Moving load induced dynamic response of functionally graded-carbon nanotubes-reinforced pipes conveying fluid subjected to thermal load

F. Vakili Tahami,H. Biglari,M. Raminnea 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.4

Dynamic response of functionally graded Carbon nanotubes (FG-CNT) reinforced pipes conveying viscous fluid under accelerated moving load is presented. The mixture rule is used for obtaining the material properties of nano-composite pipe. The radial force induced by viscous fluid is calculated by Navier–Stokes equation. The material properties of pipe are considered temperature-dependent. The structure is simulated by Reddy higher-order shear deformation shell theory and the corresponding motion equations are derived by Hamilton’s principal. Differential quadrature (DQ) method and the Integral Quadrature (IQ) are applied for analogizing the motion equations and then the Newmark time integration scheme is used for obtaining the dynamic response of structure. The effects of different parameters such as boundary conditions, geometrical parameters, velocity and acceleration of moving load, CNT volume percent and distribution type are shown on the dynamic response of pipe. Results indicate that increasing CNTs leads to decrease in transient deflection of structure. In accelerated motion of the moving load, the maximum displacement is occurred later with respect to decelerated motion of moving load.

Nonlinear higher order Reddy theory for temperature- dependent vibration and instability of embedded functionally graded pipes conveying fluid-nanoparticle mixture

M. Raminnea,H. Biglari,F. Vakili Tahami 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.1

This paper addresses temperature-dependent nonlinear vibration and instability of embedded functionally graded (FG) pipes conveying viscous fluid-nanoparticle mixture. The surrounding elastic medium is modeled by temperature-dependent orthotropic Pasternak medium. Reddy third-order shear deformation theory (RSDT) of cylindrical shells are developed using the strain-displacement relations of Donnell theory. The well known Navier-Stokes equation is used for obtaining the applied force of fluid to pipe. Based on energy method and Hamilton‟s principal, the governing equations are derived. Generalized differential quadrature method (GDQM) is applied for obtaining the frequency and critical fluid velocity of system. The effects of different parameters such as mode numbers, nonlinearity, fluid velocity, volume percent of nanoparticle in fluid, gradient index, elastic medium, boundary condition and temperature gradient are discussed. Numerical results indicate that with increasing the stiffness of elastic medium and decreasing volume percent of nanoparticle in fluid, the frequency and critical fluid velocity increase. The presented results indicate that the material in-homogeneity has a significant influence on the vibration and instability behaviors of the FG pipes and should therefore be considered in its optimum design. In addition, fluid velocity leads to divergence and flutter instabilities.

Treatment of residual stress in failure assessment procedure

Lee, Hyeong-Yeon,Biglari, Farid R.,Wimpory, Robert,Nikbin, Kamran M. Pergamon Press 2006 Engineering fracture mechanics Vol.73 No.13

<P><B>Abstract</B></P><P>The effect of residual stress on component failure has been investigated using the distributions from current failure assessment procedures, and a residual stress profile simple to apply with less conservatism has been proposed for the weld geometries of T-plate and tubular T-joint. The stress intensity factors (SIFs) in the two weld geometries under various types of loads have been calculated using the Green’s function method. The Green’s functions were determined not only for the T-plate but also for the tubular T-joint with the built-in ends. The use of a linear (bending) stress profile, derived from an analysis of measured residual stress distributions in T-plate and tubular T-joints, has been examined. The profile was validated with experimentally measured residual stress distributions in two materials, a high strength and medium strength ferritic steel and two geometries, a T-plate joint and a tubular T-joint for crack lengths up to half the plate or pipe thickness. Whereas the recommended residual stress distributions are geometry and material specific, it is shown that a simplified linear bending profile provides a possible guideline, applicable to a range of materials and geometries, where detailed information on weld procedures or residual stress profiles are unavailable.</P>

Optimization of the forging of aerofoil blade using the finite element method and fuzzy-Pareto based genetic algorithm

V. Alimirzaloo,M. H. Sadeghi,F. R. Biglari 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.6

In this research non-isothermal forging process of an aerofoil blade was simulated using 3-dimentional finite element method. Then an optimization approach integrated with the finite element method has been applied to optimize the blade forging process. Preform shape and angular position of the die parting line were optimized in order to minimize the flash volume, strain non-uniformity and lateral forces generated during the forging operation. The optimization method includes the finite element approach and the response surface method for the formulation of the objective functions. Using the multi-objective genetic algorithm, Pareto front of global optimal solutions was generated. Then a fuzzy-based membership value assignment method was used to select the best compromise solution. The simulation of the blade forging process was verified by experimental test. Results show that the numerical results and experimental tests have a good agreement. Waste material and lateral forces generated during the forging operation is decreased with optimization method significantly. Therefore the proposed approach is an appropriate method for multi-objective optimization of the forging process of aerofoil blades.

Simulation and optimization of ethanol amine production plant

Gholamreza Zahedi,Saeideh Amraei,Mazda Biglari 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6

An industrial Ethanol Amine (EA) production plant was simulated and optimized. Due to lack of accurate reaction rate information, the first step involved obtaining reliable kinetic data from the SRI (Stanford Research Institute) industrial database and calculation using error minimization method. In the next step, by implementing the obtained reaction kinetics the whole plant was simulated using Hysys software. Simulation results were compared with the SRI data and showed that there is acceptable agreement between simulation and the measured industrial data. In the next step of study by applying the gradient search (GS) optimization technique the plant was optimized using: feeding ammonia to ethylene oxide (EO) molar ratio, water flow rate in the feed stream, and reactor temperature as optimization variables. Employing process profit as objective function the optimal operating conditions were found to be: ammonia to EO ratio of 5 (mol/mol), water flow rate of 52.59 kg mol/hr and reactor temperature of 85 ℃.

FACTORS DRIVING CONSUMERS TO PURCHASE ETHNIC APPAREL: THE CASE OF HANFU

Zahra Pourabedin,Feng Qilin,Vahid Biglari 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

The purpose of this study was to identify the relationship between perceived value, ethnic identity and purchase intention of ethnic apparel. This study examines how Hanfu (traditional costume of the Han Ethnic Group of China) customers perceive certain types of values (emotional value, social value, uniqueness value, conditional value and perceived value). Then this study determined how customers’ perceptions of these values and ethnic identity were correlated with perceived value, and intention to buy Hanfu. Findings from this study indicated that perceived value and ethnic identity were generally associated with purchase intention of ethnic apparel. Hence, ethnic identity moderated the relationship between perceived value and purchase intention. Finally, compared to emotional value, social value, and uniqueness value, conditional value showed the most influential impact on the perceived value. The findings provide an insight in recognizing factors which play an important role in wearing ethnic apparel. More specifically this research provides insight for traditional apparel marketers to design apparel products and reposition the existing products.

VALUES DRIVING CONSUMERS TO PURCHASE ETHNIC APPAREL: THE CASE OF HANFU

Zahra Pourabedin,Feng Qilin,Vahid Biglari 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

The purpose of this study was to identify the relationship between perceived value, ethnic identity and purchase intention of ethnic apparel. This study examines how Hanfu (traditional costume of the Han Ethnic Group of China) customers perceive certain types of values (emotional value, social value, uniqueness value, conditional value and perceived value). Then this study determined how customers’ perceptions of these values and ethnic identity were correlated with perceived value, and intention to buy Hanfu. Findings from this study indicated that perceived value and ethnic identity were generally associated with purchase intention of ethnic apparel. Hence, ethnic identity moderated the relationship between perceived value and purchase intention. Finally, compared to emotional value, social value, and uniqueness value, conditional value showed the most influential impact on the perceived value. The findings provide an insight in recognizing factors which play an important role in wearing ethnic apparel. More specifically this research provides insight for traditional apparel marketers to design apparel products and reposition the existing products.