In order to study the influence of circular gap controlled by the tearing force on rescue parachute inflation performance, the Arbitrary Lagrange-Euler (ALE) coupling method is utilized to simulate the inflation proce...
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In order to study the influence of circular gap controlled by the tearing force on rescue parachute inflation performance, the Arbitrary Lagrange-Euler (ALE) coupling method is utilized to simulate the inflation process of the circular gap rescue parachute with fixed payload;the contact failure model of the open of circular gap was built by the sewing force of the sewing thread. The canopy structure model influenced by fabric permeability performance is proposed, and the differential pressure of permeable fabric is described in Ergun equation through the textile material permeability test. The numerical results calculated by LS-DYNA are compared with the results of airdrop test and the empirical method of parachute-payloads dynamics, and it is shown that the steady drag coefficient and transient shape during inflation are more consistent with the airdrop test results, and the dimensionless initial inflation time and the maximum equivalent opening shock are more realistic. The stress variations of each gore unity during inflation are investigated. The most dangerous time-space state point during inflation process was discovered. With the study of the influence of the circular gap structure of parachute on inflation performance, the numerical results show the circular gap structure can reduce the opening load and adjust the time of two inflation stages, which reduces the maximum effective stress in dangerous parts and improves the safety of canopy.
This work addresses some issues in the embedded interface method for the conjoined interface between fluid and structure domains in two-dimensional fluid-structure interaction (FSI) coupled problems. Our approach uses...
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This work addresses some issues in the embedded interface method for the conjoined interface between fluid and structure domains in two-dimensional fluid-structure interaction (FSI) coupled problems. Our approach uses Lagrange multipliers to enforce the kinematic condition along the interface between the non-matching overlapping meshes of the structural and fluid fields in an alternative to the usual Arbitrary Lagrangian Eulerian (ALE) approaches. The main idea of our work is to discretize the embedded interface independently of the fluid and solid mesh, using discontinuous interpolating functions. The purpose of this is to avoid numerical instabilities and to simplify the implementation. In order to illustrate the method's applicability, steady and unsteady simulations of incompressible viscous flow with a moving interface as well as FSI problems involving large structural displacements were performed.
We present an explicit numerical method for three-dimensional modeling of fast processes of fluidstructureinteraction problems in Euler variables. The method does not require complex spatial grid generation. To set ...
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We present an explicit numerical method for three-dimensional modeling of fast processes of fluidstructureinteraction problems in Euler variables. The method does not require complex spatial grid generation. To set the initial geometry and follow the deformation of the calculating domains in the process of interaction it is enough to take into account the interacting surfaces constituted by a set of triangles created by CAD systems. The method is based on the modified Godunov scheme with the increased accuracy and uniform for solving equations of fluid dynamics and elastic-plastic flows. Fixed Cartesian grid and local mobile grids associated with each triangle of the surface are used. The flow parameters are interpolated from the Cartesian grid to the local grids and vice versa. At the fluidstructureinteraction boundary the exact Riemann solver is used.
Quenching is commonly used for improving material properties of steel tubes because of their numerous applications. However, quenching generates some residual stress and deformation in the material due to rapid temper...
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Quenching is commonly used for improving material properties of steel tubes because of their numerous applications. However, quenching generates some residual stress and deformation in the material due to rapid temperature fluctuations. The properties of the steel are strong functions of these variable temperatures and therefore, the estimated stress and deformation by constant property or static quenching analysis are not very realistic. This study describes the first extensive study of the quenching process of a steel tube including temperature dependent properties by three liquid quenchants using the dynamic fluid-structure interaction quench model. The cooling characteristics of the three liquid quenchants are compared to each other along with the transient temperature distributions in the steel tube. The time-varying nodal, axial, and radial residual stress and deformation of the tube are studied. It is found that, the effectiveness of quenching does not depend only on a particular quenchant, but also on the temperature-varying properties of the steel and the uniformity of the cooling which ultimately determine the criteria for selecting a suitable quenchant for a specific purpose.
We present a new composite mesh finite element method for fluid-structure interaction problems. The method is based on surrounding the structure by a boundary-fitted fluid mesh that is embedded into a fixed background...
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We present a new composite mesh finite element method for fluid-structure interaction problems. The method is based on surrounding the structure by a boundary-fitted fluid mesh that is embedded into a fixed background fluid mesh. The embedding allows for an arbitrary overlap of the fluid meshes. The coupling between the embedded and background fluid meshes is enforced using a stabilized Nitsche formulation that allows us to establish stability and optimal-order a priori error estimates. We consider here a steady state fluid-structure interaction problem where a hyperelastic structure interacts with a viscous fluid modeled by the Stokes equations. We evaluate an iterative solution procedure based on splitting and present three-dimensional numerical examples.
A detailed knowledge of the fluid-structure interaction in hypersonic flows is important for the design of future space transportation systems. The thermal aspect of such an interaction was investigated with the help ...
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A detailed knowledge of the fluid-structure interaction in hypersonic flows is important for the design of future space transportation systems. The thermal aspect of such an interaction was investigated with the help of a generic model in the arc-heated wind tunnel L3K at the German Aerospace Center in Cologne. Flat and curved panels of the fibre-reinforced ceramics C/C-SiC with and without anti-oxidation coating where used. Several configurations with and without back plane insulation were tested at 1 degrees. and 2 degrees. angle of attack. The panel heating was measured with an infrared camera, several thermocouples and pyrometers. The experimental results show the influence of the shape as well as of radiation cooling and radiation heating. The experiments also reveal the effect of additional heating due to recombination of atomic oxygen on the surface. At certain configurations a local temperature peak moved over the panel. This thermal wave is also influenced by the silicon carbide coating. The analysis is supported by coupled fluid and structure simulations.
This paper addresses the issue of reciprocating compressors staggered labyrinth seal structure. The internal flow field of sealed structure, the displacement of cylinder and piston for different tooth profile angles a...
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This paper addresses the issue of reciprocating compressors staggered labyrinth seal structure. The internal flow field of sealed structure, the displacement of cylinder and piston for different tooth profile angles are analyzed synchronously using FLUENT software, and the effects of fluid-structure interaction on the performance of the labyrinth seal are revealed. The results indicate that with the growth of tooth profile angle, the leakage rate of labyrinth seal tends to decrease first, and then increase. The results of fluid-structure interaction analysis are close to those of actual engineering. The effect of fluid-structure interaction makes tiny deformation in calculation mesh of piston and cylinder structure, and the coupling interaction affects the performance of the labyrinth seal.
Rupture of the abdominal aortic aneurysm (AAA) is the result of the relatively complex interaction of blood hemodynamics and material behavior of arterial walls. In the present study, the cumulative effects of physiol...
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Rupture of the abdominal aortic aneurysm (AAA) is the result of the relatively complex interaction of blood hemodynamics and material behavior of arterial walls. In the present study, the cumulative effects of physiological parameters such as the directional growth, arterial wall properties (isotropy and anisotropy), iliac bifurcation and arterial wall thickness on prediction of wall stress in fully coupled fluid-structure interaction (FSI) analysis of five idealized AAA models have been investigated. In particular, the numerical model considers the heterogeneity of arterial wall and the iliac bifurcation, which allows the study of the geometric asymmetry due to the growth of the aneurysm into different directions. Results demonstrate that the blood pulsatile nature is responsible for emerging a time-dependent recirculation zone inside the aneurysm, which directly affects the stress distribution in aneurismal wall. Therefore, aneurysm deviation from the arterial axis, especially, in the lateral direction increases the wall stress in a relatively nonlinear fashion. Among the models analyzed in this investigation, the anisotropic material model that considers the wall thickness variations, greatly affects the wall stress values, while the stress distributions are less affected as compared to the uniform wall thickness models. In this regard, it is confirmed that wall stress predictions are more influenced by the appropriate structural model than the geometrical considerations such as the level of asymmetry and its curvature, growth direction and its extent.
The present paper investigates the flow induced dynamics of a non-linear fluid-structure interaction (FSI) system comprising of a symmetrical NACA 0012 airfoil supported by non-linear springs. Two methods are used in ...
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The present paper investigates the flow induced dynamics of a non-linear fluid-structure interaction (FSI) system comprising of a symmetrical NACA 0012 airfoil supported by non-linear springs. Two methods are used in calculating the aerodynamic loads: a linear analytical approach and a full Navier-Stokes (N-S) solution. The analytical approach is based on the assumption of potential flow theory and a rigid wake. Wind velocity as a bifurcation parameter shows that the structural response undergoes a supercritical Hopf bifurcation. However, the analytical loads predict unrealistic bifurcation onset at low values of solid to fluid added mass ratio (mu) relevant to the application of flapping wing micro air vehicles (MAVs), showing the extremely large amplitude of oscillations. These observations render the use of an inviscid approach meaningless at such parametric regimes. Hence, we propose to use a N-S solver to emphasize the limit of applicability of the linear aerodynamic theory. Moreover, the inclusion of the viscous effects can potentially result in interesting dynamical behavior that has not been captured by the analytical approach. A bifurcation and stability analysis has been carried out for different parametric variations of mu in the fluidstructureinteraction system. (C) 2016 The Authors. Published by Elsevier Ltd.
It is very important to study fluid-structure interaction of vehicles which move in strong crosswind environment. For solving a fluid-structure interaction problem, the effect of the deformation and vibration of the e...
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It is very important to study fluid-structure interaction of vehicles which move in strong crosswind environment. For solving a fluid-structure interaction problem, the effect of the deformation and vibration of the elastic body on the flow field should be considered. However, the reaction of the vibrating flow field on the vehicle body should be computed. A kind of coach model is selected for solving the fluid-structure coupling problem. We have considered the interaction of the deformation of vehicle suspension and the displacement of sprung mass and the flow field around the coach model using a numerical simulation. The coupling method is partitioned but loosely coupled with the Fluent software to describe the flow field and the ANSYS software to describe the reaction of the structure. The numerical results are in good agreement with the experimental data.
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