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Acta Mechanica Solida Sinica
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ISSN (Print) 0894-9166 - ISSN (Online) 1860-2134
Published by Elsevier

Dynamic response of a Q&P steel to high-strain-rate tension
- 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
A simplified fatigue assessment method for transverse fillet welded joints
- Authors: Wei Shen; Renjun Yan; Nigel Barltrop; Kai Qin; Feng He
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Wei Shen, Renjun Yan, Nigel Barltrop, Kai Qin, Feng He
  In the as-welded condition the fatigue crack initiation period was considered non-existent and Linear Elastic Fracture Mechanics (LEFM) was used to calculate fatigue strength for a range of weld geometries. Fracture mechanics assessment of welded joints requires accurate solutions for stress intensity factor (SIF). However, the solutions for the SIF of complex welded joints are difficult to determine due to the complicated correction factors. Three methods for SIF prediction are discussed on fillet welded specimens containing continuous or semi-elliptical surface cracks, including the traditional correction method Mk , the approximate correction method Kt , and the suggested additional crack size method (ac+ae). The new additional crack parameter ae is used to replace the stress concentration effect of weld profile Mk , which simplifies the calculation process. Experimental results are collected to support fatigue strength assessment of the additional crack size method.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.001
Frequency-dependent random fatigue of panel-type structures made of
ceramic matrix composites
- Authors: Yadong Zhou; Xiaochen Hang; Shaoqing Wu; Qingguo Fei; Natasa Trisovic
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Yadong Zhou, Xiaochen Hang, Shaoqing Wu, Qingguo Fei, Natasa Trisovic
  The panel-type structures used in aerospace engineering can be subjected to severe high-frequency acoustic loadings in service. This paper evaluates the frequency-dependent random fatigue of panel-type structures made of ceramic matrix composites (CMCs) under acoustic loadings. Firstly, the high-frequency random responses from the broadband random excitation will result in more stress cycles in a definite period of time. The probability density distributions of stress amplitudes will be different in different frequency bandwidths, though the peak stress estimations are identical. Secondly, the fatigue properties of CMCs can be highly frequency-dependent. The fatigue evaluation method for the random vibration case is adopted to evaluate the fatigue damage of a representative stiffened panel structure. The frequency effect through S-N curves on random fatigue damage is numerically verified. Finally, a parameter is demonstrated to characterize the mean vibration frequency of a random process, and hence this parameter can further be considered as a reasonable loading frequency in the fatigue tests of CMCs to obtain more reliable S-N curves. Therefore, the influence of vibration frequency can be incorporated in the random fatigue model from the two perspectives.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.010
Nonstationary plane contact problem in theory of elasticity for conformal
cylindrical surfaces
- Authors: Veniamin D. Kubenko; Ihor V. Yanchevskyi
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Veniamin D. Kubenko, Ihor V. Yanchevskyi
  A numerical-analytical approach is described to investigate the process of impact interaction between a long smooth rigid body and the surface of a circular cylindrical cavity in elastic space. A non-stationary mixed initial boundary value problem is formulated with a priori unknown boundaries moving with variable velocity. The problem is solved using the methods of the theory of integral transforms, expansion of desired variables into a Fourier series, and the quadrature method to reduce the problem to solving a system of linear algebraic equations at each time step. Some concrete numerical computations are presented. The cylindrical body mass and radius impact on the profile of the transient process of contact interaction has been analysed.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.002
Reflection of Elastic Waves at the Elastically Supported Boundary of a
Couple Stress Elastic Half-space
- Authors: Changda Wang; Xuejun Chen; Peijun Wei; Yueqiu Li
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Changda Wang, Xuejun Chen, Peijun Wei, Yueqiu Li
  The reflection elastic waves at the elastically supported boundary of a couple stress elastic half-space are studied in this paper. Different from the classical elastic solid, there are three kinds of elastic waves in the couple stress elastic solid, and two of them are dispersive. The boundary conditions of a couple stress elastic half-space include the couple stress vector and the rotation vector which disappear in the classical elastic solids. These boundary conditions are used to obtain a linear algebraic equation set, from which the amplitude ratios of reflection waves to the incident wave can be determined. Then, the reflection coefficients in terms of energy flux ratios are calculated numerically, and the normal energy flux conservation is used to validate the numerical results. Based on these numerical results, the influences of the boundary parameters, which reflect the mechanical behavior of elastic support, on the reflection energy partition are discussed. Both the incident longitudinal wave (the P wave) and incident transverse wave (the SV wave) are considered.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.004
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
Static response of a layered magneto-electro-elastic half-space structure
under circular surface loading
- Authors: Jiangyi Chen; Junhong Guo
  Abstract: Publication date: Available online 22 March 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Jiangyi Chen, Junhong Guo
  A cylindrical system of vector functions, the stiffness matrix method and the corresponding recursive algorithm are proposed to investigate the static response of transversely isotropic, layered magneto-electro-elastic (MEE) structures over a homogeneous half-space substrate subjected to circular surface loading. In terms of the system of vector functions, we expand the extended displacement and stresses, and deduce two sets of ordinary differential equations, which are related to the expansion coefficients. The solution to one of the two sets of these ordinary differential equations can be evaluated by using the stiffness matrix method and the corresponding recursive algorithm. These expansion coefficients are then integrated by adaptive Gaussian quadrature to obtain the displacements and stresses in the physical domain. Two types of surface loads, mechanical pressure and electric loading, are considered in the numerical examples. The calculated results show that the proposed technique is stable and effective in analyzing the layered half-space MEE structures under surface loading.
  
  PubDate: 2017-04-01T12:35:53Z
  DOI: 10.1016/j.camss.2017.03.003
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
Interaction between a screw dislocation and a circular nano-inhomogeneity
with a bimaterial interface
- Authors: Tengwu He; Wanshen Xiao; Xiangdong Li; Yan Zhang
  Abstract: Publication date: Available online 16 February 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Tengwu He, Wanshen Xiao, Xiangdong Li, Yan Zhang
  The problem of a screw dislocation interacting with a circular nano-inhomogeneity near a bimaterial interface is investigated. The stress boundary condition at the interface between the inhomogeneity and the matrix is modified by incorporating surface/interface stress. The analytical solutions to the problem in explicit series are obtained by an efficient complex variable method associated with the conformal mapping function. The image force exerted on the screw dislocation is also derived using the generalized Peach-Koehler formula. The results indicate that the elastic interference of the screw dislocation and the nano-inhomogeneity is strongly affected by a combination of material elastic dissimilarity, the radius of the inclusion, the distance from the center of inclusion to the bimaterial interface, and the surface/interface stress between the inclusion and the matrix. Additionally, it is found that when the inclusion and Material 3 are both harder than the matrix (μ1 > μ2 and μ3 > μ2), a new stable equilibrium position for the screw dislocation in the matrix appears near the bimaterial interface; when the inclusion and Material 3 are both softer than the matrix (μ1 < μ2 and μ3 < μ2), a new unstable equilibrium position exists close to the bimaterial interface.
  
  PubDate: 2017-02-18T19:00:18Z
  DOI: 10.1016/j.camss.2016.08.001
ANALYSES OF DYNAMIC CHARACTERISTICS OF A FLUID-FILLED THIN RECTANGULAR
POROUS PLATE WITH VARIOUS BOUNDARY CONDITIONS
- Authors: Yu Xiang; Honghua Jiang; Jing Lu
  Abstract: Publication date: Available online 16 February 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Yu Xiang, Honghua Jiang, Jing Lu
  Based on the classical theory of thin plate and Biot theory, a precise model of the transverse vibrations of a thin rectangular porous plate is proposed. The first order differential equations of the porous plate are derived in the frequency domain. By considering the coupling effect between the solid phase and the fluid phase and without any hypothesis for the fluid displacement, the model presented here is rigorous and close to the real materials. Owing to the use of extended homogeneous capacity precision integration method and precise element method, the model can be applied in higher frequency range than pure numerical methods. This model also easily adapts to various boundary conditions. Numerical results are given for two different porous plates under different excitations and boundary conditions.
  
  PubDate: 2017-02-18T19:00:18Z
  DOI: 10.1016/j.camss.2016.12.002
Nonlinear buckling and postbuckling behavior of cylindrical shear
deformable nanoshells subjected to radial compression including surface
free energy effects
- Authors: S. Sahmani; M.M. Aghdam; M. Bahrami
  Abstract: Publication date: Available online 13 February 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): S. Sahmani, M.M. Aghdam, M. Bahrami
  The objective of the present investigation is to predict the nonlinear buckling and postbuckling characteristics of cylindrical shear deformable nanoshells with and without initial imperfection under hydrostatic pressure load in the presence of surface free energy effects. To this end, Gurtin-Murdoch elasticity theory is implemented into the first-order shear deformation shell theory to develop a size-dependent shell model which has an excellent capability to take surface free energy effects into account. A linear variation through the shell thickness is assumed for the normal stress component of the bulk to satisfy the equilibrium conditions on the surfaces of nanoshell. On the basis of variational approach and using von Karman-Donnell-type of kinematic nonlinearity, the non-classical governing differential equations are derived. Then a boundary layer theory of shell buckling is employed incorporating the effects of surface free energy in conjunction with nonlinear prebuckling deformations, large deflections in the postbuckling domain and initial geometric imperfection. Finally, an efficient solution methodology based on a two-stepped singular perturbation technique is put to use in order to obtain the critical buckling loads and postbuckling equilibrium paths corresponding to various geometric parameters. It is demonstrated that the surface free energy effects cause increases in both the critical buckling pressure and critical end-shortening of a nanoshell made of Silicon.
  
  PubDate: 2017-02-13T17:02:22Z
  DOI: 10.1016/j.camss.2017.02.002
Stochastic Averaging of Quasi Integrable and resonant Hamiltonian Systems
Excited by Fractional Gaussian Noise with Hurst index 1/2
- Authors: Q.F. Lü; M.L. Deng; W.Q. Zhu
  Abstract: Publication date: Available online 10 February 2017
  Source:Acta Mechanica Solida Sinica
  Author(s): Q.F. Lü, M.L. Deng, W.Q. Zhu
  A stochastic averaging method of quasi integrable and resonant Hamiltonian systems under excitation of fractional Gaussian noise (fGn) with the Hurst index 1/2 < H < 1 is proposed. First, the definition and the basic property of fGn and related fractional Brownian motion (fBm) are briefly introduced. Then, the averaged fractional stochastic differential equations (SDEs) for the first integrals and combinations of angle variables of the associated Hamiltonian systems are derived. The stationary probability density and statistics of the original systems are then obtained approximately by simulating the averaged SDEs numerically. An example is worked out to illustrate the proposed stochastic averaging method. It is shown that the results obtained by using the proposed stochastic averaging method and those from digital simulation of original system agree well.
  
  PubDate: 2017-02-13T17:02:22Z
  DOI: 10.1016/j.camss.2016.05.002

Nondestructive Testing Method Based on Lamb Waves for Localization and
Extent of Damage#
Authors: Jianlin Chen; Zheng Li; Kezhuang Gong
Abstract: Publication date: Available online 10 February 2017
Source:Acta Mechanica Solida Sinica
Author(s): Jianlin Chen, Zheng Li, Kezhuang Gong
Based on Lamb wave analysis of propagation in plate-like structures, a damage detection method is proposed that not only locates the position of the damage accurately but also estimates its size. Similar damage detection methods focus only on localization giving no quantitative estimation of extent. To improve detection, we propose two predictive circle methods for size estimation. Numerical simulations and experiments were performed for an aluminum plate with a hole. Two PZT configurations of different sizes were designed to excite and detect Lamb waves. From cross-correlation analysis, the damage location and extent can be determined. Results obtained using the proposed method enable a better quantitative resolution in detection, and the size of the inspection area influences the accuracy of damage identification. The closer to the damage, the more accurate the results are. The method proposed can be developed into a multiple-step detection method for multi-scale analysis with prospective accuracy.

PubDate: 2017-02-13T17:02:22Z
DOI: 10.1016/j.camss.2016.06.001

A size-dependent composite laminated skew plate model based on a new
modified couple stress theory
Authors: He Dan; Yang Wanli; Chen Wanji
Abstract: Publication date: Available online 10 February 2017
Source:Acta Mechanica Solida Sinica
Author(s): He Dan, Yang Wanli, Chen Wanji
In this study, a size-dependent composite laminated skew Mindlin plate model is proposed based on a new modified couple stress theory. This plate model can be viewed as a simplified couple stress theory in engineering mechanics. Governing equations and related boundary conditions are derived based on the principle of minimum potential energy. The Rayleigh–Ritz method is employed to obtain the numerical solutions of the center deflections of simply supported plates with different ply orientations. Numerical results show that the normalized center deflections obtained by the proposed model are always smaller than those obtained by the classical one, i.e. the present model can capture the scale effects of microstructures. Moreover, a phenomenon is revealed that the ply orientation would make a significant influence on the magnitude of scale effects of composite laminated plates at micro scale. Additionally, the present model of thick skew plate can be degenerated to the model of Kirchhoff plate based on the modified couple stress theory by adopting the assumptions in Bernoulli-Euler beam and material isotropy.

PubDate: 2017-02-13T17:02:22Z
DOI: 10.1016/j.camss.2016.12.001

Effect of temperature on pull-in voltage and nonlinear vibration behavior
of nanoplate-based NEMS under hydrostatic and electrostatic actuations
Authors: Farzad Ebrahimi; S.H.S. Hosseini
Abstract: Publication date: Available online 10 February 2017
Source:Acta Mechanica Solida Sinica
Author(s): Farzad Ebrahimi, S.H.S. Hosseini
This paper deals with the study of the temperature effect on the nonlinear vibration behavior of nanoplate-based nano electromechanical systems (NEMS) subjected to hydrostatic and electrostatic actuations. Using Eringen's nonlocal elasticity and Gurtin–Murdoch theory, the nonlocal plate model is derived through Hamilton's principle. The governing equation which is extremely nonlinear due to the geometrical nonlinearity and electrostatic attraction forces is solved numerically using the differential quadrature method (DQM). The accuracy of the present method is verified by comparing the obtained results with the experimental data and those in the literature and very good agreement is obtained. Finally a comprehensive study is carried out to determine the influence of temperature on the nonlinear vibration characteristics of NEMS have made of two different materials including aluminum (Al) and silicon (Si) and some conclusions are drawn.

PubDate: 2017-02-13T17:02:22Z
DOI: 10.1016/j.camss.2017.02.001

A unified plasticity methodology for rate- and temperature-sensitive
alloys exhibiting a non-linear kinematic hardening behaviour
Authors: Jacques Luk-Cyr; Daniel Paquet; Jacques Lanteigne; Henri Champliaud; Aurelian Vadean
Abstract: Publication date: Available online 9 February 2017
Source:Acta Mechanica Solida Sinica
Author(s): Jacques Luk-Cyr, Daniel Paquet, Jacques Lanteigne, Henri Champliaud, Aurelian Vadean
In this paper, a novel unified plasticity methodology is proposed to allow the coupling of rate- and temperature-sensitivity of engineering alloys as well as the non-linear kinematic hardening behaviour often observed during cyclic loading. The proposed methodology is general in the sense that an arbitrary constitutive model may be chosen for the viscoplastic part, as well as the cyclic part. We adapt our model with a physically-motivated viscoplasticity flow rule and a nonlinear kinematic hardening model. In contrast with other unified plasticity models, the simplified theory involves few material parameters that can be readily calibrated from standard mechanical tests. The capabilities of the proposed theory are demonstrated for a hot rolled annealed 304L stainless steel supplied by VI-Metal Peckover. The model is tested with stress-strain curves obtained from standard tensile and cyclic uniaxial tests at various strain amplitudes and strain-rates, and good accuracy of the response is obtained for strains up to 15%, within a temperature range of 293 − 673 K. We note that the cyclic plasticity model in our adapted theory can be readily enhanced with ratchetting, mean stress relaxation, strain amplitude history, Masing effects or other complex capabilities.

PubDate: 2017-02-13T17:02:22Z
DOI: 10.1016/j.camss.2016.09.001

Differential derivation of momentum and energy equations IN
electroelasticity
Authors: Jiashi Yang
Abstract: Publication date: Available online 9 February 2017
Source:Acta Mechanica Solida Sinica
Author(s): Jiashi Yang
This paper presents a derivation of the equations of linear momentum, angular momentum, and energy of an electroelastic body using a composite particle consisting of two differential elements based on Tiersten's two-continuum model. The differential derivation shows the physics involved in a way different from the integral approach in the literature. Like the integral approach, it also produces the expressions of the electric body force, couple, and power which are fundamental to the development of the nonlinear macroscopic theory of an electroelastic body.

PubDate: 2017-02-13T17:02:22Z
DOI: 10.1016/j.camss.2016.05.001

Simulation of plastic deformation induced texture evolution using the
crystallographic homogenization finite element method
Authors: Y.P. Chen; Y.Y. Cai
Abstract: Publication date: Available online 9 February 2017
Source:Acta Mechanica Solida Sinica
Author(s): Y.P. Chen, Y.Y. Cai
A semi-implicit elastic/crystalline viscoplastic finite element (FE) method based on a “crystallographic homogenization” approach is formulated for a multi-scale analysis. In the formulation, the asymptotic series expansion is introduced to define the displacement in the micro-continuum. This homogenization FE analysis is aimed at predicting the plastic deformation induced texture evolution of polycrystalline materials, the constituent microstructure of which is represented by an assembly of single crystal grains. The rate dependent crystal plasticity model is adopted for the description of microstructures. Their displacements are decomposed into two parts: the homogenized deformation defined in the macro-continuum and the perturbed one in the micro-continuum. This multi-scale formulation makes it possible to carry out an alternative transition from a representative micro-structure to the macro-continuum. This homogenization procedure satisfies both the compatibility and the equilibrium in the micro-structure. This developed code is applied to predict the texture evolution, and its performance is demonstrated by the numerical examples of texture evolution of FCC polycrystalline metals.

PubDate: 2017-02-13T17:02:22Z
DOI: 10.1016/j.camss.2016.10.002

A new, direct approach toward modeling thermo-coupled fatigue failure
behavior of metals and alloys
Authors: Zhaoling Wang; Hao Li; Zhengnan Yin; Heng Xiao
Abstract: Publication date: Available online 9 February 2017
Source:Acta Mechanica Solida Sinica
Author(s): Zhaoling Wang, Hao Li, Zhengnan Yin, Heng Xiao
The objective of this study is two-fold. Firstly, new finite strain elastoplasticity models are proposed from a fresh standpoint to achieve a comprehensive representation of thermomechanical behavior of metals and alloys over the whole deformation range up to failure. As contrasted with the usual elastoplasticity models, such new models of much simpler structure are totally free, in the sense that both the yield condition and the loading-unloading conditions need not be introduced as extrinsic coercive conditions but are automatically incorporated as inherent constitutive features into the models. Furthermore, the new models are shown to be thermodynamically consistent, in a further sense that both the specific entropy function and the Helmholtz free energy function may be presented in explicit forms, such that the thermodynamic restriction stipulated by Clausius-Duhem inequality for the intrinsic dissipation may be identically satisfied. Secondly, it is then demonstrated that the thermo-coupled fatigue failure behavior under combined cyclic changes of stress and temperature may be derived as direct consequences from the new models. This novel result implies that the new model can directly characterize the thermo-coupled fatigue failure behavior of metals and alloys, without involving any usual damage-like variables as well as any ad hoc additional criteria for failure. In particular, numerical examples show that, under cyclic changes of temperature, the fatigue characteristic curve of fatigue life versus temperature amplitude may be obtained for the first time from model prediction both in the absence and in the presence of stress. Results are in agreement with the salient features of metal fatigue failure.

PubDate: 2017-02-13T17:02:22Z
DOI: 10.1016/j.camss.2016.10.001