numerical method. The existences and positions of cracks are identified from the measured dynamic excitation of the structure. The crack severities are found out by FEA as forward problem. The modified Elman’s Recurrent Neural Networks (ERNNs) approach has been implemented as inverse problem to predict the locations and severities of cracks in the structure by applying Levenberg-Marquardt (LM) back propagation algorithm. The present analogy has been carried out in a supervised manner to check the convergence of the proposed algorithm. The proposed ERNNs method converge good results with those of theory and FEA.
    Keywords: Crack location, crack severities, Runge-Kutta, ERNNs, Levenberg-Marquardt
  • Madalina Dumitriu * Pages 1897-1915
    To study how the suspended equipments impact the carbody flexible vibrations in railway vehicle and the ride comfort, a rigid flexible general model is required. The numerical simulations rely on three models, derived from the general model - a reference model with no equipment, a simplified model with one equipment mounted at the carbody centre and another model considering four equipments mounted along the carbody. The intent of this paper arises from the observation that the literature review does not feature any study to highlight the change in the ride comfort, exclusively due to the equipments. Similarly, there is no mention on contrasting the ride comfort results obtained from the simplified model versus the ones coming from the model with more equipments. The main characteristics of the flexible vibrations behaviour in the carbody due to the suspended equipments are made visible by comparing the frequency response functions of the carbody between the no equipment and the one equipment models. The influence of the suspended equipments on the ride comfort is established by a contrastive examination of the ride comfort index calculated in the carbody fitted with one/four equipment/s models with the ride comfort index from the no equipment model.
    Keywords: railway vehicle, flexible carbody, suspended equipments, vertical bending vibration, frequency response function, ride comfort
  • Mehdi Gharibavi *, YI Jian Jun Pages 1916-1932
    In this article, a semi-analytical solution is presented in order to analyze a functionally graded piezomagnetic (FGP) cylinder resting on an elastic foundation exposed to hygro-thermal loading. All mechanical, hygro-thermal and magnetic properties are considered to vary according to the power-law function through the thickness. The steady-state heat conduction and moisture diffusion equations are employed to attain the moisture concentration and temperature distributions in the FGP cylinder. The constitutive equations, and magnetic and mechanical equilibrium equations are combined in order to derive three second-order differential equations in terms of magnetic potential and mechanical displacements. The separation of variables and complex Fourier series method are utilized to solve governing equations. Numerical results reveal the effects of hygro-thermal loading, elastic foundation and non-homogeneity constants on hygro-thermo-magneto-elastic response of the functionally graded piezomagnetic cylinder. It is concluded that hygro-thermal loading has remarkable effects on the behavior of the cylinder leading to increase the absolute values of the radial magnetic induction, radial, circumferential and shear stresses.
    Keywords: Complex Fourier series, Functionally graded piezomagnetic material, Asymmetric loading, Winkler elastic foundation
  • Ali Golzari, H. Nejat Pishkenari * Pages 1933-1944
    In this paper, the vibrational properties of fullerene hydrides with the chemical formula C60H2n are investigated using a method based on the potential energy of the molecule. The potential used in this methodology is AIREBO (Adaptive Intermolecular Reactive Empirical Bond Order). Using this interatomic potential, some of the most important frequencies of the fullerene hydrides, such as the breathing mode frequency, were calculated and then analyzed. It was observed that in addition to the number of hydrogen atoms in the structure, their position on the C60 cage has a significant effect on the natural frequency corresponding to a particular mode shape. The results obtained by this method have been compared and validated with quantum mechanics and experimental observations. The simulations results demonstrate that the proposed method is capable of calculating the vibrational properties of fullerene hydrides with high precision and low computational cost.
    Keywords: Fullerene hydrides, Vibrational analysis, Breathing mode, AIREBO potential, DFT method
  • S. Ullah Khan, N. Ali, Sabir Shehzad *, M. Bashir Pages 1945-1954
    This attempt executes the combined heat mass transport features in steady MHD viscoelastic fluid flow through stretching walls of channel. The channel walls are considered to be porous. The analysis of heat transport is made by help Cattaneo-Christov heat diffusion formula while generalized Fick’s theory is developed for study of mass transport. The system of partial differential expressions is changed into set of ordinary differential by introducing suitable variables. The homotopic scheme is introduced for solving the resultant equations and then validity of results are verified by various graphs. An extensive analysis has been performed for the influence of involved constraints on liquid velocity, concentration and temperature profiles. It is noted that the normal component of velocity decreases by increasing Reynolds number while retards for increasing viscoelastic constraint. Both temperature and concentration profiles enhanced by increasing combined parameter and Reynolds number. The presence of thermal relaxation number and concentration relaxation number declines both temperature and concentration profiles, respectively.
    Keywords: Cattaneo-Christov model, Fick’s law, viscoelastic fluid, stretching walls channel
  • Z. Matin Ghahfarokhi, M. Salmani Tehrani, Mahdi Moghimi Zand * Pages 1955-1961

    New advances in computer technology for biomechanical numerical modeling of human body are the basis for the improvement of targeting accuracy. This is especially important for guiding surgeons during interventional procedures and locating of liver tumor for radiotherapy. This paper deals with investigating the motion and deformation of a tumor, embedded into liver, during respiration. Here, a 3D FE model of human liver as a whole is developed to simulate liver behavior during respiration. First, the cloud of point according to CT image data was imported into CATIA software. Then a spherical tumor was embedded into the different segments of liver tissue in ABAQUS. A quasi-linear hyperviscoelastic constitutive model and an elastic behavior were used to define the liver and tumor properties, respectively. Boundary conditions were defined based on the difference between end-exhale and end-inhale states of liver tissue. Deformation and motion of liver tumor was then determined at intermediate states of breathing. Finally, the new position and the deformed shape of the tumor were investigated, considering the increase of tumor stiffness. The results show that if the tumor is located in the segment VII, then maximum displacement in the y-direction is observed.

    Keywords: Liver tissue, breathing, point cloud, finite element model
  • Sh. Safary Sabet, M. Mostafa Namar, M Sheikholeslami *, A. Shafee Pages 1962-1971
    Using clean energy sources is considered as a prevention solution for global warming. Hydrogen is one of the most popular clean and renewable fuel which is widely noticed by researchers in different approaches from additive fuel of internal combustion engines to pure feed of fuel cells. Hydrogen production is also one the most interested field of studies and extended efforts are doing to fined high performance, fast and economical ways of its production. In this work, a novel high temperature steam electrolysis system with main solar integrated Brayton cycle core is proposed and numerically simulated to achieve this goal. Energy and exergy analysis having better perception of system performance is done and Rankine and organic Rankine cycles were utilized cooperating with the main core to improve its efficiency. The influences of different parameters such as turbine inlet temperature, inlet heat flux from the sun, compression ratio and also used organic fluid were investigated based first and second laws. Results show the high performance of proposed system, more than 98% energy efficiency of hydrogen production, besides the simplicity of utilizing it.
    Keywords: Energy-Exergy Analysis, HTSE, Renewable Energy, Solar Driven Cycle, ORC
  • Vishwas M, Vinyas Mahesh *, Puneeth K Pages 1972-1981
    The present study is aimed at investigating the effect of incorporating arecanut nano filler on the tribological behaviour of coir reinforced epoxy based polymer matrix composite. Areca nut nano filler is produced by grinding followed by ball milling. Particle size analyzer confirmed the size of nano fillers obtained are in the range of 20-100 nm. Composites with different weight percentage of nano filler (0%, 5%, and 10%) were studied for their mechanical and tribological behaviour using pin on disc rig. Tensile, Flexural, Interlaminar shear and impact tests are carried out on the proposed composite. Taguchi’s technique is used for analysing effect of various factors on the tribological behaviour of the composite. The results showed that inclusion of arecanut nano filler enhanced the microhardness of the composite, with inclusion of arecanut filler the tensile strength increased up to 5 %, later there is a decrease in tensile strength. Flexural strength significantly increases with increase in filler percentage from 0% to 5%, but the variation of flexural strength from 5% to 10% is negligible. Inclusion of filler has negligible effect on the interlaminar shear strength of composites. Impact strength and wear resistance of the composite is enhanced with incorporation of filler.
    Keywords: Arecanut, Coir, Wear, Nano filler, Polymer Matrix Composite, Mechanical, Tribological Properties
  • A.A. Shehab, S.K. Sadrnezhaad *, A. K. Mahmoud, M.J. Torkamany, A. H. Kokabi, M. Fakouri Hasanabadi Pages 1982-1994
    Overlapped strips of titanium grade 2 and aluminum 3105-O alloy were welded together by an innovative spot-like pulse laser procedure. The tactile seam tracking on ring paths yielded reliable weld fit-up of 1 and 0.5 mm thickness strips. Since the welding parameters of Ti-Al were narrow, three welding speeds of 4, 5 and 6.67 mm•s-1 were chosen for the pretest conditions. The microstructural investigations showed that intermetallic compound Ti3Al, formed in Ti-rich fusion zone. Cracks formed in the Al-rich fusion zone as a result of TiAl3 precipitation. Dimple fracture occurred at 6.67 mm•s-1 welding speed. Longer mixing time at Ti-Al interface occurred at lower welding speeds of 4 and 5 mm•s-1, which led to the formation of thicker intermetallic compounds and more massive crack generation. It also increases the hardness of the fusion zone and results in brittle fracture type during the tensile test. The highest strength was achieved with a welding speed of 4 mm•s-1 which was a result of more massive weld nugget and lower porosity.
    Keywords: welding, strip, joining, lasers, lapping, aluminum, titanium, keyhole
  • Wael Altabey, Mohammad Noori *, Ali Alarjani, Ying Zhao Pages 1995-2008
    In this research, the long-term tensile creep (LTTC) failure in basalt fiber reinforced polymer (BFRP) composites under ambient conditions was detected and predicted via an expert system, in order to monitor the LTTC of BFRP laminate composites. This was accomplished by using the electrical potential change (EPC) technique that employs an electrical capacitance sensor (ECS) in conjunction with an artificial neural network (ANN). A finite element (FE) simulation model for tensile creep detection is generated by ANSYS and MATLAB. Therefore, FE analyses are employed to obtain groups of data for the training of the ANNs. The proposed method is applied to minimize the number of FE analysis for keeping the cost down and save the time of the creep behavior monitoring to a minimum. The paper first presents a study on the creep monitoring for different levels of tensile creep (%σc) as a percentage of ultimate tensile strength (UTS) equal to (25%, 50% and 75%) using EPC technique. Subsequently, the trained ANN is utilized to predict the creep behavior for the level of %σc not included in the FE data. Four different values are selected for the level of %σc; (15, 35%, 60% and 85%).
    Keywords: Tensile Creep Monitoring, Creep time, Electrical Capacitance Sensor (ECS), BFRP, FEM, ANNs