Acta Mechanica Sinica
     Acta Mechanica Sinica
  Acta Mechanica Sinica--2014, 30 (3)   Published: 20 May 2014
Preface: Orbits around asteroid
Junfeng Li
A survey on orbital dynamics and navigation of asteroid missions Hot!
He-Xi Baoyin, Jun-Feng Li

Asteroid exploration is currently one of the most concerned topics among international space agencies. Orbital dynamics and navigation are obviously crucial for asteroid exploration. This paper aims to give a brief review on the dynamics, control and navigation of asteroid reconnaissance orbits, including the heliocentric transfer orbit and near asteroid orbit. The developments in optimization techniques of the transfer segment are discussed in detail. We surveyed global researches in this fi...

Averaging analyses for spacecraft orbital motions around asteroids Hot!
Wei-Duo Hu, D. J. Scheeres

This paper summarizes a few cases of spacecraft orbital motion around asteroid for which averaging method can be applied, i.e., when central body rotates slowly, fast, and when a spacecraft is near to the resonant orbits between the spacecraft mean motion and the central body's rotation. Averaging conditions for these cases are given. As a major extension, a few classes of near resonant orbits are analyzed by the averaging method. Then some resulted conclusions of these averaging analyses are...

Routing the asteroid surface vehicle with detailed mechanics Hot!
Yang Yu, He-Xi Baoyin

The motion of a surface vehicle on/above an irregular object is investigated for a potential interest in the insitu explorations to asteroids of the solar system. A global valid numeric method, including detailed gravity and geomorphology, is developed to mimic the behaviors of the test particles governed by the orbital equations and surface coupling effects. A general discussion on the surface mechanical environment of a specified asteroid, 1620 Geographos, is presented to make a global eval...

Modeling method and preliminary model of Asteroid Toutatis from Chang’E-2 optical images Hot!
Xiang-Yu Li, Dong Qiao

Shape modeling is fundamental to the analysis of dynamic environment and motion around asteroid. Chang'E-2 successfully made a flyby of Asteroid 4179 Toutatis and obtained plenty of high-resolution images during the mission. In this paper, the modeling method and preliminary model of Asteroid Toutatis are discussed. First, the optical images obtained by Chang'E-2 are analyzed. Terrain and silhouette features in images are described. Then, the modeling method based on previous radar model and ...

A method for classifying orbits near asteroids Hot!
Xian-Yu Wang, Sheng-Ping Gong, Jun-Feng Li

A method for classifying orbits near asteroids under a polyhedral gravitational field is presented, and may serve as a valuable reference for spacecraft orbit design for asteroid exploration. The orbital dynamics near asteroids are very complex. According to the variation in orbit characteristics after being affected by gravitational perturbation during the periapsis passage, orbits near an asteroid can be classified into 9 categories: (1) surroundingto-surrounding, (2) surrounding-to-surface...

Surface integral analogy approaches for predicting noise from 3D high-lift low-noise wings Hot!
Hua-Dong Yao, Lars Davidson, Lars-Erik Eriksson, Shia-Hui Peng, Olof Grundestam, Peter E. Eliasson

Three surface integral approaches of the acoustic analogies are studied to predict the noise from three conceptual configurations of three-dimensional high-lift low-noise wings. The approaches refer to the Kirchhoff method, the Ffowcs Williams and Hawkings (FW-H) method of the permeable integral surface and the Curle method that is known as a special case of the FW-H method. The first two approaches are used to compute the noise generated by the core flow region where the energetic structures...

Scaling law of resolved-scale isotropic turbulence and its application in large-eddy simulation
Le Fang, Bo Li, Li-Peng Lu

Eddy-dampingquasinormalMarkovian (EDQNM) theory is employed to calculate the resolved-scale spectrum and transfer spectrum, based on which we investigate the resolved-scale scaling law. Results show that the scaling law of the resolved-scale turbulence, which is affected by several factors, is far from that of the full-scale turbulence and should be corrected. These results are then applied to an existing subgrid model to improve its performance. A series of simulations are performed to verif...

Study on the operational safety of high-speed trains exposed to stochastic winds
Meng-Ge Yu, Ji-Ye Zhang, Ke-Yue Zhang, Wei-Hua Zhang

The characteristic wind curve (CWC) was commonly used in the previous work to evaluate the operational safety of the high-speed trains exposed to crosswinds. However, the CWC only provide the dividing line between safety state and failure state of high-speed trains, which can not evaluate the risk of derailment of high-speed trains when exposed to natural winds. In the present paper, a more realistic approach taking into account the stochastic characteristics of natural winds is proposed, whi...

Experimental investigation of the effect of Reynolds number on flow structures in the wake of a circular parachute canopy
Zhe-Yan Jin, Sylvio Pasqualini, Bo Qin

In the present study, an experimental study was conducted to characterize the effect of Reynolds number on flow structures in the turbulent wake of a circular parachute canopy by utilizing stereoscopic particle image velocimetry (Stereo-PIV) technique. The parachute model tested in the present study was attached by 28 nylon suspension lines and placed horizontally at the test section center of the wind tunnel. The obtained results showed that with the increase of Reynolds number, the intensit...

A biarc-based shape optimization approach to reduce stress concentration effects
Liang Meng, Wei-Hong Zhang, Ji-Hong Zhu, Liang Xia

In order to avoid stress concentration, the shape boundary must be properly designed via shape optimization. Traditional shape optimization approach eliminates the stress concentration effect by using free-form curve to present the design boundaries without taking the machinability into consideration. In most numerical control (NC) machines, linear as well as circular interpolations are used to generate the tool path. Non-circular curves, such as nonuniform rotational B-spline (NURBS), need o...

Fuzzy finite difference method for heat conduction analysis with uncertain parameters
Chong Wang, Zhi-Ping Qiu

A new numerical technique named as fuzzy finite difference method is proposed to solve the heat conduction problems with fuzzy uncertainties in both the physical parameters and initial/boundary conditions. In virtue of the level-cut method, the difference discrete equations with fuzzy parameters are equivalently transformed into groups of interval equations. New stability analysis theory suited to fuzzy difference schemes is developed. Based on the parameter perturbationmethod, the interval r...

Optimum design of hierarchical stiffened shells for low imperfection sensitivity
Bo Wang, Peng Hao, Gang Li, Jia-Xin Zhang, Kai-Fan Du, Kuo Tian, Xiao-Jun Wang, Xiao-Han Tang

A concept of hierarchical stiffened shell is proposed in this study, aiming at reducing the imperfection sensitivity without adding additional weight. Hierarchical stiffened shell is composed of major stiffeners and minor stiffeners, and the minor stiffeners are generally distributed between adjacent major stiffeners. For various types of geometric imperfections, e.g., eigenmode-shape imperfections, hierarchical stiffened shell shows significantly low imperfection sensitivity compared to trad...

A fractional differential constitutive model for dynamic stress intensity factors of an anti-plane crack in viscoelastic materials
Run-Tao Zhan, Zhao-Xia Li, Lei Wang

Fractional differential constitutive relationships are introduced to depict the history of dynamic stress intensity factors (DSIFs) for a semi-infinite crack in infinite viscoelastic material subjected to anti-plane shear impact load. The basic equations which govern the anti-plane deformation behavior are converted to a fractionalwave-like equation. By utilizing Laplace and Fourier integral transforms, the fractional wave-like equation is cast into an ordinary differential equation (ODE). Th...

Folding of multi-layer graphene sheets induced by van der Waals interaction
Xian-Hong Meng, Ming Li, Zhan Kang, Jian-Liang Xiao

Graphene sheets are extremely flexible, and thus small forces, such as van der Waals interaction, can induce significant out-of-plane deformation, such as folding. Folded graphene sheets show racket shaped edges, which can significantly affect the electrical properties of graphene. In this paper, we present combined theoretical and computational studies to reveal the folding behavior of multi-layer graphene sheets. A nonlinear theoretical model is established to determine the critical length ...

Corotational nonlinear analyses of laminated shell structures using a 4-node quadrilateral flat shell element with drilling stiffness
Zhen Wang, Qin Sun

A new 4-node quadrilateral flat shell element is developed for geometrically nonlinear analyses of thin and moderately thick laminated shell structures. The flat shell element is constructed by combining a quadrilateral area coordinate method (QAC) based membrane element AGQ6-Ⅱ, and a Timoshenko beam function (TBF) method based shear deformable plate bending element ARS-Q12. In order to model folded plates and connect with beam elements, the drilling stiffness is added to the element stiffnes...

Experiment and evaluation of wrinkling strain in a corner tensioned square membrane
Lan Lan, Chang-Guo Wang, Hui-Feng Tan

Prediction of wrinkling characteristics is strongly correlated with the strain perpendicular to wrinkling direction. In this paper, the strain field of wrinkled membrane is tested by VIC-3D system based on the digital image correlation technique. Experimental results are validated by the tension wrinkling simulation. The experimental strain perpendicular to wrinkling direction is analyzed in depth. The wrinkling strain of a square wrinkled membrane under corner tension is extracted from exper...

Modeling and analysis of rigid multibody systems with driving constraints and frictional translation joints
Fang-Fang Zhuang, Qi Wang

An approach is proposed for modeling and analyses of rigid multibody systems with frictional translation joints and driving constraints. The geometric constraints of translational joints with small clearance are treated as bilateral constraints by neglecting the impact between sliders and guides. Firstly, the normal forces acting on sliders, the driving constraint forces (or moments) and the constraint forces of smooth revolute joints are all described by complementary conditions. The frictio...

The impact of N-terminal phosphorylation on LHCII conformation in state transition
Jin-Hong Ding, Ning Li, Man-Liu Wang, Yan Zhang, Shou-Qin Lü, Mian Long

State transition is an important protection mechanism of plants for maintaining optimal efficiency through redistributing unbalanced excitation energy between photosystem Ⅱ (PSII) and photosystem Ⅰ (PSI). This process depends on the reversible phosphorylation/dephosphorylation of the major light-harvesting complex Ⅱ (LHCII) and its bi-directional migration between PSII and PSI. But it remains unclear how phosphorylation/dephosphorylation modulates the LHCII conformation and further regulates ...

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