Article
Materials Science, Multidisciplinary
A. Czekanski, V. V. Zozulya
Summary: New higher-order models based on the linear theory of nonlocal elasticity are developed for plane rods and beams. These models are used to analyze tension-compression and transverse bending modes of nonlocal rod and beam vibration. By considering nonlocal effects, the proposed models can be applied to vibration analysis of rods and beams at macroscales, microscales, and nanoscales.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2021)
Article
Mechanics
S. Ceballes, B. E. Saunders, A. Abdelkefi
Summary: The study focuses on extending the reliable reduced-order models of a carbon nanotube-based mass sensor using Timoshenko beam theory and Eringen's nonlocal theory. The discrepancies and limits of applicability between Timoshenko and Euler-Bernoulli models are deeply explored, showing that the nonlocal Timoshenko-based model is valuable for mass sensing applications, especially for short and stout structures. Researchers can utilize these findings for the design, modeling, and analysis of nanoscale sensors and resonators.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2022)
Article
Mechanics
Yu-Chi Su, Tse-Yu Cho
Summary: The free vibration of a single-walled carbon nanotube embedded in an elastic medium is studied using a nonlocal Timoshenko beam model. It is found that the nonlocal effect significantly influences the natural frequencies of the SWCNT in higher modes, especially when the SWCNT has a small slenderness ratio and is embedded in a soft elastic medium.
JOURNAL OF MECHANICS
(2021)
Article
Physics, Multidisciplinary
Ufuk Gul, Metin Aydogdu
Summary: This study investigates transverse wave propagation in carbon nanotubes based on doublet mechanics theory, revealing the van Hove singularity and confirming the effectiveness of the method. Additionally, the research highlights the significance of length scale on transverse wave dispersion in multi-walled carbon nanotubes.
WAVES IN RANDOM AND COMPLEX MEDIA
(2021)
Article
Mechanics
S. Ali Faghidian, Krzysztof Kamil Zur, J. N. Reddy, A. J. M. Ferreira
Summary: In this study, the dispersion characteristics of flexural waves in functionally graded porous nanobeams were analyzed using higher-order nonlocal gradient elasticity theory. The results reveal that the size-dependent response of the symmetric FG porous nanobeam and the closed-form solution of the phase velocity can be effectively utilized in the design and optimization of composite nano-structural elements.
COMPOSITE STRUCTURES
(2022)
Article
Mechanics
Raffaella Rizzoni, Serge Dumont, Frederic Lebon, Elio Sacco
Summary: Composite adhesive bonded joints are commonly used in various industries, and this study focuses on layered structures with an adhesive layer. The proposed modeling approach considers imperfect interfaces of the adhesive and is based on the classical Timoshenko beam theory.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2021)
Article
Materials Science, Multidisciplinary
Yu-Chi Su, Tse-Yu Cho
Summary: This article investigates wave propagation in embedded single-walled carbon nanotubes by modeling them as nonlocal Timoshenko beams. The analysis reveals that small scale effects smooth out transient responses and result in instantaneous wave propagation. The behavior of wave propagation is affected by the radius of the carbon nanotube, but not by its chirality. The dispersion relations with different small scale parameters are also examined.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2023)
Article
Engineering, Mechanical
Soomin Choi, Yoon Young Kim
Summary: This study proposes a new higher-order Vlasov torsion theory that includes desired torsion-related modes and provides explicit F-U and sigma-F relations consistent with Vlasov theory. By expressing the orthogonal sectional mode shapes relation, explicit relations for F-U and sigma-F are established, improving solution accuracy. This theory shows promise in interpreting physical significance of generalized forces and deriving explicit equilibrium conditions among generalized forces.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Engineering, Mechanical
Jaeyong Kim, Gang-Won Jang, Yoon Young Kim
Summary: In this study, a new method is proposed to address the issue of connection conditions for higher-order beam elements. The proposed method utilizes the vertices and intersection points of a joint section and imposes continuity conditions using Lagrange multipliers. Unlike previous studies, this method is applicable to beam frame structures with general section shapes without relying on geometric conditions.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Engineering, Multidisciplinary
Guozhe Shen, Yang Xia, Weidong Li, Guojun Zheng, Ping Hu
Summary: Peridynamics is a nonlocal theory that can handle easily discontinuities such as cracks, even though it is computationally more expensive. The study introduces new PD beam and shell models based on micro-beam bond and Timoshenko beam theory, with interpolation method used for describing various deformations and strain energy densities. The high precision of PD beam and shell models is proven through simulation results.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Optics
Niladri Modak, Swain Ashutosh, Shyamal Guchhait, Sayantan Das, Alok Kumar Pan, Nirmalya Ghosh
Summary: This study reveals the inherent non-separability of optical beam shifts and connects it to wave phenomena and metrological applications. The findings also indicate the practical impact of optical beam shifts on metrology and the generation of high-quality non-separable states of classical light fields.
LASER & PHOTONICS REVIEWS
(2023)
Article
Engineering, Multidisciplinary
Mohsen Nowruzpour, J. N. Reddy, Majid Akbarzadeh Khorshidi
Summary: Tridynamics is a nonlocal approach used to describe lower-scale multi-body interactions at the macroscopic level. By introducing basic elements like beam and plate, the computational cost can be reduced significantly. This study presents meaningful quantities to explain beam deformation and its potential applications in other mechanical problems.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2022)
Article
Engineering, Mechanical
Andrea Francesco Russillo, Giuseppe Failla
Summary: This paper focuses on the elastic wave propagation analysis of small-size planar beam lattices, proposing two novel computational approaches and comparing their advantages. Dispersion curves for a typical lattice are calculated to highlight the role of nonlocality.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Computer Science, Interdisciplinary Applications
Seungju Choi, Jaeyong Kim, Jaemin Jeon, Hongsuk Chang, Jong Chan Park, Yoon Young Kim, Gang-Won Jang
Summary: A beam-based analysis method for partially welded thin-walled multicell structures in vehicle frames is established using a higher-order beam theory. Binary design variables and a genetic algorithm are introduced to identify optimal welding locations. The developed method shows that the stiffness of the structures with optimized partial welding lines decreases by less than 6%.
COMPUTERS & STRUCTURES
(2023)
Article
Physics, Particles & Fields
Nicolo Burzilla, Breno L. Giacchini, Tiberio de Paula Netto, Leonardo Modesto
Summary: The paper investigates the Newtonian limit of higher-derivative gravity theories, including the effects of one-loop quantum corrections. It shows that curvature-derivative invariants may diverge in local theories, but can be regularized in nonlocal theories. Additionally, it demonstrates that quantum corrections do not affect the regularity of the Newtonian limit, and confirms the universality of the leading quantum correction in all theories studied.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Engineering, Multidisciplinary
Yuan Yuan, Kuo Xu, Keivan Kiani
APPLIED MATHEMATICAL MODELLING
(2020)
Article
Physics, Multidisciplinary
Keivan Kiani, Maral Ghaedi
EUROPEAN PHYSICAL JOURNAL PLUS
(2020)
Article
Mechanics
Keivan Kiani, Krzysztof Kamil Zur
Summary: In this study, suitable surface energy-nonlocal-integral and differential models were reported for investigating the mechanical behavior of a nanosystem consisting of double parallel nanorods with defects. By evaluating nonlocal-surface energy-based modes and implementing the Galerkin method, the capabilities of capturing the natural frequencies of the defected nanosystem were revealed. The roles of nonlocality, surface energy, nanorod characteristics, defect properties, and elastic interface layer constant on free vibration were explained.
COMPOSITE STRUCTURES
(2021)
Article
Mechanics
Keivan Kiani, Mahdi Efazati
Summary: This study focuses on the movements of three-dimensionally moving pretensioned wire-like nanostructures in a vacuum under static loads, considering nonlocality and surface energy. It presents governing equations for purely linear static and dynamic states, investigates the static deformations and potential divergence instability, and analyzes the free vibration response and dynamic instability under various types of motion through the Galerkin method.
ARCHIVE OF APPLIED MECHANICS
(2021)
Article
Engineering, Mechanical
Fan Fan, Keivan Kiani
Summary: This paper introduces a novel analytical solution for vibrational scrutiny of multi-layered composite nanomembranes, incorporating nonlocality and surface effects, using the isodeflection curve approach. The newly developed equations are ordinary differential equations, depending on a single parameter, which can be applied to various shapes of multi-layered nanomembranes.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Physics, Multidisciplinary
Banghua Xie, Keivan Kiani
Summary: The transverse vibration of mislocated double-parallel nanobeams under an inclined magnetic field is important, influencing both inter-structure forces and the system's stiffness. Using RKPM and AMA methods can successfully solve for nonlocal frequencies and analyze the effects of magnetic field strength, inclination, mislocation, and nonlocality on dominant frequencies.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Engineering, Multidisciplinary
Keivan Kiani
Summary: This study focuses on the twisting vibrations of coaxial-composite nanowires with damages and imperfect interface, using nonlocal models and reproducing kernel particle method for solving the problem. The results show that factors such as the location and intensity of damages, nonlocality, surface energy, imperfect interface parameter, and geometry significantly influence the twisting behavior of the nanostructure.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2022)
Article
Engineering, Multidisciplinary
Guilian Yu, Keivan Kiani, Mojtaba Roshan
Summary: This paper investigates the nonlocal transverse vibrations of vertically aligned single-layered membranes made from single-walled carbon nanotubes (SWCNTs) for the transportation of nanoparticles. The nanotubes are modeled using classical and shear deformable beams, while the moving nanoparticles are treated as rigid-in-contact particles with different velocities that take into account their weight force, inertia, and lags. The nonlocal equations of motion are derived considering the intertube van der Waals (vdW) forces and then solved systematically for elasto-dynamic fields. The effects of inertia, shear deformation, nonlocality, velocities, and lags of moving nanoparticles on the dynamic response of the nanosystem are explained in detail for two types of nanosystem decorations. The most critical case among various loadings, lags, and velocities of moving nanoparticles is introduced and discussed.
APPLIED MATHEMATICAL MODELLING
(2022)
Article
Engineering, Multidisciplinary
Jiafeng Chu, Qingjian Jiang, Keivan Kiani
Summary: This paper investigates the potential instability and vibrations of triple-nanowire systems carrying electrical current using the surface elasticity theory. The surface energy-based equations of motion are developed and the natural frequencies are evaluated using a meshless approach. The effects of various factors on the dominant frequencies are discussed.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2022)
Article
Engineering, Multidisciplinary
Boyuan Mu, Keivan Kiani
Summary: This study investigates the spatial buckling behavior of nanowires under axial force and twisting moment, and establishes the governing equations solved by the reproducing kernel particle method (RKPM). A reasonably good match between the results attained by the RKPM and those of the assumed modes approach (AMA) is achieved. The unstable conditions of the nanowires under severe axial forces and twisting moments are identified for the first time, and the critical roles of shear deformation and surface energy are methodically displayed and discussed.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2022)
Article
Engineering, Multidisciplinary
Min Li, Chenxia Wang, Keivan Kiani
Summary: The first objective of this study is to formulate the problem appropriately under the surface elasticity theory. Spatial equations of motion are established using various beam models and then analyzed via a meshless technique. The interactional role of axial force and torque on the fundamental frequency is discussed. The influences of the NW's aspect ratio and interactions with the elastic matrix on the dominant frequencies are systematically displayed. Critical values of the slenderness ratio and NW's radius are graphically illustrated, showing the crucial roles of shear deformation and surface effect on free vibration at these critical levels.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2023)
Article
Engineering, Multidisciplinary
Xiaoxia Ma, Keivan Kiani
Summary: By utilizing nonlocal continuum mechanics, the buckling characteristics of nanobeams are analyzed. Nonlocal beam models and deformation equations are established and a Galerkin-based meshless approach is used to evaluate the critical buckling response. For the first time, the spatial nonlocal buckling behavior of nanobeams is examined and the significant role of nonlocality and shear deformation is discussed.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2023)
Article
Multidisciplinary Sciences
Xiaoxia Ma, Mojtaba Roshan, Keivan Kiani, Ali Nikkhoo
Summary: In this study, the researchers investigated the dynamic deflection of a nanostructure embedded in a vibrating medium used for moving nano-objects. They derived the governing equations and developed analytical and numerical solutions to capture the nonlocal behavior. The results showed the importance of considering the inertial effect and shear effect in such systems.
Article
Environmental Sciences
Mingrui Li, Jin Hu, Pengzhen Liu, Jiayu Chen
Summary: As a new industry based on the traditional financial system and enhanced by emerging technologies, digital finance plays a significant role in the development of microenterprises. By analyzing the Digital Inclusive Finance Index of Peking University from 2011 to 2018, this study focused on inventory optimization and incremental innovation mechanisms. The research findings demonstrate that digital financing greatly contributes to the high-quality development of enterprises. Furthermore, it was revealed that digital finance effectively corrects mismatches in scale, attribute, phase, and industry, thus addressing financing constraints and promoting deleveraging of enterprises in the economic development process. However, there are still limitations for companies with high financing constraints and leverage, and financial regulation can enhance the economic performance of digital finance. These findings provide empirical evidence and policy insights for promoting the development of digital finance, deepening the supply-side structural reform of finance, serving the real economy more effectively, and achieving high-quality economic development.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2023)
Article
Physics, Multidisciplinary
Bo Xu, Keivan Kiani
Summary: This study investigates the nonlinear axial and lateral vibrations of nanoscaled beams under bidirectional support excitations. By considering various factors such as von-Karman terms, small-scale effect, and surface energy, the study derives and solves the nonlinear equations of motion for the nanobeam, while analyzing the effects of excitation parameters, geometry, and nonlocality on the dynamic response. The importance of nonlinear analysis in capturing the realistic dynamic response of the bi-directionally excited nanobeam is emphasized.
