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Neurodynamics analysis of cochlear hair cell activity

Weifeng Rong, Rubin Wang, Jianhai Zhang, Wanzeng Kong

Accepted Manuscript

[Abstract] (4) [FullText HTML] (1) [PDF 2984KB] (1)

Abstract:
There have been many studies on the effect of cochlea basal membrane movement on the resolution of different frequencies and intensities. However, these studies did not take into account the influence of power and energy consumption of the hair cells in the process of the electromotility movement, as well as the neurodynamic mechanism that produced this effect. This makes previous studies unable to fully clarify the function of outer hair cells and the mechanism of sound amplification. To this end, we introduce the gate conductance characteristics of the hair cells in the mechanical process of increasing frequency selectivity. The research finds that the low attenuation of outer hair cell (OHCs) membrane potential and the high gain in OHC power and energy consumption caused that OHC amplification is driven by electromotility. The research results show that the amplification of the outer hair cells is driven by low attenuation of membrane potential and high gain of power and energy consumption. This conclusion profoundly reveals the physiological mechanism of the electromotility movement.

Neurodynamics analysis of cochlear hair cell activity

Weifeng Rong, Rubin Wang, Jianhai Zhang, Wanzeng Kong

Accepted Manuscript

[Abstract] (2) [PDF 2984KB] (0)

Universal scaling law of an origami paper spring

Bo-Hua Sun

Accepted Manuscript

[Abstract] (1) [FullText HTML] (0) [PDF 2456KB] (0)

Abstract:
This letter solves an open question of origami paper spring risen by Yoneda et al.(2019). By using both dimensional analysis and data fitting, an universal scaling law of a paper spring is formulated. The scaling law shows that origami spring force obeys power square law of spring extension, however strong nonlinear to the total twist angle. The study has also successfully generalized the scaling law from the Poisson ratio 0.3 to an arbitrary Poisson's ratio with the help of dimensional analysis.

Universal scaling law of an origami paper spring

Bo-Hua Sun

Accepted Manuscript

[Abstract] (0) [PDF 2456KB] (0)

Dynamic response of clamped sandwich beams: analytical modeling

Lang Li, Bin Han, Qian-Cheng Zhang, Zhen-Yu Zhao, Tian-Jian Lu

Corrected proof , doi: 10.1016/j.taml.2019.06.002

[Abstract] (74) [FullText HTML] (46) [PDF 2771KB] (3)

Abstract:
An improved analytical model is developed to predict the dynamic response of clamped lightweight sandwich beams with cellular cores subjected to shock loading over the entire span. The clamped face sheets are simplified as a single-degree-of-freedom (SDOF) system, and the core is idealized using the rigid-perfectly-plastic-locking (RPPL) model. Reflection of incident shock wave is considered by incorporating the bending/stretching resistance of the front face sheet and compaction of the core. The model is validated with existing analytical predictions and FE simulation results, with good agreement achieved. Compared with existing analytical models, the proposed model exhibits superiority in two aspects: the deformation resistance of front face sheet during shock wave reflection is taken into account; the effect of pulse shape is considered. The practical application range of the proposed model is therefore wider.

The spatial evolution of velocity and density profiles in an arrested salt wedge

Adam J. K. Yang, E. W. Tedford, G. A. Lawrence

Corrected proof , doi: 10.1016/j.taml.2019.06.005

[Abstract] (36) [FullText HTML] (19) [PDF 2890KB] (10)

Abstract:
The spatial variation in the properties of an arrested salt wedge have been investigated, both analytically and in the laboratory. In the laboratory particle image velocimetry and laser induced fluorescence were used to obtain flow velocities and the height of the density interface. An analytical solution for the profile of interface height, in the absence of interfacial instabilities, has been developed from two-layer internal hydraulic theory. The evolution of the velocity profile is predicted using a momentum diffusion equation following a Lagrangian frame of reference along the interface of the salt wedge. The centre of the shear layer is predicted to lie above the density interface, with this offset decreasing in the downstream direction. Our theoretical predictions are in good agreement with our laboratory measurements.

Crack propagation simulation in brittle elastic materials by a phase field method

Xingxue Lu, Cheng Li, Ying Tie, Yuliang Hou, Chuanzeng Zhang

Corrected proof , doi: 10.1016/j.taml.2019.06.001

[Abstract] (38) [FullText HTML] (25) [PDF 4009KB] (5)

Abstract:
To overcome the difficulties of re-meshing and tracking the crack-tip in other computational methods for crack propagation simulations, the phase field method based on the minimum energy principle is introduced by defining a continuous phase field variable ϕ(x)∈[0,1] to characterize discontinuous cracks in brittle materials. This method can well describe the crack initiation and propagation without assuming the shape, size and orientation of the initial crack in advance. In this paper, a phase field method based on Miehe's approach [Miehe et al., Comp. Meth. App. Mech. Eng. (2010)] is applied to simulate different crack propagation problems in two-dimensional (2D), isotropic and linear elastic materials. The numerical implementation of the phase field method is realized within the framework of the finite element method (FEM). The validity, accuracy and efficiency of the present method are verified by comparing the numerical results with other reference results in literature. Several numerical examples are presented to show the effects of the loading type (tension and shear), boundary conditions, and initial crack location and orientation on the crack propagation path and force-displacement curve. Furthermore, for a single edge-cracked bi-material specimen, the influences of the loading type and the crack location on the crack propagation trajectory and force-displacement curve are also investigated and discussed. It is demonstrated that the phase field method is an efficient tool for the numerical simulation of the crack propagation problems in brittle elastic materials, and the corresponding results may have an important relevance for predicting and preventing possible crack propagations in engineering applications.

Modified slow-fast analysis method for slow-fast dynamical systems with two scales in frequency domain

Zhengdi Zhang, Zhangyao Chen, Qinsheng Bi

Corrected proof , doi: 10.1016/j.taml.2019.05.010

[Abstract] (40) [FullText HTML] (25) [PDF 4863KB] (4)

Abstract:
A modified slow-fast analysis method is presented for the periodically excited non-autonomous dynamical system with an order gap between the exciting frequency and the natural frequency. By regarding the exciting term as a slow-varying parameter, a generalized autonomous fast subsystem can be defined, the equilibrium branches as well as the bifurcations of which can be employed to account for the mechanism of the bursting oscillations by combining the transformed phase portrait introduced. As an example, a typical periodically excited Hartley model is used to demonstrate the validness of the method, in which the exciting frequency is far less than the natural frequency. The equilibrium branches and their bifurcations of the fast subsystem with the variation of the slow-varying parameter are presented. Bursting oscillations for two typical cases are considered, which reveals that, fold bifurcation may cause the the trajectory to jump between different equilibrium branches, while Hopf bifurcation may cause the trajectory to oscillate around the stable limit cycle.

Generalized canonical transformation for second-order Birkhoffian systems on time scales

Y. Zhang, X.H. Zhai

Corrected proof , doi: 10.1016/j.taml.2019.06.004

[Abstract] (58) [FullText HTML] (44) [PDF 2395KB] (2)

Abstract:
The theory of time scales, which unifies continuous and discrete analysis, provides a powerful mathematical tool for the study of complex dynamic systems. It enables us to understand more clearly the essential problems of continuous systems and discrete systems as well as other complex systems. In this paper, the theory of generalized canonical transformation for second-order Birkhoffian systems on time scales is proposed and studied, which extends the canonical transformation theory of Hamilton canonical equations. First, the condition of generalized canonical transformation for the second-order Birkhoffian system on time scales is established. Second, based on this condition, six basic forms of generalized canonical transformation for the second-order Birkhoffian system on time scales are given. Also, the relationships between new variables and old variables for each of these cases are derived. In the end, an example is given to show the application of the results.

On time independent Schrödinger equations in quantum mechanics by the homotopy analysis method

Jyotirmoy Rana, Shijun Liao

Corrected proof , doi: 10.1016/j.taml.2019.05.006

[Abstract] (57) [FullText HTML] (44) [PDF 2539KB] (1)

Abstract:
A general analytic approach, namely the homotopy analysis method (HAM), is applied to solve the time independent Schrödinger equations. Unlike perturbation method, the HAM-based approach does not depend on any small physical parameters, corresponding to small disturbances. Especially, it provides a convenient way to gain the convergent series solution of quantum mechanics. This study illustrates the advantages of this HAM-based approach over the traditional perturbative approach, and its general validity for the Schrödinger equations. Note that perturbation methods are widely used in quantum mechanics, but perturbation results are hardly convergent. This study suggests that the HAM might provide us a new, powerful alternative to gain convergent series solution for some complicated problems in quantum mechanics, including many-body problems, which can be directly compared with the experiment data to improve the accuracy of the experimental findings and/or physical theories.

Sensitivity analysis of the vane length and passage width for a radial type swirler employed in a triple swirler configuration

Foad Vashahi, Shahnaz Rezaei, Reza Alidoost Dafsari, Jeekeun Lee

Corrected proof , doi: 10.1016/j.taml.2019.05.004

[Abstract] (46) [FullText HTML] (36) [PDF 3859KB] (1)

Abstract:
The design of axial or radial swirlers typically governs a number of geometrical parameters that are determined by the desired flow field. In the meantime, the number of unknown parameters increases with the number of concentrically mounted swirlers. The available literature is nonetheless limited, and designers are obligated to increase the number of initial assumptions. In this article, three kinds of triple swirlers are employed and simulations are performed to determine the effect of each parameter on the swirler performance. Based on the correlation provided, over-lengthening the radial vane length could result in significant changes in the flow field from the jet-like pattern to a wide swirl-jet angle due to the Coanda effect. Passage width should also have the potential to alter the swirl-jet angle and velocity field at the exit of the swirler.

Creep relaxation in FGM rotating disc with nonlinear axisymmetric distribution of heterogeneity

Hodais Zharfi

Corrected proof , doi: 10.1016/j.taml.2019.05.005

[Abstract] (59) [FullText HTML] (42) [PDF 3403KB] (10)

Abstract:
Rotating discs are the vital part of many types of machineries. Usually there is a tendency to make use of them in higher rotational speeds, but ahead of their complete break down the incidence of vibration, plastic failure or creep relaxation can create serious damages which finally prevent the increase of the rotational speed. The invention of new materials has provided new opportunities to increase the loading capacity and speed of the discs. Functionally graded materials (FGMs) are a kind of new materials utilized in the construction of rotating discs. Consequently an important aspect in the analyses of heterogeneous FGM discs is the study of their creep relaxation. One of the well known constitutive equations for the modeling of creep phenomenon is known as the Sherby's law. Based on the steady state creep, the behavior of a variety of FGM rotating discs are studied. The analysis considers the conditions in which the distribution of volume fraction follows a power-law pattern. The required mathematical model and its solution for the analysis of stress and creep strain rate is represented. Some case studies are considered in which the effects of nonlinearly distributed volume fractions are studied. In the case studies, the analysis of rotating FGM discs made of Aluminum-Silicon Carbide compounds is considered. Besides, the analyses of discs with outside tractions are considered and the effects of typical material compositions upon the creep deformations are studied. For instance, the investigation discloses the significance of the use of FGM hubs in the turbine constructions.

Molecular investigation on the compatibility of epoxy resin with liquid oxygen

Mingfa Ren, Lei Wang, Tong Li, Bingqing Wei

Accepted Manuscript

[Abstract] (25) [FullText HTML] (14) [PDF 3254KB] (1)

Abstract:
Conventional fiber reinforced plastics (FRPs) have compatibility issues with solid oxygen while used as a fuel tank, which might cause combustion and explosion. To study the compatibility of different epoxy resins with liquid oxygen, molecular dynamics was used to simulate the phase changes of cross-linked epoxy resins under the impact of solid oxygen. Three curing resin systems, which are bisphenol A epoxy resin (DGEBA), bisphenol F epoxy resin (DGEBF), and tetrahydrophthalate diglycidyl ester (epoxy resin 711), are modeled to investigate the rational material system for the application of fuel tanks in launching vehicles. The simulation results show that the order of solid oxygen compatibility of these epoxy resins is DGEBA > DGEBF > epoxy resin 711 at the same density of crosslinking. The selection of curing agent also has an impact on the compatibility, with the same epoxy, diaminodiphenyl methane (DDM) has more advanced performance comparing to diaminodiphenyl sulfone (DDS).

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Editorial: Thermal Stresses

2019, 9(5): 277 -278. doi: 10.1016/j.taml.2019.05.011

[Abstract] (31) [FullText HTML] (13) [PDF 2563KB] (8)

Abstract:
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Letter

Stresses of orthotropic laminated beams subjected to high temperature and mechanical load

Zhong Zhang, Ding Zhou, Xiuli Xu, Xuehong Li

2019, 9(5): 279 -284. doi: 10.1016/j.taml.2019.06.006

[Abstract] (56) [FullText HTML] (32) [PDF 2826KB] (14)

Abstract:
Thermo-elastic analysis of simply-supported orthotropic laminated beams subjected to high temperature and mechanical load is presented on the basis of the exact two-dimensional thermo-elasticity theory. The beam is composed of several orthotropic layers, each with temperature-dependent material properties. The governing equation for each layer is analytically solved using the state space method. The displacement and stress solutions of the beam are obtained using the transfer-matrix method. A numerical example is included to study the effects of temperature on the mechanical responses of a sandwich beam. The results reveal two main effects of temperature: (i) inducing deformations and stresses by itself; (ii) affecting the deformations and stresses induced by the mechanical load.

Thermoelastic stability of closed cylindrical shell in supersonic gas flow

G.Y. Baghdasaryan, M.A. Mikilyan, I.A. Vardanyan, P. Marzocca

2019, 9(5): 285 -288. doi: 10.1016/j.taml.2019.05.001

[Abstract] (104) [FullText HTML] (43) [PDF 2506KB] (12)

Abstract:
In this paper the problem of linear stability of a closed cylindrical shell under the action of both non-uniform temperature field and supersonic gas flow is considered. The stability conditions for the unperturbed state of the aerothermoelastic system are obtained. It is shown that, by the combined action of the temperature field and the ambient supersonic flow, the process of linear stability can be controlled and the temperature field affects significantly the critical flutter speed.

Transient thermal response of functionally graded piezoelectric laminates with an infinite row of parallel cracks normal to the bimaterial interface

Yoshiyuki Mabuchi, Sei Ueda

2019, 9(5): 289 -292. doi: 10.1016/j.taml.2019.06.009

[Abstract] (54) [FullText HTML] (29) [PDF 2656KB] (3)

Abstract:
In this paper, the problem of a functionally graded piezoelectric material strip (FGPM strip) containing an infinite row of parallel cracks perpendicular to the interface between the FGPM strip and a homogeneous layer is analyzed under transient thermal loading condition. The crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the interface. Using the Fourier transforms, the electro-thermo-elastic problem is reduced to a singular integral equation, which is solved numerically. The stress intensity factors are computed and presented as a function of the normalized time, the nonhomogeneous and geometric parameters.

Stochastic transient analysis of thermal stresses in solids by explicit time-domain method

Houzuo Guo, Cheng Su, Jianhua Xian

2019, 9(5): 293 -296. doi: 10.1016/j.taml.2019.05.007

[Abstract] (49) [FullText HTML] (46) [PDF 2591KB] (3)

Abstract:
Stochastic heat conduction and thermal stress analysis of structures has received considerable attention in recent years. The propagation of uncertain thermal environments will lead to stochastic variations in temperature fields and thermal stresses. Therefore, it is reasonable to consider the variability of thermal environments while conducting thermal analysis. However, for ambient thermal excitations, only stationary random processes have been investigated thus far. In this study, the highly efficient explicit time-domain method (ETDM) is proposed for the analysis of non-stationary stochastic transient heat conduction and thermal stress problems. The explicit time-domain expressions of thermal responses are first constructed for a thermoelastic body. Then the statistical moments of thermal displacements and stresses can be directly obtained based on the explicit expressions of thermal responses. A numerical example involving non-stationary stochastic internal heat generation rate is investigated. The accuracy and efficiency of the proposed method are validated by comparison with the Monte-Carlo simulation.

3D thermally induced analysis of annular plates of functionally graded materials

Yun-Fang Yang, Ding Chen, Bo Yang

2019, 9(5): 297 -301. doi: 10.1016/j.taml.2019.05.008

[Abstract] (54) [FullText HTML] (42) [PDF 2899KB] (4)

Abstract:
Within the framework of three-dimensional elasticity theory, this paper investigates the thermal response of functionally graded annular plates in which the material can be transversely isotropic and vary along the thickness direction in an arbitrary manner. The generalized Mian and Spencer method is utilized to obtain the analytical solutions of annular plates under a through-thickness steady temperature field. The present analytical solutions are validated through comparisons against those available in open literature. A parametric study is conducted to examine the effects of gradient distribution, different temperature fields, different diameter ratio and boundary conditions on the deformation and stress fields of the plate. The results show that these factors can have obvious effects on the thermo-elastic behavior of functionally gradient materials (FGM) annular plates.

Thermoelastic waves in helical strands with Maxwell–Cattaneo heat conduction

Dansong Zhang, Martin Ostoja-Starzewski

2019, 9(5): 302 -307. doi: 10.1016/j.taml.2019.05.003

[Abstract] (60) [FullText HTML] (43) [PDF 2663KB] (5)

Abstract:
Harmonic thermoelastic waves in helical strands with Maxwell–Cattaneo heat conduction are investigated analytically and numerically. The corresponding dispersion relation is a sixth-order algebraic equation, governed by six non-dimensional parameters: two thermoelastic coupling constants, one chirality parameter, the ratio between extensional and torsional moduli, the Fourier number, and the dimensionless thermal relaxation. The behavior of the solutions is discussed from two perspectives with an asymptotic-numerical approach: (1) the effect of thermal relaxation on the elastic wave celerities, and (2) the effect of thermoelastic coupling on the thermal wave celerities. With small wavenumbers, the adiabatic solution for Fourier helical strands is recovered. However, with large wavenumbers, the solutions behave differently depending on the thermal relaxation and chirality. Due to thermoelastic coupling, the thermal wave celerity deviates from the classical result of the speed of second sound.

Experimental study on the temperature evolution in the railway brake disc

Aleksander Yevtushenko, Michał Kuciej, Piotr Wasilewski

2019, 9(5): 308 -311. doi: 10.1016/j.taml.2019.06.008

[Abstract] (32) [FullText HTML] (26) [PDF 2645KB] (3)

Abstract:
Increasing operating speed of modern passenger railway vehicles leads to higher thermal load on the braking system. Organic composite brake pads are poor thermal conductors, hence frictional heat is absorbed mainly by the disc. In this study three brake pad types were tested on the dynamometer. Metallic fibres, steel and copper, were introduced to the formulation of two materials. The third was a non-metallic material - a reference case. Dynamometer test comprised emergency brake applications to determine the frictional characteristics of the materials and constant-power drag braking to analyse the effect of metal fibres on temperature evolution, measured by six thermocouples embedded in the brake disc. Mean friction coefficient is analysed and discussed. It is concluded that conductive fibre in the friction material formulation may influence its tribological characteristics. Despite high thermal conductivity, metal fibres in the concentration tested in this study, did not reduce temperature of the brake disc.

Iterative technique for circular thin plates on Gibson elastic foundation using modified Vlasov model

Feng Yue, Ziyan Wu, Haifeng Yang, Mengying Li

2019, 9(5): 312 -319. doi: 10.1016/j.taml.2019.04.007

[Abstract] (98) [FullText HTML] (55) [PDF 2869KB] (13)

Abstract:
In this paper, to investigate the influence of soil inhomogeneity on the bending of circular thin plates on elastic foundations, the static problem of circular thin plates on Gibson elastic foundation is solved using an iterative method based on the modified Vlasov model. On the basis of the principle of minimum potential energy, the governing differential equations and boundary conditions for circular thin plates on modified Vlasov foundation considering the characteristics of Gibson soil are derived. The equations for the attenuation parameter in bending problem are also obtained, and the issue of unknown parameters being difficult to determine is solved using the iterative method. Numerical examples are analyzed and the results are in good agreement with those form other literatures. It proves that the method is practical and accurate. The inhomogeneity of modified Vlasov foundations has some influence on the deformation and internal force behavior of circular thin plates. The effects of various parameters on the bending of circular plates and characteristic parameters of the foundation are discussed. The modified model further enriches and develops the elastic foundations. Relevant conclusions that are meaningful to engineering practice are drawn.

Crashworthiness assessment of thin-walled double bottom tanker: A variety of ship grounding incidents

Aditya Rio Prabowo, Sukmaji Indro Cahyono, Jung Min Sohn

2019, 9(5): 320 -327. doi: 10.1016/j.taml.2019.05.002

[Abstract] (83) [FullText HTML] (50) [PDF 3085KB] (8)

Abstract:
This study addresses the issue of ship accidental grounding as an impact phenomenon, with the assumption that an interaction of its structure with the oceanic seabed (obstruction), idealized as rock topology, is capable of initiating a so-called hard ground scenario. This occurrence variation was considered by performing two main instances, encompassing raking and stranding, often experienced by oil/chemical tankers as thin-walled structures. In addition, a failure criterion was implemented on the structural geometry, in order to define its ultimate limit and possible damage, during interaction with the obstructions. Subsequently, the analysis results were compiled to assess structural crashworthiness as well as progressive failure of the double bottom part of the tanker, where energy criterion indicated the raking to be more destructive. Meanwhile, detailed observation of the failure sequence indicated the stranding to have successfully breached the inner bottom shell.

Numerical investigations of fully nonlinear water waves generated by moving bottom topography

Mian Wang

2019, 9(5): 328 -337. doi: 10.1016/j.taml.2019.05.009

[Abstract] (52) [FullText HTML] (33) [PDF 3436KB] (6)

Abstract:
This paper is concerned with propagation of water waves induced by moving bodies with uniform velocity on the bottom of a channel, a simple model for prescribed underwater landslides. The fluid is assumed to be inviscid and incompressible, and the flow, irrotational. We apply this model to a variety of test problems, and particular attention is paid to long-time dynamics of waves induced by two landslide bodies moving with the same speed. We focus on the transcritical regime where the linear theory fails to depict the wave phenomena even in the qualitative sense since it predicts an infinite growth in amplitude. In order to resolve this problem, weakly nonlinear theory or direct numerical simulations for the fully nonlinear equations is required. Comparing results of the linear full-dispersion theory, the linear shallow water equations, the forced Korteweg-de Vries model, and the full Euler equations, we show that water waves generated by prescribed underwater landslides are characterized by the Froude number, sizes of landslide bodies and distance between them. Particularly, in the transcritical regime, the second body plays a key role in controlling the criticality for equal landslide bodies, while for unequal body heights, the higher one controls the criticality. The results obtained in the current paper complement numerical studies based on the forced Korteweg-de Vries equation and the nonlinear shallow water equations by Grimshaw and Maleewong (J. Fluid Mech. 2015, 2016).