Table of Content

01 March 2020, Volume 41 Issue 3

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Articles

Suppression of multiple modal resonances of a cantilever beam by an impact damper

Xiaofeng GENG, Hu DING, Kexiang WEI, Liqun CHEN

2020, 41(3):  383-400.  doi:10.1007/s10483-020-2588-9

Abstract ( 441 )   HTML ( 18)   PDF (1420KB) ( 223 )  

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Impact dampers are usually used to suppress single mode resonance. The goal of this paper is to clarify the difference when the impact damper suppresses the resonances of different modes. A cantilever beam equipped with the impact damper is modeled. The elastic contact of the ball and the cantilever beam is described by using the Hertz contact model. The viscous damper between the ball and the cantilever beam is modeled to consume the vibrational energy of the cantilever beam. A piecewise ordinary differential-partial differential equation of the cantilever beam is established, including equations with and without the impact damper. The vibration responses of the cantilever beam with and without the impact damper are numerically calculated. The effects of the impact absorber parameters on the vibration reduction are examined. The results show that multiple resonance peaks of the cantilever beam can be effectively suppressed by the impact damper. Specifically, all resonance amplitudes can be reduced by a larger weight ball. Moreover, the impacting gap is very effective in suppressing the vibration of the cantilever beam. More importantly, there is an optimal impacting gap for each resonance mode of the cantilever beam, but the optimal gap for each mode is different.

Elastic field near the tip of an anticrack in a decagonal quasicrystalline material

Xu WANG, P. SCHIAVONE

2020, 41(3):  401-408.  doi:10.1007/s10483-020-2582-8

Abstract ( 344 )   HTML ( 8)   PDF (122KB) ( 73 )  

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We investigate the elastic field near the tip of an anticrack in a homogeneous decagonal quasicrystalline material subject to plane strain deformations. The phonon and phason stresses exhibit a square root singularity at the anticrack tip. Two realvalued phonon stress intensity factors and two real-valued phason stress intensity factors are introduced to scale four separate modes of deformation. We obtain four analytic functions which completely characterize the induced phonon and phason stresses as well as the displacement field. In particular, we derive a concise yet elegant representation of the anticrack contraction force.

Finite deformation swelling of a temperature-sensitive hydrogel cylinder under combined extension-torsion

M. SHOJAEIFARD, M. BAGHANI

2020, 41(3):  409-424.  doi:10.1007/s10483-020-2585-6

Abstract ( 333 )   HTML ( 4)   PDF (854KB) ( 145 )  

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The swelling behavior of a temperature-sensitive poly-N-isopropylacrylamide (PNIPAM) hydrogel circular cylinder is studied subjected to combined extension-torsion and varied temperature. In this regard, a semi-analytical solution is proposed for general combined loading. A finite element (FE) analysis is conducted, subjecting a hydrogel cylinder to the combined extension-torsion and the varied temperature to evaluate the validity and accuracy of the solution. A user-defined UHYPER subroutine is developed and verified under free and constrained swelling conditions. The FE results illustrate excellent agreement with the semi-analytical solution. Due to the complexity of the problem, some compositions and applied loading factors are analyzed. It is revealed that for larger cross-linked density and larger ending temperature, the cylinder yields higher stresses and smaller radial swelling deformation. Besides, the radial and hoop stresses increase by applying larger twist and axial stretch. The hoop stresses intersect at approximately R/R_out=0.58, where the hoop stress vanishes. Besides, the axial force has direct and inverse relationships with the axial stretch and the twist, respectively. However, the resultant torsional moment behavior is complex, and the position of the maximum point varies significantly by altering the axial stretch and the twist.

Electro-mechanical coupling wave propagating in a locally resonant piezoelectric/elastic phononic crystal nanobeam with surface effects

Denghui QIAN

2020, 41(3):  425-438.  doi:10.1007/s10483-020-2586-5

Abstract ( 423 )   HTML ( 5)   PDF (599KB) ( 52 )  

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The model of a "spring-mass" resonator periodically attached to a piezoelectric/elastic phononic crystal (PC) nanobeam with surface effects is proposed, and the corresponding calculation method of the band structures is formulized and displayed by introducing the Euler beam theory and the surface piezoelectricity theory to the plane wave expansion (PWE) method. In order to reveal the unique wave propagation characteristics of such a model, the band structures of locally resonant (LR) elastic PC Euler nanobeams with and without resonators, the band structures of LR piezoelectric PC Euler nanobeams with and without resonators, as well as the band structures of LR elastic/piezoelectric PC Euler nanobeams with resonators attached on PZT-4, with resonators attached on epoxy, and without resonators are compared. The results demonstrate that adding resonators indeed plays an active role in opening and widening band gaps. Moreover, the influence rules of different parameters on the band gaps of LR elastic/piezoelectric PC Euler nanobeams with resonators attached on epoxy are discussed, which will play an active role in the further realization of active control of wave propagations.

Nonlinear dynamic analysis of moving bilayer plates resting on elastic foundations

M. ESMAEILZADEH, M. KADKHODAYAN, S. MOHAMMADI, G. J. TURVEY

2020, 41(3):  439-458.  doi:10.1007/s10483-020-2587-8

Abstract ( 493 )   HTML ( 11)   PDF (914KB) ( 69 )  

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The aim of this study is to investigate the dynamic response of axially moving two-layer laminated plates on the Winkler and Pasternak foundations. The upper and lower layers are formed from a bidirectional functionally graded (FG) layer and a graphene platelet (GPL) reinforced porous layer, respectively. Henceforth, the combined layers will be referred to as a two-dimensional (2D) FG/GPL plate. Two types of porosity and three graphene dispersion patterns, each of which is distributed through the plate thickness, are investigated. The mechanical properties of the closed-cell layers are used to define the variation of Poisson's ratio and the relationship between the porosity coefficients and the mass density. For the GPL reinforced layer, the effective Young's modulus is derived with the Halpin-Tsai micro-system model, and the rule of mixtures is used to calculate the effective mass density and Poisson's ratio. The material of the upper 2D-FG layer is graded in two directions, and its effective mechanical properties are also derived with the rule of mixtures. The dynamic governing equations are derived with a first-order shear deformation theory (FSDT) and the von Kármán nonlinear theory. A combination of the dynamic relaxation (DR) and Newmark's direct integration methods is used to solve the governing equations in both time and space. A parametric study is carried out to explore the effects of the porosity coefficients, porosity and GPL distributions, material gradients, damping ratios, boundary conditions, and elastic foundation stiffnesses on the plate response. It is shown that both the distributions of the porosity and graphene nanofillers significantly affect the dynamic behaviors of the plates. It is also shown that the reduction in the dynamic deflection of the bilayer composite plates is maximized when the porosity and GPL distributions are symmetric.

Incremental harmonic balance method for periodic forced oscillation of a dielectric elastomer balloon

Yin WANG, Ling ZHANG, Jinxiong ZHOU

2020, 41(3):  459-470.  doi:10.1007/s10483-020-2590-7

Abstract ( 456 )   HTML ( 5)   PDF (2047KB) ( 96 )  

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Dielectric elastomer (DE) is suitable in soft transducers for broad applications, among which many are subjected to dynamic loadings, either mechanical or electrical or both. The tuning behaviors of these DE devices call for an efficient and reliable method to analyze the dynamic response of DE. This remains to be a challenge since the resultant vibration equation of DE, for example, the vibration of a DE balloon considered here is highly nonlinear with higher-order power terms and time-dependent coefficients. Previous efforts toward this goal use largely the numerical integration method with the simple harmonic balance method as a supplement. The numerical integration and the simple harmonic balance method are inefficient for large parametric analysis or with difficulty in improving the solution accuracy. To overcome the weakness of these two methods, we describe formulations of the incremental harmonic balance (IHB) method for periodic forced solutions of such a unique system. Combined with an arc-length continuation technique, the proposed strategy can capture the whole solution branches, both stable and unstable, automatically with any desired accuracy.

System-size effect on the friction at liquid-solid interfaces

Liang ZHAO, Jiajia SUN, Xian WANG, Li ZENG, Chunlei WANG, Yusong TU

2020, 41(3):  471-478.  doi:10.1007/s10483-020-2591-5

Abstract ( 323 )   HTML ( 5)   PDF (853KB) ( 29 )  

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The friction at the liquid-solid interfaces is widely involved in various phenomena ranging from nanometer to micrometer scales. By the molecular dynamic (MD) simulation, the friction properties of liquid-solid interfaces at the molecular level are calculated via the Green-Kubo relation. It is found that the system size will influence the value of the friction coefficient, especially for the solid surfaces with the larger polar charge. The value of the friction coefficient decreases with the increase in the system size and converges at large system sizes. The large polar charge will lead to a significant friction coefficient. However, the diffusion of water molecules on this surface is almost a constant, indicating that the diffusion coefficient seems to be independent of the system size and polar charge. This work provides insights for the selection of the system size in modeling the frictional properties of hydrophobic/hydrophilic surfaces.

A modified model for isothermal homogeneous and heterogeneous reactions in the boundary-layer flow of a nanofluid

Naili XU, Hang XU

2020, 41(3):  479-490.  doi:10.1007/s10483-020-2589-6

Abstract ( 404 )   HTML ( 6)   PDF (918KB) ( 64 )  

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The homogeneous and heterogeneous reactions in the boundary-layer of a flat surface are considered. The autocatalysts are assumed to be of regular sizes, while the solution is a dilute nanofluid. The heat release due to the chemical reactions is taken into account. The Buongiorno's model is used to describe the behaviors of this reaction system. This configuration makes the current model be different from all previous publications. Multiple solutions are given numerically to the rescaled nonlinear system, whose stability is verified. The results show that the strength coefficients of the homogeneous and heterogeneous reactions are key factors to cause the appearance of the multiple solutions in the distribution of the chemical reactions. Nanofluids enhance the diffusion of heat and help maintain the stability of chemical reactions.

Stochastic and upscaled analytical modeling of fines migration in porous media induced by low-salinity water injection

Yulong YANG, Weifeng YUAN, Jirui HOU, Zhenjiang YOU, Jun LI, Yang LIU

2020, 41(3):  491-506.  doi:10.1007/s10483-020-2583-9

Abstract ( 460 )   HTML ( 6)   PDF (558KB) ( 104 )  

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Fines migration induced by injection of low-salinity water (LSW) into porous media can lead to severe pore plugging and consequent permeability reduction. The deepbed filtration (DBF) theory is used to model the aforementioned phenomenon, which allows us to predict the effluent concentration history and the distribution profile of entrapped particles. However, the previous models fail to consider the movement of the waterflood front. In this study, we derive a stochastic model for fines migration during LSW flooding, in which the Rankine-Hugoniot condition is used to calculate the concentration of detached particles behind and ahead of the moving water front. A downscaling procedure is developed to determine the evolution of pore-size distribution from the exact solution of a large-scale equation system. To validate the proposed model, the obtained exact solutions are used to treat the laboratory data of LSW flooding in artificial soil-packed columns. The tuning results show that the proposed model yields a considerably higher value of the coefficient of determination, compared with the previous models, indicating that the new model can successfully capture the effect of the moving water front on fines migration and precisely match the effluent history of the detached particles.

MHD flow and heat transfer of a hybrid nanofluid past a permeable stretching/shrinking wedge

I. WAINI, A. ISHAK, I. POP

2020, 41(3):  507-520.  doi:10.1007/s10483-020-2584-7

Abstract ( 520 )   HTML ( 1340)   PDF (811KB) ( 301 )  

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The steady flow and heat transfer of a hybrid nanofluid past a permeable stretching/shrinking wedge with magnetic field and radiation effects are studied. The governing equations of the hybrid nanofluid are converted to the similarity equations by techniques of the similarity transformation. The bvp4c function that is available in MATLAB software is utilized for solving the similarity equations numerically. The numerical results are obtained for selected different values of parameters. The results discover that two solutions exist, up to a certain value of the stretching/shrinking and suction strengths. The critical value in which the solution is in existence decreases as nanoparticle volume fractions for copper and wedge angle parameter increase. It is also found that the hybrid nanofluid enhances the heat transfer rate compared with the regular nanofluid. The reduction of the heat transfer rate is observed with the increase in radiation parameter. The temporal stability analysis is performed to analyze the stability of the dual solutions, and it is revealed that only one of them is stable and physically reliable.

A revised Cattaneo-Christov micropolar viscoelastic nanofluid model with combined porosity and magnetic effects

S. A. SHEHZAD, S. U. KHAN, Z. ABBAS, A. RAUF

2020, 41(3):  521-532.  doi:10.1007/s10483-020-2581-5

Abstract ( 375 )   HTML ( 5)   PDF (385KB) ( 168 )  

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The dynamics of non-Newtonian fluids along with nanoparticles is quite interesting with numerous industrial applications. The current predominately predictive modeling deals with the flow of the viscoelastic micropolar fluid in the presence of nanoparticles. A progressive amendment in the heat and concentration equations is made by exploiting the Cattaneo-Christov (C-C) heat and mass flux expressions. Besides, the thermal radiation effects are contributed in the energy equation and aspect of the radiation parameter, and the Prandtl number is specified by the one-parameter approach. The formulated expressions are converted to the dimensionless forms by relevant similarity functions. The analytical solutions to these expressions have been erected by the homotopy analysis method. The variations in physical quantities, including the velocity, the temperature, the effective local Nusselt number, the concentration of nanoparticles, and the local Sherwood number, have been observed under the influence of emerging parameters. The results have shown good accuracy compared with those of the existing literature.