Table of Content

01 April 2024, Volume 45 Issue 4

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Articles

Theoretical and experimental investigation of the resonance responses and chaotic dynamics of a bistable laminated composite shell in the dynamic snap-through mode

Meiqi WU, Peng LV, Hongyuan LI, Jiale YAN, Huiling DUAN, Wei ZHANG

2024, 45(4):  581-602.  doi:10.1007/s10483-024-3105-6

Abstract ( 136 )   HTML ( 9)   PDF (15400KB) ( 189 )  

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The dynamic model of a bistable laminated composite shell simply supported by four corners is further developed to investigate the resonance responses and chaotic behaviors. The existence of the 1:1 resonance relationship between two order vibration modes of the system is verified. The resonance response of this class of bistable structures in the dynamic snap-through mode is investigated, and the four-dimensional (4D) nonlinear modulation equations are derived based on the 1:1 internal resonance relationship by means of the multiple scales method. The Hopf bifurcation and instability interval of the amplitude frequency and force amplitude curves are analyzed. The discussion focuses on investigating the effects of key parameters, e.g., excitation amplitude, damping coefficient, and detuning parameters, on the resonance responses. The numerical simulations show that the foundation excitation and the degree of coupling between the vibration modes exert a substantial effect on the chaotic dynamics of the system. Furthermore, the significant motions under particular excitation conditions are visualized by bifurcation diagrams, time histories, phase portraits, three-dimensional (3D) phase portraits, and Poincare maps. Finally, the vibration experiment is carried out to study the amplitude frequency responses and bifurcation characteristics for the bistable laminated composite shell, yielding results that are qualitatively consistent with the theoretical results.

Adaptive state-constrained/model-free iterative sliding mode control for aerial robot trajectory tracking

Chen AN, Jiaxi ZHOU, Kai WANG

2024, 45(4):  603-618.  doi:10.1007/s10483-024-3103-8

Abstract ( 116 )   HTML ( 3)   PDF (1245KB) ( 208 )  

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This paper develops a novel hierarchical control strategy for improving the trajectory tracking capability of aerial robots under parameter uncertainties. The hierarchical control strategy is composed of an adaptive sliding mode controller and a model-free iterative sliding mode controller (MFISMC). A position controller is designed based on adaptive sliding mode control (SMC) to safely drive the aerial robot and ensure fast state convergence under external disturbances. Additionally, the MFISMC acts as an attitude controller to estimate the unmodeled dynamics without detailed knowledge of aerial robots. Then, the adaption laws are derived with the Lyapunov theory to guarantee the asymptotic tracking of the system state. Finally, to demonstrate the performance and robustness of the proposed control strategy, numerical simulations are carried out, which are also compared with other conventional strategies, such as proportional-integral-derivative (PID), backstepping (BS), and SMC. The simulation results indicate that the proposed hierarchical control strategy can fulfill zero steady-state error and achieve faster convergence compared with conventional strategies.

Love wave propagation in one-dimensional piezoelectric quasicrystal multilayered nanoplates with surface effects

Xin FENG, Liaoliang KE, Yang GAO

2024, 45(4):  619-632.  doi:10.1007/s10483-024-3104-9

Abstract ( 128 )   HTML ( 3)   PDF (393KB) ( 164 )  

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The exact solutions for the propagation of Love waves in one-dimensional (1D) hexagonal piezoelectric quasicrystal (PQC) nanoplates with surface effects are derived. An electro-elastic model is developed to investigate the anti-plane strain problem of Love wave propagation. By introducing three shape functions, the wave equations and electric balance equations are decoupled into three uncorrelated problems. Satisfying the boundary conditions of the top surface on the covering layer, the interlayer interface, and the matrix, a dispersive equation with the influence of multi-physical field coupling is provided. A surface PQC model is developed to investigate the surface effects on the propagation behaviors of Love waves in quasicrystal (QC) multilayered structures with nanoscale thicknesses. A novel dispersion relation for the PQC structure is derived in an explicit closed form according to the non-classical mechanical and electric boundary conditions. Numerical examples are given to reveal the effects of the boundary conditions, stacking sequence, characteristic scale, and phason fluctuation characteristics on the dispersion curves of Love waves propagating in PQC nanoplates with surface effects.

Nonlinear wave dispersion in monoatomic chains with lumped and distributed masses: discrete and continuum models

E. GHAVANLOO, S. EL-BORGI

2024, 45(4):  633-648.  doi:10.1007/s10483-024-3100-9

Abstract ( 117 )   HTML ( 1)   PDF (966KB) ( 116 )  

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The main objective of this paper is to investigate the influence of inertia of nonlinear springs on the dispersion behavior of discrete monoatomic chains with lumped and distributed masses. The developed model can represent the wave propagation problem in a non-homogeneous material consisting of heavy inclusions embedded in a matrix. The inclusions are idealized by lumped masses, and the matrix between adjacent inclusions is modeled by a nonlinear spring with distributed masses. Additionally, the model is capable of depicting the wave propagation in bi-material bars, wherein the first material is represented by a rigid particle and the second one is represented by a nonlinear spring with distributed masses. The discrete model of the nonlinear monoatomic chain with lumped and distributed masses is first considered, and a closed-form expression of the dispersion relation is obtained by the second-order Lindstedt-Poincare method (LPM). Next, a continuum model for the nonlinear monoatomic chain is derived directly from its discrete lattice model by a suitable continualization technique. The subsequent use of the second-order method of multiple scales (MMS) facilitates the derivation of the corresponding nonlinear dispersion relation in a closed form. The novelties of the present study consist of (ⅰ) considering the inertia of nonlinear springs on the dispersion behavior of the discrete mass-spring chains; (ⅱ) developing the second-order LPM for the wave propagation in the discrete chains; and (ⅲ) deriving a continuum model for the nonlinear monoatomic chains with lumped and distributed masses. Finally, a parametric study is conducted to examine the effects of the design parameters and the distributed spring mass on the nonlinear dispersion relations and phase velocities obtained from both the discrete and continuum models. These parameters include the ratio of the spring mass to the lumped mass, the nonlinear stiffness coefficient of the spring, and the wave amplitude.

Indentation behavior of a semi-infinite piezoelectric semiconductor under a rigid flat-ended cylindrical indenter

Shijing GAO, Lele ZHANG, Jinxi LIU, Guoquan NIE, Weiqiu CHEN

2024, 45(4):  649-662.  doi:10.1007/s10483-024-3107-5

Abstract ( 151 )   HTML ( 1)   PDF (795KB) ( 88 )  

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This paper theoretically studies the axisymmetric frictionless indentation of a transversely isotropic piezoelectric semiconductor (PSC) half-space subject to a rigid flat-ended cylindrical indenter. The contact area and other surface of the PSC half-space are assumed to be electrically insulating. By the Hankel integral transformation, the problem is reduced to the Fredholm integral equation of the second kind. This equation is solved numerically to obtain the indentation behaviors of the PSC half-space, mainly including the indentation force-depth relation and the electric potential-depth relation. The results show that the effect of the semiconductor property on the indentation responses is limited within a certain range of variation of the steady carrier concentration. The dependence of indentation behavior on material properties is also analyzed by two different kinds of PSCs. Finite element simulations are conducted to verify the results calculated by the integral equation technique, and good agreement is demonstrated.

Supposition of graphene stacks to estimate the contact resistance and conductivity of nanocomposites

Y. ZARE, M. T. MUNIR, G. J. WENG, K. Y. RHEE

2024, 45(4):  663-676.  doi:10.1007/s10483-024-3102-7

Abstract ( 102 )   HTML ( 1)   PDF (1022KB) ( 413 )  

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In this study, the effects of stacked nanosheets and the surrounding interphase zone on the resistance of the contact region between nanosheets and the tunneling conductivity of samples are evaluated with developed equations superior to those previously reported. The contact resistance and nanocomposite conductivity are modeled by several influencing factors, including stack properties, interphase depth, tunneling size, and contact diameter. The developed model's accuracy is verified through numerous experimental measurements. To further validate the models and establish correlations between parameters, the effects of all the variables on contact resistance and nanocomposite conductivity are analyzed. Notably, the contact resistance is primarily dependent on the polymer tunnel resistivity, contact area, and tunneling size. The dimensions of the graphene nanosheets significantly influence the conductivity, which ranges from 0 S/m to 90 S/m. An increased number of nanosheets in stacks and a larger gap between them enhance the nanocomposite's conductivity. Furthermore, the thicker interphase and smaller tunneling size can lead to higher sample conductivity due to their optimistic effects on the percolation threshold and network efficacy.

Study of hybrid nanofluid flow in a stationary cone-disk system with temperature-dependent fluid properties

A. S. JOHN, B. MAHANTHESH, G. LORENZINI

2024, 45(4):  677-694.  doi:10.1007/s10483-024-3089-5

Abstract ( 111 )   HTML ( 2)   PDF (4688KB) ( 67 )  

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Cone-disk systems find frequent use such as conical diffusers, medical devices, various rheometric, and viscosimetry applications. In this study, we investigate the three-dimensional flow of a water-based Ag-MgO hybrid nanofluid in a static cone-disk system while considering temperature-dependent fluid properties. How the variable fluid properties affect the dynamics and heat transfer features is studied by Reynolds's linearized model for variable viscosity and Chiam's model for variable thermal conductivity. The single-phase nanofluid model is utilized to describe convective heat transfer in hybrid nanofluids, incorporating the experimental data. This model is developed as a coupled system of convective-diffusion equations, encompassing the conservation of momentum and the conservation of thermal energy, in conjunction with an incompressibility condition. A self-similar model is developed by the Lie-group scaling transformations, and the subsequent self-similar equations are then solved numerically. The influence of variable fluid parameters on both swirling and non-swirling flow cases is analyzed. Additionally, the Nusselt number for the disk surface is calculated. It is found that an increase in the temperature-dependent viscosity parameter enhances heat transfer characteristics in the static cone-disk system, while the thermal conductivity parameter has the opposite effect.

Analytical solutions of turbulent boundary layer beneath forward-leaning waves

Yiqin XIE, Jifu ZHOU, Xu WANG, Jinlong DUAN, Yongjun LU, Shouqian LI

2024, 45(4):  695-710.  doi:10.1007/s10483-024-3099-8

Abstract ( 102 )   HTML ( 1)   PDF (4803KB) ( 87 )  

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As a typical nonlinear wave, forward-leaning waves can be frequently encountered in the near-shore areas, which can impact coastal sediment transport significantly. Hence, it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately, especially for the turbulent boundary layer. In this work, the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied, and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary layer. Then, a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel function. Consequently, an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable transformation. The analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.

The viscous strip approach to simplify the calculation of the surface acoustic wave generated streaming

F. JAZINIDORCHEH, M. GHASSEMI

2024, 45(4):  711-724.  doi:10.1007/s10483-024-3101-6

Abstract ( 113 )   HTML ( 4)   PDF (2235KB) ( 105 )  

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In recent decades, the importance of surface acoustic waves, as a biocompatible tool to integrate with microfluidics, has been proven in various medical and biological applications. The numerical modeling of acoustic streaming caused by surface acoustic waves in microchannels requires the effect of viscosity to be considered in the equations which complicates the solution. In this paper, it is shown that the major contribution of viscosity and the horizontal component of actuation is concentrated in a narrow region alongside the actuation boundary. Since the inviscid equations are considerably easier to solve, a division into the viscous and inviscid domains would alleviate the computational load significantly. The particles' traces calculated by this approximation are excellently alongside their counterparts from the completely viscous model. It is also shown that the optimum thickness for the viscous strip is about 9-fold the acoustic boundary layer thickness for various flow patterns and amplitudes of actuation.

Aerodynamic/stealth design of S-duct inlet based on discrete adjoint method

Jun DENG, Ke ZHAO, Lin ZHOU, Wei ZHANG, Bowen SHU, Jiangtao HUANG, Zhenghong GAO

2024, 45(4):  725-746.  doi:10.1007/s10483-024-3106-7

Abstract ( 110 )   HTML ( 3)   PDF (8514KB) ( 112 )  

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It is a major challenge for the airframe-inlet design of modern combat aircrafts, as the flow and electromagnetic wave propagation in the inlet of stealth aircraft are very complex. In this study, an aerodynamic/stealth optimization design method for an S-duct inlet is proposed. The upwind scheme is introduced to the aerodynamic adjoint equation to resolve the shock wave and flow separation. The multilevel fast multipole algorithm (MLFMA) is utilized for the stealth adjoint equation. A dorsal S-duct inlet of flying wing layout is optimized to improve the aerodynamic and stealth characteristics. Both the aerodynamic and stealth characteristics of the inlet are effectively improved. Finally, the optimization results are analyzed, and it shows that the main contradiction between aerodynamic characteristics and stealth characteristics is the centerline and cross-sectional area. The S-duct is smoothed, and the cross-sectional area is increased to improve the aerodynamic characteristics, while it is completely opposite for the stealth design. The radar cross section (RCS) is reduced by phase cancelation for low frequency conditions. The method is suitable for the aerodynamic/stealth design of the aircraft airframe-inlet system.