Acta Mechanica Sinica
     Acta Mechanica Sinica
  Acta Mechanica Sinica--2011, 27 (5)   Published: 18 October 2011
Research Papers
The criterion of the existence or inexistence of transverse shock wave at wedge supported oblique detonation wave Hot!
Ai-Feng Wang, Wei Zhao, Zong-Lin Jiang
Abstract
A simplified theoretic method and numerical simulations were carried out to investigate the characterization of propagation of transverse shock wave at wedge supported oblique detonation wave. After solution validation, a criterion which is associated with the ratio Φ (u2/uCJ) of existence or inexistence of the transverse shock wave at the region of the primary triple was deduced systematically by 38 cases. It is observed that for abrupt obliq...
Doubly periodic patterns of modulated hydrodynamic waves: exact solutions of the Davey-Stewartson system
J.-H. Li, S.-Y. Lou, K.-W. Chow
Abstract
Exact doubly periodic standing wave patterns of the Davey-Stewartson (DS) equations are derived in terms of rational expressions of elliptic functions. In fluid mechanics, DS equations govern the evolution of weakly nonlinear, free surface wave packets when long wavelength modulations in two mutually perpendicular, horizontal directions are incorporated. Elliptic functions with two different moduli (periods) are necessary in the two directions. The relation between the moduli and the wave number...
Experimental and numerical studies of micro PEM fuel cell
Rong-Gui Peng, Chen-Chung Chung, Chiun-Hsun Chen
Abstract
A single micro proton exchange membrane fuel cell (PEMFC) has been produced using Micro-electromechanical systems (MEMS) technology with the active area of 2.5 cm2 and channel depth of about 500 μm. A theoretical analysis is performed in this study for a novel MEMS-based design of a micro PEMFC. The model consists of the conservation equations of mass, momentum, species and electric current in a fully integrated finite-volume solver using the CFD-ACE+ commercial code. The polarizat...
Steady thermocapillary-buoyant convection in a shallow annular pool. Part 2: Two immiscible fluids
You-Rong Li, Shuang-Cheng Wang , Chun-Mei Wu
Abstract
This work is devoted to the study of steady thermocapillary-buoyant convection in a system of two horizontal superimposed immiscible liquid layers filling a lateral heated thin annular pool. The governing equations are solved using an asymptotic theory for the aspect ratios ε → 0. Asymptotic solutions of the velocity and temperature fields are obtained in the core region away from the cylinder walls. In order to validate the asymptotic solutions, numerical simulations are a...
Derivation of a second-order model for Reynolds stress using renormalization group analysis and the two-scale expansion technique
Xiao-Hong Wang, Zheng-Feng Liu, Xiao-Xia Lu
Abstract
With the two-scale expansion technique proposed by Yoshizawa, the turbulent fluctuating field is expanded around the isotropic field. At a low-order two-scale expansion, applying the mode coupling approximation in the Yakhot-Orszag renormalization group method to analyze the fluctuating field, the Reynolds-average terms in the Reynolds stress transport equation, such as the convective term, the pressure-gradient-velocity correlation term and the dissipation term, are modeled. Two numerical examp...
Scale-adaptive simulation of flow past wavy cylinders at a subcritical Reynolds number
Rui Zhao, Jing-Lei Xu, Chao Yan, Jian Yu
Abstract
The Xu & Yan scale-adaptive simulation (XYSAS) model is employed to simulate the flows past wavy cylinders at Reynolds number 8 × 103. This approach yields results in good agreement with experimental measurements. The mean flow field and near wake vortex structure are replicated and compared with that of a corresponding circular cylinder. The effects of wavelength ratios λ/Dm from 3 to 7, together with the amplitude ratios a/...
The influences of wall Lorentz force and field Lorentz force on the cylinder drag reduction
Hui Zhang, Bao-Chun Fan, Zhi-Hua Chen, Yan-Ling Li
Abstract
In this paper, the effects of Lorentz force on drag reduction for a circular cylinder have been studied experimentally and numerically. Based on its effects on drag reduction, the Lorentz force is found to be classified into two parts: one acts directly on the cylinder, named as the wall Lorentz force, and the other called the field Lorentz force acts on the fluid inside the boundary layer. The wall Lorentz force leads to the generation of a thrust, whereas the field Lorentz force results in dra...
Research of air-cushion isolation effects on high arch dam reservoir
Shao-Jie Zhang, Jiang Chen, Yuan-Ze Zhang, Hao-Wu Liu
Abstract
A three-dimensional (3D) finite element model of air-cushion isolated arch dam is presented with the nonlinear gas-liquid-solid multi-field dynamic coupling effect taken into account. In this model, the displacement formulation in Lagrange method, pressure formulation in Euler method, nonlinear contact model based on Coulomb friction law are applied to the air-cushion, reservoir and contraction joint domain, respectively. The dynamic response of Jinping I arch dam with a height of 305m is analyz...
Interference effects of two and three super-tall buildings under wind action
Ming Gu, Zhuang-Ning Xie
Abstract
Most previous investigations on interference effects of tall buildings under wind actions focused on the wind induced interference effects between two buildings, and the interference effects of three or more buildings have seldom been studied so far due to the huge workload involved in experiments and data processing. In this paper, mean and dynamic force/response interference effects and peak wind pressure interference effects of two and three tall buildings, especially the three-building confi...
Formulations of a hydromechanical interface element
Zhong-Zhi Fu, Si-Hong Liu
Abstract
A hydromechanical interface element is proposed for the consideration of the hydraulic-mechanical coupling effect along the interface. The fully coupled governing equations and the relevant finite element formulations are derived in detail for the interface element. All the involved matrices are of the same form as those of a solid element, which makes the incorporation of the model into a finite element program straightforward. Three examples are then numerically simulated using the interface e...
Study on fluid-structure interaction in liquid oxygen feeding pipe systems using finite volume method
Xin Wei, Bing Sun
Abstract
The fluid-structure interaction may occur in space launch vehicles, which would lead to bad performance of vehicles, damage equipments on vehicles, or even affect astronauts’ health. In this paper, analysis on dynamic behavior of liquid oxygen (LOX) feeding pipe system in a large scale launch vehicle is performed, with the effect of fluid-structure interaction (FSI) taken into consideration. The pipe system is simplified as a planar FSI model with Poisson coupling and junction coupling. Nu...
Static analysis of ultra-thin beams based on a semi-continuum model
Cheng Li, Zhi-Jun Zheng, Ji-Lin Yu, C.W. Lim
Abstract
A linear semi-continuum model with discrete atomic layers in the thickness direction was developed to investigate the bending behaviors of ultra-thin beams with nanoscale thickness. The theoretical results show that the deflection of an ultra-thin beam may be enhanced or reduced due to different relaxation coefficients. If the relaxation coefficient is greater/less than one, the deflection of micro/nano-scale structures is enhanced/reduced in comparison with macro-scale structures. So, two oppos...
An advanced higher-order theory for laminated composite plates with general lamination angles
Zhen Wu, Hong Zhu, Wan-Ji Chen
Abstract
This paper proposes a higher-order shear deformation theory to predict the bending response of the laminated composite and sandwich plates with general lamination configurations. The proposed theory a priori satisfies the continuity conditions of transverse shear stresses at interfaces. Moreover, the number of unknown variables is independent of the number of layers. The first derivatives of transverse displacements have been taken out from the inplane displacement fields, so that the C0...
Design of piezoelectric energy harvesting devices subjected to broadband random vibrations by applying topology optimization
Zhe-Qi Lin, Hae Chang Gea, Shu-Tian Liu
Abstract
Converting ambient vibration energy into electrical energy by using piezoelectric energy harvester has attracted a lot of interest in the past few years. In this paper, a topology optimization based method is applied to simultaneously determine the optimal layout of the piezoelectric energy harvesting devices and the optimal position of the mass loading. The objective function is to maximize the energy harvesting performance over a range of vibration frequencies. Pseudo excitation method (PEM) i...
Finite element analysis of 2D SMA beam bending
Shi-Bin Yang, Min Xu
Abstract
A thermomechanical model of a shape memory alloy beam bending under tip force loading is implemented in finite element codes. The constitutive model is a one dimensional model which is based on free energy and motivated by statistical thermodynamics. The particular focus of this paper is on the aspects of finite element modeling and simulation of the inhomogeneous beam bending problem. This paper extends previous work which is based on the small deformation Euler-Bernoulli beam theory and by tre...
Parametric study on supersonic flutter of angle-ply laminated plates using shear deformable finite element method
Wei Xia, Qiao Ni
Abstract
The influence of fiber orientation, flow yaw angle and length-to-thickness ratio on flutter characteristics of angle-ply laminated plates in supersonic flow is studied by finite element approach. The structural model is established using the Reissner-Mindlin theory in which the transverse shear deformation is considered. The aerodynamic pressure is evaluated by the quasi-steady first-order piston theory. The equations of motion are formulated based on the principle of virtual work. With the harm...
An efficient technique for recovering responses of parameterized structural dynamic problems
Zheng Zhang, Xu Han, Chao Jiang
Abstract
In this article, an effective technique is developed to efficiently obtain the output responses of parameterized structural dynamic problems. This technique is based on the conception of reduced basis method and the usage of linear interpolation principle. The original problem is projected onto the reduced basis space by linear interpolation projection, and subsequently an associated interpolation matrix is generated. To ensure the largest nonsingularity, the interpolation matrix needs to go thr...
Large deflection of flexible tapered functionally graded beam
A.R. Davoodinik, G.H. Rahimi
Abstract
In this paper the semi-analytical analyses of the flexible cantilever tapered functionally graded beam under combined inclined end loading and intermediate loading are studied. In order to derive the fully non-linear equations governing the non-linear deformation, a curvilinear coordinate system is introduced. A general non-linear second order differential equation that governs the shape of a deflected beam is derived based on the geometric nonlinearities, infinitesimal local displacements and l...
Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengths
Zheng Duan, Xian-Feng Ma, Hui-Ji Shi, Ryosuke Murai, Eiichi Yanagisawa
Abstract
Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengthes were experimentally studied by rotating bending tests, to investigate the effects of the tensile strength obtained by different heat treatment processes on very high cycle fatigue failure mechanisms. The material with higher tensile strength of 1 710MPa exhibited typical gigacycle fatigue failure characteristics, whereas one with lower tensile strength of 1 010MPa showed only traditional fatigue limit during the ...
The wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply supported opposite edges
Chun-Chuan Liu, Feng-Ming Li, Ting-Wei Liang, Wen-Hu Huang
Abstract
In this paper, wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply supported opposite edges are investigated using the wave approach. The dynamic responses, active and reactive power flow in the finite plate are calculated by the Mindlin plate theory (MPT) and classic plate theory (CPT). To satisfy the boundary conditions and continuous conditions at the coupled junction of the finite L-shaped plate, the near-field and far-field waves are entirely contained i...
Influence of specimen-reconstituting method on the undrained response of loose granular soil under static loading
Noureddine Della, Ahmed Arab, Mostefa Belkhatir
Abstract
This paper describes the results of an experimental study on the undrained shear behaviour of loose sand collected from the location close to the epicenter of the recent Chlef (Algeria) Earthquake (October 10, 1980). The study focuses on the effects of the mode of the soil deposition on the liquefaction resistance of the Chlef sand. For this purpose, the results of undrained monotonic triaxial compression tests performed on samples with initial density of 0.29 under initial confining pressures r...
Error analysis and a new steering law design for spacecraft control system using SGCMGs
Jin Jin, Jing-Rui Zhang, Zao-Zhen Liu
Abstract
Based on the singular value decomposition theory, this paper analyzed the mechanism of escaping/avoiding singularity using generalized and weighted singularity-robust steering laws for a spacecraft that uses single gimbal control moment gyros (SGCMGs) as the actuator for the attitude control system. The expression of output-torque error is given at the point of singularity, proving the incompatible relationship between the gimbal rate and the output-torque error. The method of establishing a bal...
Artificial Sun synchronous frozen orbit control scheme design based on J2 perturbation
Gong-Bo Wang, Yun-He Meng, Wei Zheng, Guo-Jian Tang
Abstract
Sun synchronous orbit and frozen orbit formed due to J2 perturbation have very strict constraints on orbital parameters, which have restricted the application a lot. In this paper, several control strategies were illustrated to realize Sun synchronous frozen orbit with arbitrary orbital elements using continuous low-thrust. Firstly, according to mean element method, the averaged rate of change of the orbital elements, originating from disturbing constant accelerations over on...
Active TLCGD control of plane asymmetric buildings under earthquake excitation
Chuan Fu
Abstract
The sealed, tuned liquid column gas damper (TLCGD) with gas-spring effect extends the frequency range of application and efficiently increases the modal structural damping. Active tuned liquid column gas damper (ATLCGD) is developed for the vibration control of plane asymmetric buildings subjected to earthquake excitation, improving the performance of the passive control scheme. The active behaviour is obtained by adjusting the pressure at the end of the liquid column using a pressurised reservo...
Stabilization control of a hovering model insect: lateral motion
Yan-Lai Zhang, Mao Sun
Abstract
Our previous study shows that the lateral disturbance motion of a model drone fly does not have inherent stability (passive stability), because of the existence of an unstable divergence mode. But drone flies are observed to fly stably. Constantly active control must be applied to stabilize the flight. In this study, we investigate the lateral stabilization control of the model drone fly. The method of computational fluid dynamics is used to compute the lateral control derivatives and the techni...
Effect of swirling flow on platelet concentration distribution in small-caliber artificial grafts and end-to-end anastomoses
Fan Zhan, Yu-Bo Fan, Xiao-Yan Deng
Abstract
Platelet concentration near the blood vessel wall is one of the major factors in the adhesion of platelets to the wall. In our previous studies, it was found that swirling flows could suppress platelet adhesion in small-caliber artificial grafts and end-to-end anastomoses. In order to better understand the beneficial effect of the swirling flow, we numerically analyzed the near-wall concentration distribution of platelets in a straight tube and a sudden tubular expansion tube under both swirling...
Technical note
Flexural rigidity of honeycomb consisting of hexagonal cells
Dai-Heng Chen
Abstract
In this study, the flexural rigidity of a honeycomb consisting of regular hexagonal cells is investigated. It is found that the honeycomb bending can not be evaluated by using the equivalent elastic moduli obtained from the in-plane deformation because the moments acting on the inclined cell wall are different for in-plane deformation and bending deformation. Based on the fact that the inclined wall is twisted under the condition of the rotation angle in both connection edges being zero, a theor...
 
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