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Artigos de revistas sobre o tema "Beams dynamics"

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Autor: Grafiati

Publicado: 25 de maio de 2024

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1

Stempin, Paulina, e Wojciech Sumelka. "Dynamics of Space-Fractional Euler–Bernoulli and Timoshenko Beams". Materials 14, n.º 8 (7 de abril de 2021): 1817. http://dx.doi.org/10.3390/ma14081817.

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This paper investigates the dynamics of the beam-like structures whose response manifests a strong scale effect. The space-Fractional Euler–Bernoulli beam (s-FEBB) and space-Fractional Timoshenko beam (s-FTB) models, which are suitable for small-scale slender beams and small-scale thick beams, respectively, have been extended to a dynamic case. The study provides appropriate governing equations, numerical approximation, detailed analysis of free vibration, and experimental validation. The parametric study presents the influence of non-locality parameters on the frequencies and shape of modes delivering a depth insight into a dynamic response of small scale beams. The comparison of the s-FEBB and s-FTB models determines the applicability limit of s-FEBB and indicates that the model (also the classical one) without shear effect and rotational inertia can only be applied to beams significantly slender than in a static case. Furthermore, the validation has confirmed that the fractional beam model exhibits very good agreement with the experimental results existing in the literature—for both the static and the dynamic cases. Moreover, it has been proven that for fractional beams it is possible to establish constant parameters of non-locality related to the material and its microstructure, independent of beam geometry, the boundary conditions, and the type of analysis (with or without inertial forces).

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2

Wei, Jian Zheng, Hui Feng Tan, Jian Xin Yu e Xing Wen Du. "Dynamic Testing and Analysis of Inflatable Beams". Applied Mechanics and Materials 226-228 (novembro de 2012): 546–52. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.546.

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Dynamic testing of an inflatable beam has been performed to evaluate structural natural frequencies and modal damping ratios. The inflatable beam has a pattern of six composite fiber strips inside thin-film structure that increases its local stiffness that the structure can be self-supporting in the gravity environment when the internal pressure is released. A measurement setup was installed, and the dynamic testing was performed in this self-supporting state. Dynamic characters of the beams were tested with internal pressure or not when the beam had a 2.0kg mass on the top. Moreover, the dynamic characters before rolled up were contrasted to one after. The experimental results indicate that the self-supporting inflatable beams had better bending stiffness, and the curl folding process had an impact on the dynamic characteristics of the inflatable beam. The pressure affection is not obvious on dynamics of the beam.

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3

Jiang, Li Zhong, Xin Kang e Chang Qing Li. "Dynamics Analysis of Steel-Concrete Composite Box Beams". Applied Mechanics and Materials 528 (fevereiro de 2014): 94–100. http://dx.doi.org/10.4028/www.scientific.net/amm.528.94.

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Steel-concrete composite box beams have been widely used in high rise buildings and long-span bridge structures. But so far, almost all researches have been aimed at the static behavior of the composite beams and dynamic behavior of steel and concrete composite beams have been rarely studied. In this paper, by using general finite element program ANSYS to analyze the dynamic performance of the composite box beam under different geometric parameters. Research is focused on the slip stiffness、width-to-thickness ratio、depth-span ratio and the height ratio of cross section to the vibration characteristics of composite box beam. The results indicate that these factors affect the seismic dynamic response of steel-concrete composite box beams most and they should be controlled according to different situations in seismic design stage.

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4

EL HARTI, Khalid, Rachid SAADANI e Miloud RAHMOUNE. "Dynamic Control of Non-Linearly Tapering FGM Beams". Eurasia Proceedings of Science Technology Engineering and Mathematics 18 (20 de outubro de 2022): 46–54. http://dx.doi.org/10.55549/epstem.1192327.

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This work presents the dynamics and active vibration control of a non-uniform functionally graded beam. Thanks to the strong use of beams and specifically with non-uniform section, in the different industrial applications, such as helicopter rotor blades, wind turbines, space and marine structures, we present in this article, a comparison of linearly and non-linearly tapering beams. The FGM beam is equipped with four layers of piezoelectric materials as sensors and actuators, bonded on the upper and lower surfaces of the main structure, on different finite elements to see the influence of its location on the dynamics and active control. In this study, the Timoshenko beam’s theory combined with FEM is applied to a beam divided into a finite number of elements. Hamilton's principle is applied to generate the equation of motion. The structure is modeled analytically and numerically and the simulation results are presented at the end. The optimal LQG control with Kalman filtering is applied.

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5

Gupta, Mohit, e Massimo Ruzzene. "Dynamics of Quasiperiodic Beams". Crystals 10, n.º 12 (16 de dezembro de 2020): 1144. http://dx.doi.org/10.3390/cryst10121144.

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Quasiperiodic metastrucures are characterized by edge localized modes of topological nature, which can be of significant technological interest. We here investigate such topological modes for stiffened and sandwich beams, which can be employed as structural members with inherent vibration localization capabilities. Quasiperiodicity is achieved by altering the geometric properties and material properties of the beams. Specifically, in the stiffened beams, the geometric location of stiffeners is modulated to quasiperiodic patterns, while, in the sandwich beams, the core’s material properties are varied in a step-wise manner to generate such patterns. The families of periodic and quasiperiodic beams for both stiffened and sandwich-type are obtained by varying a projection parameter that governs the location of the center of the stiffener or the alternating core, respectively. The dynamics of stiffened quasiperiodic beams is investigated through 3-D finite element simulations, which leads to the observation of the fractal nature of the bulk spectrum and the illustration of topological edge modes that populate bulk spectral bandgaps. The frequency spectrum is further elucidated by employing polarization factors that distinguish multiple contributing modes. The frequency response of the finite stiffened cantilever beams confirms the presence of modes in the non-trivial bandgaps and further demonstrates that those modes are localized at the free edge. A similar analysis is conducted for the analysis of sandwich composite beams, for which computations rely on a dynamic stiffness matrix approach. This work motivates the use of quasiperiodic beams in the design of stiffened and sandwich structures as structural members in applications where vibration isolation is combined with load-carrying functions.

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6

Luo, H., e S. Hanagud. "Dynamics of delaminated beams". International Journal of Solids and Structures 37, n.º 10 (março de 2000): 1501–19. http://dx.doi.org/10.1016/s0020-7683(98)00325-4.

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7

Yingkang Chen, Yingkang Chen, Xiwen Lin Xiwen Lin, Shuyu Lin Shuyu Lin, Shaoying Mo Shaoying Mo, Lingyu Wan Lingyu Wan e Yi Liang Yi Liang. "Propagation dynamics of deformed 2D vortex Airy beams". Chinese Optics Letters 15, n.º 8 (2017): 080801. http://dx.doi.org/10.3788/col201715.080801.

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8

Du, Xiaokang, Jing Zhang, Xian Guo, Liang Li e Dingguo Zhang. "Dynamics Analysis of Rotating Cantilever Beams with Free End Mass". Applied Sciences 12, n.º 15 (27 de julho de 2022): 7553. http://dx.doi.org/10.3390/app12157553.

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An improved modeling method for the dynamics analysis of rotating cantilever beams with free end mass is introduced. The proposed improved modeling method is based on the nonlinear Green strain theory in this study. By using the Hamilton principle and the Galerkin method, the discrete dynamic equations of the axial and chordwise motions are obtained. Meanwhile, the equations for free vibrations analysis of the rotating cantilever beam with free end mass are derived by introducing the equilibrium axial deformation into both axial and chordwise motions. Numerical simulations are performed to validate the proposed model, and the results are compared and discussed with the other modeling methods. The comparison shows that even a small free end mass has an important influence on the dynamic characteristics of the rotating beam. Furthermore, the influences of various parameters on the vibration frequencies and axial deformations of the rotating cantilever beams are analyzed, such as the angular speed, the free end mass to beam mass ratio, and the center body radius to beam length ratio. Under the same conditions, the influence of the free end mass on the variation in the first- and high-order frequencies with the increasing angular speed are different.

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9

Hao, Ying, Ming Gao e Jiajie Gong. "Parametric Random Vibration Analysis of an Axially Moving Laminated Shape Memory Alloy Beam Based on Monte Carlo Simulation". Materials 15, n.º 2 (12 de janeiro de 2022): 562. http://dx.doi.org/10.3390/ma15020562.

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The study of the bifurcation, random vibration, chaotic dynamics, and control of laminated composite beams are research hotspots. In this paper, the parametric random vibration of an axially moving laminated shape memory alloy (SMA) beam was investigated. In light of the Timoshenko beam theory and taking into consideration axial motion effects and axial forces, a random dynamic equation of laminated SMA beams was deduced. The Falk’s polynomial constitutive model of SMA was used to simulate the nonlinear random dynamic behavior of the laminated beam. Additionally, the numerical of the probability density function and power spectral density curves was obtained through the Monte Carlo simulation. The results indicated that the large amplitude vibration character of the beam can be caused by random perturbation on axial velocity.

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10

Liu, Jinyu, Ruiyun Jiao, Jing Wang, Zhendong Yang e Kaiyun Zhan. "Propagation dynamics of cosh-Airy beams in Kerr nonlinear media". Journal of Nonlinear Optical Physics & Materials 28, n.º 03 (setembro de 2019): 1950030. http://dx.doi.org/10.1142/s0218863519500309.

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We investigate propagation dynamics of cosh- and cosine-Airy beams in Kerr nonlinear media. The cosh-Airy and cosine-Airy beam can be considered as a superposition of two Airy beams with different decay factors and different propagation trajectories, respectively. It is shown that the solitons shedding from cosh-Airy and cosine-Airy beams and their interaction in both in-phase and out-of-phase cases are strongly dependent on the modulation parameter associated with the cosh function. The interaction between two cosine-Airy beams can exhibit attraction or repulsion under proper interval and initial angle condition in both in-phase and out-of-phase cases.

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11

Sytova, S. N. "Nonlinear Dynamics of Radiation in Multiple-Beam Vacuum Electronic Devices". Nonlinear Phenomena in Complex Systems 25, n.º 4 (12 de dezembro de 2022): 359–67. http://dx.doi.org/10.33581/1561-4085-2022-25-4-359-367.

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The article is devoted to overview of different types of vacuum electronic devices with two or more charged particle beams. There are travelling wave and backward wave tubes, free electron lasers and masers, volume free electron lasers. Two different cases take place in such situation: multiple-beam instability in such devices and multiple-stream instability. In the first case some charged particle beams moves in the system with different velocities. In the second one there are beams with almost equal velocities (streams). Two systems of equations for volume free electron laser with two electron beams are proposed. Some numerical results of VFEL numerical simulation are given and discussed.

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12

Nuwal, Nakul, Deborah A. Levin e Igor D. Kaganovich. "Kinetic modeling of solitary wave dynamics in a neutralizing ion beam". Physics of Plasmas 30, n.º 1 (janeiro de 2023): 012110. http://dx.doi.org/10.1063/5.0131059.

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In this work, we characterize the formation and evolution of electrostatic solitary waves (ESWs) in the space-charge neutralization of ion beams using particle-in-cell simulations. These waves become excited when the electrons emitted from an external filament source initiate a two-stream instability in the beam. We show that such electrostatic waves become excited in both two-dimensional (2D) and three-dimensional (3D) beams with different shapes and sizes. Through a 1D Bernstein–Greene–Kruskal (BGK) analysis of the 2D beam, we find that the non-Maxwellian nature of the beam electrons gives rise to large-sized ESWs that are not predicted by BGK theory since it assumes a Maxwellian electron velocity distribution in the beam. Finally, we show that a 1D BGK theory is inadequate to describe ESWs in 3D beams because of complex electron trajectories.

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13

Fossat, Pascal, Madhurima Kothakota, Mohamed Ichchou e Olivier Bareille. "Dynamic Bending Model Describing the Generation of Negative Stiffness by Buckled Beams: Qualitative Analysis and Experimental Verification". Applied Sciences 13, n.º 16 (21 de agosto de 2023): 9458. http://dx.doi.org/10.3390/app13169458.

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This work addresses the dynamic modeling of a negative stiffness absorber consisting of an assembly of curved beams. Design rules are derived from the orders of magnitude of stiffness and elastic energy stored by the negative stiffness elements. Although static and dynamic performances are widely documented using equivalent spring–mass system equations of motion, this paper presents a modeling approach based on beam dynamics to predict the behavior by incorporating the generation of negative stiffness with prestressed Euler beams. The static behavior is first recalled to feed the dynamic beam model with realistic orders of magnitude. The latter is derived from the beam balance instead of the spring–mass system and aims at solving the beam problem, which encompasses more realistic phenomena compared to introducing the equivalent stiffness in the spring–mass equation of motion. The consistency of the beam modeling is confirmed by comparison with available models in the literature and finite element simulations. A mock-up is built in which beam-type components are 3D-printed. Axial loading is introduced on the curved beams to evaluate its influence on the response of the isolator, and the observed softening trend complies with the theoretical predictions.

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14

Zhou, Liangqiang, e Wen Wang. "Chaotic Dynamics of Piezoelectric Composite Laminated Beams". Shock and Vibration 2021 (26 de abril de 2021): 1–14. http://dx.doi.org/10.1155/2021/5582201.

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Chaos in piezoelectric composite laminated beams has significant implications in the design of this model. Some results for this model have been obtained numerically. With the energy-phase method and numerical simulations, global dynamics of piezoelectric composite laminated beams is investigated in this paper. The average equation of the piezoelectric composite laminated beam is obtained by the normal form theory. The existence of multipulse homoclinic orbits for undisturbed and dissipative cases is analyzed by the energy-phase method, and the mechanism of chaotic motion of the system is given. The effect of the dissipation factor on pulse sequence and layer radius is studied in detail. The chaotic motion of the system is verified by numerical simulations.

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15

Yu, Chia Chun, Shih Cheng Wang, Cherng Shing Lin e Te Chi Chen. "CFD Application for Performance Based Safety Verification of Reinforced Concrete Beam in Computer Simulation Building Fire". Advanced Materials Research 601 (dezembro de 2012): 190–95. http://dx.doi.org/10.4028/www.scientific.net/amr.601.190.

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More than 90% of the buildings in Taiwan use reinforced concrete (RC) structures. Before or after fire damage, whether the RC structure accord Performance Based Design (PBD) fire code or safe evaluation are important in building fire protection verification. However, obtaining fire thermal parameters detailed quantitative data from building fire tests or actual building fires are difficult. Therefore, computational fluid dynamic (CFD) integration to simulate fire scenarios has been widely utilized in fire protection engineering. This study utilizes Fire Dynamics Simulator (FDS) fire model and PHOENICS field model software to simulate fire development and beams inner temperature variation. The structural strength estimated using beam cross-sections temperature to investigate dynamic ultimate bending moment (Mu) of RC beams. This integration method can investigate the influence of different beam positions, fire intensity, fire duration and fire damage sustained (two or three faces heated) for RC beams fire protection safe verification.

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16

Huang, C.-K., Q. Tang, Y. K. Batygin, O. Beznosov, J. Burby, A. Kim, S. Kurennoy, T. Kwan e H. N. Rakotoarivelo. "Symplectic neural surrogate models for beam dynamics". Journal of Physics: Conference Series 2687, n.º 6 (1 de janeiro de 2024): 062026. http://dx.doi.org/10.1088/1742-6596/2687/6/062026.

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Abstract Development of robust machine-learning (ML) based surrogates for particle accelerators can significantly benefit the modeling, design, optimization, monitoring and control of such accelerators. It is desirable that the surrogate models embed fundamental physical constraints to the interaction and dynamics of the beams, for which an accelerator must be designed to operate upon. We implement and train a class of phase space structure-preserving neural networks — Henon Neural Networks (HenonNets) [1], for nonlinear beam dynamics problems. It is demonstrated that the trained HenonNet model predicts the beam transfer matrix to a reasonably good accuracy while strongly maintaining the symplecticity. To explore such model’s applicability and flexibility for high brightness or intensity beams, we further test it with beam dynamics in the presence of electrostatic and radiative collective effects. Our results indicate that HenonNet may be used as a base ML model for the surrogate of complex beam dynamics, thus opening up a wide range of applications.

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17

Anguiano-Morales, Marcelino. "Conical dynamics of Bessel beams". Optical Engineering 46, n.º 7 (1 de julho de 2007): 078001. http://dx.doi.org/10.1117/1.2752167.

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18

Johnson, A. R., A. Tessler e M. Dambach. "Dynamics of Thick Viscoelastic Beams". Journal of Engineering Materials and Technology 119, n.º 3 (1 de julho de 1997): 273–78. http://dx.doi.org/10.1115/1.2812256.

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A viscoelastic higher-order thick beam finite element formulation is extended to include elastodynamic deformations. The material constitutive law is a special differential form of the Maxwell solid, which employs viscous strains as internal variables to determine the viscous stresses. The total time-dependent stress is the superposition of its elastic and viscous components. In the constitutive model, the elastic strains and the conjugate viscous strains are coupled through a system of first-order ordinary differential equations. The use of the internal strain variables allows for a convenient finite element formulation. The elastodynamic equations of motion are derived from the virtual work principle. Computational examples are carried out for a thick orthotropic cantilevered beam. Relaxation, creep, relaxation followed by free damped vibrations, and damping related modal interactions are discussed.

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19

Yigit, A. S., e A. P. Christoforou. "Impact dynamics of composite beams". Composite Structures 32, n.º 1-4 (janeiro de 1995): 187–95. http://dx.doi.org/10.1016/0263-8223(95)00072-0.

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20

Gounaris, G., N. Anifantis e A. D. Dimarogonas. "Dynamics of cracked hollow beams". Engineering Fracture Mechanics 39, n.º 6 (janeiro de 1991): 931–40. http://dx.doi.org/10.1016/0013-7944(91)90101-6.

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21

Feng, B., T. F. Ma, R. N. Monteiro e C. A. Raposo. "Dynamics of Laminated Timoshenko Beams". Journal of Dynamics and Differential Equations 30, n.º 4 (10 de julho de 2017): 1489–507. http://dx.doi.org/10.1007/s10884-017-9604-4.

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22

Roy, H., J. K. Dutt e P. K. Datta. "Dynamics of multilayered viscoelastic beams". Structural Engineering and Mechanics 33, n.º 4 (10 de novembro de 2009): 391–406. http://dx.doi.org/10.12989/sem.2009.33.4.391.

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23

Siviloglou, G. A., J. Broky, A. Dogariu e D. N. Christodoulides. "Ballistic dynamics of Airy beams". Optics Letters 33, n.º 3 (15 de janeiro de 2008): 207. http://dx.doi.org/10.1364/ol.33.000207.

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24

XU, LIZHONG, e XIAOLI JIA. "ELECTROMECHANICAL DYNAMICS FOR MICRO BEAMS". International Journal of Structural Stability and Dynamics 06, n.º 02 (junho de 2006): 233–51. http://dx.doi.org/10.1142/s0219455406001939.

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In this paper, an electromechanical coupled dynamic equation of a micro beam under an electrostatic force as well as under an electromechanical coupled force is presented. The linearization of above dynamic equation is made, allowing the equation to be divided into a linear dynamic equation for dynamic displacement and a static balance equation for static displacement. Using the balance equation, the changes of the voltage along with displacement are studied. It is shown that there is a critical voltage at which the micro beam will buckle. From the linear dynamic equation, natural frequencies and vibration modes of the micro beam, and its forced responses to voltage excitation are derived. The results show that the natural frequencies and vibrating magnitudes of the micro beam are affected by mechanical and electric parameters. Smaller beam length and voltage as well as larger beam thickness and clearance should be selected in order to obtain smaller vibrating magnitudes. It is also shown that for higher vibration modes, more positions of the peak dynamic displacements occur.

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25

Manoach, Emil, Anna Warminska e Jerzy Warminski. "Dynamics of Beams under Coupled Thermo-Mechanical Loading". Applied Mechanics and Materials 849 (agosto de 2016): 57–64. http://dx.doi.org/10.4028/www.scientific.net/amm.849.57.

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An effect of thermal loading on vibrations of beams is investigated in the paper. A beam is considered as an extended Timoshenko beam model with nonlinear terms resulted from large deflections. Dynamics of the structure is analysed under thermal and mechanical loadings considering transient dynamics due to a heat pulse imposed to the beam. The numerical method for solving coupled thermo-mechanical problem is presented. On this basis the importance of the heat pulse intensity around the first resonance condition is demonstrated. The effect of the heat on the the complex transient dynamics of the beam and its qualitatively different response is shown as well.

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26

Peters, Eduardo, Gustavo Funes, L. Martínez-León e Enrique Tajahuerce. "Dynamics of Fractional Vortex Beams at Fraunhofer Diffraction Zone". Photonics 9, n.º 7 (9 de julho de 2022): 479. http://dx.doi.org/10.3390/photonics9070479.

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Fractional vortex beams (FVBs) possess unique topological properties that are manifested in the vortex distribution. However, there are still discrepancies in the value of the vortex strength of FVBs at the far field. In this work we present a complete picture of the behavior of the phase singularities of non-integer (commonly known as fractional) beams in the Fraunhofer diffraction region and demonstrate a very good correspondence between experiments and simulations. As shown in the text, the original beam waist ω0 was found to be a key factor relating to the beam profile topology. This variable was measured in the process of calibrating the experiment. Finally, an experimental method to obtain the non-integer topological charge is proposed. This method only requires an analysis of the intensity, knowledge of the transition behaviors, and the beam waist.

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27

Spicer, D. S., e R. N. Sudan. "Beam-Return Current Systems in Solar Flares". Symposium - International Astronomical Union 107 (1985): 519–20. http://dx.doi.org/10.1017/s0074180900076051.

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The importance of electron beams in solar flare dynamics is well known. In order to understand the dynamics produced by beams it is essential to have a clear understanding of the role beam driven return currents play and whether electrostatic or inductive electric fields maintain the return current. We show that inductive electric fields are responsible for driving return currents under solar conditions.

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28

Fan, Yin, Y. Xiang e Hui-Shen Shen. "Nonlinear Dynamics of Temperature-Dependent FG-GRC Laminated Beams Resting on Visco-Pasternak Foundations". International Journal of Structural Stability and Dynamics 20, n.º 01 (28 de novembro de 2019): 2050012. http://dx.doi.org/10.1142/s0219455420500121.

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This paper studies the nonlinear dynamic responses of graphene-reinforced composite (GRC) beams in a thermal environment. It is assumed that a laminated beam rests on a Pasternak foundation with viscosity and consists of GRC layers with various volume fractions of graphene reinforcement to construct a functionally graded (FG) pattern along the transverse direction of the beam. An extended Halpin–Tsai model which is calibrated against the results from molecular dynamics (MD) simulations is used to evaluate the material properties of GRC layers. The mechanical model of the beam is on the establishment of a third-order shear deformation beam theory and includes the von-Kármán nonlinearity effect. The model also considers the foundation support and the temperature variation. The two-step perturbation technique is first applied to solve the beam motion equations and to derive the nonlinear dynamic load–deflection equation of the beam. Then a Runge–Kutta numerical method is applied and the solutions for this nonlinear equation are obtained. The influence of FG patterns, visco-elastic foundation, ambient temperature and applied load on transient response behaviors of simply supported FG-GRC laminated beams is revealed and examined in detail.

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29

Liu, Yang. "Dynamic Analysis of Elastic Support Beam Subject to Moving Load". Applied Mechanics and Materials 256-259 (dezembro de 2012): 918–21. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.918.

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The dynamics of elastic support beam are studied and the latent equation of the freely vibration modes of elastic bearing beam is deduced. The equation of the forced vibration of an elastically supported beam is obtained by the Lagrange equations and the influence of spring stiffness and moving load speed are analyzed. Calculation results show: the elastic supports have great effects on responses of beams, the dynamic amplification of deflections and stresses increases with the spring stiffness; the dynamic response of beam also increase with the increase of the speed of moving loads.

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30

Cao, Dong Xing, Bao Chen e Wei Zhang. "Nonlinear Dynamics of Simple-Supported Beam under Concentrated Moving Load". Applied Mechanics and Materials 226-228 (novembro de 2012): 541–45. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.541.

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The dynamic responses of two kinds of simple-supported beams with single layer and double-layer under a moving load were analyzed based on the theory of nonlinear dynamics. The equations of motion are derived by using Hamilton’s principle and von Karman type equations for the two models. Galerkin’s method was employed to obtain the ordinary differential equations of motion. First we obtain the periodic motion waveforms in the mid-point of the beams at the same initial velocity, and the result show that the amplitude of the double-layer model is much smaller then that of the single-layer model. Then for the two models, the vibration response and critical velocity were studied considering the effect of the structural parameters, the magnitude and velocity of moving load. The results of numerical simulation show that double-layer beam model has better vibration suppression performance than single-layer beam model.

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31

Gholipour, Alireza, Mergen H. Ghayesh e Yueqiang Zhang. "A Comparison between Elastic and Viscoelastic Asymmetric Dynamics of Elastically Supported AFG Beams". Vibration 3, n.º 1 (31 de janeiro de 2020): 3–17. http://dx.doi.org/10.3390/vibration3010002.

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This investigation compares the dynamic simulation results of perfect, elastically-supported, axially-functionally-graded (AFG) beams between viscoelastic and elastic models. When modeling and simulating the dynamics of AFG beams, the elastic model is commonly assumed so as to simplify calculations. This investigation shows how the dynamics varies if viscosity is present. The nonlinear continuous/discretized, axial/transverse motion derivation procedure is explained briefly based on Hamilton’s principle for energy/energy-loss, Kelvin–Voigt viscosity, elastic foundation assumption, and exponential functions for material and geometric variations along the axial axis. A comparison between elastic and Kelvin–Voigt viscoelastic AFG beams on an elastic foundation shows that the viscosity influences the asymmetric dynamics of AFG beams; the viscosity effects become more dominant for larger motion amplitudes, for example.

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32

Yousfi, Assia, Abdelhalim Bencheikh, Madjeda Kherif, Abdeljalil Benstiti, Saoussane Chabou e Ouis Chouaib Boumeddine. "Free space dynamics of Laguerre-Gaussian-vortex beam". Journal of Physical & Chemical Research 1, n.º 2 (7 de janeiro de 2023): 10–15. http://dx.doi.org/10.58452/jpcr.v1i2.22.

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In this paper, we analytically demonstrate the propagation of a useful structured light laser beam;namely, the vortex Laguerre-Gaussian beam, the latter is an eigenmode of free space propagation,which is invariant under propagation in lossless systems. Through some numerical simulations, weshow the main spatial features of such interesting beams.

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Gans, Roger F. "On the Dynamics of a Conservative Elastic Pendulum". Journal of Applied Mechanics 59, n.º 2 (1 de junho de 1992): 425–30. http://dx.doi.org/10.1115/1.2899537.

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This paper presents a finite element model of the elastica, without dissipation, in a form realizable in the laboratory: a set of rigid links connected by torsion springs. The model is shown to reproduce the linear elastic behavior of beams. The linear beam, and most nonlinear beams are not periodic. (The linear eigenfrequencies are incommensurate.) They do exhibit a basic cyclic behavior, the beam waving back and forth with a measurable period. Extensive exploration of the behavior of a fourlink model reveals windows of periodicity—isolated points in parameter space where the motion is nearly periodic. (The basic phase plane diagrams are asymmetric, and the time evolution of the motion distributes this asymmetry symmetrically in time.) The first such window shows a period twice the basic cycle time, the next, less well observed one, four times the basic cycle time.

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34

Batoo, K. M., S. M. Husein Kamona, Sh H. Zaki, H. A. Lafta, S. Hussain, W. M. Khazaal, A. H. M. Hamoody et al. "Coherent control of parametric generation of laser beams via intersubband transitions in quantum wells". Laser Physics Letters 21, n.º 2 (9 de janeiro de 2024): 026001. http://dx.doi.org/10.1088/1612-202x/ad1096.

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Abstract This paper investigates the propagation dynamics of laser beams within a semiconductor quantum well (QW) system. The study explores various scenarios involving different detuning values and spatially varying incident beams. The light–matter interaction within the QW system shows a complex interplay between detuning, spatial characteristics, and beam properties. In the resonant case, where the detuning values for probe and signal beams are zero, we observe exponential relaxation of both beams reaching a common value. Introducing detuning leads to oscillatory behaviors, with larger detuning values promoting more pronounced oscillations and an enhanced signal beam. The investigation takes an intriguing turn when we consider position-dependent incident beams. In these cases, the spatial patterns of the initial beam are transferred to the generated beam, leading to soliton-like propagation and the creation of beams with specific spatial dependencies. Remarkably, under substantial detuning, both incident and generated beams adopt periodic patterns in two dimensions, forming lattice structures with spot-like peak intensities. These findings underscore the versatility and controllability of the QW system, offering opportunities for engineered spatial and spectral properties in laser beams.

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35

Baumgärtel, K. "Ion dynamics in electron beam–plasma interaction: particle-in-cell simulations". Annales Geophysicae 32, n.º 8 (22 de agosto de 2014): 1025–33. http://dx.doi.org/10.5194/angeo-32-1025-2014.

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Abstract. Electron beam–plasma interaction including ions is studied by particle-in-cell (PIC) simulations using a one-dimensional, electrostatic code. Evidence for Langmuir wave decay is given for sufficiently energetic beams, as in previous Vlasov–Maxwell simulations. The mechanism for the generation of localized finite-amplitude ion density fluctuations is analyzed. Amplitude modulation due to interference between the beam-generated Langmuir waves causes random wave localization including strong transient spikes in field intensity which create bursty ion density structures via ponderomotive forces. More dense beams may quench the decay instability and generate low-frequency variations dominated by the wave number of the fastest growing Langmuir mode.

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36

Adhikari, Sondipon, e C. S. Manohar. "Transient Dynamics of Stochastically Parametered Beams". Journal of Engineering Mechanics 126, n.º 11 (novembro de 2000): 1131–40. http://dx.doi.org/10.1061/(asce)0733-9399(2000)126:11(1131).

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37

Grow, Taylor D., Amiel A. Ishaaya, Luat T. Vuong, Alexander L. Gaeta, Nir Gavish e Gadi Fibich. "Collapse dynamics of super-Gaussian Beams". Optics Express 14, n.º 12 (2006): 5468. http://dx.doi.org/10.1364/oe.14.005468.

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38

Casavecchia, Piergiorgio. "Chemical reaction dynamics with molecular beams". Reports on Progress in Physics 63, n.º 3 (28 de fevereiro de 2000): 355–414. http://dx.doi.org/10.1088/0034-4885/63/3/203.

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39

Mustafaev, A. S. "Dynamics of electron beams in plasmas". Technical Physics 46, n.º 4 (abril de 2001): 472–83. http://dx.doi.org/10.1134/1.1365475.

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Rosenzweig, J. B. "Injection and dynamics of accelerated beams". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 410, n.º 3 (junho de 1998): 335–39. http://dx.doi.org/10.1016/s0168-9002(98)00161-2.

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41

Chan, Ally S. Y., e Robert G. Jones. "Surface dynamics using pulsed electron beams". Surface Science 451, n.º 1-3 (abril de 2000): 232–37. http://dx.doi.org/10.1016/s0039-6028(00)00032-7.

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42

Betsch, P., e P. Steinmann. "Constrained dynamics of geometrically exact beams". Computational Mechanics 31, n.º 1-2 (1 de maio de 2003): 49–59. http://dx.doi.org/10.1007/s00466-002-0392-1.

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43

Du, Guangqing, Fangrui Yu, Yu Lu, Lin Kai, Caiyi Chen, Qing Yang, Xun Hou e Feng Chen. "Ultrafast Dynamics of Extraordinary Optical Transmission through Two-Slit Plasmonic Antenna". Nanomaterials 13, n.º 16 (9 de agosto de 2023): 2284. http://dx.doi.org/10.3390/nano13162284.

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We have theoretically investigated the spatial-temporal dynamics of extraordinary optical transmission (EOT) through a two-slit plasmonic antenna under femtosecond laser dual-beam irradiation. The dynamic interference of the crossed femtosecond laser dual-beam with the transiently excited surface plasmon polariton waves are proposed to characterize the particular spatial-temporal evolutions of EOT. It is revealed that the dynamic EOT can be flexibly switched with tunable symmetry through the respective slit of a two-slit plasmonic antenna by manipulating the phase correlation of the crossed femtosecond laser dual-beam. This is explained as tunable interference dynamics by phase control of surface plasmon polariton waves, allowing the dynamic modulation of EOT at optimized oblique incidences of dual-beams. Furthermore, we have obtained the unobserved traits of symmetry-broken transient spectra of EOT from the respective up- and down-slit of the antenna under crossed femtosecond laser dual-beam irradiation. This study can provide fundamental insights into the ultrafast dynamics of EOT in two-slit plasmonic antennas, which can be helpful to advance a wide range of applications, such as ultrafast plasmonic switch, ultrahigh resolution imaging, the transient amplification of non-linear effects, etc.

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44

Lu, Yixin, e Xiaochao Chen. "Nonlinear Parametric Dynamics of Bidirectional Functionally Graded Beams". Shock and Vibration 2020 (20 de julho de 2020): 1–13. http://dx.doi.org/10.1155/2020/8840833.

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http://mts.hindawi.com/update/) in our Manuscript Tracking System and after you have logged in click on the ORCID link at the top of the page. This link will take you to the ORCID website where you will be able to create an account for yourself. Once you have done so, your new ORCID will be saved in our Manuscript Tracking System automatically."?>In this paper, the parametric dynamics of bidirectional functionally graded (BDFG) beams subjected to a time-dependent axial force are studied. The material properties of beam which vary along both thickness and axial directions follow the power law, and four different distribution patterns are considered. The coupled nonlinear partial differential equations describing the longitudinal-transverse displacements and the shear deformation are derived using Hamilton’s principle based on Timoshenko beam theory. The Galerkin scheme is employed to discrete the continuous model resulting in a multiple degree-of-freedom system, namely, the reduced order model. The nonlinear parametric response of the beam is obtained by solving the discrete system numerically, and the frequency- and force-response curves are constructed by tracing the period motion using the pseudoarclength continuation technique. Numerical results are presented to examine the effects of system parameters, e.g., gradient parameters, magnitude and frequency of external excitation, and damping coefficients. Cyclic-fold bifurcation and branch points of the period motion are spotted in parametric resonance of the BDFG beam. Results show that the asymmetrical material distribution in thickness direction of beam leads to the asymmetry of dynamic responses. Moreover, the gradient of material in axial direction has more significant effect on the dynamic features of BDFG beam than that in the thickness direction.

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45

MEL'NIK, V. N., e E. P. KONTAR. "Gasdynamic description of electron-beam flying-off in a plasma". Journal of Plasma Physics 60, n.º 1 (agosto de 1998): 49–64. http://dx.doi.org/10.1017/s0022377898006539.

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The propagation of one and two electron beams in a plasma is considered in the case when the source is time-dependent. When the electron-plasmon interaction time is assumed to be much less than the electron flying-off time, the main gasdynamic equations are obtained on the basis of the quasilinear theory of weak turbulence. The solution for a monoenergetic beam is a beam–plasma structure moving with constant velocity. In general, two beams propagate as two beam–plasma structures with constant velocities. However, the second electron beam influences the flying-off dynamics of both beams. This peculiar interaction modifies the shapes of the structures.

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46

Samborski, Sylwester. "Experimental Verification of Defect’s Influence on Beams’ Dynamics Using Laser Scanning Vibrometry". Solid State Phenomena 240 (agosto de 2015): 36–41. http://dx.doi.org/10.4028/www.scientific.net/ssp.240.36.

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This article presents paper deals with experimental verification of defect’s influence on the beam structures’ eigenfrequency extraction performed numerically with the ABAQUS Finite Element Analysis (FEA) software. The results for beams with defects were compared to those obtained for their undamaged (healthy) counterparts. The beams were made of aluminum and of a laminated glass-epoxy composite. The experiments confirmed the numerical results both quantitatively and qualitatively showing also some differences between the two materials.

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47

Curcio, Alessandro, Jon Imanol Apiñaniz Aginako, Teresa Cebriano Ramírez, Michael Ehret, Berkahoum Kebladj, Antonia Morabito, Alberto Pérez Delgado, Carlos Salgado López, Luca Volpe e Giancarlo Gatti. "Liouville Theory for Fully Analytic Studies of Transverse Beam Dynamics in Laser-Plasma Ion Accelerators". Symmetry 14, n.º 9 (8 de setembro de 2022): 1875. http://dx.doi.org/10.3390/sym14091875.

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The exact solution of the Liouville equation expressed in terms of exponential operators can describe the phase space evolution of particle beams in transport lines. In this paper, we generalize the solution of the above equation for the case of beam losses induced by apertures and for particle beams with large spreads in the momentum space. We discuss the applicability of such approach to ion beams produced by high-intensity lasers interacting with critical plasmas, based on the comparison between theoretical findings and measurements.

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48

Krafft, Catherine, Alexander S. Volokitin e Gaëtan Gauthier. "Turbulence and Microprocesses in Inhomogeneous Solar Wind Plasmas". Fluids 4, n.º 2 (11 de abril de 2019): 69. http://dx.doi.org/10.3390/fluids4020069.

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The random density fluctuations observed in the solar wind plasma crucially influence on the Langmuir wave turbulence generated by energetic electron beams ejected during solar bursts. Those are powerful phenomena consisting of a chain of successive processes leading ultimately to strong electromagnetic emissions. The small-scale processes governing the interactions between the waves, the beams and the inhomogeneous plasmas need to be studied to explain such macroscopic phenomena. Moreover, the complexity induced by the plasma irregularities requires to find new approaches and modelling. Therefore theoretical and numerical tools were built to describe the Langmuir wave turbulence and the beam’s dynamics in inhomogeneous plasmas, in the form of a self-consistent Hamiltonian model including a fluid description for the plasma and a kinetic approach for the beam. On this basis, numerical simulations were performed in order to shed light on the impact of the density fluctuations on the beam dynamics, the electromagnetic wave radiation, the generation of Langmuir wave turbulence, the waves’ coupling and decay phenomena involving Langmuir and low frequency waves, the acceleration of beam electrons, their diffusion mechanisms, the modulation of the Langmuir waveforms and the statistical properties of the radiated fields’ distributions. The paper presents the main results obtained in the form of a review.

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49

Boutaghou, Z. E., Arthur G. Erdman e Henryk K. Stolarski. "Dynamics of Flexible Beams and Plates in Large Overall Motions". Journal of Applied Mechanics 59, n.º 4 (1 de dezembro de 1992): 991–99. http://dx.doi.org/10.1115/1.2894071.

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The dynamic response of flexible beams, plates, and solids undergoing arbitrary spatial motions are systematically derived via a proposed approach. This formulation is capable of incorporating arbitrary representation of the kinematics of deformation, phenomenon of dynamic stiffening, and complete nonlinear interaction between elastic and rigid-body dynamics encountered in constrained multibody systems. It is shown that the present theory captures the phenomenon of dynamic stiffening due to the transfer of the axial and membrane forces to the bending equations of beams and plates, respectively. Examples are presented to illustrate the proposed formulations.

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50

Perelomova, A. "Unusual divergence of magnetoacoustic beams". Physics of Plasmas 29, n.º 4 (abril de 2022): 042111. http://dx.doi.org/10.1063/5.0084431.

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Two-dimensional magnetosonic beams directed along a line forming a constant angle θ with the equilibrium straight magnetic field are considered. Perturbations in a plasma are described by the system of ideal magnetohydrodynamic equations. The dynamics of perturbations in a beam are different in the cases of fast and slow modes, and it is determined by θ and equilibrium parameters of a plasma. In particular, a beam divergence may be unusual in the case of parallel propagation ( θ = 0). Diffraction is more pronounced in the case of parallel propagation as compared to a flow without magnetic field, and less manifested in the case of perpendicular propagation. The beams propagating oblique to the magnetic field do not reveal diffraction. The dynamics of perturbations in a beam are analytically described in the cases of weak and strong nonlinearity compared to diffraction. Small magnitude perturbations at the axis of a beam in unusual cases propagate slower than that in the plane wave. Involving of thermal conduction leads to the coupling equations describing thermal self-action of a beam, which behaves differently in the ordinary and unusual cases. Self-focusing may occur in the presence of a magnetic field instead of conventional defocusing in gases.

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