ORIGINAL_ARTICLE
DYNAMIC STABILITY OF EMBEDDED SINGLE WALLED CARBON NANOTUBES INCLUDING THERMAL EFFECTS
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.
https://ijstm.shirazu.ac.ir/article_2995_ff4e796b647503622a3be13846daf6c1.pdf
2015-05-01
153
161
10.22099/ijstm.2015.2995
carbon nanotube
dynamic stability
Floquet-Lyapunov
Mathieu-Hill
R.
ANSARI
1
Dept. of Mechanical Engineering, University of Guilan, P.O. Box 3756, Rasht, I. R. of Iran
AUTHOR
R.
GHOLAMI
gholami_r@liau.ac.ir
2
Dept. of Mechanical Engineering, Lahijan Branch, Islamic Azad University, P.O. Box 1616, Lahijan, I. R. of Iran
LEAD_AUTHOR
ORIGINAL_ARTICLE
INFLUENCE OF ROLLING VISCO-ELASTIC COUPLING ON NON-LINEAR DYNAMICS OF DOUBLE PLATES SYSTEM
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
https://ijstm.shirazu.ac.ir/article_2996_69b3d27a5285c85a1bcea25858af0f83.pdf
2015-05-01
163
173
10.22099/ijstm.2015.2996
Hybrid nonlinear system
circular plates
rolling visco nonlinear elastic rheological element
multi frequency
resonance
resonant jumps
mutual mode interaction
stationary resonant regimes
J. D.
SIMONOVIĆ
bjulijana@masfak.ni.ac.rs
1
Faculty of Mechanical Engineering,University of Niš, A. Medvedeva 14, 18000 Niš, Serbia
LEAD_AUTHOR
ORIGINAL_ARTICLE
COLLABORATIVE OPTIMIZATION OF DIFFERENTIAL STEERING FOR IN-WHEEL ELECTRIC VEHICLE
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.
https://ijstm.shirazu.ac.ir/article_2997_97097fb50efec0c159d57b3b82d4a2bb.pdf
2015-05-01
175
184
10.22099/ijstm.2015.2997
In-wheel electric vehicle
differential steering
collaborative optimization
particle swarm algorithm
W. Z.
ZHAO
zhaowanzhong@126.com
1
Dept. of Vehicle Eng., Nanjing University of Aeronautics and Astronautics, P. R. China AND Dept. of Mechanical Eng., University of Michigan, USA
LEAD_AUTHOR
C. Y.
Wang
chengyuan.wang@swansea.ac.uk
2
Dept. of Vehicle Eng., Nanjing University of Aeronautics and Astronautics, P. R. China AND Dept. of Mechanical Eng., University of Michigan, USA
AUTHOR
Z. Q.
ZHANG
3
Dept. of Vehicle Eng., Nanjing University of Aeronautics and Astronautics, P. R. China
AUTHOR
ORIGINAL_ARTICLE
AN INVESTIGATION ON THE ENERGY ABSORPTION OF ALUMINUM FOAM CORE SANDWICH PANEL VIA QUASI-STATIC PERFORATION TEST
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.
https://ijstm.shirazu.ac.ir/article_2998_1c3b495078853bdacf1670ef21ad42b0.pdf
2015-05-01
185
196
10.22099/ijstm.2015.2998
Sandwich panel
aluminum foam
perforation
Energy absorption
M.
GOLESTANIPOUR
1
Dept. of Materials and Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111, Mashhad, I. R. of Iran
AUTHOR
A.
BABAKHANI
2
Dept. of Materials and Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111, Mashhad, I. R. of Iran
AUTHOR
S. M.
ZEBARJAD
zebarjad@um.ac.ir
3
Dept. of Materials and Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111, Mashhad, I. R. of Iran
LEAD_AUTHOR
ORIGINAL_ARTICLE
THE EFFECTS OF HUMIDITY, COMPRESSOR OPERATION TIME AND AMBIENT TEMPERATURE ON FROST FORMATION IN AN INDUSTRIAL FRIDGE
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.
https://ijstm.shirazu.ac.ir/article_2999_7ad52f6d752e62304e85b50e269130be.pdf
2015-05-01
197
203
10.22099/ijstm.2015.2999
Frost formation
fridge
defrost
compressor operation time
humidity
A. R.
TAHAVVOR
tahavvor@iaushiraz.ac.ir
1
Dept. of Mechanical Eng., College of Engineering, Shiraz Branch, Islamic Azad University, Shiraz, I. R. of Iran
LEAD_AUTHOR
S.
HOSSEINI
2
Dept. of Mechanical Eng., College of Engineering, Shiraz Branch, Islamic Azad University, Shiraz, I. R. of Iran
AUTHOR
ORIGINAL_ARTICLE
PERFORMANCE EVALUATION OF CONTINUOUSLY REGENERATING TRAPS FOR CONTROLLING THE CARBONYL EMISSIONS FROM A TURBOCHARGED COMPRESSION IGNITION ENGINE
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.
https://ijstm.shirazu.ac.ir/article_3000_68468a84f68b6f8ac1fa444dce28139d.pdf
2015-05-01
205
217
10.22099/ijstm.2015.3000
diesel engine
exhaust emissions
carbonyls
unregulated emissions
continuously regenerating trap
A. N.
SHAH
anaeems@uet.edu.pk
1
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
LEAD_AUTHOR
G.
YUNSHAN
2
School of Mechanical and Vehicular Engineering, Beijing Institute of Technology, Beijing 100081, P.R. China
AUTHOR
F. H.
SHAH
3
Dept. of Mechanical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan
AUTHOR
H. U.
MUGHAL
4
Dept. of Mechanical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan
AUTHOR
A.
NAVEED
5
Dept. of Mechanical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan
AUTHOR
ORIGINAL_ARTICLE
EFFECT OF AIR JET AT THE VARIOUS RATE OF FUEL INJECTION IN A DIRECT INJECTION DIESEL ENGINE
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.
https://ijstm.shirazu.ac.ir/article_3001_0de8b9bffeefc09645c4bb0081d58df6.pdf
2015-05-01
219
231
10.22099/ijstm.2015.3001
Air jet
air cell
combustion
emission
diesel engine
injection rate
M.
MANSOURY
mehdimansury@yahoo.com
1
Dept. of Mechanical Engineering, University of Urmia, Urmia, West Azerbaijan 57561-15311, I. R. of Iran
LEAD_AUTHOR
S.
JAFARMADAR
2
Dept. of Mechanical Engineering, University of Urmia, Urmia, West Azerbaijan 57561-15311, I. R. of Iran
AUTHOR
S. M.
LASHKARPOUR
3
Dept of Mechanical Engineering, Olum Tahghighat University of Tehran, Tehran, I. R. of Iran
AUTHOR
M.
TALEI
4
Dept. of Mechanical Engineering, University of Urmia, Urmia, West Azerbaijan 57561-15311, I. R. of Iran
AUTHOR
ORIGINAL_ARTICLE
STEADY STATE AND TRANSIENT THERMALHYDRAULIC ANALYSIS OF PHWR USING COBRA-3C/RERTR
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.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.
https://ijstm.shirazu.ac.ir/article_3002_66540ac492e3491944e2aef324b1f55d.pdf
2015-05-01
233
242
10.22099/ijstm.2015.3002
Thermal hydraulic analysis
PHWRs
fuel temperatures
COBRA/RERTR code
reactor safety
A.
HUSSAIN
ahassain@kau.edu.sa
1
Dept. of Nuclear Engineering, King Abdulaziz University, Jeddah, KSA
LEAD_AUTHOR
F.
ABOLABAN
2
Dept. of Nuclear Engineering, King Abdulaziz University, Jeddah, KSA
AUTHOR
S. M.
KHUBAIB
3
Dept. of Mechanical Engineering, Nazeer Hussain University, Karachi, Pakistan
AUTHOR
S.
MUBIN
4
Dept. of Civil Engineering, University of Engineering & Technology, Lahore, Pakistan
AUTHOR
I.
AHMED
5
4Dept. of Chemical Engineering, University Technology PETRONAS, Perak, Malaysia
AUTHOR
ORIGINAL_ARTICLE
THERMOMECHANICAL STRESS ANALYSIS OF VEHICLES GRAY CAST BRAKE
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.
https://ijstm.shirazu.ac.ir/article_3003_9722faa5666bb6107dd3c9d801004430.pdf
2015-05-01
243
252
10.22099/ijstm.2015.3003
Brake discs
heat flux
heat transfer coefficient
Von Mises stress
contact pressure
A.
BELHOCINE
al.belhocine@yahoo.fr
1
Dept. of Mechanical Engineering, University of Sciences and the Technology of Oran, L.P 1505 El -MNAOUER, USTO 31000 ORAN (Algeria)
LEAD_AUTHOR
ORIGINAL_ARTICLE
ASSEMBLY PERFORMANCE OF A GASKETED BOLTED FLANGED PIPE JOINT USING DIFFERENT BOLT TIGHTENING STRATEGIES
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.
https://ijstm.shirazu.ac.ir/article_3004_2ffa902a959415d4833f1e26447c278c.pdf
2015-05-01
253
260
10.22099/ijstm.2015.3004
Pipe flange joint
assembly process
torque control
clamping force
Finite Element Analysis
M.
ABID
drabid@ciitwah.edu.pk
1
Interdisciplinary Research Center, COMSATS Institute of Information Technology, Wah Cantt, Pakistan
LEAD_AUTHOR
H.
ABDUL WAJID
2
Department of Mathematics, COMSATS Institute of Information Technology, Lahore, Pakistan AND Department of Electrical Engineering, Islamic University Medina, KSA
AUTHOR
A.
ABBAS
3
Faculty of Mechanical Engineering, GIK Institute of Engineering Sciences and Technology, Topi, Pakistan
AUTHOR
Y.
MEHMOOD
4
Faculty of Mechanical Engineering, GIK Institute of Engineering Sciences and Technology, Topi, Pakistan
AUTHOR
ORIGINAL_ARTICLE
EFFECTS OF ELEMENT TYPES FOR CRACK TIPS IN WOVEN DCB MADE OF GLASS FIBRE-EPOXY RESIN
Nowadays, textile and woven fabric composites are taken into consideration forapplications in high mechanical properties and every in-plane direction. However, developments inmodelling and characterisation of the fabric reinforced composite materials are considered more inthe effects of element types used in the mesh generation of the crack tip. The type of elementselected for the crack tip, a critical point for evaluation of crack growth in a double cantileverbeam (DCB) sample, is extremely important. In this study, results of strain energy release rate(SERR) meshed with singular and or brick elements with the experimental data were compared toselect better element type. The plotted results of the crack tips meshed with the brick elements andthe diagrams revealing the SERR in contrast to the crack length was evaluated. In addition, theaforementioned operation has been repeated for singular elements. The theory of the failuremechanics has been used to calculate the amounts of SERR for several crack lengths. It isconcluded that, numerical results from SERR of the crack tip when meshed with singular elementswere closer to the experimental results compared with data of SERR when meshed with brickelements.
https://ijstm.shirazu.ac.ir/article_3005_554e6f5f5535547081e8ba1abb6568aa.pdf
2015-05-01
261
271
10.22099/ijstm.2015.3005
Woven composite
Finite element method
fracture analysis
brick elements
singular elements
F.
AZIMPOUR
farzin.azimpour@atauni.edu.t
1
1,3,4Faculty of Mechanical Engineering, Islamic Azad University, Bonab Branch, East Azarbaijan, I. R. of Iran
LEAD_AUTHOR
H.
AKBULUT
2
Faculty of Mechanical Engineering, Ataturk University, Erzurum, Turkey
AUTHOR
H.
GHAFFARZADEH JAHANPASAND
3
Faculty of Mechanical Engineering, Islamic Azad University, Bonab Branch, East Azarbaijan, I. R. of Iran
AUTHOR
H.
AKBARI KHANTAKHTI
4
Faculty of Mechanical Engineering, Islamic Azad University, Bonab Branch, East Azarbaijan, I. R. of Iran
AUTHOR
ORIGINAL_ARTICLE
VARIATIONAL APPROACH FOR APPROXIMATE ANALYTICAL SOLUTION TO NON-NATURAL VIBRATION EQUATIONS
In this study, He’s Variational Approach (VA) is used to solve the non-naturalvibrations and oscillations. The method works very well for the whole range of initial amplitudesand does not demand small perturbation. It is also sufficiently accurate to both linear and nonlinearphysics and engineering problems. We consider some examples to illustrate the effectiveness andconvenience of the method. Runge-Kutta’s [RK] algorithm was also implemented to show theexamples through a numerical method. Finally, to show the accuracy of the VA, the results havebeen shown graphically and compared with numerical and exact solution.
https://ijstm.shirazu.ac.ir/article_3006_293d42006d76bcb236ebca19ff151a25.pdf
2015-05-01
273
282
10.22099/ijstm.2015.3006
Variational approach (VA)
nonlinear oscillators
analytical method
I.
PAKAR
1
Young Researchers and Elites Club, Mashhad Branch, Islamic Azad University, Mashhad, I. R. of Iran
AUTHOR
M.
BAYAT
2
Department of Civil Engineering, Mashhad Branch, Islamic Azad University, Mashhad, I. R. of Iran
AUTHOR
M.
BAYAT
mbayat14@yahoo.com
3
Department of Civil Engineering, Mashhad Branch, Islamic Azad University, Mashhad, I. R. of Iran
LEAD_AUTHOR