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Acta Mechanica Solida Sinica
[SJR: 0.442] [H-I: 21] [9 followers] Follow

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ISSN (Print) 0894-9166 - ISSN (Online) 1860-2134
Published by Elsevier

[3175 journals]

Closed-form solution of beam on Pasternak foundation under inclined
dynamic load
- Authors: Yu Miao; Yang Shi; Guobo Wang; Yi Zhong
  Abstract: Publication date: Available online 5 December 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Yu Miao, Yang Shi, Guobo Wang, Yi Zhong
  The dynamic response of an infinite Euler–Bernoulli beam resting on Pasternak foundation under inclined harmonic line loads is developed in this study in a closed-form solution. The conventional Pasternak foundation is modeled by two parameters wherein the second parameter can account for the actual shearing effect of soils in the vertical direction. Thus, it is more realistic than the Winkler model, which only represents compressive soil resistance. However, the Pasternak model does not consider the tangential interaction between the bottom of the beam and the foundation; hence, the beam under inclined loads cannot be considered in the model. In this study, a series of horizontal springs is diverted to the face between the bottom of the beam and the foundation to address the limitation of the Pasternak model, which tends to disregard the tangential interaction between the beam and the foundation. The horizontal spring reaction is assumed to be proportional to the relative tangential displacement. The governing equation can be deduced by theory of elasticity and Newton's laws, combined with the linearly elastic constitutive relation and the geometric equation of the beam body under small deformation condition. Double Fourier transformation is used to simplify the geometric equation into an algebraic equation, thereby conveniently obtaining the analytical solution in the frequency domain for the dynamic response of the beam. Double Fourier inverse transform and residue theorem are also adopted to derive the closed-form solution. The proposed solution is verified by comparing the degraded solution with the known results and comparing the analytical results with numerical results using ANSYS. Numerical computations of distinct cases are provided to investigate the effects of the angle of incidence and shear stiffness on the dynamic response of the beam. Results are realistic and can be used as reference for future engineering designs.
  
  PubDate: 2017-12-13T08:37:30Z
  DOI: 10.1016/j.camss.2017.10.006
Study on behaviors of functionally graded shape memory alloy cylinder
- Authors: Bingfei Liu; Qingfei Wang; Rui Zhou; Chunzhi Du; Yanan Zhang; Pan Zhang
  Abstract: Publication date: Available online 2 December 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Bingfei Liu, Qingfei Wang, Rui Zhou, Chunzhi Du, Yanan Zhang, Pan Zhang
  For better controllability in actuations, it is desirable to create Functionally Graded Shape Memory Alloys (FG-SMAs) in the actuation direction. It can be achieved by applying different heat treatment processes to create the gradient along the radius of a SMA cylinder. Analytical solutions are derived to predict the macroscopic behaviors of such a functionally graded SMA cylinder. The Tresca yield criterion and linear hardening are used to describe the different phase transformations with different gradient parameters. The numerical results for an example of the model exhibit different pseudo-elastic behaviors from the non-gradient case, as well as a variational hysteresis loop for the transformation, providing a mechanism for easy actuation control. When the gradient disappears, the model can degenerate to the non-gradient case.
  
  PubDate: 2017-12-13T08:37:30Z
  DOI: 10.1016/j.camss.2017.11.004
Damage evolution and crack propagation in rocks with dual elliptic flaws
in compression
- Authors: Jun Xu; Zhaoxia Li
  Abstract: Publication date: Available online 2 December 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Jun Xu, Zhaoxia Li
  To give an insight into the understanding of damage evolution and crack propagation in rocks, a series of uniaxial and biaxial compression numerical tests are carried out. The investigations show that damage evolution occurs firstly in the weak rock, the area around the flaw and the area between the flaw and the neighboring rock layer. Cracks mostly generate as tensile cracks under uniaxial compression and shear cracks under biaxial compression. Crack patterns are classified and divided. The relationship between the accumulated lateral displacement and the short radius (b) is fitted, and the equation of crack path is also established.
  
  PubDate: 2017-12-13T08:37:30Z
  DOI: 10.1016/j.camss.2017.11.001
Analysis of meso-inhomogeneous deformation on a metal material surface
under low-cycle fatigue
- Authors: Gui-Long Liu; Ke-Shi Zhang; Xian-Ci Zhong; Jiann Woody Ju
  Abstract: Publication date: Available online 2 December 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Gui-Long Liu, Ke-Shi Zhang, Xian-Ci Zhong, Jiann Woody Ju
  A polycrystalline Voronoi aggregation with a free surface is applied as the representative volume element (RVE) of the nickel-based GH4169 superalloy. Considering the plastic deformation mechanism at the grain level and the Bauschinger effect, a crystal plasticity model reflecting the nonlinear kinematic hardening of crystal slipping system is applied. The microscopic inhomogeneous deformation during cyclic loading is calculated through numerical simulation of crystal plasticity. The deformation inhomogeneity on the free surface of the RVE under cyclic loading is described respectively by using the following parameters: standard deviation of the longitudinal strain in macro tensile direction, statistical average of first principal strains, and standard deviation of longitudinal displacement. The relationship between the fatigue cycle number and the evolution of inhomogeneous deformation of the material's free surface is investigated. This research finds that: (1) The inhomogeneous deformation of the material free surface is significantly higher than that of the RVE inside; (2) the increases of the characterization parameters of inhomogeneous deformation on the free surface with cycles reflect the local maximum deformation of the RVE growing during cyclic loading; (3) these parameters can be used as criteria to assess and predict the low-cycle fatigue life rationally.
  
  PubDate: 2017-12-13T08:37:30Z
  DOI: 10.1016/j.camss.2017.11.002
Theoretical analysis of non-probabilistic reliability based on interval
model
- Authors: Xu-Yong Chen; Jian-Ping Fan; Xiao-Ya Bian
  Abstract: Publication date: Available online 1 December 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Xu-Yong Chen, Jian-Ping Fan, Xiao-Ya Bian
  The aim of this paper is to propose a theoretical approach for performing the non-probabilistic reliability analysis of structure. Due to a great deal of uncertainties and limited measured data in engineering practice, the structural uncertain parameters were described as interval variables. The theoretical analysis model was developed by starting from the 2-D plane and 3-D space. In order to avoid the loss of probable failure points, the 2-D plane and 3-D space were respectively divided into two parts and three parts for further analysis. The study pointed out that the probable failure points only existed among extreme points and root points of the limit state function. Furthermore, the low-dimensional analytical scheme was extended to the high-dimensional case. Using the proposed approach, it is easy to find the most probable failure point and to acquire the reliability index through simple comparison directly. A number of equations used for calculating the extreme points and root points were also evaluated. This result was useful to avoid the loss of probable failure points and meaningful for optimizing searches in the research field. Finally, two kinds of examples were presented and compared with the existing computation. The good agreements show that the proposed theoretical analysis approach in the paper is correct. The efforts were conducted to improve the optimization method, to indicate the search direction and path, and to avoid only searching the local optimal solution which would result in missed probable failure points.
  
  PubDate: 2017-12-13T08:37:30Z
  DOI: 10.1016/j.camss.2017.11.003
Influence of desert sand on the mechanical properties of concrete
subjected to impact loading
- Authors: Liu Haifeng; Ma Jurong; Wang Yiying; Ning Jianguo
  Abstract: Publication date: Available online 10 November 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Liu Haifeng, Ma Jurong, Wang Yiying, Ning Jianguo
  A74-mm-diameter Split Hopkinson pressure bar was used to carry out the dynamic compression experiment of concrete made of desert sand. The dynamic failure processes of concrete different in specimen size, impact velocity, desert sand replacement ratio, size and volume content of coarse aggregate were simulated. Research results showed that concrete made of desert sand had size-effect and was rate-dependent. The peak stress of concrete made of desert sand declined with the minimum size of coarse aggregate. However, the peak stress of concrete made of desert sand increased first, and then declined with the volume content and maximum size of coarse aggregate.
  
  PubDate: 2017-11-11T13:10:23Z
  DOI: 10.1016/j.camss.2017.10.007
Effect of imperfect bonding on the dynamic response of a pre-stressed
sandwich plate-strip with elastic layers and a piezoelectric core
- Authors: Ahmet
  Abstract: Publication date: Available online 10 November 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Ahmet Daşdemir
  In this paper, we consider the dynamic response of a pre-stressed sandwich plate-strip with a piezoelectric core and elastic layers under the action of a time-harmonic force resting on a rigid foundation. The investigation is carried out within the framework of the piecewise homogeneous body model by utilizing the exact equations of motion and relations of the linear theory of electro-elasticity. It is assumed that there is a shear-spring-type imperfect contact between the layers, but a complete contact between the plate-strip and the rigid foundation. A mathematical model of the problem is constructed, and the governing equations of motion are solved by employing the Finite Element Method (FEM). Numerical results illustrating the influence of a change in the value of the shear-spring parameter on the dynamic response of the plate-strip are then presented.
  
  PubDate: 2017-11-11T13:10:23Z
Wave propagation analysis of rotating thermoelastically-actuated nanobeams
based on nonlocal strain gradient theory
- Authors: Farzad Ebrahimi; Parisa Haghi
  Abstract: Publication date: Available online 28 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Farzad Ebrahimi, Parisa Haghi
  This paper is concerned with the wave propagation behavior of rotating functionally graded (FG) temperature-dependent nanoscale beams subjected to thermal loading based on nonlocal strain gradient stress field. Uniform, linear and nonlinear temperature distributions across the thickness are investigated. Thermo-elastic properties of FG beam change gradually according to the Mori-Tanaka distribution model in the spatial coordinate. The nanobeam is modeled via a higher-order shear deformable refined beam theory which has a trigonometric shear stress function. The governing equations are derived by Hamilton's principle as a function of axial force due to centrifugal stiffening and displacement. The solution of these equations is provided employing a Galerkin-based approach which has the potential to capture various boundary conditions. By applying an analytical solution and solving an eigenvalue problem, the dispersion relations of rotating FG nanobeam are obtained. Numerical results illustrate that various parameters including temperature change, angular velocity, nonlocality parameter, wave number and gradient index have significant effects on the wave dispersion characteristics of the nanobeam under study. The outcome of this study can provide beneficial information for the next-generation research and the exact design of nano-machines including nanoscale molecular bearings, nanogears, etc.
  
  PubDate: 2017-11-05T11:31:21Z
  DOI: 10.1016/j.camss.2017.09.007
The application of nonlocal theory method in the coarse-grained molecular
dynamics simulations of long-chain polylactic acid
- Authors: Xiongjun Li; Tan Xiao; Neng Xiao
  Abstract: Publication date: Available online 25 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Xiongjun Li, Tan Xiao, Neng Xiao
  The micro-capsules used for drug delivery are fabricated using polylactic acid (PLA), which is a biomedical material approved by the FDA. A coarse-grained model of long-chain PLA was built, and molecular dynamics (MD) simulations of the model were performed using a MARTINI force field. Based on the nonlocal theory, the formula for the initial elastic modulus of polymers considering the nonlocal effect was derived, and the scaling law of internal characteristic length of polymers was proposed, which was used to adjust the cut-off radius in the MD simulations of PLA. The results show that the elastic modulus should be computed using nonlinear regression. The nonlocal effect has a certain influence on the simulation results of PLA. According to the scaling law, the cut-off radius was determined and applied to the MD simulations, the results of which reflect the influence of the molecular weight change on the elastic moduli of PLA, and are in agreement with the experimental outcome.
  
  PubDate: 2017-11-05T11:31:21Z
  DOI: 10.1016/j.camss.2017.10.003
Influences of initial porosity, stress triaxiality and Lode parameter on
plastic deformation and ductile fracture
- Authors: Ying-Song Ma; Dong-Zhi Sun; Florence Andrieux; Ke-Shi Zhang
  Abstract: Publication date: Available online 20 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Ying-Song Ma, Dong-Zhi Sun, Florence Andrieux, Ke-Shi Zhang
  Local mechanical properties in aluminum cast components are inhomogeneous as a consequence of spatial distribution of microstructure, e.g., porosity, inclusions, grain size and arm spacing of secondary dendrites. In this work, the effect of porosity is investigated. Cast components contain voids with different sizes, forms, orientations and distributions. This is approximated by a porosity distribution in the following. The aim of this paper is to investigate the influence of initial porosity, stress triaxiality and Lode parameter on plastic deformation and ductile fracture. A micromechanical model with a spherical void located at the center of the matrix material, called the representative volume element (RVE), is developed. Fully periodic boundary conditions are applied to the RVE and the values of stress triaxiality and Lode parameter are kept constant during the entire course of loading. For this purpose, a multi-point constraint (MPC) user subroutine is developed to prescribe the loading. The results of the RVE model are used to establish the constitutive equations and to further investigate the influences of initial porosity, stress triaxiality and Lode parameter on elastic constant, plastic deformation and ductile fracture of an aluminum die casting alloy.
  
  PubDate: 2017-11-05T11:31:21Z
  DOI: 10.1016/j.camss.2017.10.002
A quadratic yield function with multi-involved-yield surfaces describing
anisotropic behaviors of sheet metals under tension/compression
- Authors: Haibo Wang; Yu Yan; Min Wan; Zhengyang Chen; Qiang Li; Dong He
  Abstract: Publication date: Available online 20 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Haibo Wang, Yu Yan, Min Wan, Zhengyang Chen, Qiang Li, Dong He
  A quadratic yield function which can describe the anisotropic behaviors of sheet metals with tension/compression symmetry and asymmetry is proposed. Five mechanical properties are adopted to determine the coefficients of each part of the yield function. For particular cases, the proposed yield function can be simplified to Mises or Hill's quadratic yield function. The anisotropic mechanical properties are expressed by defining an angle between the current normalized principal stress space and the reference direction with the assumption of orthotropic anisotropy. The accuracy of the proposed yield function in describing the anisotropy under tension and compression is demonstrated.
  
  PubDate: 2017-11-05T11:31:21Z
  DOI: 10.1016/j.camss.2017.10.004
Nonlinear frequency analysis of buckled nanobeams in the presence of
longitudinal magnetic field
- Authors: Xi-Ping Sun; Yuan-Zhuo Hong; Hu-Liang Dai; Lin Wang
  Abstract: Publication date: Available online 20 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Xi-Ping Sun, Yuan-Zhuo Hong, Hu-Liang Dai, Lin Wang
  The nonlinear free vibration around the postbuckling configuration of nonlocal nanobeams with pinned–pinned boundary conditions are analytically investigated, considering the geometric nonlinearity arising from the mid-plane stretching and particularly the effect of a longitudinal magnetic field. When the applied axial force is small, the nanobeam is stable and its free vibration is around the straight equilibrium position. As the axial force becomes large and is beyond a certain critical value (critical axial force), however, either positive or negative non-trivial equilibrium configuration occurs and the free vibration is around the buckled configuration. The governing equation for the nanobeam before buckling exhibits a cubic nonlinearity while for a buckled nanobeam it contains both cubic and quadratic nonlinearities. Based on the nonlinear governing equations, approximate analytical solutions for the postbuckling configuration in terms of the applied axial force are evaluated, showing that the magnetic field parameter has a great effect on the critical axial force, buckled displacement and linear frequencies of the nanobeam system. More interestingly, the nonlinear frequency is found to be generally higher than the linear frequency in the case of prebuckling regime while it could be lower than the linear one in the case of postbuckling regime. The nonlinear frequency can be significantly influenced by the magnetic field, the nonlinear coefficient associated with the mid-plane stretching, and the initial vibration amplitude.
  
  PubDate: 2017-11-05T11:31:21Z
  DOI: 10.1016/j.camss.2017.08.002
Topology optimization of piezocomposite resonator for maximizing
excitation strength and synthesizing desired eigenmodes
- Authors: Xuansheng Wang; Zheqi Lin; Yiru Ren
  Abstract: Publication date: Available online 18 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Xuansheng Wang, Zheqi Lin, Yiru Ren
  A topology optimization method is proposed for the design of piezocomposite resonator with the aim of maximizing excitation strength and synthesizing desired eigenmodes. The objective function consists of maximizing the electromechanical coupling strength at the mode of interest. The topology layout of a structure with desired eigenmodes is obtained by adding the modal assurance criterion as additional constraint in the topology optimization model. Numerical examples are presented and the results illustrate that aside from maximizing the electromechanical coupling strength, the existing eigenmode of the piezocomposite resonator can be modified to be the desired one at the mode of interest.
  
  PubDate: 2017-11-05T11:31:21Z
  DOI: 10.1016/j.camss.2017.10.001
Forced vibration control of an axially moving beam with an attached
nonlinear energy sink
- Authors: Ye-Wei Zhang; Shuai Hou; Ke-Fan Xu; Tian-Zhi Yang; Li-Qun Chen
  Abstract: Publication date: Available online 5 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Ye-Wei Zhang, Shuai Hou, Ke-Fan Xu, Tian-Zhi Yang, Li-Qun Chen
  This paper investigates a highly efficient and promising control method for forced vibration control of an axially moving beam with an attached nonlinear energy sink (NES). Because of the axial velocity, external force and external excitation frequency, the beam undergoes a high-amplitude vibration. The Galerkin method is applied to discretize the dynamic equations of the beam–NES system. The steady-state responses of the beams with an attached NES and with nothing attached are acquired by numerical simulation. Furthermore, the fast Fourier transform (FFT) is applied to get the amplitude–frequency responses. From the perspective of frequency domain analysis, it is explained that the NES has little effect on the natural frequency of the beam. Results confirm that NES has a great potential to control the excessive vibration.
  
  PubDate: 2017-11-05T11:31:21Z
  DOI: 10.1016/j.camss.2017.09.004
Dynamic response of a pile embedded in elastic half space subjected to
harmonic vertical loading
- Authors: Changjie Zheng; Shishun Gan Xuanming Ding Lubao Luan
  Abstract: Publication date: Available online 7 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Changjie Zheng, Shishun Gan, Xuanming Ding, Lubao Luan
  An analytical method is developed to investigate the dynamic response of a pile subjected to harmonic vertical loading. The pile is modeled as a one-dimensional (1D) elastic rod. The elastic soil is divided into a homogeneous half space underlying the base of pile and a series of infinitesimally thin layers along the vertical shaft of pile. The analytical solution for the soil-pile dynamic interaction problem is obtained by the method of Hankel transformation. The proposed solution is compared with the classical plane strain solution. Arithmetical examples are presented to demonstrate the sensitivity of the vertical impedance of the pile to relevant parameters.
  
  PubDate: 2017-10-08T06:27:19Z
Vibration analysis of atomic force microscope cantilevers in contact
resonance force microscopy using Timoshenko beam model
- Authors: Xilong Zhou; Pengfei Wen Faxin
  Abstract: Publication date: Available online 6 October 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Xilong Zhou, Pengfei Wen, Faxin Li
  Timoshenko beam model is employed to investigate the vibration of atomic force microscope (AFM) cantilevers in contact resonance force microscopy (CRFM). Characteristic equation with both vertical and lateral tip-sample contact is derived. The contact resonance frequencies (CRFs) obtained by the Timoshenko model are compared with those by the Euler-Bernoulli model. A method is proposed to correct the wave number obtained by the Euler-Bernoulli model. The forced vibration is compared between the two models. Results reveal that the Timoshenko model is superior to the Euler-Bernoulli model in predicting the vibration characteristics for cantilevers’ higher eigenmodes.
  
  PubDate: 2017-10-08T06:27:19Z
Dynamic response of a Q&P steel to high-strain-rate tension
- Authors: Huanran Wang; Wenchao Zhang Dongfang Bohan Danian Chen Xin Yang
  Abstract: Publication date: Available online 22 September 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Huanran Wang, Wenchao Zhang, Dongfang Ma, Bohan Ma, Danian Chen, Xin Yang, Chunlei Fan
  The experimental study on the volume fraction of retained austenite for QP980CR steel under high-strain-rate tension is briefly described. An interrupted tensile split Hopkinson bar (TSHB) is developed to control the elongation of specimens. The QP980CR steel samples recovered from the interrupted TSHB tests are investigated using synchrotron X-ray diffraction (XRD) to analyze the effects of strain and strain rate on the martensitic transformation of retained austenite. A constitutive model of QP980CR steel coupling with the transformation-induced plasticity (TRIP) effect is presented based on Delannay's mean-field modeling. The stress-strain curves of quasi-static and dynamic tensile tests for QP980CR steel are compared with the results predicted by the presented constitutive model. The diffuse necking of QP980CR steel sheet specimens in TSHB tests is analyzed using Bratra and Wei's instability criterion and the presented constitutive model. The effects of strain rate and temperature on the dynamic tensile fracture strain of QP980CR steel are also given.
  
  PubDate: 2017-09-24T00:35:27Z
Experimental and numerical studies of impact on filament-wound composite
cylinder
- Authors: Qiaoguo Wu; Xuedong Chen; Zhichao Fan; Yong Jiang; Defu Nie
  Abstract: Publication date: Available online 14 September 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Qiaoguo Wu, Xuedong Chen, Zhichao Fan, Yong Jiang, Defu Nie
  This study focused on the impact behavior of carbon-fiber-wrapped composite cylinders subjected to impact from flat-ended, hemispherical-nosed and conical-nosed impactors. Damage morphologies of the cylinders and mechanisms of the damage were analyzed. Change laws of the maximum impact forces, durations of impact processes and energies absorbed by the cylinders after impact with different impactors and impact energies were obtained. A finite element model was developed and the simulation results were in reasonable agreement with the tests. Finally, taking the flat-ended impactor as an example, stress distributions of the cylinders under pressurization and impact were discussed.
  
  PubDate: 2017-09-17T22:11:34Z
  DOI: 10.1016/j.camss.2017.09.001
Development and application of state-dependent fractional plasticity in
modelling the non-associated behavior of granular aggregates
- Authors: Yifei Sun; Shunxiang Song; Yang Xiao; Jiancheng Zhang
  Abstract: Publication date: Available online 14 September 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Yifei Sun, Shunxiang Song, Yang Xiao, Jiancheng Zhang
  To characterize the constitutive behavior of granular aggregates, a non-associated plasticity model with two different yield and plastic potential surfaces was usually used. However, in this paper, a state-dependent fractional elastoplastic model is proposed by only performing the first- and fractional-order differentiations of the yield function. The non-associated plastic flow is obtained without using any plastic potential functions. The state dependence is considered by correlating the fractional order with a state parameter. The model is then validated by simulating a series of test results of different granular aggregates, including sand, ballast and rockfill, under a variety of loading conditions.
  
  PubDate: 2017-09-17T22:11:34Z
  DOI: 10.1016/j.camss.2017.09.002
Transient heat conduction analysis using the NURBS-enhanced scaled
boundary finite element method and modified precise integration method
- Authors: Gao Lin; Peng Li; Jun Liu; Pengchong Zhang
  Abstract: Publication date: Available online 25 August 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Gao Lin, Peng Li, Jun Liu, Pengchong Zhang
  The Non-uniform rational B-spline (NURBS) enhanced scaled boundary finite element method in combination with the modified precise integration method is proposed for the transient heat conduction problems in this paper. The scaled boundary finite element method is a semi-analytical technique, which weakens the governing differential equations along the circumferential direction and solves those analytically in the radial direction. In this method, only the boundary is discretized in the finite element sense leading to a reduction of the spatial dimension by one with no fundamental solution required. Nevertheless, in case of the complex geometry, a huge number of elements are generally required to properly approximate the exact shape of the domain and distorted meshes are often unavoidable in the conventional finite element approach, which leads to huge computational efforts and loss of accuracy. NURBS are the most popular mathematical tool in CAD industry due to its flexibility to fit any free-form shape. In the proposed methodology, the arbitrary curved boundary of problem domain is exactly represented with NURBS basis functions, while the straight part of the boundary is discretized by the conventional Lagrange shape functions. Both the concepts of isogeometric analysis and scaled boundary finite element method are combined to form the governing equations of transient heat conduction analysis and the solution is obtained using the modified precise integration method. The stiffness matrix is obtained from a standard quadratic eigenvalue problem and the mass matrix is determined from the low-frequency expansion. Finally the governing equations become a system of first-order ordinary differential equations and the time domain response is solved numerically by the modified precise integration method. The accuracy and stability of the proposed method to deal with the transient heat conduction problems are demonstrated by numerical examples.
  Graphical abstract
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.013
Analytical Solutions for Thermal Vibration of Nanobeams with Elastic
Boundary Conditions
- Authors: Jingnong Jiang; Lifeng Wang
  Abstract: Publication date: Available online 24 August 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Jingnong Jiang, Lifeng Wang
  A nonlocal Euler beam model with second-order gradient of stress taken into consideration is used to study the thermal vibration of nanobeams with elastic boundary. An analytical solution is proposed to investigate the free vibration of nonlocal Euler beams subjected to axial thermal stress. The effects of the nonlocal parameter, thermal stress and stiffness of boundary constraint on the vibration behaviors of nanobeams are revealed. The results show that natural frequencies including the thermal stress are lower than those without the thermal stress when temperature rises. The boundary-constrained springs have significant effects on the vibration of nanobeams. In addition, numerical simulations also indicate the importance of small-scale effect on the vibration of nanobeams.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.08.001
Quantum effects on thermal vibration of single-walled carbon nanotubes
conveying fluid
- Authors: Ye-Wei Zhang; Lin Zhou; Bo Fang; Tian-Zhi Yang
  Abstract: Publication date: Available online 10 August 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Ye-Wei Zhang, Lin Zhou, Bo Fang, Tian-Zhi Yang
  In this paper, we investigate the microfluid induced vibration of a nanotube in thermal environment. Attention is focused on a special case that the law of energy equipartition is unreliable unless the quantum effect is taken into account. A nonlocal Euler–Bernoulli beam model is used to model the transverse vibration of a single-walled nanotube (SWCNT). Results reveal that the root of mean squared (RMS) amplitude of thermal vibration of the fluid-conveying SWCNT predicted from the quantum theory is lower than that predicted from the law of energy equipartition. The quantum effect on the thermal vibration of the fluid-conveying SWCNT is more significant for the cases of higher-order modes, lower flow velocity, lower temperature, and lower fluid density.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.007
A 3D multi-field element for simulating the electromechanical coupling
behavior of dielectric elastomers
- Authors: Jun Liu; Choon Chiang Foo; Zhi-Qian Zhang
  Abstract: Publication date: Available online 8 August 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Jun Liu, Choon Chiang Foo, Zhi-Qian Zhang
  We propose a multi-field implicit finite element method for analyzing the electromechanical behavior of dielectric elastomers. This method is based on a four-field variational principle, which includes displacement and electric potential for the electromechanical coupling analysis, and additional independent fields to address the incompressible constraint of the hyperelastic material. Linearization of the variational form and finite element discretization are adopted for the numerical implementation. A general FEM program framework is developed using C++ based on the open-source finite element library deal.II to implement this proposed algorithm. Numerical examples demonstrate the accuracy, convergence properties, mesh-independence properties, and scalability of this method. We also use the method for eigenvalue analysis of a dielectric elastomer actuator subject to electromechanical loadings. Our finite element implementation is available as an online supplementary material.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.005
Semi-permeable Yoffe-type interfacial crack analysis in MEE composites
based on the strip electro-magnetic polarization saturation model
- Authors: Xiaodong Xia; Zheng Zhong
  Abstract: Publication date: Available online 28 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Xiaodong Xia, Zheng Zhong
  Fracture analysis of a semi-permeable Yoffe-type interfacial crack propagating subsonically in magneto-electro-elastic (MEE) composites is presented based on the strip electro-magnetic polarization saturation (SEMPS) model. The electro-magnetic fields inside the crack are considered under the semi-permeable boundary condition. Nonlinear effects near the interfacial crack tip are represented by different electro-magnetic saturation zones. Utilizing the extended Stroh's method, we derive the moving dislocation densities as well as intensity factor and energy release rate for Yoffe-type MEE interfacial crack. Numerical results through an iterative approach are presented to show the characteristics of fracture-dominant parameters with respect to propagation velocity and boundary condition category. The fracture-dominant parameters under the semi-permeable boundary condition are lower than those under the impermeable one, which implies that the electro-magnetic fields in the crack gap can retard the propagation of MEE interfacial crack.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.011
A mechanical model for the adhesive contact with local sliding induced by
a tangential force
- Authors: Gan-Yun Huang; Ji-Feng Yan
  Abstract: Publication date: Available online 28 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Gan-Yun Huang, Ji-Feng Yan
  Adhesion has been demonstrated to play an important role in contact and friction between objects at small scales. While various models have been established for adhesive contact under normal forces, studies on the adhesive contact under tangential force have been far fewer, which if any, are mostly confined to the non-slipping situations. In the present work, a model has been proposed for adhesive contact with local sliding under tangential forces. Herein, the onset of local sliding in adhesive contact has been addressed by assuming the nucleation of dislocations. By analogy with the emission of dislocations at a crack tip, the critical tangential force for the onset of sliding has been determined, and its effect on the evolution of contact size has also been studied. Comparison with relevant experiments has verified the validity of the present model.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.008
Band structures of elastic SH waves in nanoscale multi-layered
functionally graded phononic crystals with/without nonlocal interface
imperfections by using a local RBF collocation method
- Authors: Zhizhong Yan; Chunqiu Wei; Chuanzeng Zhang
  Abstract: Publication date: Available online 28 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Zhizhong Yan, Chunqiu Wei, Chuanzeng Zhang
  A meshless radial basis function (RBF) collocation method based on the Eringen nonlocal elasticity theory is developed to calculate the band structures of ternary and quaternary nanoscale multi-layered phononic crystals (PNCs) with functionally graded (FG) interlayers. Detailed calculations are performed for anti-plane transverse waves propagating in such PNCs. The influences of FG and homogeneous interlayers, component number, nonlocal interface imperfections and nanoscale size on cut-off frequency and band structures are investigated in detail. Numerical results show that these factors have significant effects on band structures at the macroscopic and microscopic scales.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.012
Quantitative study on interactions between interfacial misfit dislocation
networks and matrix dislocations in Ni-based single crystal superalloys
- Authors: Jun Xiong; Yaxin Zhu; Zhenhuan Li; Minsheng Huang
  Abstract: Publication date: Available online 28 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Jun Xiong, Yaxin Zhu, Zhenhuan Li, Minsheng Huang
  The interactions between the moving dislocation within matrix channel and the interfacial misfit dislocation networks on the two-phase interfaces in Ni-based single crystal superalloys are studied carefully via atomic modeling, with special focus on the factors influencing the critical bowing stress of moving dislocations in the matrix channel. The results show that the moving matrix dislocation type and its position with respect to the interfacial misfit dislocation segments have considerable influences on the interactions. If the moving matrix dislocation is pure screw, it reacts with the interfacial misfit dislocation segments toward dislocation linear energy reduction, which decreases the critical bowing stress of screw dislocation due to dislocation linear energy release during the dislocation reactions. If the moving matrix dislocation is of 60○-mixed type, it is obstructed by the interaction between the mixed matrix dislocations and the misfit interfacial dislocation segments. As a result, the critical bowing stress increases significantly because extra interactive energy needs to be overcome. These two different effects on the critical bowing stress become increasingly significant when the moving matrix dislocation is very close to the interfacial misfit dislocation segments. In addition, the matrix channel width also has a significant influence on the critical bowing stress, i.e. the narrower the matrix channel is, the higher the critical bowing stress is. The classical Orowan formula is modified to predict these effects on the critical bowing stress of moving matrix dislocation, which is in good agreement with the computational results.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.004
Vibrational frequency analysis of finite elastic tube filled with
compressible viscous fluid
- Authors: Ilyess Mnassri; Adil El Baroudi
  Abstract: Publication date: Available online 28 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Ilyess Mnassri, Adil El Baroudi
  The vibrational frequency analysis of finite elastic tube filled with compressible viscous fluid has received plenty of attention in recent years. To apply frequency analysis to defect detection for example, it is necessary to investigate the vibrational behavior under appropriate boundary conditions. In this paper, we present a detailed theoretical study of the three dimensional modal analysis of compressible fluid within an elastic cylinder. The dispersion equations of flexural, torsional and longitudinal modes are derived by elastodynamic theory and the unsteady Stokes equation. The symbolic software Mathematica is used in order to find the coupled vibration frequencies. The dispersion equation is deduced and analytically solved. The finite element results are compared with the present method for validation and an acceptable match between them are obtained.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.010
Assumed stress quasi-conforming triangular element for couple stress
theory
- Authors: Changsheng Wang; Xiangkui Zhang; Ping Hu
  Abstract: Publication date: Available online 27 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Changsheng Wang, Xiangkui Zhang, Ping Hu
  In this paper, a 3-node triangular element for couple stress theory is proposed based on the assumed stress quasi-conforming method. The formulation starts from polynomial approximation of stresses. Then the stress-function matrix is treated as the weighted function to weaken the strain-displacement equations. Finally, the string-net functions are introduced to calculate strain integration and the stress smooth technique is adopted to improve the stress accuracy. Numerical results show that the proposed new model can pass the C 0 − 1 patch test with excellent precision, does not exhibit extra zero energy modes and can capture the scale effects of microstructure.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.006
Micromechanical simulation on strength and ductility of two kinds of
Al-based nanostructural materials
- Authors: Xu He; Linli Zhu; Jinling Liu; Linan An
  Abstract: Publication date: Available online 27 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Xu He, Linli Zhu, Jinling Liu, Linan An
  The nanostructured Al-based composites possess the combination of high yield strength and good ductility. In this paper, a micromechanical model is presented to simulate the mechanical response of bimodal nanostructured Al and the particle-reinforced aluminum matrix composite (PAMC). The constitutive relations for different phases are addressed in the model, as well as the contribution of microcracks. Numerical results show that the model can successfully describe the enhanced strength and ductility of the bimodal nanostructured Al, and the predictions of the PAMC are in good agreement with the experimental data. It is worth noting that the strength and ductility are sensitive to the volume fraction of constituents and the distribution of microcracks in both bimodal nanostructured Al and PAMC. Therefore, the present theoretical results can be used to optimize the microstructure for improving the mechanical properties of nanostructured Al-based composites.
  
  PubDate: 2017-08-27T14:43:36Z
  DOI: 10.1016/j.camss.2017.07.009
Minimizing stress concentrations around an elliptical hole by concentrated
forces acting on the uniaxially loaded plate
- Authors: Aizhong Lu; Ning Zhang; Guisen Zeng
  Abstract: Publication date: Available online 8 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Aizhong Lu, Ning Zhang, Guisen Zeng
  When concentrated forces are applied at any points of the outer region of an ellipse in an infinite plate, the complex potentials are determined using the conformal mapping method and Cauchy's integral formula. And then, based on the superposition principle, the analytical solutions for stress around an elliptical hole in an infinite plate subjected to a uniform far-field stress and concentrated forces, are obtained. Tangential stress concentration will occur on the hole boundary when only far-field uniform loads are applied. When concentrated forces are applied in the reversed directions of the uniform loads, tangential stress concentration on the hole boundary can be released significantly. In order to minimize the tangential stress concentration, we need to determine the optimum positions and values of the concentrated forces. Three different optimization methods are applied to achieve this aim. The results show that the tangential stress can be released significantly when the optimized concentrated forces are applied.
  
  PubDate: 2017-07-21T00:59:35Z
  DOI: 10.1016/j.camss.2017.07.002
Nonlinear vibration analysis of fractional viscoelastic Euler-Bernoulli
nanobeams based on the surface stress theory
- Authors: M. Faraji Oskouie; R. Ansari; F. Sadeghi
  Abstract: Publication date: Available online 8 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): M. Faraji Oskouie, R. Ansari, F. Sadeghi
  The nonlinear vibrations of viscoelastic Euler-Bernoulli nanobeams are studied using the fractional calculus and the Gurtin-Murdoch theory. Employing Hamilton's principle, the governing equation considering surface effects is derived. The fractional integro-partial differential governing equation is first converted into a fractional ordinary differential equation in the time domain using the Galerkin scheme. Thereafter, the set of nonlinear fractional time-dependent equations expressed in a state-space form is solved using the predictor-corrector method. Finally, the effects of initial displacement, fractional derivative order, viscoelasticity coefficient, surface parameters and thickness-to-length ratio on the nonlinear time response of simply-supported and clamped-free silicon viscoelastic nanobeams are investigated.
  
  PubDate: 2017-07-21T00:59:35Z
  DOI: 10.1016/j.camss.2017.07.003
Effects of irregularity and initial stresses on the dynamic response of
viscoelastic half-space due to a moving load
- Authors: A.K. Singh; A. Das; A. Lakshman; A. Negi; A. Chattopadhyay
  Abstract: Publication date: Available online 8 July 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): A.K. Singh, A. Das, A. Lakshman, A. Negi, A. Chattopadhyay
  The present article deals with the stresses developed in an initially stressed irregular viscoelastic half-space due to a load moving with a constant velocity at a rough free surface. Expressions for normal and shear stresses are obtained in closed form. The substantial effects of influence parameters, viz., depth (from the free surface), irregularity factor, maximum depth of irregularity, viscoelastic parameter, horizontal and vertical initial stresses, and frictional coefficient, on normal and shear stresses are investigated. Moreover, comparative study is carried out for three different cases of irregularity, viz., rectangular irregularity, parabolic irregularity and no irregularity, which is manifested through graphs.
  
  PubDate: 2017-07-21T00:59:35Z
  DOI: 10.1016/j.camss.2017.07.001
TIMOSHENKO INCLUSIONS IN ELASTIC BODIES CROSSING AN EXTERNAL BOUNDARY AT
ZERO ANGLE
- Authors: A.M. Khludnev; T.S. Popova
  Abstract: Publication date: Available online 20 June 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): A.M. Khludnev, T.S. Popova
  The paper concerns an analysis of equilibrium problems for 2D elastic bodies with a thin Timoshenko inclusion crossing an external boundary at zero angle. The inclusion is assumed to be delaminated, thus forming a crack between the inclusion and the body. We consider elastic inclusions as well as rigid inclusions. To prevent a mutual penetration between the crack faces, inequality type boundary conditions are imposed at the crack faces. Theorems of existence and uniqueness are established. Passages to limits are investigated as a rigidity parameter of the elastic inclusion going to infinity.
  
  PubDate: 2017-06-26T15:32:37Z
  DOI: 10.1016/j.camss.2017.05.005
Torsional wave in a circular micro-tube with clogging attached to the
inner surface
- Authors: Limei Xu; Hui Fan; Yufeng Zhou
  Abstract: Publication date: Available online 17 June 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Limei Xu, Hui Fan, Yufeng Zhou
  In the present paper, we study the torsional wave propagation along a micro-tube with clogging attached to its inner surface. The clogging accumulated on the inner surface of the tube is modeled as an “elastic membrane” which is described by the so-called surface elasticity. A power-series solution is particularly developed for the lowest order of wave propagation. The dispersion diagram of the lowest-order wave is numerically presented with the surface (clogging) effect.
  
  PubDate: 2017-06-26T15:32:37Z
  DOI: 10.1016/j.camss.2017.06.001
The microbuckling failure of Dyneema® composites under compression
- Authors: Guangyan Liu; Wei Zhu; Guangyan Huang
  Abstract: Publication date: Available online 15 June 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Guangyan Liu, Wei Zhu, Guangyan Huang
  Two grades of Dyneema® composite laminates with the commercial designations of HB26 and HB50 were cut into blocks with or without an edge crack and compressed in the longitudinal fiber direction. The cracked and uncracked specimens show similar compressive responses including failure pattern and failure load. The two grades of Dyneema® composites exhibits different failure modes: a diffuse, sinusoidal buckling pattern for Dyneema® HB50 due to its weak matrix constituent and a kink band for Dyneema® HB26 due to its relatively stronger matrix constituent. An effective finite element model is used to simulate the collapse of Dyneema® composites, and the sensitivity of laminate compressive responses to the overall effective shear modulus, interlaminar shear strength, thickness and imperfection angle are investigated. The change of failure mode from kink band to sinusoidal buckling pattern by decreasing the interlaminar shear strength is validated by the finite element analyses.
  
  PubDate: 2017-06-19T13:00:34Z
  DOI: 10.1016/j.camss.2017.06.002
Stress-mediated lithiation in nanoscale phase transformation electrodes
- Authors: Yuyang Lu; Yong Ni
  Abstract: Publication date: Available online 16 May 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Yuyang Lu, Yong Ni
  Development of high-performance phase transformation electrodes in lithium ion batteries requires comprehensive studies on stress-mediated lithiation involving migration of the phase interface. It brings out many counter-intuitive phenomena, especially in nanoscale electrodes, such as the slowing down migration of phase interface, the vanishing of miscibility gap under high charge rate, and the formation of surface crack during lithiation. However, it is still a challenge to simulate the evolution of stress in arbitrarily-shaped nanoscale electrodes, accompanied with phase transformation and concurrent plastic deformation. This article gives a brief review of our efforts devoted to address these issues by developing phase field model and simulation. We demonstrate that the miscibility gap of two-phase state is affected not only by stress but also by surface reaction rate and particle size. In addition, the migration of phase interface slows down due to stress. It reveals that the plastic deformation generates large radial expansion, which is responsible for the transition from surface hoop compression to surface hoop tension that may induce surface crack during lithiation. We hope our effort can make a contribution to the understanding of stress-coupled kinetics in phase transformation electrodes.
  
  PubDate: 2017-05-20T17:06:37Z
  DOI: 10.1016/j.camss.2017.05.004
Influence of the Connecting Condition on the Dynamic Buckling of
Longitudinal Impact for an Elastic Rod
- Authors: Xiaojuan Jiao; Jianmin Ma
  Abstract: Publication date: Available online 11 May 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Xiaojuan Jiao, Jianmin Ma
  The stress wave propagation law and dynamic buckling critical velocity are formulated and solved by considering a general axial connecting boundary for a slender elastic straight rod impacted by a rigid body. The influence of connecting stiffness on the critical velocity is investigated with varied impactor mass and buckling time. The influences of rod length and rod mass on the critical velocity are also discussed. It is found that greater connecting stiffness leads to larger stress amplitude, and further results in lower critical velocity. It is particularly noteworthy that when the connecting stiffness is less than a certain value, dynamic buckling only occurs before stress wave reflects off the connecting end. It is also shown that longer rod with larger slenderness ratio is easier to buckle, and the critical velocity for a larger-mass rod is higher than that for a lighter rod with the same geometry.
  
  PubDate: 2017-05-15T15:41:36Z
  DOI: 10.1016/j.camss.2017.05.003
Interlayer Shear of Nanomaterials: Graphene-Graphene, Boron Nitride-Boron
Nitride and Graphene-Boron Nitride
- Authors: Yinfeng Li; Weiwei Zhang; Bill Guo; Dibakar Datta
  Abstract: Publication date: Available online 8 May 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Yinfeng Li, Weiwei Zhang, Bill Guo, Dibakar Datta
  In this paper, the interlayer sliding between graphene and boron nitride (h-BN) is studied by molecular dynamics simulations. The interlayer shear force between h-BN/h-BN is found to be six times higher than that of Graphene/Graphene, while the interlayer shear between Graphene/h-BN is approximate to that of Graphene/Graphene. The Graphene/h-BN heterostructure shows several anomalous interlayer shear characteristics compared to its bilayer counterparts. For Graphene/Graphene and h-BN/h-BN, interlayer shears only exit along the sliding direction while interlayer shear for Graphene/h-BN is observed along both the translocation and perpendicular directions. Our results provide significant insight into the interlayer shear characteristics of 2D nanomaterials.
  
  PubDate: 2017-05-10T13:55:31Z
  DOI: 10.1016/j.camss.2017.05.002
Modeling nanoscale ice adhesion
- Authors: Senbo Xiao; Jianying He; Zhiliang Zhang
  Abstract: Publication date: Available online 6 May 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Senbo Xiao, Jianying He, Zhiliang Zhang
  Anti-icing is crucial for numerous instruments and devices in low temperature circumstance. One of the approaches in anti-icing is to reduce ice adhesion strength, seeking spontaneous de-icing processes by natural forces of gravity or by winds. In order to enable tailored surface icephobicity design, research requires a good theoretical understanding of the atomistic interacting mechanisms between water/ice molecules and their adhering substrates. Herein, this work focuses on using atomistic modeling and molecular dynamics simulation to build a nanosized ice-cube adhering onto silicon surface, with different contact modes of solid-solid and solid-liquid-solid patterns. This study provides atomistic models for probing nanoscale ice adhesion mechanics and theoretical platforms for explaining experimental results.
  
  PubDate: 2017-05-06T12:45:24Z
  DOI: 10.1016/j.camss.2017.05.001
An Empirical Description for the Hinge-Like Mechanism in Single-Layer
Black Phosphorus: the Angle-Angle Cross Interaction
- Authors: Jin-Wu Jiang
  Abstract: Publication date: Available online 5 May 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Jin-Wu Jiang
  The single-layer black phosphorus is characterized by its puckered configuration that possesses the hinge-like behavior, which leads to the highly anisotropic in-plane Poisson's ratios and the negative out-of-plane Poisson's ratio. We demonstrate that the hinge-like mechanism can be described by the angle-angle cross interaction, which, combined with the bond stretching and angle bending interactions, is able to provide a good description for the mechanical properties of single-layer black phosphorus. We also propose a nonlinear angle-angle cross interaction, which follows the form of Stillinger-Weber potential and can be advantageous for molecular dynamics simulations of single-layer black phosphorus under large deformation.
  
  PubDate: 2017-05-06T12:45:24Z
  DOI: 10.1016/j.camss.2017.04.002
An elastic electrode model for wave propagation analysis in piezoelectric
layered structures of film bulk acoustic resonators
- Authors: Feng Zhu; Yuxing Zhang; Bin Wang; Zhenghua Qian
  Abstract: Publication date: Available online 27 April 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Feng Zhu, Yuxing Zhang, Bin Wang, Zhenghua Qian
  Wave propagation in a piezoelectric layered structure of a film bulk acoustic resonator (FBAR) is studied. The accurate results of dispersion relation are calculated using the proposed elastic electrode model for both electroded and unelectroded layered plates. The differences of calculated cut-off frequencies between the current elastic electrode model and the simplified inertial electrode model (often used in the quartz resonator analysis) are illustrated in detail, which shows that an elastic electrode model is indeed needed for the accurate analysis of FBAR. These results can be used as an accurate criterion to calibrate the 2-D theoretical model for a real finite-size structure of FBAR.
  
  PubDate: 2017-04-30T11:50:06Z
  DOI: 10.1016/j.camss.2017.04.001
NMolecular dynamics simulation of diffusion of nanoparticles in mucus
- Authors: Jiuling Wang; Xinghua Shi
  Abstract: Publication date: Available online 6 April 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Jiuling Wang, Xinghua Shi
  The rapid diffusion of nanoparticles (NPs) through mucus layer is critical for efficient transportation of NPs-loaded drug delivery system. To understand how the physical and surface properties of NPs affect their diffusion in mucus, we have developed a coarse-grained molecular dynamics model to study the diffusion of NPs in modeled mucus layer. Both steric obstruction and hydrodynamic interaction are included in the model capable of capturing the key characteristics of NPs’ diffusion in mucus. The results show that both particle size and surface properties significantly affect the diffusivities of NPs in mucus. Furthermore, we find rodlike NPs can gain a higher diffusivity than spherical NPs with the same hydrodynamic diameter. In addition, the disturbed environment can enhance the diffusivity of NPs. Our findings can be utilized to design mucus penetrating NPs for targeted drug delivery system.
  
  PubDate: 2017-04-09T04:39:07Z
  DOI: 10.1016/j.camss.2017.03.012
NMolecular dynamics simulation of diffusion of nanoparticles in mucus
- Authors: Jiuling Wang; Xinghua Shi
  Abstract: Publication date: Available online 6 April 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Jiuling Wang, Xinghua Shi
  The rapid diffusion of nanoparticles (NPs) through mucus layer is critical for efficient transportation of NPs-loaded drug delivery system. To understand how the physical and surface properties of NPs affect their diffusion in mucus, we have developed a coarse-grained molecular dynamics model to study the diffusion of NPs in modeled mucus layer. Both steric obstruction and hydrodynamic interaction are included in the model capable of capturing the key characteristics of NPs’ diffusion in mucus. The results show that both particle size and surface properties significantly affect the diffusivities of NPs in mucus. Furthermore, we find rodlike NPs can gain a higher diffusivity than spherical NPs with the same hydrodynamic diameter. In addition, the disturbed environment can enhance the diffusivity of NPs. Our findings can be utilized to design mucus penetrating NPs for targeted drug delivery system.
  
  PubDate: 2017-04-09T04:39:07Z
  DOI: 10.1016/j.camss.2017.03.012
Lithiation-Enhanced Charge Transfer and Sliding Strength at the
Silicon-Graphene Interface: a First-Principles Study
- Authors: Cheng Chang; Xiaoyan Li; Zhiping Xu; Huajian Gao
  Abstract: Publication date: Available online 31 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Cheng Chang, Xiaoyan Li, Zhiping Xu, Huajian Gao
  The application of silicon as ultrahigh capacity electrodes in lithium-ion batteries has been limited by a number of mechanical degradation mechanisms including fracture, delamination and plastic ratcheting, as a result of its large volumetric change during lithiation and delithiation. Graphene coating is one feasible technique to mitigate the mechanical degradation of Si anode and improve its conductivity. In this paper, first-principles calculations are performed to study the atomic structure, charge transfer and sliding strength of the interface between lithiated silicon and graphene. Our results show that Li atoms segregate at the (lithiated) Si-graphene interface preferentially, donating electrons to graphene and enhancing the interfacial sliding resistance. Moreover, the interfacial cohesion and sliding strength can be further enhanced by introducing single-vacancy defects into graphene. These findings provide insights that can guide the design of stable and efficient anodes of silicon/graphene hybrids for energy storage applications.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.011
Band Structure Properties of Elastic Waves Propagating in the Nanoscaled
Nearly Periodic Layered Phononic Crystals
- Authors: A-Li Chen; Li-Zhi Tian; Yue-Sheng Wang
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): A-Li Chen, Li-Zhi Tian, Yue-Sheng Wang
  The localization factor is used to describe the band structures for P wave propagating normally in the nanoscaled nearly periodic layered phononic crystals. The localization factor is calculated by the transfer matrix method based on the nonlocal elastic continuum theory. Three kinds of nearly periodic arrangements are concerned, i.e., random disorder, quasi-periodicity and defects. The influences of randomly disordered degree of the sub-layer's thickness and mass density, the arrangement of quasi-periodicity and the location of defect on the band structures and cut-off frequency are analyzed in detail.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.005
Numerical simulation of quasi-static compression on a complex rubber foam
- Authors: Huyi Wang; Wenjun Hu; Fengpeng Zhao
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Huyi Wang, Wenjun Hu, Fengpeng Zhao
  A complex rubber foam under quasi-static compression is simulated using the finite element method (FEM). The present work sets up the phenomenological constitutive model for the silicon rubber. The computerized tomography (CT) technique is utilized to reconstruct the real complex foam geometries. The quasi-static uniaxial compression on the foam is simulated in ABAQUS. The present work obtains the stress response as the nominal strain nearly reaches 80% and the foam exhibits hyper-elastic behavior. The FEM results achieve good agreements with the data obtained from the multi-scale simulation and the tests as the nominal strain is less than 60%.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.009
SHEAR RESPONSE OF β-SIC BULK DEPENDENT ON TEMPERATURE AND STRAIN RATE
- Authors: Liang Wang; Qunfeng Liu; Wenshan Yu; Shengping Shen
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Liang Wang, Qunfeng Liu, Wenshan Yu, Shengping Shen
  The shear responses of β-SiC are investigated using molecular dynamics simulation with the Tersoff interatomic potential. Results show a clear decreasing trend in critical stress, fracture strain and shear modulus as temperature increases. Above a critical temperature, β-SiC bulk just fractures after the elastic deformation. However, below the critical temperature, an interesting pattern in β-SiC bulk emerges due to the elongation of Si-C bonds before fracture. Additionally, the shear deformation of β-SiC at room temperature is found to be dependent on the strain rate. This study may shed light on the deformation mechanism dependent on temperature and strain rate.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.008
A Refined Global-Local Approach for Evaluation of Singular Stress Field
Based on Scaled Boundary Finite Element Method
- Authors: Lin Pang; Gao Lin; Zhiqiang Hu
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Lin Pang, Gao Lin, Zhiqiang Hu
  A refined global-local approach based on the scaled boundary finite element method (SBFEM) is proposed to improve the accuracy of predicted singular stress field. The proposed approach is carried out in conjunction with two steps. First, the entire structure is analyzed by employing an arbitrary numerical method. Then, the interested region, which contains stress singularity, is re-solved using the SBFEM by placing the scaling center right at the singular stress point with the boundary conditions evaluated from the first step imposed along the whole boundary including the side-faces. Benefiting from the semi-analytical nature of the SBFEM, the singular stress field can be predicted accurately without highly refined meshes. It provides the FEM or other numerical methods with a rather simple and convenient way to improve the accuracy of stress analysis. Numerical examples validate the effectiveness of the proposed approach in dealing with various kinds of problems.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.006
A comparative study of wave localization in locally resonant Thue-Morse,
Rudin-Shapiro and Period-Doubling aperiodic structures
- Authors: Zhizhong Yan; Yangyang Wang; Chuanzeng Zhang
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Zhizhong Yan, Yangyang Wang, Chuanzeng Zhang
  The localization characteristics of the in-plane elastic waves in locally resonant aperiodic phononic crystals are examined in this study. In particular, the phononic crystals generated according to the Thue-Morse, Rudin-Shapiro and Period-Doubling sequences are theoretically investigated by using the extended transfer matrix method. For comparison, the binary and ternary locally resonant systems are considered, and their band structures are characterized by using the localization factors. Moreover, the influences of structural arrangement, material combination, incidence angle, number of components, length ratio, and random disorder on the band structures are also discussed. Some novel and interesting phenomena are observed and discussed.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.007