Abstract
The present research investigates the thermodynamically bending behavior of FG sandwich plates, laying on the
Winkler/Pasternak/Kerr foundation with various boundary conditions, subjected to harmonic thermal load varying through thickness. The supposed FG sandwich plate has three layers with a ceramic core. The constituents' volume fractions of the lower and upper faces vary gradually in the direction of the FG sandwich plate thickness. This variation is performed according to various models: a Power law, Trigonometric, Viola-Tornabene, and the Exponential model, while the core is constantly homogeneous. The displacement field considered in the current work contains integral terms and fewer unknowns than other theories in the literature. The corresponding equations of motion are derived based on Hamilton's principle. The impact of the distribution model, scheme, aspect ratio, side-to-thickness ratio, boundary conditions, and elastic foundations on thermodynamic
bending are examined in this study. The deflections obtained for the sandwich plate without elastic foundations have the lowest values for all boundary conditions. In addition, the minimum deflection values are obtained for the exponential volume fraction law model. The sandwich plate's non-dimensional deflection increases as the aspect ratio increases for all distribution models.
Key Words
boundary conditions; distribution models; FG sandwich plates; harmonic thermal load; thermodynamic bending; Winkler/Pasternak/Kerr foundation
Address
Djamel Eddine Lafi: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abdelhakim Bouhadra: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Department of Civil Engineering, Faculty of Science and Technology, Abbès Laghrour University of Khenchela, Algeria
Belgacem Mamen: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Department of Civil Engineering, Faculty of Science and Technology, Abbès Laghrour University of Khenchela, Algeria
Abderahmane Menasria: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Department of Civil Engineering, Faculty of Science and Technology, Abbès Laghrour University of Khenchela, Algeria
Mohamed Bourada: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abdelmoumen Anis Bousahla: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
Fouad Bourada: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Science and Technology Department, Faculty of Science and Technology, Tissemsilt University, Algeria
Abdelouahed Tounsi: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; 5YFL (Yonsei Frontier Lab.), Yonsei University, Seoul, Korea; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia; Department of Civil and Environmental Engineering, Lebanese American University, 309 Bassil Building, Byblos, Lebanon
Abdeldjebbar Tounsi: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Murat Yaylaci: Department of Civil Engineering, Recep Tayyip Erdogan University, 53100, Rize, Turkey
Abstract
In this paper, the performance of under-foundation isolators against generally annoying train-induced vibrations was examined experimentally. The effect of foundation type on the efficacy of such isolators was investigated for the first time. To this end, laboratory models including a soil container, soil, building with three types of foundation (i.e., single, strip, and mat), and isolator layer were employed. Through various dynamic tests, the effects of foundation type, isolation frequency, and the dominant frequency of train load on the isolator's performance were studied. The results demonstrated that the vibration level in the unisolated building with the strip and mat foundation was, respectively, 29 and 38% lower than in the building with the single foundation. However, the efficacy of the isolator in the building with the single foundation was, respectively, 21 and 40% higher than in the building with the strip and mat foundation. Furthermore, a lower isolation frequency and a higher excitation frequency resulted in greater isolator efficacy. The best vibration suppression occurred when the excitation frequency was close to the floor's natural frequency.
Key Words
base isolation; physical experiment; railway vibration; soil-structure interaction; structural dynamics
Address
Ehsan Haghighi, Javad Sadeghi and Morteza Esmaeili: School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran
Abstract
In this study, the impact response of a nanobeam with a moving nanoparticle is investigated. Timoshenko beam theory is used to model the nanobeam behavior and nonlocal elasticity theory is used to consider the effects of small dimensions. The interaction between the nanoparticle and nanobeam has been described using Lennard-Jones potential theory and the equations are discretized by the radial basis meshless method and a mathematical model is presented for the nanobeamnanoparticle system. Validation of the proposed model is achieved by comparing the obtained natural frequencies with reference values, demonstrating good agreement. Dimensionless frequency analysis reveals a decrease with increasing nonlocal parameter, pointing out a toughening effect in nanobeam. The dynamic response of the nanobeam and nanoparticle is obtained by time integration of equations of motion using Newmark and Wilson-o methods. A comparative analysis of the two methods is conducted to determine the most suitable approach for this study. As a distinctive aspect in this study, the analysis incorporates the deformation of the nanobeam resulting from the nanoparticle-nanobeam interaction when calculating the Lennard-Jones force in the nanobeam-nanoparticle system. The numerical findings explore the impact of various factors, including the nonlocal parameter, initial velocity, nanoparticle mass, and boundary conditions.
Key Words
dynamic solution; Lennard-Jones potential; meshless method; nanoparticle-nanobeam impact; nonlocal elasticity theory
Address
Isa Ahmadi, Mohammad Naeim Moradi and Mahdi Davar Panah: Advanced Materials and Computational Mechanics Lab., Department of Mechanical Engineering, University of Zanjan,
45371-38791, Zanjan, Iran
Abstract
Several types of column-beam connections are used in the design of steel structures. This situation causes different cross-section effects and, therefore, different displacements and deformations. In other words, connection elements such as welds, bolts, continuity plates, end plates, and stiffness plates used in steel column-beam connections directly affect the section effects. This matter reveals the necessity of knowing the steel column-beam connection behaviours. In this article, behaviours of bolted column-beam connection with end plate widely used in steel structures are investigated comparatively the effects of the stiffness plates added to the beam body, the change in the end plate thickness and bolt diameter. The results obtained reveal that the moment and force carrying capacity of the said connection increases with the increase in the end plate thickness and bolt diameter. In contrast, it causes the other elements to deform and lose their capacity. This matter shows that optimum dimensions are very important in steel column-beam connections. In addition, it has been seen that adding a stiffness plate to the beam body part positively contributes to the connection's moment-carrying capacity.
Key Words
bolted connections; column-beam connection; finite element method; steel structures
Address
Samet Oğuzhan Doğan, Şenol Gürsoy: Department of Civil Engineering, Karabük University, 78050 Karabük, Turkey
Ramazan Özmen: Department of Mechatronics Engineering, Karabük University, 78050 Karabük, Turkey
Abstract
The market of the floating solar photovoltaic system is rapidly growing around the world with the rise of renewable energy that can replace fossil energy. While the floating solar photovoltaic system is operating and being installed in several countries, the system is exposed to the risk in terms of structural safety due to the absence of the proper design guideline. In this paper, design loads suitable for the floating solar photovoltaic system are presented. Utilizing the existing reliable design standards such as ASCE 7-16 (ASCE 7-16 2016) and DNV-RP-C205 (DNV-RP-C205 2010), the appropriate design loads for the floating solar photovoltaic system are presented. The proper load combinations are also presented by putting wave load based on DNV standards (DNV-OS-C101 2015 and DNV-OS-C201 2015) into the load combinations in ASCE standards (ASCE 7-16 2016). We present the load combinations for the allowable stress design and load and resistance factor design, respectively.
Key Words
design guideline; design load; floating solar photovoltaic system; load combination; structural design
Address
Gihwan Kim: Korea Atomic Energy Research Institute, 111 Daedeok-daero, 989 Beon-gil, Yuseong-gu, Daejeon 34057, Republic of Korea; Department of Mechanical Engineering, Korean Advanced Institute for Science and Technology,
291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Moonsu Park: Department of Mechanical Engineering, Korean Advanced Institute for Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Abstract
A numerical method is presented in this paper, for buckling analysis of thin arbitrary stiffened composite cylindrical shells under axial compression. The stiffeners can be placed inside and outside of the shell. The shell and stiffeners are operated as discrete elements, and their interactions are taking place through the compatibility conditions along their intersecting lines. The governing equations of motion are obtained based on Koiter's theory and solved by utilizing the principle of the minimum potential energy. Then, the buckling load coefficient and the critical buckling load are computed by solving characteristic equations. In this formulation, the elastic and geometric stiffness matrices of a single curved strip of the shell and stiffeners can be located anywhere within the shell element and in any direction are provided. Moreover, five stiffened composite shell specimens are made and tested under axial compression loading. The reliability of the presented method is validated by comparing its numerical results with those of commercial software, experiments, and other published numerical results. In addition, by using the ANSYS code, a 3-D finite element model that takes the exact geometric arrangement and the properties of the stiffeners and the shell into consideration is built. Finally, the effects of Poisson's ratio, shell length-to-radius ratio, shell thickness, cross-sectional area, angle, eccentricity, torsional stiffness, numbers and geometric configuration of stiffeners on the buckling of stiffened composite shells with various end conditions are computed. The results gained can be used as a meaningful benchmark for researchers to validate their analytical and numerical methods.
Abstract
The loading capacity of engineering structures/components reduces after the initiation and propagation of crack
eventually leads to the final failure. Hence, it becomes essential to deal with the crack and its effects at the design and simulation stages itself, by detecting the prone area of the fracture. The phase-field (PF) method has been accepted widely in simulating fracture problems in complex geometries. However, most of the PF methods are formulated with second order continuity theoryinvolving C0 continuity. In the present study, PF method based on fourth-order (i.e., higher order) theory, maintaining C1 continuity has been proposed for ductile fracture simulation. The formulation includes fourth-order derivative terms of phase field variable, varying between 0 and 1. Applications of fourth-order PF theory to ductile fracture simulation resulted in novelty in this area. The proposed formulation is numerically solved using a two-dimensional finite element (FE) framework in 3-layered manner system. The solutions thus obtained from the proposed fourth order theory for different benchmark problems portray the improvement in the accuracy of the numerical results and are well matched with experimental results available in the literature. These results are also compared with second-order PF theory and a comparison study demonstrated the robustness of the proposed model in capturing ductile behaviour close to experimental observations.
Key Words
finite element method; fourth order theory; phase field method; second order theory; user-defined element
Address
Nitin Khandelwal and Ramachandra A. Murthy: CSIR-Structural Engineering Research Centre, Taramani, Chennai, 600113, India
Abstract
This paper proposes a composite design of fuzzy adaptive control scheme based on TMD RC structural system and the gain of two-dimensional fuzzy control is controlled by parameters. Monitoring and learning in LMI then produces performance indicators with a weighting matrix as a function of cost. It allows to control the trade-off between the two efficiencies by adjusting the appropriate weighting matrix. The two-dimensional Boost control model is equivalent to the LMI-constrained multi-objective optimization problem under dual performance criteria. By using the proposed intelligent control model, the fuzzy nonlinear criterion is satisfied. Therefore, the data connection can be further extended. Evaluation of controller performance the proposed controller is compared with other control techniques. This ensures good performance of the control routines used for position and trajectory control in the presence of model uncertainties and external influences. Quantitative verification of the effectiveness of monitoring and control. The purpose of this article is to ensure access to adequate, safe and affordable housing and basic services. Therefore, it is assumed that this goal will be achieved in the near future through the continuous development of artificial intelligence and control theory.
Address
Jenchung Shao: College of Electrical Engineering and Computer Science, National Kaohsiung University of Science and Technology, Taiwan
M. Nasir Noor: College of Maritime, National Kaohsiung University of Science and Technology, Taiwan
P. Ken: Information and Research Center of China, 1/9, Road: 2, Block: D, Section: 15, Dhaka 1216, Bangladesh
Chuho Chang: College of Electrical Engineering and Computer Science, National Kaohsiung University of Science and Technology, Taiwan
R. Wang: Information and Research Center of China, 1/9, Road: 2, Block: D, Section: 15, Dhaka 1216, Bangladesh
