ZnO-cellulose nanofibril (ZnO-CNF) hybrid synthesized via a sol-gel process with excellent productivity for a safer sunscreen

( Iqra Rabani ),서영수 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Zinc Oxide (ZnO) nanoparticles (NPs) integrated on the surface of cellulose nanofibril (CNF) were prepared by a sol-gel reaction and its size was controlled under various synthesis conditions. ZnO-CNF hybrid as a sunscreen has merits such as skin non-penetration of ZnO nanoparticle, enhanced water solubility or dispersibility, reduced photodamage of the skin from ZnO-mediated free radical formations (photocatalytic effect). Especially, photocatalytic effect of ZnO in water was found to be completely reduced by the hybridization, where it was measured by decolouration degree of an organic dye under UV irradiation. Integrated amount of ZnO on the CNF was obtained to be up to 78 wt% of the hybrid, which indicates that the hybridization was cost-effective as for a sunscreen with high sun protection impact factor.

Viscous fluid induced vibration and instability of FG-CNT-reinforced cylindrical shells integrated with piezoelectric layers

Mahmood Rabani Bidgoli,Mohammad Saeed Karimi,Ali Ghorbanpour Arani 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.19 No.3

In this paper, viscous fluid induced nonlinear free vibration and instability analysis of a functionally graded carbon nanotube-reinforced composite (CNTRC) cylindrical shell integrated with two uniformly distributed piezoelectric layers on the top and bottom surfaces of the cylindrical shell are presented. Single-walled carbon nanotubes (SWCNTs) are selected as reinforcement and effective material properties of FG-CNTRC cylindrical shell are assumed to be graded through the thickness direction and are estimated through the rule of mixture. The elastic foundation is modeled by temperature-dependent orthotropic Pasternak medium. Considering coupling of mechanical and electrical fields, Mindlin shell theory and Hamilton's principle, the motion equations are derived. Nonlinear frequency and critical fluid velocity of sandwich structure are calculated based on differential quadrature method (DQM). The effects of different parameters such as distribution type of SWCNTs, volume fractions of SWCNTs, elastic medium and temperature gradient are discussed on the vibration and instability behavior of the sandwich structure. Results indicate that considering elastic foundation increases frequency and critical fluid velocity of system.

Time-dependent buckling analysis of SiO2 nanoparticles reinforced concrete columns exposed to fire

M. Rabani Bidgoli,M. Saeidifar 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.2

Time-dependent buckling of embedded straight concrete columns armed with Silicon dioxide(SiO2) nano-particles exposed to fire is investigated in the present study for the fire time. The column is simulated mathematically with Timoshenko beam model. The governing mass conservation equations to describe heat and moisture transport in concrete containing free water, water vapor, and dry air in conjunction with the conversion of energy are considered. The characteristics of the equivalent composite are determined using Mori-Tanaka approach. The foundation around the column is simulated with spring and shear layer. Employing nonlinear strains-displacements, energy methods and Hamilton\'s principal, the governing equations are derived. Differential quadrature method (DQM) is used in order to obtain the critical buckling load and critical buckling time of structure. The influences of volume percent of SiO2nano-particles, geometrical parameters, elastic foundation and concrete porosity are investigated on the time-dependent buckling behaviours of structure. Numerical results indicate that reinforcing the concrete column with SiO2nano-particles, the structure becomes stiffer and the critical buckling load and time increase.

An experimental study and new correlations of viscosity of ethylene glycol-water based nanofluid at various temperatures and different solid concentrations

Mahmood Rabani Bidgoli,Reza Kolahchi,Mohammad Saeed Karimi 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.1

This article presents an experimental study on the effect of temperature and solid volume fraction of nanoparticles on the dynamic viscosity for the CuO/EG-water nanofluid. Nanoparticles with diameter of 40 nm are used in the present study to prepare nanofluid by two-step method. A “Brookfield viscometer” has been used to measure the dynamic viscosity of nanofluid with solid volume fraction up to 2% at the temperature range between 20 to 60°C. The findings have shown that dynamic viscosity of nanofluid increases with increasing particle volume fraction and decreasing temperature. Nine different correlations are developed on experimental data point to predict the relative dynamic viscosity of nanofluid at different temperatures. To make sure of accuracy of the proposed correlations, margin of deviation is presented at the end of this study. The results show excellent agreement between experimental data and those obtained through the correlations.

Buckling analysis of plates reinforced by Graphene platelet based on Halpin-Tsai and Reddy theories

Rasool Javani,Mahmood Rabani Bidgoli,Reza Kolahchi 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.4

In this paper, buckling analyses of composite plate reinforced by Graphen platelate (GPL) is studied. The Halphin- Tsai model is used for obtaining the effective material properties of nano composite plate. The nano composite plate is modeled by Third order shear deformation theory (TSDT). The elastic medium is simulated by Winkler model. Employing nonlinear strains-displacements, stress-strain, the energy equations of plate are obtained and using Hamilton’s principal, the governing equations are derived. The governing equations are solved based on Navier method. The effect of GPL volume percent, geometrical parameters of plate and elastic foundation on the buckling load are investigated. Results showed that with increasing GPLs volume percent, the buckling load increases.

Vibration analysis of concrete foundation armed by silica nanoparticles based on numerical methods

Mahdi Mahjoobi,Mahmood Rabani Bidgoli 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.5

In this study, vibration analysis of a concrete foundation-reinforced by SiO2 nanoparticles resting on soil bed is investigated. The soil medium is simulated with spring constants. Furthermore, the Mori-Tanaka low is used for obtaining the material properties of nano-composite structure and considering agglomeration effects. Using third order shear deformation theory or Reddy theory, the total potential energy of system is calculated and by means of the Hamilton’s principle, the coupled motion equations are obtained. Also, based an analytical method, the frequency of system is calculated. The effects of volume percent and agglomeration of SiO2 nanoparticles, soil medium and geometrical parameters of structure are shown on the frequency of system. Results show that with increasing the volume percent of SiO2 nanoparticles, the frequency of structure is increased.

A nonlocal nonlinear analysis for buckling in embedded FG-SWCNT-reinforced microplates subjected to magnetic field

Reza Kolahchi,Mahmood Rabani Bidgoli,Gholamhossein Beygipoor,Mohammad Hosein Fakhar 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.9

In this study, nonlocal nonlinear buckling analysis of embedded polymeric temperature-dependent microplates resting on an elasticmatrix as orthotropic temperature-dependent elastomeric medium is investigated. The microplate is reinforced by single-walled carbonnanotubes (SWCNTs) in which the equivalent material properties of nanocomposite are estimated based on the rule of mixture. Due tomagnetic properties of SWCNTs, the structure is subjected to magnetic field. For the carbon-nanotube reinforced composite (CNTRC)plate, both cases of uniform distribution (UD) and functionally graded (FG) distribution patterns of SWCNT reinforcements are considered. The small size effects of microplate are considered based on Eringen’s nonlocal theory. Based on orthotropic Mindlin plate theoryalong with von Kármán geometric nonlinearity and Hamilton's principle, the governing equations are derived. Generalized differentialquadrature method (GDQM) is applied for obtaining the buckling load of system. The effects of different parameters such as magneticfield, nonlocal parameters, volume fractions of SWCNTs, distribution type of SWCNTs in polymer, elastomeric medium, aspect ratioand temperature are considered on the nonlinear buckling of the microplate. Results indicate that the buckling load increases with increasingmagnetic field.

Seismic response of underwater fluid-conveying concrete pipes reinforced with SiO2 nanoparticles using DQ and Newmark methods

Mostafa Maleki,Mahmood Rabani Bidgoli 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.6

Concrete pipelines are the most efficient and safe means for gas and oil transportation over a long distance. The use of nano materials and nono-engineering can be considered for enhancing concrete pipelines properties. the tests show that SiO2 nanoparticles can improve the mechanical behavior of concrete. Moreover, severe hazard for pipelines is seismic ground motion. Over the years, scientists have attempted to understand pipe behavior against earthquake most frequently via numerical modeling and simulation. Therefore, in this paper, the dynamic response of underwater nanocomposite submerged pipeline conveying fluid is studied. The structure is subjected to the dynamic loads caused by earthquake and the governing equations of the system are derived using mathematical model via Classic shell theory and Hamilton’s principle. Navier-Stokes equation is employed to calculate the force due to the fluid in the pipe. As well, the effect of external fluid is modeled with an external force. Mori-Tanaka approach is used to estimate the equivalent material properties of the nanocomposite. 1978 Tabas earthquake in Iran is considered for modelling seismic load. The dynamic displacement of the structure is extracted using differential quadrature method (DQM) and Newmark method. The effects of different parameters such as SiO2 nanoparticles volume percent, boundary conditions, thickness to radius ratios, length to radius ratios, internal and external fluid pressure and earthquake intensity are discussed on the seismic response of the structure. From results obtained in this paper, it can be found that the dynamic response of the pipe is increased in the presence of internal and external fluid. Furthermore, the use of SiO2 nanoparticles in concrete pipeline reduces the displacement of the structure during an earthquake.

Mathematical modeling of smart nanoparticles-reinforced concrete foundations: Vibration analysis

Masood Kargar,Mahmood Rabani Bidgoli 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.27 No.4

In this research, vibration and smart control analysis of a concrete foundation reinforced by SiO₂ nanoparticles and covered by piezoelectric layer on soil medium is investigated. The soil medium is simulated with spring constants and the Mori-Tanaka low is used for obtaining the material properties of nano-composite structure and considering agglomeration effects. With considering first order shear deformation theory, the total potential energy of system is calculated and by means of Hamilton.s principle in three displacement directions and electric potential, the six coupled equilibrium equations are obtained. Also, based an analytical method, the frequency of system is calculated. The effects of applied voltage, volume percent and agglomeration of SiO₂ nanoparticles, soil medium and geometrical parameters of structure are shown on the frequency of system. Results show that with applying negative voltage, the frequency of structure is increased.

Earthquake response of nanocomposite concrete pipes conveying and immersing in fluid using numerical methods

Mostafa Maleki,Mahmood Rabani Bidgoli,Reza Kolahchi 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.24 No.2

Concrete pipelines are the most efficient and safe means for gas and oil transportation over a long distance. The use ofnano materials and nono-engineering can be considered for enhancing concrete pipelines properties. the tests show that SiO2 nanoparticles can improve the mechanical behavior of concrete.Moreover, severe hazard for pipelines is seismic ground motion. Over the years, scientists have attempted to understand pipe behavior against earthquake most frequently via numerical modeling and simulation. Therefore, in this paper, the dynamic response of underwater nanocomposite submerged pipeline conveying fluid is studied. The structure is subjected to the dynamic loads caused by earthquake and the governing equations of the system are derived using mathematical model via Classic shell theory and Hamilton's principle. Navier-Stokes equation is employed to calculate the force due to the fluid in the pipe. As well, the effect of external fluid is modeled with an external force. Mori-Tanaka approach is used to estimate the equivalent material properties of the nanocomposite. 1978 Tabas earthquake in Iran is considered for modelling seismic load.The dynamic displacement of the structure is extracted using differential quadrature method (DQM) and Newmark method.The effects of different parameters such asSiO2 nanoparticles volume percent,boundary conditions, thickness to radius ratios, length to radius ratios, internal and external fluidpressure and earthquake intensity are discussed on the seismic response of the structure.From results obtained in this paper, it can be found that the dynamic response of the pipe is increased in the presence of internal and external fluid. Furthermore, the use of SiO2 nanoparticles in concrete pipeline reduces the displacement of the structure during an earthquake.