In order to analyze the supersonic and transonic panel flutter behaviors quantitatively and accurately, a fluid-structure coupling algorithm based on the finite element method (FEM) is proposed to study the two-dimens...
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In order to analyze the supersonic and transonic panel flutter behaviors quantitatively and accurately, a fluid-structure coupling algorithm based on the finite element method (FEM) is proposed to study the two-dimensional panel flutter problem. First, the Von Karman's large deformation is used to model the panel, and the high speed airflow is approached by the Euler equations. Then, the equation of panel is discretized spatially by the standard Galerkin FEM, and the equations of fluid are discretized by the characteristic-based split finite element method (CBS-FEM) with dual time stepping;thus, the numerical oscillation encountered frequently in the numerical simulation of flow field could be removed efficiently. Further, a staggered algorithm is used to transfer the information on the interface between the fluid and the structure. Finally, the aeroelastic behaviors of the panel in both the supersonic and transonic airflows are studied in details. And the results show that the system can present the flat and stable, simple harmonic oscillation, buckling, and inharmonic oscillation states at Mach 2, considering the effect of the pretightening force;at Mach 1.2, as the panel loses stability, the ensuing limit cycle oscillation is born;at Mach 0.8 and 0.9, positive and negative bucklings are the typical states of the panel as it loses its stability. Further, the transonic stability boundary is obtained and the transonic bucket is precisely captured. More, this algorithm can be applied to the numerical analysis of other complicated problems related to aeroelasticity.
作者：
Khanafer, KhalilUniv Michigan
Dept Biomed Engn Frankel Vasc Mech Lab Ann Arbor MI 48109 USA Univ Michigan
Vasc Surg Sect Samuel & Jean Frankel Cardiovasc Ctr Ann Arbor MI 48109 USA
A numerical investigation of steady laminar mixed convection flow and heat transfer in a lid driven cavity with a flexible heated bottom surface is investigated. Moreover, the heated bottom wall is characterized by re...
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A numerical investigation of steady laminar mixed convection flow and heat transfer in a lid driven cavity with a flexible heated bottom surface is investigated. Moreover, the heated bottom wall is characterized by rectangular and sinusoidal wavy profiles for a rigid wall analysis. A stable thermal stratification configuration was considered by imposing a vertical temperature gradient while the vertical walls were considered to be insulated. The transport equations are solved using a finite element formulation based on the Galerkin method of weighted residuals. For a flexible bottom wall case, a fully coupled fluid-structure interaction (FSI) analysis is utilized and the fluid domain is described by an Arbitrary-Lagrangian-Eulerian (ALE) formulation that is fully coupled to the structure domain. The results of this investigation revealed that the heat transfer enhancement is noticed in all the studied cases compared with a flat bottom wall case. Furthermore, the contribution of the forced convection heat transfer to that offered by natural convection heat transfer has a profound effect on the behavior of the flexible wall as well as the momentum and energy transport processes within the cavity. Flexible bottom wall case is found to exhibit significant heat transfer enhancement (61.4%) compared with a flat bottom wall case at Grashof number of 10(4) and Re < 400. However, rectangular wavy profile exhibits higher heat transfer enhancement (maximum: 14.4% at Re = 200) than sinusoidal wavy profile (9.6% at Re = 200) and flexible bottom wall (12.3% at Re = 200) at a low Grashof number of 10(2). This investigation shows the benefits of using flexible walls when augmentation of heat transfer is sought at high Grashof numbers. (C) 2014 Elsevier Ltd. All rights reserved.
A horizontal water storage tank was analyzed for seismic shaking at the ITER Tokamak Complex in France. The objectives were to (a) estimate the seismic forces in the tank;(b) calculate the sloshing response of the tan...
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A horizontal water storage tank was analyzed for seismic shaking at the ITER Tokamak Complex in France. The objectives were to (a) estimate the seismic forces in the tank;(b) calculate the sloshing response of the tank;(c) determine if baffles are needed to control sloshing;and (d) evaluate the possibility of using a single fixed support in the longitudinal direction to allow free thermal expansion of the tank. An approximate conservative analysis predicted very high sloshing waves and seismic forces in the tank. The fluid-structure interaction in the tank showed that only about 28% of the liquid moves with the tank wall and generates seismic forces in the longitudinal direction. The remaining 72% of the liquid sloshes near the free surface and does not generate significant seismic forces. The sloshing wave is not high enough in the longitudinal direction as the fundamental sloshing mode is not excited because of its very low natural frequency. Hence, baffles are not needed to control sloshing. The seismic force is low enough for a single fixed support to resist the entire seismic force in the longitudinal direction.
作者：
Liu, HuiZhang, HongwuDalian Univ Technol
Fac Vehicle Engn & Mech Dept Engn Mech State Key Lab Struct Anal Ind Equipment Dalian 116024 Peoples R China Wuhan Univ
Sch Civil Engn Dept Engn Mech Wuhan 430072 Peoples R China
The two-dimensional dynamic analysis of the coupling system of fluid and heterogeneous structure is investigated by using an efficient multiscale computational method. The macroscopic equations of the coupling system ...
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The two-dimensional dynamic analysis of the coupling system of fluid and heterogeneous structure is investigated by using an efficient multiscale computational method. The macroscopic equations of the coupling system are deduced. The liquid pressure-based and solid displacement-based coarse elements are employed for the numerical simulation. In addition, the piecewise oscillating boundary condition and the Lagrange polynomial boundary condition are used to construct the displacement base function of the solid coarse element and the pressure base function of the liquid coarse element, respectively. Furthermore, the generalized mode base functions are introduced into the multiscale base functions of both the fluid and structure coarse elements to capture the dynamic effect of the coarse element and improve the computational accuracy effectively. The predictor-corrector scheme is applied to solve the macroscopic transient response equation of the coupling system. Finally, several numerical examples are carried out to verify the validity and high efficiency of the proposed multiscale method by comparison with the fine-scale reference solutions. (C) 2014 Elsevier B.V. All rights reserved.
The fluid-solid interface-tracking/interface-capturing technique (FSITICT) with arbitrary Lagrangian-Eulerian interface-tracking and Eulerian interface-capturing is applied to computations of fluid-structure interacti...
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The fluid-solid interface-tracking/interface-capturing technique (FSITICT) with arbitrary Lagrangian-Eulerian interface-tracking and Eulerian interface-capturing is applied to computations of fluid-structure interaction problems with flapping and contact. The two-dimensional model with contacting flaps is intended to represent a valve problem from biomechanics. The FSITICT is complemented with local mesh adaptivity, which significantly increases the performance of the interface-capturing component of the method. The test computations presented demonstrate how our approach works.
In this paper, the necessary scaling laws for flutter speeds of laminated cylindrical shells are developed using the similitude theory. To consider the effect of mode shape factor, the characteristic equation of the s...
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In this paper, the necessary scaling laws for flutter speeds of laminated cylindrical shells are developed using the similitude theory. To consider the effect of mode shape factor, the characteristic equation of the system is used directly to derive the similarity conditions. The Love's shell theory and Von-Karman-Donnell type of kinematic relations along with first-order potential theory have been employed to construct the aeroelastic equations of motion. Two types of similarity namely, complete and partial similarities are discussed. Based on the results of this study, for the special case of ply-level scaling, the complete similarity can be achieved. Additionally, set of distorted models with different stacking sequences, number of layers, and geometrical dimensions than prototypes are introduced which are able to predict the flutter speeds of laminated cylindrical shell with good accuracy.
The purpose of this note is to prove a version of the Trace Theorem for domains which are locally subgraph of a Holder continuous function. More precisely, let eta epsilon C-0,C-alpha (omega), 0 < alpha < 1 and ...
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The purpose of this note is to prove a version of the Trace Theorem for domains which are locally subgraph of a Holder continuous function. More precisely, let eta epsilon C-0,C-alpha (omega), 0 < alpha < 1 and let Omega(eta) be a domain which is locally subgraph of a function eta. We prove that mapping gamma(eta) : u (bar right arrow) u (x, eta (x)) an be extended by continuity to a linear, continuous mapping from H-1 (Omega(eta)) to H-s(omega), s < alpha/2. This study is motivated by analysis of fluid-structure interaction problems.
This paper proposes a coupled particle-finite element method for fluid-membrane structureinteraction problems. The material point method (MPM) is employed to model the fluid flow and the membrane element is used to m...
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This paper proposes a coupled particle-finite element method for fluid-membrane structureinteraction problems. The material point method (MPM) is employed to model the fluid flow and the membrane element is used to model the membrane structure. The interaction between the fluid and the membrane structure is handled by a contact method, which is implemented on an Eulerian background grid. Several numerical examples, including membrane sphere interaction, water sphere impact and gas expansion problems, are studied to validate the proposed method. The numerical results show that the proposed method offers advantages of both MPM and finite element method, and it can be used to simulate fluid-membrane interaction problems.
In this work, we develop a partitioned algorithm for three-dimensional geometric non-linear fluid-structure interaction analysis using the finite element method. The fluid solver is explicit and its time integration b...
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In this work, we develop a partitioned algorithm for three-dimensional geometric non-linear fluid-structure interaction analysis using the finite element method. The fluid solver is explicit and its time integration based on characteristics, which automatically introduces stabilising terms on stream direction. The Navier-Stokes equations are written using the arbitrary Lagrangian-Eulerian (ALE) description, in order to accept moving boundaries and coupling with Lagrangian shell elements. The structure is modelled using a novel finite element method formulation for geometric non-linear shell dynamics. Such shell formulation, so-called positional formulation, is based on the minimum potential energy theorem, written regarding nodal positions and generalised unconstrained vectors, not displacements and rotations. These characteristics avoid the use of large rotation approximations. The coupling between the two different meshes is done by mapping the fluid boundary nodes local positions over the shell elements and vice versa, avoiding the need for matching fluid and shell nodes. The fluid mesh is adapted using a simple approach based on shell positions and velocities. The efficiency and robustness of the proposed approach is demonstrated by examples. (C) 2013 Elsevier Inc. All rights reserved.
In this work, the process of impact that takes place in a partially filled tank is analyzed, performing a numerical simulation, in order to understand the response of the composite laminated structure. The commercial ...
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In this work, the process of impact that takes place in a partially filled tank is analyzed, performing a numerical simulation, in order to understand the response of the composite laminated structure. The commercial finite-element code LS-DYNA v.R7 has been used to simulate an Hydrodynamic RAM event created by a steel spherical projectile impacting a partially water-filled woven CFRP square tube using two different approaches (MM-ALE and SPH). The intralaminar and interlaminar damage have been taken into account implementing an user subroutine and by means of a cohesive interaction, respectively. Once the numerical model is validated using available experimental data, the effect of the filling level in the failure of the tank is analyzed in detail taking advantage of the information provided by the numerical model. (C) 2013 Elsevier Ltd. All rights reserved.
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