Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
DYNAMIC STABILITY OF EMBEDDED SINGLE WALLED CARBON NANOTUBES INCLUDING THERMAL EFFECTS
153
161
EN
R.
ANSARI
Dept. of Mechanical Engineering, University of Guilan, P.O. Box 3756, Rasht, I. R. of Iran
R.
GHOLAMI
Dept. of Mechanical Engineering, Lahijan Branch, Islamic Azad University, P.O. Box 1616, Lahijan, I. R. of Iran
gholami_r@liau.ac.ir
10.22099/ijstm.2015.2995
A nonlocal beam model based on the Bernoulli–Euler beam theory is presented to investigate the dynamic stability of embedded single-walled carbon nanotubes (SWCNTs) in thermal environment under combined static and periodic axial loads. The dynamic stability analysis is carried out by including the effects of small-scale parameter, temperature change and elastic medium. The equation of motion is reduced to the extended Mathieu-Hill equation, the stability of which is analyzed through the Floquet-Lyapunov theory as well as bounded and unbounded solution theory. The instability regions obtained from both theories are examined and compared with each other. Also, the effects of the small-scale parameter, temperature change, elastic medium, compressive static axial load and excitation frequency on the dynamic stability of SWCNTs are discussed in detail. The prediction of dynamic instability of carbon nanotubes enables one to eliminate this phenomenon in cases that may fall within the range of practical significance.
carbon nanotube,dynamic stability,Floquet-Lyapunov,Mathieu-Hill
https://ijstm.shirazu.ac.ir/article_2995.html
https://ijstm.shirazu.ac.ir/article_2995_ff4e796b647503622a3be13846daf6c1.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
INFLUENCE OF ROLLING VISCO-ELASTIC COUPLING ON NON-LINEAR DYNAMICS OF DOUBLE PLATES SYSTEM
163
173
EN
J. D.
SIMONOVIĆ
Faculty of Mechanical Engineering,University of Niš, A. Medvedeva 14, 18000 Niš, Serbia
bjulijana@masfak.ni.ac.rs
10.22099/ijstm.2015.2996
Multi frequency vibrations of a system of two isotropic circular plates interconnected by a rolling visco-elastic layer that has nonlinear characteristics are considered. The system with two circular plates and interconnecting discrete continually distributed rolling visco nonlinear elastic rheological elements presents the model of hybrid nonlinear system. The analytical solutions of first asymptotic approximation describing stationary behavior, in the regions around the resonances, are the principal results of the author. On the basis of those results the influence on the system dynamics of rolling coupling element was numerically analyzed. A series of the amplitude-frequency and phase-frequency curves of the two-frequency like vibration regimes were numerically obtained and presented. These curves present the evolution of the first asymptotic approximation of solutions for different nonlinear harmonics obtained by changing external excitation frequencies through discrete as well as continuous values for different values of rolling elements masses. Such an analysis proves that the presence of rolling elements in the interconnected layer of two plates causes frequency overlap of resonant regions of nonlinear modes, which at the same time causes the enlargement of the mode mutual interactions
Hybrid nonlinear system,circular plates,rolling visco nonlinear elastic rheological element,multi frequency,resonance,resonant jumps,mutual mode interaction,stationary resonant regimes
https://ijstm.shirazu.ac.ir/article_2996.html
https://ijstm.shirazu.ac.ir/article_2996_69b3d27a5285c85a1bcea25858af0f83.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
COLLABORATIVE OPTIMIZATION OF DIFFERENTIAL STEERING FOR IN-WHEEL ELECTRIC VEHICLE
175
184
EN
W. Z.
ZHAO
Dept. of Vehicle Eng., Nanjing University of Aeronautics and Astronautics, P. R. China
AND
Dept. of Mechanical Eng., University of Michigan, USA
zhaowanzhong@126.com
C. Y.
Wang
Dept. of Vehicle Eng., Nanjing University of Aeronautics and Astronautics, P. R. China
AND
Dept. of Mechanical Eng., University of Michigan, USA
chengyuan.wang@swansea.ac.uk
Z. Q.
ZHANG
Dept. of Vehicle Eng., Nanjing University of Aeronautics and Astronautics, P. R. China
10.22099/ijstm.2015.2997
Differential steering of in-wheel electric vehicle provides the functions of both active steering and power assisted steering with the coupling control of force and displacement transfer characteristic of system. A collaborative optimization model of the differential power-assisted steering system of in-wheel electric vehicle is built, with steering economy as the main system optimization goal, steering road feel, steering sensitivity and torque sensor performance as the subsystem optimization goals. Considering the coupled relationship of each discipline, the main system is optimized by the particle swarm algorithm, and the subsystems are optimized by the directional heuristic search algorithm which is good on local optimization. The simulation results show that the collaborative optimization based on particle swarm algorithm has more optimal solution sets and fast convergence by considering the coupling relationship between different disciplines, and the comprehensive performance of in-wheel electric vehicle is improved.
In-wheel electric vehicle,differential steering,collaborative optimization,particle swarm algorithm
https://ijstm.shirazu.ac.ir/article_2997.html
https://ijstm.shirazu.ac.ir/article_2997_97097fb50efec0c159d57b3b82d4a2bb.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
AN INVESTIGATION ON THE ENERGY ABSORPTION OF ALUMINUM FOAM CORE SANDWICH PANEL VIA QUASI-STATIC PERFORATION TEST
185
196
EN
M.
GOLESTANIPOUR
Dept. of Materials and Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111, Mashhad, I. R. of Iran
A.
BABAKHANI
Dept. of Materials and Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111, Mashhad, I. R. of Iran
S. M.
ZEBARJAD
Dept. of Materials and Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111, Mashhad, I. R. of Iran
zebarjad@um.ac.ir
10.22099/ijstm.2015.2998
Aluminum foams are a novel branch of advanced materials with superior properties. Sandwich structures with aluminum foam core are good energy absorbers. In this paper, mechanical properties and energy absorption of aluminum foam sandwich panels subjected to quasi-static perforation tests with conical-nosed indenter were investigated experimentally. For this purpose sandwich panels consisting of two aluminum face-sheets and a closed cell aluminum foam core were fabricated. Quasi-static perforation tests on fully fixed sandwich panels were carried out by a universal testing machine at a cross head speed of 0.02 mm/s. Force-displacement curves were recorded and peak piercing force and absorbed energy of sandwich panels were calculated accordingly. Effects of foam core density (0.5, 0.6 and 0.7 g/cm3) and thickness of face-sheets (0.6, 1 and 2 mm) and foam core (10, 20 and 30 mm) on the mechanical properties and energy absorption of samples were discussed. The results showed that increasing foam core and face-sheet thickness and foam core density led to more total absorbed energy being achieved and higher piercing force.<br /><br />
Sandwich panel,aluminum foam,perforation,Energy absorption
https://ijstm.shirazu.ac.ir/article_2998.html
https://ijstm.shirazu.ac.ir/article_2998_1c3b495078853bdacf1670ef21ad42b0.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
THE EFFECTS OF HUMIDITY, COMPRESSOR OPERATION TIME AND AMBIENT TEMPERATURE ON FROST FORMATION IN AN INDUSTRIAL FRIDGE
197
203
EN
A. R.
TAHAVVOR
Dept. of Mechanical Eng., College of Engineering, Shiraz Branch, Islamic Azad University, Shiraz, I. R. of Iran
tahavvor@iaushiraz.ac.ir
S.
HOSSEINI
Dept. of Mechanical Eng., College of Engineering, Shiraz Branch, Islamic Azad University, Shiraz, I. R. of Iran
10.22099/ijstm.2015.2999
Fridges are used in various industries, and heat exchanger is one of the main components of these systems; therefore, efficiency analysis of these systems is very important. In many fridges, frost over the heat exchanger tubes or pipes affects the system operation and reduces heat transfer between the refrigerant and ambient, so defrosting systems are usually used to enhance heat transfer. Designing defrosting systems requires sufficient information about frost formation processes. Therefore, the objective of this study is experimental investigation of frost formation over a heat exchanger pipe in a pilot fridge. To do this, some steps are considered. For distinct cases, experiments are done to collect database for frost parameters under desired conditions. Then, based on experimental measurements some correlations are proposed for practical applications of frost growth and defrosting process over heat exchanger tubes.
Frost formation,fridge,defrost,compressor operation time,humidity
https://ijstm.shirazu.ac.ir/article_2999.html
https://ijstm.shirazu.ac.ir/article_2999_7ad52f6d752e62304e85b50e269130be.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
PERFORMANCE EVALUATION OF CONTINUOUSLY REGENERATING TRAPS FOR CONTROLLING THE CARBONYL EMISSIONS FROM A TURBOCHARGED COMPRESSION IGNITION ENGINE
205
217
EN
A. N.
SHAH
Dept. of Mechanical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan
AND
School of Mechanical and Vehicular Engineering, Beijing Institute of Technology, Beijing 100081, P.R. China
anaeems@uet.edu.pk
G.
YUNSHAN
School of Mechanical and Vehicular Engineering, Beijing Institute of Technology, Beijing 100081, P.R. China
F. H.
SHAH
Dept. of Mechanical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan
H. U.
MUGHAL
Dept. of Mechanical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan
A.
NAVEED
Dept. of Mechanical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan
10.22099/ijstm.2015.3000
Two continuously regenerating traps CRT-A and CRT-B were evaluated under the controlled carbonyl emissions from a turbocharged diesel engine run on an AC electrical dynamometer. The gas-phase carbonyls were taken in silica gel cartridges coated with 2,4-dinitrophenylhydrazine both upstream (baseline) and downstream of the traps, and a total of fourteen carbonyls were identified and then quantified using the high performance liquid chromatography (HPLC) with ultraviolet (UV) detector. Carbonyls were predominant during higher load modes as well as at maximum speed modes. The conversion/reduction rate (CR) of carbonyls was directly affected by the physical characteristics of the traps. The CR revealed a strong correlation with NO2/NOx ratios of CRT units, and the performance of retrofits was adversely affected by the increasing upstream back pressure (P) due to the clogging phenomenon. Carbonyls such as formaldehyde, acetaldehyde, acrolein + acetone and propionaldehyde were in abundance, and abated up to 75.4, 83, 60, and 69.3% respectively with CRT-A, and 81.2, 81.5, 57.3, and 65.2% respectively with CRT-B. Nevertheless, formaldehyde and propionaldehyde exhibited reluctance to CR during lower load modes, which was higher with CRT-B relative to CRT-A due to the different features of the traps. A positive correlation was observed between the conversion of acetaldehyde and propionaldehyde within the cycle, and between the mean relative contributions of formaldehyde and acetaldehyde within the CRT units. Moreover, total carbonyls including aromatic aldehydes, and their specific reactivity (SR) both were reduced with CRT technologies showing the order of magnitude as Baseline > CRT-A > CRT-B.
diesel engine,exhaust emissions,carbonyls,unregulated emissions,continuously regenerating trap
https://ijstm.shirazu.ac.ir/article_3000.html
https://ijstm.shirazu.ac.ir/article_3000_68468a84f68b6f8ac1fa444dce28139d.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
EFFECT OF AIR JET AT THE VARIOUS RATE OF FUEL INJECTION IN A DIRECT INJECTION DIESEL ENGINE
219
231
EN
M.
MANSOURY
Dept. of Mechanical Engineering, University of Urmia, Urmia, West Azerbaijan 57561-15311, I. R. of Iran
mehdimansury@yahoo.com
S.
JAFARMADAR
Dept. of Mechanical Engineering, University of Urmia, Urmia, West Azerbaijan 57561-15311, I. R. of Iran
S. M.
LASHKARPOUR
Dept of Mechanical Engineering, Olum Tahghighat University of Tehran, Tehran, I. R. of Iran
M.
TALEI
Dept. of Mechanical Engineering, University of Urmia, Urmia, West Azerbaijan 57561-15311, I. R. of Iran
10.22099/ijstm.2015.3001
In the present work, the simultaneous effects of fuel injection rate and injection of air jet into the combustion chamber on exhaust emissions, combustion process and performance parameters in a direct injection diesel engine were investigated. In order to create an air jet, a design was presented in which a secondary chamber (air cell) was created inside the cylinder and was joined to the main chamber by throats. The obtained results showed that creating the air cell had no major effect on the power and specific fuel consumption, and brought about the reduction of emitted smoke particles from the combustion chamber in all four conditions of 100% load, 75% load, 50% load and 25% load. In comparison with the base engine, the rates of oxides of nitrogen (NOx) emissions decreased at 100% and 75% loads, yet increased at 50% and 25% loads. The outcomes of the current study were compared with those existing in the relevant literature and displayed acceptable behavior.
Air jet,air cell,combustion,emission,diesel engine,injection rate
https://ijstm.shirazu.ac.ir/article_3001.html
https://ijstm.shirazu.ac.ir/article_3001_0de8b9bffeefc09645c4bb0081d58df6.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
STEADY STATE AND TRANSIENT THERMALHYDRAULIC ANALYSIS OF PHWR USING COBRA-3C/RERTR
233
242
EN
A.
HUSSAIN
Dept. of Nuclear Engineering, King Abdulaziz University, Jeddah, KSA
ahassain@kau.edu.sa
F.
ABOLABAN
Dept. of Nuclear Engineering, King Abdulaziz University, Jeddah, KSA
S. M.
KHUBAIB
Dept. of Mechanical Engineering, Nazeer Hussain University, Karachi, Pakistan
S.
MUBIN
Dept. of Civil Engineering, University of Engineering & Technology, Lahore, Pakistan
I.
AHMED
4Dept. of Chemical Engineering, University Technology PETRONAS, Perak, Malaysia
10.22099/ijstm.2015.3002
Nuclear cross sections that determine core multiplication strongly depend on core temperature (e.g., the Doppler, moderator density effects etc). On the other hand, since this heat is generated by the neutron flux in the reactor core, the temperature distribution in the core will depend heavily on its neutronic behavior. Fuel centerline temperature could be the limiting constraint on reactor power because of the concern for fuel melting. Likewise, high clad temperature is also a possible limiting factor on reactor power because of the potential degradation of clad material or on-set of critical heat flux phenomenon.<br />An assessment of the steady state and transient thermal hydraulic capabilities of the computer code COBRA 3C/RERTR was made using model for a PHWRs reactor core. The temperature distributions determined for fuel, clad and coolant are compared with analytical results and with the results quoted in safety report. It was found that when the code was run for full power at reduced flow of 70% the bulk coolant temperature remained below the saturation temperature, so there is an adequate design margin is available for safety related scenarios.
Thermal hydraulic analysis,PHWRs,fuel temperatures,COBRA/RERTR code,reactor safety
https://ijstm.shirazu.ac.ir/article_3002.html
https://ijstm.shirazu.ac.ir/article_3002_66540ac492e3491944e2aef324b1f55d.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
THERMOMECHANICAL STRESS ANALYSIS OF VEHICLES GRAY CAST BRAKE
243
252
EN
A.
BELHOCINE
Dept. of Mechanical Engineering, University of Sciences and the Technology of Oran,
L.P 1505 El -MNAOUER, USTO 31000 ORAN (Algeria)
al.belhocine@yahoo.fr
10.22099/ijstm.2015.3003
The vehicle braking system is considered to be one of the most fundamental safety-critical systems in modern vehicles, as its main purpose is to stop or decelerate the vehicle. The frictional heat generated during braking application can cause numerous negative effects on the brake assembly, such as brake fade, premature wear, thermal cracks and disc thickness variation. In the past, surface roughness and wear at the pad interface have rarely been considered in studies of the thermal analysis of a disc brake assembly using the finite element method. The ventilated pad-disc brake assembly is built by a three-dimensional model with a thermomechanical coupling boundary condition and multi-body model technique. The numerical simulation for the coupled transient thermal field and stress field is carried out sequentially with the thermal-structural coupled method, based on ANSYS software, to evaluate the stress fields of deformations that are established in the disc with the pressure of the pads and in the conditions of tightening of the disc; thus, the contact pressure distributions field in the pads is obtained, which is another significant aspect in this research. The results obtained by the simulation are satisfactorily compared with those of the specialized literature.
Brake discs,heat flux,heat transfer coefficient,Von Mises stress,contact pressure
https://ijstm.shirazu.ac.ir/article_3003.html
https://ijstm.shirazu.ac.ir/article_3003_9722faa5666bb6107dd3c9d801004430.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
ASSEMBLY PERFORMANCE OF A GASKETED BOLTED FLANGED PIPE JOINT USING DIFFERENT BOLT TIGHTENING STRATEGIES
253
260
EN
M.
ABID
Interdisciplinary Research Center, COMSATS Institute of Information Technology, Wah Cantt, Pakistan
drabid@ciitwah.edu.pk
H.
ABDUL WAJID
Department of Mathematics, COMSATS Institute of Information Technology, Lahore, Pakistan
AND
Department of Electrical Engineering, Islamic University Medina, KSA
A.
ABBAS
Faculty of Mechanical Engineering, GIK Institute of Engineering Sciences and Technology, Topi, Pakistan
Y.
MEHMOOD
Faculty of Mechanical Engineering, GIK Institute of Engineering Sciences and Technology, Topi, Pakistan
10.22099/ijstm.2015.3004
This paper presents the results of the assembly process of a gasketed bolted flanged pipe joint for two different bolt tightening strategies, i.e. ASME and Industrial using torque control of preload method. The final clamping force is achieved in four and five passes in ASME and Industrial strategy respectively. Axial bolt stress variation, at the end of each pass, individual bolt bending behavior, gasket stress and flange stress variations for both strategies are discussed.
Pipe flange joint,assembly process,torque control,clamping force,Finite Element Analysis
https://ijstm.shirazu.ac.ir/article_3004.html
https://ijstm.shirazu.ac.ir/article_3004_2ffa902a959415d4833f1e26447c278c.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
EFFECTS OF ELEMENT TYPES FOR CRACK TIPS IN WOVEN DCB MADE OF GLASS FIBRE-EPOXY RESIN
261
271
EN
F.
AZIMPOUR
1,3,4Faculty of Mechanical Engineering, Islamic Azad University, Bonab Branch, East Azarbaijan, I. R. of Iran
farzin.azimpour@atauni.edu.t
H.
AKBULUT
Faculty of Mechanical Engineering, Ataturk University, Erzurum, Turkey
H.
GHAFFARZADEH JAHANPASAND
Faculty of Mechanical Engineering, Islamic Azad University, Bonab Branch, East Azarbaijan, I. R. of Iran
H.
AKBARI KHANTAKHTI
Faculty of Mechanical Engineering, Islamic Azad University, Bonab Branch, East Azarbaijan, I. R. of Iran
10.22099/ijstm.2015.3005
Nowadays, textile and woven fabric composites are taken into consideration for<br />applications in high mechanical properties and every in-plane direction. However, developments in<br />modelling and characterisation of the fabric reinforced composite materials are considered more in<br />the effects of element types used in the mesh generation of the crack tip. The type of element<br />selected for the crack tip, a critical point for evaluation of crack growth in a double cantilever<br />beam (DCB) sample, is extremely important. In this study, results of strain energy release rate<br />(SERR) meshed with singular and or brick elements with the experimental data were compared to<br />select better element type. The plotted results of the crack tips meshed with the brick elements and<br />the diagrams revealing the SERR in contrast to the crack length was evaluated. In addition, the<br />aforementioned operation has been repeated for singular elements. The theory of the failure<br />mechanics has been used to calculate the amounts of SERR for several crack lengths. It is<br />concluded that, numerical results from SERR of the crack tip when meshed with singular elements<br />were closer to the experimental results compared with data of SERR when meshed with brick<br />elements.
Woven composite,Finite element method,fracture analysis,brick elements,singular elements
https://ijstm.shirazu.ac.ir/article_3005.html
https://ijstm.shirazu.ac.ir/article_3005_554e6f5f5535547081e8ba1abb6568aa.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Mechanical Engineering
2228-6187
39
M1+
2015
05
01
VARIATIONAL APPROACH FOR APPROXIMATE ANALYTICAL SOLUTION TO NON-NATURAL VIBRATION EQUATIONS
273
282
EN
I.
PAKAR
Young Researchers and Elites Club, Mashhad Branch, Islamic Azad University, Mashhad, I. R. of Iran
M.
BAYAT
Department of Civil Engineering, Mashhad Branch, Islamic Azad University, Mashhad, I. R. of Iran
M.
BAYAT
Department of Civil Engineering, Mashhad Branch, Islamic Azad University, Mashhad, I. R. of Iran
mbayat14@yahoo.com
10.22099/ijstm.2015.3006
In this study, He’s Variational Approach (VA) is used to solve the non-natural<br />vibrations and oscillations. The method works very well for the whole range of initial amplitudes<br />and does not demand small perturbation. It is also sufficiently accurate to both linear and nonlinear<br />physics and engineering problems. We consider some examples to illustrate the effectiveness and<br />convenience of the method. Runge-Kutta’s [RK] algorithm was also implemented to show the<br />examples through a numerical method. Finally, to show the accuracy of the VA, the results have<br />been shown graphically and compared with numerical and exact solution.
Variational approach (VA),nonlinear oscillators,analytical method
https://ijstm.shirazu.ac.ir/article_3006.html
https://ijstm.shirazu.ac.ir/article_3006_293d42006d76bcb236ebca19ff151a25.pdf