Acta Mechanica Sinica
     Acta Mechanica Sinica
  Acta Mechanica Sinica--2012, 28 (5)   Published: 25 October 2012
Research papers
Simulation of the Brownian coagulation of nanoparticles with initial bimodal size distribution via moment method Hot!
Jian-Zhong Lin, Fu-Jun Gan

The Brownian coagulation of nanoparticles with initial bimodal size distribution, i.e., mode em and j, is numerically studied using the moment method. Evolutions of particle number concentration, geometric average diameter and geometric standard deviation are given in the free molecular regime, the continuum regime, the free molecular regime and transition regime, the free molecular regime and continuum regime, respectively. The results show that, both in the free molecular ...

Investigation of vortical flow over bluff bodies with base cavities
Shu-Cheng Pan, Jin-Sheng Cai

Based on our previous research about drag reduction in term of the base cavity length using two dimensional simulations, this paper describes a numerical study of a bluff body of which the number of base cavities is successively increased and the cavity geometries are also modified to assume different shapes. Here we attempt to find an effective configuration to reduce the drag by increasing the number of base cavities. The numerical simulations examining varied number of base cavities reveal...

Experimental and numerical study on the growth and collapse of a bubble in a narrow tube
Bao-Yu Ni, A-Man Zhang, Qian-Xi Wang, Bin Wang

The growth, expansion and collapse of a bubble in a narrow tube are studied using both experiments and numerical simulations. In experiment, the bubble is generated by an electric spark in a water tank and recorded by a highspeed camera system. In numerical simulation, the evolution of the bubble is solved by adopting axisymmetric boundary integral equation, considering the surface tension effect. The results of experiments and numerical simulations are compared and good agreements are achiev...

Measurement of surface shear stress vector distribution using shear-sensitive liquid crystal coatings
Ji-Song Zhao, Peter Scholz, Liang-Xian Gu

The global wall shear stress measurement technique using shear-sensitive liquid crystal (SSLC) is extended to wind tunnel measurements. Simple and common everyday equipment is used in the measurement; in particular a tungsten-halogen light bulb provides illumination and a saturation of SSLC coating color change with time is found. Spatial wall shear stress distributions of several typical flows are obtained using this technique, including wall-jet flow, vortex flow generated by a delta wing a...

Starting flow in a rotating parallel plate channel
Chang Yi Wang

The starting flow due to a suddenly applied pressure gradient in a parallel plate channel which is rotating as a system is studied. Exact analytic series solutions to the unsteady Navier-Stokes equations are found by both the Laplace transform method and the separation of parameters method, the latter is shown to be superior. Rotation not only induces a secondary transverse flow but also alters the character of the transient flow rate and velocity profiles. Back flow and inertial oscillations...

Topological analysis of plasma flow control on corner separation in a highly loaded compressor cascade
Xiao-Hu Zhao, Yun Wu, Ying-Hong Li, Xue-De Wang, Qin Zhao

In this paper, flow behavior and topology structure in a highly loaded compressor cascade with and without plasma aerodynamic actuation (PAA) are investigated. Streamline pattern, total pressure loss coefficient, outlet flow angle and topological analysis are considered to study the effect and mechanism of the plasma flow control on corner separation. Results presented include the boundary layer flow behavior, effects of three types of PAA on separated flows and performance parameters, topolo...

The simulation of gas production from oceanic gas hydrate reservoir by the combination of ocean surface warm water flooding with depressurization
Hao Yang, Yu-Hu Bai, Qing-Ping Li

A new method is proposed to produce gas from oceanic gas hydrate reservoir by combining the ocean surface warm water flooding with depressurization which can efficiently utilize the synthetic effects of thermal, salt and depressurization on gas hydrate dissociation. The method has the advantage of high efficiency, low cost and enhanced safety. Based on the proposed conceptual method, the physical and mathematical models are established, in which the effects of the flow of multiphase fluid, th...

Measurements of non-equilibrium and equilibrium temperature behind a strong shock wave in simulated martian atmosphere
Xin Lin, Xi-Long Yu, Fei Li, Shao-Hua Zhang, Jian-Guo Xin, Xin-Yu Zhang

Non-equilibrium radiation measurements behind strong shock wave for simulated Martian atmosphere are presented in this paper. The shock wave is established in a hydrogen oxygen combustion driven shock tube. Timeresolved spectra of the Δv = 0 sequence of the B2Σ+X2Σ+ electronic transition of CN have been observed through optical emission spectroscopy (OES). A new method, which is b...

The prediction on in-line vortex-induced vibration of slender marine structures
Wan-Hai Xu, Xi-Feng Gao, Jie Du

The in-line (IL) vortex-induced vibration (VIV) that occurs frequently in ocean engineering may cause severe fatigue damage in slender marine structures. To the best knowledge of the authors, in existing literatures, there is no efficient analytical model for predicting pure IL VIV. In this paper, a wake oscillator model capable of analyzing the IL VIV of slender marine structures has been developed. Two different kinds of van der Pol equations are used to describe the near wake dynamics rela...

A consistent projection-based SUPG/PSPG XFEM for incompressible two-phase flows
Jian-Hui Liao, Zhuo Zhuang

In this paper, a consistent projection-based streamline upwind/pressure stabilizing Petrov-Galerkin (SUPG/PSPG) extended finite element method (XFEM) is presented to model incompressible immiscible two-phase flows. As the application of linear elements in SUPG/PSPG schemes gives rise to inconsistency in stabilization terms due to the inability to regenerate the diffusive term from viscous stresses, the numerical accuracy would deteriorate dramatically. To address this issue, projections of co...

The effect of agglomerate on micro-structural evolution in solid-state sintering
Chao Wang, Shao-Hua Chen

Discrete element method (DEM) is used in the present paper to simulate the microstructural evolution of a planar layer of copper particles during sintering. Formation of agglomerates and the effect of their rearrangement on densification are mainly focused on. Comparing to the existing experimental observations, we find that agglomerate can form spontaneously in sintering and its rearrangement could accelerate the densification of compacts. Snapshots of numerical simulations agree qualitative...

The second Eshelby problem and its solvability
Wen-Nan Zou, Quan-Shui Zheng

It is still a challenge to clarify the dependence of overall elastic properties of heterogeneous materials on the microstructures of non-elliposodal inhomogeneities (cracks, pores, foreign particles). From the theory of elasticity, the formulation of the perturbance elastic fields, coming from a non-ellipsoidal inhomogeneity embedded in an infinitely extended material with remote constant loading, inevitably involve one or more integral equations. Up to now, due to the mathematical difficulty...

Effects of laser power density on static and dynamic mechanical properties of dissimilar stainless steel welded joints
Yan-Peng Wei, Mao-Hui Li, Gang Yu, Xian-Qian Wu, Chen-Guang Huang, Zhu-Ping Duan

The mechanical properties of laser welded joints under impact loadings such as explosion and car crash etc. are critical for the engineering designs. The hardness, static and dynamic mechanical properties of AISI304 and AISI316 L dissimilar stainless steel welded joints by CO2 laser were experimentally studied. The dynamic strain- stress curves at the strain rate around 103 s-1 were obtained by the split Hopkinson tensile bar (SHTB). The static mechanical prop...

Bounds on the overall properties of composites with ellipsoidal inclusions
Lin-Zhi Wu, Shi-Dong Pan

A new model is put forward to bound the effective elastic moduli of composites with ellipsoidal inclusions. In the present paper, transition layer for each ellipsoidal inclusion is introduced to make the trial displacement field for the upper bound and the trial stress field for the lower bound satisfy the continuous interface conditions which are absolutely necessary for the application of variational principles. According to the principles of minimum potential energy and minimum complementa...

Experimental study on mechanical properties of methane-hydrate-bearing sediments
Xu-Hui Zhang, Xiao-Bing Lu, Li-Min Zhang, Shu-Yun Wang, Qing-Ping Li

Mechanical properties of methane hydratebearing- sediments (MHBS) are basic parameters for safety analysis of hydrate exploration and exploitation. Young’s modulus, cohesion, and internal friction angle of hydratebearing sediments synthesized in laboratory, are investigated using tri-axial tests. Stress-strain curves and strength parameters are obtained and discussed for different compositions and different hydrate saturation, followed by empirical expressions related to the cohesion, i...

A quadrilateral membrane hybrid stress element with drilling degrees of freedom
An-Ping Wang

A new kind of quadrilateral assumed stress hybrid membrane element with drilling degrees of freedom and a traction-free inclined side has been developed based on an extended Hellinger-Reissner principle which is established by expanding the essential terms of the assumed stress field as polynomials in the natural coordinates of the element. The homogeneous equilibrium equations are imposed in a variational sense through the internal displacements which are also expanded in the natural coordin...

Tensionless contact of a finite circular plate
Yin Zhang, Kevin D. Murphy

A general formulation is developed for the contact behavior of a finite circular plate with a tensionless elastic foundation. The gap distance between the plate and elastic foundation is incorporated as an important parameter. Unlike the previous models with zero gap distance and large/infinite plate radius, which assumes the lift-off/separation of a flexural plate from its supporting elastic foundation, this study shows that lift-off may not occur. The results show how the contact area varie...

Effect of ion-beam assisted deposition on the film stresses of TiO2 and SiO2 and stress control
Yu-Qiong Li, Hua-Qing Wang, Wu-Yu Wang, Zhi-Nong Yu, He-Shan Liu, Gang Jin

Based on Hartmann-Shack sensor technique, an online thin film stress measuring system was introduced to measure the film stresses of TiO2 and SiO2, and comparison was made between the film stresses prepared respectively by the conventional process and the ion-beam assisted deposition. The effect of ion-beam assisted deposition on the film stresses of TiO2 and SiO2 was investigated in details, and the stress control methodologies using on-line adjust...

Numerical analysis of confinement effect on crack propagation mechanism from a flaw in a pre-cracked rock under compression
Amin Manouchehrian, Mohammad Fatehi Marji

In many situations rocks are subjected to biaxial loading and the failure process is controlled by the lateral confinement stresses. The importance of confinement stresses has been recognized in the literature by many researchers, in particular, its influence on strength and on the angle of fracture, but still there is not a clear description for the influence of confining stress on the crack propagation mechanism of rocks. This paper presents a numerical procedure for the analysis of crack p...

Upper-bound limit analysis based on the natural element method
Shu-Tao Zhou, Ying-Hua Liu

The natural element method (NEM) is a newlydeveloped numerical method based on Voronoi diagram and Delaunay triangulation of scattered points, which adopts natural neighbour interpolation to construct trial functions in the framework of Galerkin method. Owing to its distinctive advantages, the NEM is used widely in many problems of computational mechanics. Utilizing the NEM, this paper deals with numerical limit analysis of structures made up of perfectly rigid-plastic material. According to ...

A kind of noise-induced transition to noisy chaos in stochastically perturbed dynamical system
Chun-Biao Gan, Shi-Xi Yang, Hua Lei

We investigate a kind of noise-induced transition to noisy chaos in dynamical systems. Due to similar phenomenological structures of stable hyperbolic attractors excited by various physical realizations from a given stationary random process, a specific Poincaré map is established for stochastically perturbed quasi-Hamiltonian system. Based on this kind of map, various point sets in the Poincaré’s cross-section and dynamical transitions can be analyzed. Results from the cu...

Synchronization of three homodromy coupled exciters in a non-resonant vibrating system of plane motion
Xue-Liang Zhang, Bang-ChunWen, Chun-Yu Zhao

In this paper, the synchronization problem of three homodromy coupled exciters in a non-resonant vibrating system of plane motion is studied. By introducing the average method of modified small parameters, we deduced dimensionless coupling equation of three exciters, which converted the problem of synchronization into that of the existence and stability of zero solutions for the average differential equations of the small parameters. Based on the dimensionless coupling torques and characteris...

Reducing force transmissibility in multiple degrees of freedom structures through anti-symmetric nonlinear viscous damping
Z.-K. Peng, Z.-Q. Lang, G. Meng, S. A. Billings

In the present study, the Volterra series theory is adopted to theoretically investigate the force transmissibility of multiple degrees of freedom (MDOF) structures, in which an isolator with nonlinear anti-symmetric viscous damping is assembled. The results reveal that the anti-symmetric nonlinear viscous damping can significantly reduce the force transmissibility over all resonance regions for MDOF structures with little effect on the transmissibility over non-resonant and isolation regions...

Motion planning for redundant prismatic-jointed manipulators in the free-floating mode
Xiao-Dong Liu, He-Xi Baoyin, Xing-Rui Ma

This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. ...

Modeling and analysis of passive dynamic bipedal walking with segmented feet and compliant joints
Yan Huang, Qi-Ning Wang, Yue Gao, Guang-Ming Xie

Passive dynamic walking has been developed as a possible explanation for the efficiency of the human gait. This paper presents a passive dynamic walking model with segmented feet, which makes the bipedal walking gait more close to natural human-like gait. The proposed model extends the simplest walking model with the addition of flat feet and torsional spring based compliance on ankle joints and toe joints, to achieve stable walking on a slope driven by gravity. The push-off phase includes fo...

First-round design of the flight scenario for Chang’e-2’s extended mission: takeoff from lunar orbit
Yang Gao, Heng-Nian Li, Sheng-Mao He

Chang’e-2, Chinese second lunar probe, was inserted into a 100 km altitude low lunar orbit on October 9th, 2010, its purpose is to continuously photograph the lunar surface and possibly chosen landing sites for future lunar missions. The probe will still carry considerable amount of propellant after completing all prescribed tasks in about six months. After the successful launch of Chang’e-2, we began designing the probe’s subsequent flight scenario, considering a total impu...

Influence of flexible solar arrays on vibration isolation platform of control moment gyroscopes
Yao Zhang, Jing-Rui Zhang, Shi-Jie Xu

A high-performance vibration isolation platform (VIP) has been developed for a cluster of control moment gyroscopes (CMGs). CMGs have long been used for satellite attitude control. In this paper, the influence of flexible solar arrays on a passive multi-strut VIP of CMGs for a satellite is analyzed. The reasonable parameters design of flexible solar arrays is discussed. Firstly, the dynamic model of the integrated satellite with flexible solar arrays, the VIP and CMGs is conducted by Newton-E...

The study on the mechanical characteristics of articular cartilage in simulated microgravity
Hai-Jun Niu, Qing Wang, Yue-Xiang Wang, Ang Li, Lian-Wen Sun, Yan Yan, Fan Fan, De-Yu Li, Yu-Bo Fan

The microgravity environment of a long-term space flight may induce acute changes in an astronaut’s musculo-skeletal systems. This study explores the effects of simulated microgravity on the mechanical characteristics of articular cartilage. Six rats underwent tail suspension for 14 days and six additional rats were kept under normal earth gravity as controls. Swelling strains were measured using high-frequency ultrasound in all cartilage samples subject to osmotic loading. Site-specifi...

Investigation on 3Dt wake flow structures of swimming bionic fish
G.-X. Shen, G.-K. Tan, G.-J. Lai

A bionic experimental platform was designed for the purpose of investigating time accurate three-dimensional flow field, using digital particle image velocimetry (DSPIV). The wake behind the flapping trail of a robotic fish model was studied at high spatial resolution. The study was performed in a water channel. A robot fish model was designed and built. The model was fixed onto a rigid support framework using a cable-supporting method, with twelve stretched wires. The entire tail of the mode...

Retraction Note: Effects of boundary slippage on thin-film lubrication between two nonparallel plane plates
Shu-Hao Ban, Xiao-Yan Li

This article is retracted at the request of the Editor-in- Chief and the author due to copyright issues concerning all the research data, theory, method and conclusion.

Retraction Note: A note on the unsteady flow of a fractional Maxwell fluid through a circular cylinder
M. Athar, A. U. Awan, Corina Fetecau

This article is retracted at the request of the Editorin- Chief because of similarity to previously published material, specifically that in the first paragraph of article: Exact solutions for the Poiseuille flow of a generalized Maxwell fluid induced by time-dependent shear stress published on Anziam J. 51, 416-429 (2010) with DOI: 10.1017/S1446181111000514.

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