Acta Mechanica Sinica
     Acta Mechanica Sinica
  Acta Mechanica Sinica--2019, 35 (3)   Published: 15 June 2019
FLUID MECHANICS
Two-point statistics of coherent structures in turbulent flow over riblet-mounted surfaces
Weipeng Li, Hong Liu
Abstract
Direct numerical simulations (DNS) of turbulent flow over a drag-reducing and a drag-increasing riblet configuration are performed. Three-dimensional two-point statistics are presented for the first time to quantify the interaction of the riblet surfaces with the coherent, energy-bearing eddy structures in the near-wall region. Results provide statistical evidence that the averaged organization of the streamwise vortices in the drag-reducing case is lifted above the riblet tip, while in the drag...
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Modified smoothed particle hydrodynamics approach for modelling dynamic contact angle hysteresis
Yanyao Bao, Ling Li, Luming Shen, Chengwang Lei, Yixiang Gan
Abstract
Dynamic wetting plays an important role in the physics of multiphase flow, and has a significant influence on many industrial and geotechnical applications. In this work, a modified smoothed particle hydrodynamics (SPH) model is employed to simulate surface tension, contact angle and dynamic wetting effects at meso-scale. The wetting and dewetting phenomena are simulated in a capillary tube, where the liquid particles are raised or withdrawn by a shifting substrate. The SPH model is modified by ...
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Applying resolved-scale linearly forced isotropic turbulence in rational subgrid-scale modeling
Chuhan Wang, Mingwei Ge
Abstract
In previous attempts of rational subgrid-scale (SGS) modeling by employing the Kolmogorov equation of filtered (KEF) quantities, it was necessary to assume that the resolved-scale second-order structure function is stationary. Forced isotropic turbulence is often used as a framework for establishing and validating such SGS models based on stationary restrictions, for it generates statistical stationary samples. However, traditional forcing method at low wavenumbers cannot provide an analytic for...
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SOLID MECHANICS
Constitutive modeling of viscoelastic-viscoplastic behavior of short fiber reinforced polymers coupled with anisotropic damage and moisture effects
Ge He, Yucheng Liu, Xingqiao Deng, Lei Fan
Abstract
In this paper, a combined viscoelasticity-viscoplasticity model, coupled with anisotropic damage and moisture effects, is developed for short fiber reinforced polymers (SFRPs) with different fiber contents and subjected to a variety of strain rates. In our model, a rate-dependent yield surface for the matrix phase is employed to identify initial yielding of the material. When an SFRP is loaded at small deformation before yielding, its viscoelastic behavior can be described using the generalized ...
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A new design of dual-constituent triangular lattice metamaterial with unbounded thermal expansion
Y. C. Zhang, Y. J. Liang, S. T. Liu, Y. D. Su
Abstract
Triangular lattice metamaterials composed of bi-layer curved rib elements (called the Lehman-Lakes lattice) possess unbounded thermal expansion, high stiffness and impossibility of thermal buckling, which are highly desirable in many engineering structural applications subjected to large fluctuations in temperature. However, the requirement of such lattice metamaterial is that it must be a hinged joint in order to achieve the bending deformation upon heating freely, which directly leads to poor ...
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Modified spherical cavity-expansion model for projectile penetration into concrete targets
Y. Peng, H. Wu, Q. Fang, X. Z. Kong
Abstract
A modified spherical cavity-expansion model is developed in this paper. (1) We introduce a piecewise hyperbolic yield criterion suitable for pressure less than fc/3 to describe the mechanical behavior in the elastic region for the elastic-plastic response and modify the crack occurrence condition for the elastic-cracked-plastic response. (2) The hyperbolic yield criterion and a piecewise equation of state (EOS) are adopted for a better description of the plastic behavior of c...
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Spherical cavity-expansion model for penetration of reinforced-concrete targets
Y. J. Deng, W. J. Song, X. W. Chen
Abstract
The feature of reinforcing bars is introduced into dynamic cavity-expansion theory. Based on the elastic-plastic response penetration model of plain (i.e., unreinforced) concrete (Forrestal and Tzou, 1997), a dynamic spherical cavity-expansion penetration model for reinforced-concrete targets is developed with consideration of the circumferential restriction effect derived from reinforcing bars in the crushed region. The theoretical solution and simplified calculation formula for the cavity radi...
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ICM method for topology optimization of multimaterial continuum structure with displacement constraint
Hong-Ling Ye, Zong-Jie Dai, Wei-Wei Wang, Yun-Kang Sui
Abstract
A new topology optimization method is formulated for lightweight design of multimaterial structures, using the independent continuous mapping (ICM) method to minimize the weight with a prescribed nodal displacement constraint. Two types of independent topological variable are used to identify the presence of elements and select the material for each phase, to realize the interpolations of the element stiffness matrix and total weight. Furthermore, an explicit expression for the optimized formula...
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Three-dimensional constitutive model for magneto-mechanical deformation of NiMnGa ferromagnetic shape memory alloy single crystals
Chao Yu, Guozheng Kang, Di Song, Xi Xie
Abstract
Existing experimental results have shown that four types of physical mechanisms, namely, martensite transformation, martensite reorientation, magnetic domain wall motion and magnetization vector rotation, can be activated during the magneto-mechanical deformation of NiMnGa ferromagnetic shape memory alloy (FSMA) single crystals. In this work, based on irreversible thermodynamics, a three-dimensional (3D) single crystal constitutive model is constructed by considering the aforementioned four mech...
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One-dimensional analysis of the coupling between diffusion and deformation in a bilayer electrode
Yaohong Suo, Fuqian Yang
Abstract
Diffusion-induced deformation during electrochemical cycling plays an important role in determining structural durability of the electrodes in lithium-ion batteries. In this work, we investigate the coupling between diffusion and stress in the boundary conditions of a bilayer electrode, and analyze the evolution of the lithium concentration and stress. Numerical simulations are performed under four different combinations of the boundary conditions between diffusion and mechanical deformation. Th...
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Simulation of ductile fracture initiation in steels using a stress triaxiality-shear stress coupled model
Yazhi Zhu, Michael D. Engelhardt, Zuanfeng Pan
Abstract
Micromechanics-based models provide powerful tools to predict initiation of ductile fracture in steels. A new criterion is presented herein to study the process of ductile fracture when the effects of both stress triaxiality and shear stress on void growth and coalescence are considered. Finite-element analyses of two different kinds of steel, viz. ASTM A992 and AISI 1045, were carried out to monitor the history of stress and strain states and study the methodology for determining fracture initi...
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Multi-scale fatigue damage model for steel structures working under high temperature
Huajing Guo, Bin Sun, Zhaoxia Li
Abstract
In order to better understand the fatigue mechanisms of steel structures working under high temperature, a multi-scale fatigue damage model at high temperature is developed. In the developed model, the macroscopic fatigue damage of metallic materials due to the collective behavior of micro-cracks is quantified by using the generalized self-consistent method. The influence of temperature on fatigue damage of steel structures is quantified by using the previous creep damage model. In addition, the...
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DYNAMICS, VIBRATION, AND CONTROL
Parameter design for a vibration absorber with time-delayed feedback control
Feng Wang, Jian Xu
Abstract

Traditional passive vibration absorbers are effective only when their natural frequencies are close to those of the excitations. To solve this problem, a vibration absorber with time-delayed feedback control is proposed to suppress vibration of the primary system under excitation with changing frequency. Firstly, the mechanical model of the delay coupled system is established. Then, the displacement transfer ratio of the system is obtained. The stability of the system is analyzed since delay ...

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Accurate real-time truck simulation via semirecursive formulation and Adams-Bashforth-Moulton algorithm
Yongjun Pan, Yansong He, Aki Mikkola
Abstract
In this paper, a tailored four-step Adams-Bashforth-Moulton (ABM) algorithm is applied to a semirecursive formulation to perform a real-time simulation of a semitrailer truck. In the ABM algorithm, each integration step involves two function evaluations, namely predictor and corrector. This is fundamentally different when compared to the classic fourth-order Runge-Kutta (RK) integrator approach that contains four function evaluations. A semitrailer truck under investigation is modeled in term of...
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Axially variable-length solid element of absolute nodal coordinate formulation
Jialiang Sun, Qiang Tian, Haiyan Hu, Niels L. Pedersen
Abstract
An axially variable-length solid element with eight nodes is proposed by integrating the arbitrary Lagrangian-Eulerian (ALE) formulation and the absolute nodal coordinate formulation (ANCF). In addition to the nodal positions and slopes of eight nodes, two material coordinates in the axial direction are used as the generalized coordinates. As a consequence, the nodes in the ALE-ANCF are not associated with any specific material points and the axial length of the solid element can be varied over ...
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Extraction of mode shapes of beam-like structures from the dynamic response of a moving mass
Yao Zhang, Longqi Wang, Haisheng Zhao, Seng Tjhen Lie
Abstract
This paper proposes an approach to extract the mode shapes of beam-like structures from the dynamic response of a moving mass. When a mass passes through a beam containing several artificially installed humps, its vertical acceleration can be recorded. After applying fast Fourier transformation to the dynamic response, one can extract the mode shapes of the beam. The surface roughness was neglected compared to the humps and its adverse effect on the extraction was reduced. The passing mass perfo...
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Combined approach for analysing evolutionary power spectra of a track-soil system under moving random loads
Y. Zhao, L. T. Si, H. Ouyang
Abstract
The pseudo-excitation method combined with the integral transform method (PEM-ITM) is presented to investigate the ground vibration of a coupled track-soil system induced by moving random loads. Commonly in the track model, the rail, sleepers, rail pads, and ballast are modelled as an infinite Euler beam, discretely distributed masses, discretely distributed vertical springs, and a viscoelastic layer, respectively. The soil is regarded as a homogenous isotropic half-space coupled with the track ...
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BIOMECHANICS
Numerical study of clathrin-mediated endocytosis of nanoparticles by cells under tension
Xinyue Liu, Hongwei Yang, Yunqiao Liu, Xiaobo Gong, Huaxiong Huang
Abstract
In this study, a three-dimensional mathematical model was used to study the contribution of clathrins during the process of cellular uptake of spherical nanoparticles under different membrane tensions. The clathrin-coated pit (CCP) that forms around the inward budding of the cell membrane was modeled as a vesicle with bending rigidity. An optimization algorithm was proposed for minimizing the total energy of the system, which comprises the deforming nanoparticle, receptor-ligand bonds, cell memb...
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Macroscopic and microscopic mechanical behaviors of climbing tendrils
Q. Guo, J. J. Dong, Y. Liu, X. H. Xu, Q. H. Qin, J. S. Wang
Abstract
Tendril-bearing climbing plants must recur to the tendril helices with chiral perversion or dual chirality for climbing and to obtain sun exposure. Despite researchers' prolonged fascination with climbing tendrils since Darwin's time and even earlier, why the soft and slender tendrils can bear heavy loads such as the self-weight of a plant or additional load caused by rain remains elusive. In this paper, we take towel gourd tendrils as an example and investigate the macroscopic and microscopic m...
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CORRECTION
Correction to: Approximate solutions of the Alekseevskii-Tate model of long-rod penetration
W. J. Jiao, X. W. Chen
Abstract
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