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Surface effect on forced vibration of DNS by viscoelastic layer under a moving load
Hosseini, S.A.H.,Rahmani, O.,Hayati, H.,Jahanshir, A. Techno-Press 2021 Coupled systems mechanics Vol.10 No.4
The surface effect for a forced vibration of a double-nanobeam-system (DNS) coupled by a viscoelastic layer under a moving constant load is studied in this paper. The viscoelastic layer that couples the nanobeams to each other, is modelled as spring-damper system. The Euler- Bernoulli theory and a simply supported boundary condition are considered for both nanobeams. By using the analytical solution, the dynamic displacement is obtained by considering the surface elasticity and residual tension effect on each nanobeams. Furthermore, the several significant parameters such as the velocity of the moving load, spring constant, damping coefficient and also the surface effect have been studied using some plots and examples. Finally, by observing the diagrams it was concluded that as the length of the beams reduces, the surface effect has a considerable effect on each of nanobeams especially at Nano scale, where it was not achieved by classic theories.
A new solution for dynamic response of FG nonlocal beam under moving harmonic load
S.A.H. Hosseini,O. Rahmani,S. Bayat 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.2
A Closed-form solution for dynamic response of a functionally graded (FG) nonlocal nanobeam due to action of moving harmonic load is presented in this paper. Due to analyzing in small scale, a nonlocal elasticity theory is utilized. The governing equation and boundary conditions are derived based on the Euler-Bernoulli beam theory and Hamilton’s principle. The material properties vary through the thickness direction. The harmonic moving load is modeled by Delta function and the FG nanobeam is simply supported. Using the Laplace transform the dynamic response is obtained. The effect of important parameters such as excitation frequency, the velocity of the moving load, the power index law of FG material and the nonlocal parameter is analyzed. To validate, the results were compared with previous literature, which showed an excellent agreement.
A computational model of ureteral peristalsis and an investigation into ureteral reflux
G. Hosseini,C. Ji,D. Xu,M. A. Rezaienia,E. Avital,A. Munjiza,J. J. R. Williams,J. S. A. Green 대한의용생체공학회 2018 Biomedical Engineering Letters (BMEL) Vol.8 No.1
The aim of this study is to create a computationalmodel of the human ureteral system that accuratelyreplicates the peristaltic movement of the ureter for avariety of physiological and pathological functions. Theobjectives of this research are met using our in-house fluidstructuraldynamics code (CgLes–Y code). A realisticperistaltic motion of the ureter is modelled using a novelpiecewise linear force model. The urodynamic responsesare investigated under two conditions of a healthy and adepressed contraction force. A ureteral pressure during thecontraction shows a very good agreement with correspondingclinical data. The results also show a dependencyof the wall shear stresses on the contraction velocity and itconfirms the presence of a high shear stress at the proximalpart of the ureter. Additionally, it is shown that an inefficientlumen contraction can increase the possibility of acontinuous reflux during the propagation of peristalsis.
M. Zamanian,H. Rezaei,M. Hadilu,S.A.A. Hosseini 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.5
In many of microdevices a part of a microbeam is covered by a piezoelectric layer. Depend on the application a DC or AC voltage is applied between upper and lower side of the piezoelectric layer. A common method in many of previous works for evaluating the response of these structures is discretizing by Galerkin method. In these works often single mode shape of a uniform microbeam i.e. the microbeam without piezoelectric layer has been used as comparison function, and so the convergence of the solution has not been verified. In this paper the Galerkin method is used for discretization, and a comprehensive analysis on the convergence of solution of equation that is discretized using this comparison function is studied for both clamped-clamped and clamped-free microbeams. The static and dynamic solution resulted from Galerkin method is compared to the modal expansion solution. In addition the static solution is compared to an exact solution. It is denoted that the required numbers of uniform microbeam mode shapes for convergence of static solution due to DC voltage depends on the position and thickness of deposited piezoelectric layer. It is shown that when the clamped-clamped microbeam is coated symmetrically by piezoelectric layer, then the convergence for static solution may be obtained using only first mode. This result is valid for clamped –free case when it is covered by piezoelectric layer from left clamped side to the right. It is shown that when voltage is AC then the number of required uniform microbeam shape mode for convergence is much more than the number of required mode in modal expansion due to the dynamic effect of piezoelectric layer. This difference increases by increasing the piezoelectric thickness, the closeness of the excitation frequency to natural frequency and decreasing the damping coefficient. This condition is often indefeasible in microresonator system. It is concluded that discreitizing the equation of motion using one mode shape of uniform microbeam as comparison function in many of previous works causes considerable errors.
Selecting Optimal Location for Electric Recharging Stations with Queue
Meysam Hosseini,S. A. MirHassani 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.7
Dominance of fossil fuels in the transportation sector has led to environmental and economical problems and transition to Alternative Fuel Vehicle (AFV) has become a necessity. Electric Vehicle (EV) is one of the AFVs that deliver clear benefit of zero tailpipe emissions. The EVs have a limited range and their use is influenced by the location of recharging facilities. The charging time of EV is long and recharging in stations take a lot of time. In addition, the capacity of recharging stations is limited and if the capacity is occupied the vehicles must wait in queues. In this paper, a recharging station location model with queue is proposed which considers capacity, recharging time, and waiting time. The presented model is a set covering and can easily become a maximum cover model with or without predefined activities. A heuristic algorithm to solve the model is proposed and the model is evaluated using two networks under various conditions; a random generated and a network of Penghu County. The obtained results indicate that the model is able to identify the location and the number of the recharging stations and provide a good travel plan especially for tourism.
A Comparison between Three Numerical Criteria for Prediction the Forming Limit Diagram of St14 Steel
M. Moslemi,S.J. Hosseinipour,M.E. Hosseini,A.H. Gorji 한국소성가공학회 2011 기타자료 Vol.2011 No.8
In this paper, the forming limit diagram (FLD) of a low carbon steel St14 (DIN 1623) is investigated experimentally and numerically. The objective of this study is to find a numerical criterion which enables a simple and reliable determination of the FLD. For this purpose, Out-of-plane stretching test method with hemispherical punch was simulated by using commercial finite element software, ABAQUSE 6.9. One-quarter of the geometry was used due to symmetry. The material was modeled as elastoplastic and the anisotropic properties were described by the Hill quadratic yield criterion. The model was assumed to be rate independent. Coulomb friction law was defined for all contact surfaces. The simulation process was performed in two steps. In the first step the blank-holder moves down and deforms the blank into the draw-bead. Then the punch moves up at 20 increments and deforms the specimen to a specified displacement. Three numerical criteria including maximum second thickness strain derivative (CRIT1), equivalent plastic strain increment ratio (CRIT2), and total equivalent plastic strain ratio (CRIT3) were evaluated and the forming limit curve (FLC) were obtained. The predicted FLC were compared with experimental data. Unlike the CRIT2, the CRIT1 and CRIT3 were in good agreements with were experimental data. The CRIT1 criterion predicted the lower bound of the experimental results. While by using the CRIT3 criterion both the lower and upper bounds of the experimental results were predicted.
Exact solution for axial vibration of the power, exponential and sigmoid FG nonlocal nanobeam
Hosseini, S.A.H.,Moghaddam, M.H. Noroozi,Rahmani, O. Techno-Press 2020 Advances in aircraft and spacecraft science Vol.7 No.6
The present study investigates axial vibration of a FG nanobeam using nonlocal elasticity theory under clamped-clamped and clamped-free boundary conditions. Power law, exponential law and sigmoid law are applied as grading laws to examine the effect of the material distribution on axial vibration of the FG nanobeam. A parametric study was done to examine the effect of length scale on the dynamic behavior of the structure and the results are presented. It was observed that consideration of the nonlocal length scale is essential when analyzing the free vibration of a FG nanobeam. The results of the present study can be used as benchmarks in future studies of FG nanostructures.