Abstract
Microscopic defects within the microstructure of hardened cement paste are the main source of weakness in concrete. As a solution, nano-graphene oxide (GO) can be employed to improve the cement paste microstructure. However, there is a number of disadvantages, e.g., fluidity reduction and non-uniform dispersion. The present study sought to modify GO by fabricating a copolymer (PSGO) in a novel process to exploit the advantages of nano-GO while minimizing its disadvantages. Using 0.03wt% copolymerled to 38.8% higher tensile strength, 29.3% higher compressive strength and 25% higher workability. The SEM images revealed that GO and modified GO enhanced concrete by secondary hydration and bonding with C-S-H, creating a firm, integrated, and foil-like structure, and reducing the crack size and depth.
Key Words
compressive strength; copolymer; graphene oxide; scanning electron microscopy; tensile strength
Address
Maryam Ashouri, Ehsanollah Zeighami and Seyyed Mohammad Mirhosseini: Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
Alireza Azarioon: Department of Civil and Architectural Engineering, Malayer University, Malayer, Iran
Sattar Ebrahimi Yonesi: Department of Chemistry, Malayer Branch, Islamic Azad University, Malayer, Iran
Abstract
The objective of this paper is to present free vibration and static stability analyses of rotating composite beams reinforced with carbon nanotubes (CNTs) under uniform thermal loads. Beam structural equations and CNT-reinforced composite (CNTRC) beam formulations are derived based on Timoshenko beam theory (TBT). The temperature-dependent properties of the beam material, such as the elastic modulus, shear modulus, and material density, are assumed to vary over the thickness according to the rule of mixture. The beam material is modeled as a mixture of single-walled carbon nanotubes (SWCNTs) in an isotropic matrix. The SWCNTs are aligned and distributed in the isotropic matrix with different patterns of reinforcement, namely the UD (uniform), FG-O, FG-V, FG-Λ and FG-X distributions, where FG-V and FG-Λ are asymmetric patterns. Numerical examples are presented to illustrate the effects of several essential parameters, including the rotational speed, hub radius, effective material properties, slenderness ratio, boundary conditions, thermal force, and moments due to temperature variation. To the best of the authors' knowledge, this study represents the first attempt at the finite element modeling of rotating CNTRC Timoshenko beams under a thermal environment. The results are presented in tables and figures for both symmetric and asymmetric distribution patterns, and can be used as benchmarks for further validation.
Key Words
carbon-nanotube-reinforced composite beam; finite element method; stability analysis; thermal analysis; vibration analysis
Address
Özge Özdemir and Hüseyin Ural: Department of Aeronautical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkiye
Alexandre de Macêdo Wahrhaftig: Department of Construction and Structures, Polytechnic School, Federal University of Bahia, BA, Brazil
Abstract
Nanotechnology is a popular field in the construction industry due to its multiple functions. It mitigates CO2 emissions and enhances the desirable properties of concrete by replacing small amounts of cement with supplements. This study assess the sustainability impact of using two different nanoparticles partially replacing the cement with 0.3%, 0.6%, 1.0% of nano silica (NS) and 0.03%, 0.045%, 0.06% of Multi-Walled Carbon Nanotubes (MWCNT) in the green concrete mix developement. Nano-sized fragments at the atomic scale tends to modify the properties of concrete. Concrete may increase its strength, durability by adding nanocomposite materials, which will decrease the amount of nano and micropores in structural parts. The strength of the structural elements can be greatly improved and allowing them to withstand higher loads and resist deformation. It improved durability properties by 64.8% in water absorption, 56.4% in acid attack, 78.1% in sulphate attack, and 53.4% in chloride attack. There was an improvement in compressive strength of 37% and split tensile strength of 90%. SEM, FTIR, and XRD investigations have used to look at the microstructural characteristics of nanoconcrete dictated the micro-structure characteristics may be made more consistent and dense by adding nanocomposite materials.
Key Words
carbon nanotubes; microstructure; nano-silica; nanocomposite; sustainability
Address
Breetha Yesudhas Jayakumari and Pachaivannan Partheeban: Department of Civil Engineering, Chennai Institute of Technology, Kundrathur, Chennai 600069, India
Elangovan Nattanmai Swaminathan: Department of Civil Engineering, Jerusalem College of Engineering, Chennai 600100, India
Abstract
The current study employs the nonlocal Timoshenko beam (NTB) theory and von-Kármán's geometric nonlinearity to develop a non-classic beam model for evaluating the nonlinear free vibration of bi-directional functionally-graded (BFG) nanobeams. In order to avoid the stretching-bending coupling in the equations of motion, the problem is formulated based on the physical middle surface. The governing equations of motion and the relevant boundary conditions have been determined using Hamilton's principle, followed by discretization using the differential quadrature method (DQM). To determine the frequencies of nonlinear vibrations in the BFG nanobeams, a direct iterative algorithm is used for solving the discretized underlying equations. The model verification is conducted by making a comparison between the obtained results and benchmark results reported in prior studies. In the present work, the effects of amplitude ratio, nanobeam length, material distribution, nonlocality, and boundary conditions are examined on the nonlinear frequency of BFG nanobeams through a parametric study. As a main result, it is observed that the nonlinear vibration frequencies are greater than the linear vibration frequencies for the same amplitude of the nonlinear oscillator. The study finds that the difference between the dimensionless linear frequency and the nonlinear frequency is smaller for CC nanobeams compared to SS nanobeams, particularly within the
Address
Elnaz Zare and Mohammad Gholami:Department of Civil Engineering, Yasouj University, Yasouj, Iran
Daria K. Voronkova: Department of Mathematics and Natural Sciences, Gulf University for Science and Technology, Mishref Campus, Kuwait/ Bauman Moscow State Technical University Moscow, Russia
Omid Faraji: Department of Civil Engineering, Imam Hossein University, Tehran, Iran
Hamidreza Aghajanirefah: Department of Civil Engineering, Faculty of Engineering, Qazvin Branch Islamic Azad University, Qazvin,Iran
Hamid Malek Nia: Department of of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
Mojtaba Gorji Azandariani: Department of Civil Engineering, Semnan University, Semnan, Iran/ Centre for Infrastructure Engineering, Western Sydney University, Sydney, Australia
Abstract
This paper studies the free vibration analysis of the piezo-magneto-thermo-elastic FG nanobeam submerged in a fluid environment. The problem governed by the partial differential equations is determined by refined higher-order State Space Strain Gradient Theory (SSSGT). Hamilton's principle is applied to discretize the differential equation and transform it into a coupled Euler-Lagrange equation. Furthermore, the equations are solved analytically using Navier's solution technique to form stiffness, damping, and mass matrices. Also, the effects of nonlocal ceramic and metal parts over various parameters such as temperature, Magnetic potential and electric voltage on the free vibration are interpreted graphically. A comparison with existing published findings is performed to showcase the precision of the results.
Key Words
FG piezoelectric beam; higher order refined shear deformation theory; spatial nonlocal wave; variable nonlocal elasticity
Address
Selvamani Rajendran and Rubine Loganathan: Karunya Institute of Technology and Sciences, Coimbatore, Tamilnadu, India
Murat Yaylaci: Department of Civil Engineering, Recep Tayyip Erdogan University, 53100, Rize, Turkey/ Turgut Kiran Maritime Faculty, Recep Tayyip Erdogan University, 53900, Rize, Turkey/ Murat Yaylaci-Luzeri R&D Engineering Company, 53100, Rize, Turkey
Ecren Uzun Yaylaci: Faculty of Engineering and Architecture, Recep Tayyip Erdogan University, 53100, Rize, Turkey
Mehmet Emin Özdemir: Department of Civil Engineering, Cankiri Karatekin University, 18100, Çankiri, Turkey
Abstract
In this study, nanotoxicity tests were made by exposure of Artemia salina to copper (Cu 60-80 nm) and copper oxide (CuO 40 nm) nanoparticles (NPs) at different concentrations (0.2, 1, 5, 10, 25, and 50 mg/L). The LC50 value of Cu (60-80 nm) NPs on the A. salina individuals at the beginning (0), 24th, 48th and 72nd hours and elimination period was 52.37 mg/L while the LC50 value of CuO (40 nm) NPs was 55.39 mg/L. The results of UV-Vis absorbance values showed that all statistical data revealed that maximum effect was observed between 24-30 hours and 25 ppm absorbance concentration was more effective. The multiple R, correlation coefficient (R2) and adjusted R2 values of Cu NP for the suitable Quadratic model were, respectively; 92.96 %, 86.42 % and 76.71 % while they are 98.31 %, 96.64 % and 94.25 % for CuO NP. Also, the data, was indicated effect size significantly changed based on the type and size of NP. Considering the microscope results, it was clearly noticed that A. salina organisms took the NPs in to their body. The accumulation in the gut of A. salina was observed and the images were taken with phase contrast microscope for both of NPs. The highest decrease for survival rates of A. salina individuals exposed to Cu NP was observed in the 10 ppm concentration (43.47 %) and in the 5 ppm concentration (46.20 %) for CuO NP. The results revealed that Cu and CuO NPS showed different toxic effects and that Cu NPs were more toxic than CuO.
Key Words
elimination; nanoparticles; LC50; survival rates; zooplankton
Abstract
In this study, the static analysis of carbon nanotube-reinforced composites (CNTRC) beams resting on a Winkler-Pasternak elastic foundation is presented. The developed theories account for higher-order variation of transverse shear strain through the depth of the beam and satisfy the stress-free boundary conditions on the top and bottom surfaces of the beam. To study the effect of carbon nanotubes distribution in functionally graded (FG-CNT), we introduce in the equation of CNT volume fraction a new exponent equation. The SWCNTs are assumed to be aligned and distributed in the polymeric matrix with different patterns of reinforcement. The rule of mixture is used to describe the material properties of the CNTRC beams. The governing equations were derived by employing Hamilton's principle. The models presented in this work are numerically provided to verify the accuracy of the present theory. The analytical solutions are presented, and the obtained results are compared with the existing solutions to verify the validity of the developed theories. Many parameters are investigated, such as the Pasternak shear modulus parameter, the Winkler modulus parameter, the volume fraction, and the order of the exponent in the volume fraction equation. New results obtained from bending and stresses are presented and discussed in detail. From the obtained results, it became clear the influence of the exponential CNTs distribution and Winkler-Pasternak model improved the mechanical properties of the CNTRC beams.
Address
Mostefa Sekkak and Mohamed Bourada: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Rachid Zerrouki and Mohamed Zidour: Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria
Abdelouahed Tounsi: Department of Civil and Environmental Engineering, Lebanese American University, 309 Bassil Building, Byblos, Lebanon/ Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia
Mahmoud M Selim: Department of Mathematics, College of Science and Humanities, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
Hosam A. Saad: Department of Chemistry, College of Science, Taif University, P.O. Box 11099, Taif, 21944, Saudi Arabia
Abstract
The integration of nanoparticles into various industries has spurred interest in understanding their impact on logistics and transportation systems. In this study, we investigate the effect of nanoparticles on the economic aspects of railway logistics transport using a mathematical model. By incorporating factors such as transportation costs, time efficiency, and environmental considerations, we aim to assess the overall economic feasibility of integrating nanoparticles into railway logistics operations. Through mathematical modeling and analysis, we explore how the introduction of nanoparticles affects cost-benefit analyses, resource allocation, and decision-making processes within railway logistics. Our findings provide valuable insights into the economic implications of nanoparticle integration in railway transport, offering potential strategies for optimizing logistics operations and enhancing overall efficiency and sustainability.
Key Words
economics study; mathematical model; nanoparticles; railway logistics transport
Address
Yanlong Zhao: School of Economics and Management, Harbin University, Harbin 150086, Heilongjiang, China
Mohsen Nasihatgozar: Department of Mechanical Engineering, Kashan Branch, Islamic Azad University, Kashan, Iran
F. Ming: Department of Engineering, Malaya University, Malaysia
