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2022年 第43卷 第9期    刊出日期：2022-09-01

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论文

Analytical modeling and vibration analysis of fiber reinforced composite hexagon honeycomb sandwich cylindrical-spherical combined shells

Hui LI, Bocheng DONG, Zhijiang GAO, Jing ZHAO, Haiyang ZHANG, Xiangping WANG, Qingkai HAN

2022, 43(9):  1307-1322.  doi:10.1007/s10483-022-2858-7

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This study analyzes and predicts the vibration characteristics of fiber-reinforced composite sandwich (FRCS) cylindrical-spherical (CS) combined shells with hexagon honeycomb core (HHC) for the first time based on an analytical model developed, which makes good use of the advantage of the first-order shear deformation theory (FSDT), the multi-segment decomposition technique, the virtual spring technology, the Jacobi-Ritz approach, and the transfer function method. The equivalent material properties of HHC are firstly determined by the modified Gibson's formula, and the related energy equations are derived for the HHC-FRCS-CS combined shells, from which the fundamental frequencies, the mode shapes, and the forced vibration responses are solved. The current model is verified through the discussion of convergence and comparative analysis with the associated published literature and finite element (FE) results. The effects of geometric parameters of HHC on the dynamic property of the structure are further investigated with the verified model. It reveals that the vibration suppression capability can be greatly enhanced by reducing the ratio of HHC thickness to total thickness and the ratio of wall thickness of honeycomb cell to overall radius, and by increasing the ratio of length of honeycomb cell to overall radius and honeycomb characteristic angle of HHC.



Nonlinear magneto-mechanical-thermo coupling characteristic analysis for transport behaviors of carriers in composite multiferroic piezoelectric semiconductor nanoplates with surface effect

Wenjun WANG, Feng JIN, Tianhu HE, Yongbin MA

2022, 43(9):  1323-1338.  doi:10.1007/s10483-022-2894-9

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In this paper, to better reveal the surface effect and the screening effect as well as the nonlinear multi-field coupling characteristic of the multifunctional piezoelectric semiconductor (PS) nanodevice, and to further improve its working performance, a magneto-mechanical-thermo coupling theoretical model is theoretically established for the extensional analysis of a three-layered magneto-electro-semiconductor coupling laminated nanoplate with the surface effect. Next, by using the current theoretical model, some numerical analyses and discussion about the surface effect, the corresponding critical thickness of the nanoplate, and the distributions of the physical fields (including the electron concentration perturbation, the electric potential, the electric field, the average electric displacement, the effective polarization charge density, and the total charge density) under different initial state electron concentrations, as well as their active manipulation via some external magnetic field, pre-stress, and temperature stimuli, are performed. Utilizing the nonlinear multi-field coupling effect induced by inevitable external stimuli in the device operating environment, this paper not only provides theoretical support for understanding the size-dependent tuning/controlling of carrier transport as well as its screening effect, but also assists the design of a series of multiferroic PS nanodevices.

Study on wave dispersion characteristics of piezoelectric sandwich nanoplates considering surface effects

Biao HU, Juan LIU, Yuxing WANG, Bo ZHANG, Jing WANG, Huoming SHEN

2022, 43(9):  1339-1354.  doi:10.1007/s10483-022-2897-9

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In this study, the wave propagation properties of piezoelectric sandwich nanoplates deposited on an orthotropic viscoelastic foundation are analyzed by considering the surface effects (SEs). The nanoplates are composed of a composite layer reinforced by graphene and two piezoelectric surface layers. Utilizing the modified Halpin-Tsai model, the material parameters of composite layers are obtained. The displacement field is determined by the sinusoidal shear deformation theory (SSDT). The Euler-Lagrange equation is derived by employing Hamilton's principle and the constitutive equations of piezoelectric layers considering the SEs. Subsequently, the nonlocal strain gradient theory (NSGT) is used to obtain the equations of motion. Next, the effects of scale parameters, graphene distribution, orthotropic viscoelastic foundation, and SEs on the propagation behavior are numerically examined. The results reveal that the wave frequency is a periodic function of the orthotropic angle. Furthermore, the wave frequency increases with the increase in the SEs.

Influence of nonlinear spatial distribution of stress and strain on solving problems of solid mechanics

Chunyu ZHANG, Biao WANG

2022, 43(9):  1355-1366.  doi:10.1007/s10483-022-2899-7

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The stress and the strain should be defined as statistical variables averaged over the representative volume elements for any real continuum system. It is shown that their nonlinear spatial distributions undermine the classical framework of solid mechanics and may cause non-ignorable errors to the solutions. With considering the high-order gradients of the stress and the strain, a two-step solution scheme is proposed to compensate for the influence. Through a revisit to three simple but typical problems, i.e., the hole size-dependence of the fracture strength of perforated plates, the indentation depth-dependence of the measured elastic modulus by micro-indentation tests, and the tensile necking of metallic materials as well as hyperelastic materials, the effect of the nonlinear spatial distribution of stress and strain on solving these problems is illustrated. The observed size effect and the instability of deformation can be quantitatively explained if the effect is properly considered by the proposed method.

Effects of an attached functionally graded layer on the electromechanical behaviors of piezoelectric semiconductor fibers

Kai FANG, Nian LI, Peng LI, Zhenghua QIAN, V. KOLESOV, I. KUZNETSOVA

2022, 43(9):  1367-1380.  doi:10.1007/s10483-022-2900-5

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In this paper, we propose a specific two-layer model consisting of a functionally graded (FG) layer and a piezoelectric semiconductor (PS) layer. Based on the macroscopic theory of PS materials, the effects brought about by the attached FG layer on the piezotronic behaviors of homogeneous n-type PS fibers and PN junctions are investigated. The semi-analytical solutions of the electromechanical fields are obtained by expanding the displacement and carrier concentration variation into power series. Results show that the antisymmetry of the potential and electron concentration distributions in homogeneous n-type PS fibers is destroyed due to the material inhomogeneity of the attached FG layer. In addition, by creating jump discontinuities in the material properties of the FG layer, potential barriers/wells can be produced in the middle of the fiber. Similarly, the potential barrier configuration near the interface of a homogeneous PS PN junction can also be manipulated in this way, which offers a new choice for the design of PN junction based devices.

Characteristic analysis of mechanical thermal coupling model for bearing rotor system of high-speed train

Yongqiang LIU, Baosen WANG, Shaopu YANG, Yingying LIAO, Tao GUO

2022, 43(9):  1381-1398.  doi:10.1007/s10483-022-2893-5

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Based on Newton's second law and the thermal network method, a mechanical thermal coupling model of the bearing rotor system of high-speed trains is established to study the interaction between the bearing vibration and temperature. The influence of lubrication on the vibration and temperature characteristics of the system is considered in the model, and the real-time relationship between them is built up by using the transient temperature field model. After considering the lubrication, the bearing outer ring vibration acceleration and node temperature considering grease are lower, which shows the necessity of adding the lubrication model. The corresponding experiments for characteristics of vibration and temperature of the model are respectively conducted. In the envelope spectrum obtained from the simulation signal and the experimental signal, the frequency values corresponding to the peaks are close to the theoretical calculation results, and the error is very small. In the three stages of the temperature characteristic experiment, the node temperature change of the simulation model is consistent with the experiment. The good agreement between simulation and experiments proves the effectiveness of the model. By studying the influence of the bearing angular and fault size on the system node temperature, as well as the change law of bearing lubrication characteristics and temperature, it is found that the worse the working condition is, the higher the temperature is. When the ambient temperature is low, the viscosity of grease increases, and the oil film becomes thicker, which increases the sliding probability of the rolling element, thus affecting the normal operation of the bearing, which explains the phenomenon of frequent bearing faults of high-speed trains in the low-temperature area of Northeast China. Further analysis shows that faults often occur in the early stage of train operation in the low-temperature environment.

Regulating absence seizures by tri-phase delay stimulation applied to globus pallidus internal

Songan HOU, Denggui FAN, Qingyun WANG

2022, 43(9):  1399-1414.  doi:10.1007/s10483-022-2896-7

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In this paper, a reduced globus pallidus internal (GPI)-corticothalamic (GCT) model is developed, and a tri-phase delay stimulation (TPDS) with sequentially applying three pulses on the GPI representing the inputs from the striatal $D_{1}$ neurons, subthalamic nucleus (STN), and globus pallidus external (GPE), respectively, is proposed. The GPI is evidenced to control absence seizures characterized by 2Hz-4,Hz spike and wave discharge (SWD). Hence, based on the basal ganglia-thalamocortical (BGCT) model, we firstly explore the triple effects of $D_{1}$-GPI, GPE-GPI, and STN-GPI pathways on seizure patterns. Then, using the GCT model, we apply the TPDS on the GPI to potentially investigate the alternative and improved approach if these pathways to the GPI are blocked. The results show that the striatum $D_{1}$, GPE, and STN can indeed jointly and significantly affect seizure patterns. In particular, the TPDS can effectively reproduce the seizure pattern if the $D_{1}$-GPI, GPE-GPI, and STN-GPI pathways are cut off. In addition, the seizure abatement can be obtained by well tuning the TPDS stimulation parameters. This implies that the TPDS can play the surrogate role similar to the modulation of basal ganglia, which hopefully can be helpful for the development of the brain-computer interface in the clinical application of epilepsy.

Dynamic analysis and regulation of the flexible pipe conveying fluid with a hard-magnetic soft segment

Zilong GUO, Qiao NI, Wei CHEN, Huliang DAI, Lin WANG

2022, 43(9):  1415-1430.  doi:10.1007/s10483-022-2901-9

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The recently developed hard-magnetic soft (HMS) materials can play a significant role in the actuation and control of medical devices, soft robots, flexible electronics, etc. To regulate the mechanical behaviors of the cantilevered pipe conveying fluid, the present work introduces a segment made of the HMS material located somewhere along the pipe length. Based on the absolute node coordinate formulation (ANCF), the governing equations of the pipe conveying fluid with an HMS segment are derived by the generalized Lagrange equation. By solving the derived equations with numerical methods, the static deformation, linear vibration characteristic, and nonlinear dynamic response of the pipe are analyzed. The result of the static deformation of the pipe shows that when the HMS segment is located in the middle of the pipe, the downstream portion of the pipe centerline will keep a straight shape, providing that the pipe is stable with a relatively low flow velocity. Therefore, it is possible to precisely regulate the ejection direction of the fluid flow by changing the magnetic and fluid parameters. It is also found that the intensity and direction of the external magnetic field greatly affect the stability and dynamic response of the pipe with an HMS segment. In most cases, the magnetic actuation increases the critical flow velocity for the flutter instability of the pipe system and suppresses the vibration amplitude of the pipe.

Numerical simulation for 2D double-diffusive convection (DDC) in rectangular enclosures based on a high resolution upwind compact streamfunction model I: numerical method and code validation

Yaping YAN, Shuang WU, Kaiyuan TIAN, Zhenfu TIAN

2022, 43(9):  1431-1448.  doi:10.1007/s10483-022-2895-6

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A high resolution upwind compact streamfunction numerical algorithm for two-dimensional (2D) double-diffusive convection (DDC) is developed. The unsteady Navier-Stokes (N-S) equations in the streamfunction-velocity form and the scalar temperature and concentration equations are used. An optimized third-order upwind compact (UCD3_opt) scheme with a low dispersion error for the first derivatives is utilized to approximate the third derivatives of the streamfunction in the advection terms of the N-S equations and the first derivatives in the advection terms of the scalar temperature and concentration equations. The remaining first derivatives of the streamfunction (velocity), temperature, and concentration variables used in the governing equations are discretized by the fourth-order compact Padé (SCD4) schemes. With the temperature and concentration variables and their approximate values of the first derivatives obtained by the SCD4 schemes, the explicit fourth-order compact schemes are suggested to approximate the second derivatives of temperature and concentration in the diffusion terms of the energy and concentration equations. The discretization of the temporal term is executed with the second-order Crank-Nicolson (C-N) scheme. To assess the spatial behavior capability of the established numerical algorithm and verify the developed computer code, the DDC flow is numerically solved. The obtained results agree well with the benchmark solutions and some accurate results available in the literature, verifying the accuracy, effectiveness, and robustness of the provided algorithm. Finally, a preliminary application of the proposed method to the DDC is carried out.

Effects of size and location of distal tear on hemodynamics and wave propagation in type B aortic dissection

Huimin CHEN, Qingzhuo CHI, Ying HE, Lizhong MU, Yong LUAN

2022, 43(9):  1449-1468.  doi:10.1007/s10483-022-2898-6

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The type B aortic dissection (TBAD) is a perilous disease with high morbidity and mortality rates. The hemodynamics of TBAD in different scenarios has been widely studied by computational fluid dynamics (CFD) research. However, the flow pattern and wave propagation characteristics in the cardiovascular system with TBAD are not yet clear, and the effect of the distal tear is still unknown. In this work, a one-dimensional (1D) cardiovascular system model coupling with a zero-dimensional (0D) lumped-parameter model is introduced to study the hemodynamics and wave propagation in the cardiovascular system. The results show that the proposed 0D-1D method well captures the oscillation and retrograde characteristics for the flow in the false lumen (FL), and the smaller distal tear damps the retrograde flow. Besides, the distal tear should also be paid attention to, and the wave intensity (WI) can be used as an access mark of the degree of the aortic dissection (AD).