Advances in Fracture and Materials Behavior

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Authors: Xamxinur Abdikerem, Zhong Hua Xu, Mamtimin Gheni
Abstract: In this study, to conduct numerical simulation of desert physiognomy forming process in fixed, semi-fixed and free sand desert field by considering the sand flow process by wind, the numerical model based on the hydrodynamics and sand grains kinemics are proposed. For analyze the actual characteristic of sand movement phenomenon, the stream flow field and desert flow field are introduced and mathematical model for numerical analysis are established by considering the sand shape, size and mass in order to describe the fixed, semi-fixed and fully free sand desert physiographical process. Then according to the real fixed, semi-fixed and free sand flow field by coupling with stream flow field, several models are made and numerical simulations are conducted.
Authors: Abudoukelimu Abudoureheman, Xamxinur Abdikerem, Mamtimin Gheni
Abstract: In this study, for the numerical simulation of the sand ripple’s forming process which caused by the sand flow, the simulation models based on the fluid dynamics and the sand flow field by the wind are analyzed. Due to sand field’s characteristics is very complex, the establishing process of stream flow field constitutive equations analyzed at first, and then the implication relations and independency between stream flow field and the sand flow field analyzed. Finally, the sand ripple forming and moving process simulated in uniform and non-uniform stream flow field.
Authors: Xamxinur Abdikerem, Akbar Eziz, Abudoukelimu Abudoureheman, Mamtimin Gheni
Abstract: In this study, to conduct numerical simulation of sand dune forming processes, the mathematical model for sand dune dynamics are studied. Due to sand dune dynamics and the stream field, which includes wind flow over a dune field, analyses process is complex the uniform sand field and stream fields are consider for the numerical simulation process. Then the dune forming process simulated by considering the dunes induced factor and interactions phenomenon.
Authors: A Fang Jin, Mamtimin Gheni, Zhi Chun Yang
Abstract: The sand cover is the main form of sand disaster for the desert highway induced by the wind-blown-sand flow over the highway. As a kind of two-phase flow of air and sand, it is necessary to study the physical principle and the mode of its migration. The Smoothing Particle Hydrodynamic (SPH) method is adopted to simulate the movement of the wind-blown-sand flow. A two dimensional model of the sand cover for desert highway with embankment is built with SPH method. The numerical simulations are carried for different embankment height to investigate the sand cover distribution on the road surface of desert highway. The results show that the migration of sand with wind blow can be well simulated using SPH method and the embankment height is an important factor for controlling sand cover disaster of desert highway.
Authors: Norio Arai, Kota Fujimura, Yoko Takakura
Abstract: When a bluff body is located in a uniform flow, the flow is separated and vortices are formed. Consequently, the vortices cause “flow-induced vibrations”. Especially, if the Strouhal number and the frequency of the body oscillation coincide with the natural frequency, the lock-in regime will occur and we could find the large damages on it. Therefore, it is profitable, in engineering problems, to clarify this phenomenon and to suppress the vibration, in which the effect of elastic walls on the suppression is focused. Then, the aims of this article are to clarify the oscillatory characteristics of the elastic body and the flowfield around the body by numerical simulations, in which a square pillar with elastic walls is set in a uniform flow. Two dimensional incompressible flows are solved by the continuity equation, Navier-Stokes equation and the Poisson equation which are derived by taking divergence of Navier-Stokes equation. Results show that a small deformation of elastic walls has a large influence on the body motion. In particular, the effect is very distinct at the back.
Authors: Yoon Suk Chang, Hyuk Soo Chang, Jae Boong Choi, Young Jin Kim, Poong Hwan Chun, Jae Youn Kong
Abstract: The purpose of this paper is to investigate fluid characteristics and flat panel display behaviours on contact-free flat panel display handler nozzles. Since air force distributions streaming bottom surface of a flat panel display highly dependent on operating as well as design conditions and configuration of contact-free handler nozzle, influences of various parameters such as flow rate, supply air pressure, floating height are examined through a series of computational fluid dynamics analyses. Moreover, dynamic finite element analyses of the flat panel display are carried out to assure that an oscillation effect caused by disturbances is not significant. Key findings from the both computational fluid dynamics and structural integrity analysis results are presented and discussed, which can be figured out an optimized operating condition of contact-free handler nozzles.
Authors: Yong Wen Lin, Xiao Chuan You, Zhuo Zhuang
Abstract: In this article we presented a method of Fluid-Solid coupled simulation via FLUNET and ABAQUS in problems such as Aero/Hydro-Elasticity problems. UDF (user define function) script file in the Fluent software was utilized as the ‘Connecting File’ between FLUENT and ABAQUS for Aero-Elastic computations. Firstly, the fluid field was computed by Navier-Stokes Equation and the structure movement was directly integrated by the dynamics Equation, respectively. Then, the ‘Connecting File’ exchanged the computed data through the fluid and structure’s interface. The next analysis step continued. Analysis of the computed results showed that this coupling method designed for aero-elastic system was feasible and can be also used for other Fluid-Structure Coupling problems.
Authors: Zhi Chun Yang, Wei Xia
Abstract: An investigation on the stability of heated panels in supersonic airflow is performed. The nonlinear aeroelastic model for a two-dimensional panel is established using Galerkin method and the thermal effect on the panel stiffness is also considered. The quasi-steady piston theory is employed to calculate the aerodynamic load on the panel. The static and dynamic stabilities for flat panels are studied using Lyapunov indirect method and the stability boundary curve is obtained. The static deformation of a post-buckled panel is then calculated and the local stability of the post-buckling equilibrium is analyzed. The limit cycle oscillation of the post-buckled panel is simulated in time domain. The results show that a two-mode model is suitable for panel static stability analysis and static deformation calculation; but more than four modes are required for dynamic stability analysis. The effects of temperature elevation and dimensionless parameters related to panel length/thickness ratio, material density and Mach number on the stability of heated panel are studied. It is found that panel flutter may occur at relatively low aerodynamic pressure when several stable equilibria exist for the aeroelastic system of heated panel.
Authors: Ying Hao Yu, Mamtimin Gheni, Zhong Yuan Lu, Wei Jiang
Abstract: In this study, the meso-scale analysis are conducted by using the Disperse Particle Dynamics(DPD) analysis, and the constitutive equation model between viscosity and shear velocity are obtained by using different constrained mutual sufficient area. The macro-scale analysis are conducted by using Finite Element Method(FEM) based on the Computational Fluid Dynamics(CFD). The meso-scale model is smoothly coupled with in macro-scale model by using the relationships between the DPD meso-scale model and the FEM macro-scale model.
Authors: Yong Jian Zhu
Abstract: Conventional stability analysis of slopes is established on vertical slices with a linear Mohr-Coulomb (MC) failure criterion. In this paper, the soil mass of slopes is assumed to follow linear and nonlinear failure criteria. A new procedure is proposed for determination of stability factors of slopes using triangular slices within the framework of limit analysis method under plane strain condition. The potential sliding mass is divided into a series of triangular slices, rather than vertical slices as usual. Using a generalized tangential technique, the nonlinear failure criterion is simplified as a set of straight lines according to the linear MC failure criterion. The straight line is tangential to the curve of the nonlinear failure criterion. With a linear MC failure criterion, solutions to stability factors are determined by limit analysis theory, which agree well with the published solutions. With triangular slices method, a study is carried out to investigate the influences of nonlinear parameter on stability of the soil slope.

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