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2022年 第43卷 第12期    刊出日期：2022-12-01

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论文

NES cell

Hu DING, Yufei SHAO

2022, 43(12):  1793-1804.  doi:10.1007/s10483-022-2934-6

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A broadband adaptive vibration control strategy with high reliability and flexible versatility is proposed. The high vibration damping performance of nonlinear energy sink (NES) has attracted attention. However, targeted energy transfer may cause severe vibration of NES. Besides, it is difficult to realize pure nonlinear stiffness without the linear part. As a result, the reliability of NES is not high. The low reliability of NES has hindered its application in engineering. In addition, the performance of NES depends on its mass ratio of the primary system, and NES lacks versatility for different vibration systems. Therefore, this paper proposes the concept of NES cell. The advantages of the adaptive vibration control of NES are applied to cellular NES. By applying a large number of NES cells in parallel, the reliability of NES and its versatility to complex vibration structures are improved. An elastic beam is used as the primary vibration structure, and a limited NES is used as the cell. The relationship between the vibration suppression effect of NES cells and the number of NES cell is studied. In addition, the effect of the distribution of NES cells on the multi-mode resonance suppression of the beam is also studied. In summary, the mode of the primary structure can be efficiently controlled by a large number of lightweight NES cell. Therefore, the lightweight NES cell is flexible for vibration control of complex structures. In addition, it improves the reliability of NES applications. Therefore, the distributed application of NES cells proposed in this paper is a valuable vibration suppression strategy.



Internal resonance of an axially transporting beam with a two-frequency parametric excitation

Dengbo ZHANG, Youqi TANG, Ruquan LIANG, Yuanmei SONG, Liqun CHEN

2022, 43(12):  1805-1820.  doi:10.1007/s10483-022-2930-9

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This paper investigates the transverse 3:1 internal resonance of an axially transporting nonlinear viscoelastic Euler-Bernoulli beam with a two-frequency parametric excitation caused by a speed perturbation. The Kelvin-Voigt model is introduced to describe the viscoelastic characteristics of the axially transporting beam. The governing equation and the associated boundary conditions are obtained by Newton’s second law. The method of multiple scales is utilized to obtain the steady-state responses. The Routh-Hurwitz criterion is used to determine the stabilities and bifurcations of the steady-state responses. The effects of the material viscoelastic coefficient on the dynamics of the transporting beam are studied in detail by a series of numerical demonstrations. Interesting phenomena of the steady-state responses are revealed in the 3:1 internal resonance and two-frequency parametric excitation. The approximate analytical method is validated via a differential quadrature method.

Nonlinear in-plane thermal buckling of rotationally restrained functionally graded carbon nanotube reinforced composite shallow arches under uniform radial loading

Cheng LI, Chengxiu ZHU, C. W. LIM, Shuang LI

2022, 43(12):  1821-1840.  doi:10.1007/s10483-022-2917-7

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The nonlinear in-plane instability of functionally graded carbon nanotube reinforced composite (FG-CNTRC) shallow circular arches with rotational constraints subject to a uniform radial load in a thermal environment is investigated. Assuming arches with thickness-graded material properties, four different distribution patterns of carbon nanotubes (CNTs) are considered. The classical arch theory and Donnell’s shallow shell theory assumptions are used to evaluate the arch displacement field, and the analytical solutions of buckling equilibrium equations and buckling loads are obtained by using the principle of virtual work. The critical geometric parameters are introduced to determine the criteria for buckling mode switching. Parametric studies are carried out to demonstrate the effects of temperature variations, material parameters, geometric parameters, and elastic constraints on the stability of the arch. It is found that increasing the volume fraction of CNTs and distributing CNTs away from the neutral axis significantly enhance the bending stiffness of the arch. In addition, the pretension and initial displacement caused by the temperature field have significant effects on the buckling behavior.

Transient analysis on surface heated piezoelectric semiconductor plate lying on rigid substrate

Luke ZHAO, Sen GU, Yaqin SONG, Feng JIN

2022, 43(12):  1841-1856.  doi:10.1007/s10483-022-2927-6

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Based on the thermo-electro-elastic coupling theory, the mathematical model for a surface heated piezoelectric semiconductor (PS) plate is developed in the time domain. Applying the direct and inverse Laplace transformations to the established model, the mechanical and electrical responses are investigated. The comparison between the analytical solution and the finite element method (FEM) is conducted, which illustrates the validity of the derivation. The calculated results show that the maximum values of the mechanical and electrical fields appear at the heating surface. Importantly, the perturbation carriers tend to concentrate in the zone near the heating surface under the given boundary conditions. It can also be observed that the heating induced elastic wave leads to jumps for the electric potential and perturbation carrier density at the wavefront. When the thermal relaxation time is introduced, all the field quantities become smaller because of the thermal lagging effect. Meanwhile, it can be found that the thermal relaxation time can describe the smooth variation at the jump position. Besides, for a plate with P-N junction, the effect of the interface position on the electrical response is studied. The effects of the initial carrier density on the electrical properties are discussed in detail. The conclusions in this article can be the guidance for the design of PS devices serving in thermal environment.

Effects of layer number and initial pressure on continuum-based buckling analysis of multi-walled carbon nanotubes accounting for van der Waals interaction

Xinlei LI, Jianfei WANG

2022, 43(12):  1857-1872.  doi:10.1007/s10483-022-2909-6

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The structural instability of multi-walled carbon nanotubes (MWCNTs) has captured extensive attention due to the unique characteristic of extremely thin hollow cylinder structure. The previous studies usually focus on the buckling behavior without considering the effects of the wall number and initial pressure. In this paper, the axial buckling behavior of MWCNTs with the length-to-outermost radius ratio less than 20 is investigated within the framework of the Donnell shell theory. The governing equations for the infinitesimal buckling of MWCNTs are established, accounting for the van der Waals (vdW) interaction between layers. The effects of the wall number, initial pressure prior to buckling, and aspect ratio on the critical buckling mode, buckling load, and buckling strain are discussed, respectively. Specially, the four-walled and twenty-walled CNTs are studied in detail, indicating the fact that the buckling instability may occur in other layers besides the outermost layer. The obtained results extend the buckling analysis of the continuum-based model, and provide theoretical support for the application of CNTs.

Resonance response of fluid-conveying pipe with asymmetric elastic supports coupled to lever-type nonlinear energy sink

Runqing CAO, Zhijian WANG, Jian ZANG, Yewei ZHANG

2022, 43(12):  1873-1886.  doi:10.1007/s10483-022-2925-8

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This paper studies the vibration absorber for a fluid-conveying pipe, where the lever-type nonlinear energy sink (LNES) and spring supports are coupled to the asymmetric ends of the system. The pseudo-arc-length method integrated with the harmonic balance method is used to investigate the steady-state responses analytically. Meanwhile, the numerical solution of the fluid-conveying pipe is calculated with the Runge-Kutta method. Moreover, a special response, called the collapsible closed detached response (CCDR), is first observed when the vibration response of mechanical structures is studied. Then, the relationship between the CCDR and the main structure primary response (PR) is obtained. In addition, the closed detached response (CDR) is also observed to research the resonance response of the fluid-conveying pipe. The appearance of either the CCDR or the CDR does affect the resonance attenuation. Furthermore, the mentioned two phenomena underline that the trend of vibration responses under external excitation goes continuous and gradual. Besides, the main advantage of the LNES is presented by contrasting the LNES with the nonlinear energy sink (NES) coupled to the same pipe system. It is found that the LNES can reduce the resonance response amplitude by 91.33%.

Local parameter identification with neural ordinary differential equations

Qiang YIN, Juntong CAI, Xue GONG, Qian DING

2022, 43(12):  1887-1900.  doi:10.1007/s10483-022-2926-9

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The data-driven methods extract the feature information from data to build system models, which enable estimation and identification of the systems and can be utilized for prognosis and health management (PHM). However, most data-driven models are still black-box models that cannot be interpreted. In this study, we use the neural ordinary differential equations (ODEs), especially the inherent computational relationships of a system added to the loss function calculation, to approximate the governing equations. In addition, a new strategy for identifying the local parameters of the system is investigated, which can be utilized for system parameter identification and damage detection. The numerical and experimental examples presented in the paper demonstrate that the strategy has high accuracy and good local parameter identification. Moreover, the proposed method has the advantage of being interpretable. It can directly approximate the underlying governing dynamics and be a worthwhile strategy for system identification and PHM.

Three-dimensional interfacial fracture analysis of a one-dimensional hexagonal quasicrystal coating

Xin ZHANG, Minghao ZHAO, Cuiying FAN, C. S. LU, Huayang DANG

2022, 43(12):  1901-1920.  doi:10.1007/s10483-022-2942-7

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In this paper, the three-dimensional (3D) interfacial fracture is analyzed in a one-dimensional (1D) hexagonal quasicrystal (QC) coating structure under mechanical loading. A planar interface crack with arbitrary shape is studied by a displacement discontinuity method. Fundamental solutions of interfacial concentrated displacement discontinuities are obtained by the Hankel transform technique, and the corresponding boundary integral-differential equations are constructed with the superposition principle. Green’s functions of constant interfacial displacement discontinuities within a rectangular element are derived, and a boundary element method is proposed for numerical simulation. The singularity of stresses near the crack front is investigated, and the stress intensity factors (SIFs) as well as energy release rates (ERRs) are determined. Finally, relevant influencing factors on the fracture behavior are discussed.

Active control of flow past an elliptic cylinder using an artificial neural network trained by deep reinforcement learning

Bofu WANG, Qiang WANG, Quan ZHOU, Yulu LIU

2022, 43(12):  1921-1934.  doi:10.1007/s10483-022-2940-9

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The active control of flow past an elliptical cylinder using the deep reinforcement learning (DRL) method is conducted. The axis ratio of the elliptical cylinder $\Gamma$ varies from 1.2 to 2.0, and four angles of attack $\alpha=0^\circ, 15^\circ, 30^\circ$, and $45^\circ$ are taken into consideration for a fixed Reynolds number $Re=100$. The mass flow rates of two synthetic jets imposed on different positions of the cylinder $\theta_1$ and $\theta_2$ are trained to control the flow. The optimal jet placement that achieves the highest drag reduction is determined for each case. For a low axis ratio ellipse, i.e., $\Gamma=1.2$, the controlled results at $\alpha=0^\circ$ are similar to those for a circular cylinder with control jets applied at $\theta_1=90^\circ$ and $\theta_2=270^\circ$. It is found that either applying the jets asymmetrically or increasing the angle of attack can achieve a higher drag reduction rate, which, however, is accompanied by increased fluctuation. The control jets elongate the vortex shedding, and reduce the pressure drop. Meanwhile, the flow topology is modified at a high angle of attack. For an ellipse with a relatively higher axis ratio, i.e., $\Gamma\ge1.6$, the drag reduction is achieved for all the angles of attack studied. The larger the angle of attack is, the higher the drag reduction ratio is. The increased fluctuation in the drag coefficient under control is encountered, regardless of the position of the control jets. The control jets modify the flow topology by inducing an external vortex near the wall, causing the drag reduction. The results suggest that the DRL can learn an active control strategy for the present configuration.

Effect of anisotropic resistance characteristic on boundary-layer transitional flow

Zheng HONG, Zhengyin YE, Kangling WU, Kun YE

2022, 43(12):  1935-1950.  doi:10.1007/s10483-022-2932-7

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It is observed that the feather surface exhibits anisotropic resistances for the streamwise and spanwise flows. To obtain a qualitative understanding about the effect of this anisotropic resistance feature of surface on the boundary-layer transitional flow over a flat plate, a simple phenomenological model for the anisotropic resistance is established in this paper. By means of the large eddy simulation (LES) with high-order accurate finite difference method, the numerical investigations are conducted. The numerical results show that with the spanwise resistance hindering the formation of vortexes, the transition from laminar flow to turbulent flow can be delayed, and turbulence is weakened when the flow becomes fully turbulent, which leads to significant drag reduction for the plate. On the contrary, the streamwise resistance renders the flow less stable, which leads to the earlier transition and enhances turbulence in the turbulent region, causing a drag increase for the plate. Thus, it is indicated that a surface with large resistance for spanwise flow and small resistance for streamwise flow can achieve significant drag reduction. The present results highlight the anisotropic resistance characteristic near the feather surface for drag reduction, and shed a light on the study of bird’s efficient flight.

Repercussion of Hall effect and nonlinear radiation on Couette-Poiseuille flow of Casson-Williamson fluid through upright microchannel

B. J. GIREESHA, L. ANITHA

2022, 43(12):  1951-1964.  doi:10.1007/s10483-022-2929-8

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The main aim of the present work is to investigate the flow and heat transport properties of non-Newtonian Casson-Williamson fluid through an upright microchannel along with entropy generation analysis, and explore the effects of convective boundary conditions, Couette-Poiseuille flow, and nonlinear radiation. The movement of liquid is scrutinized with the Hall effect and exponential heat source. The rheological characteristics of the Casson-Williamson fluid model are also considered. By considering the desirable similarity variables, the equations of motion are reduced to nonlinear ordinary differential equations. The Runge-Kutta-Fehlberg fourth-fifth order method along with the shooting method is adopted to solve these dimensionless expressions. The detailed investigation is pictorially displayed to show the influence of effective parameters on the entropy generation and the Bejan number. One of the major tasks of the exploration is to compare the Casson fluid and the Williamson fluid. The results show that the rate of heat transfer in the Casson fluid is more remarkable than that in the Williamson fluid.