A computational method of fluid-structure coupling is implemented to predict the fatigue response of a high-pressure turbine blade. Two coupling levels, herein referred to as a "fully coupled" and "deco...
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A computational method of fluid-structure coupling is implemented to predict the fatigue response of a high-pressure turbine blade. Two coupling levels, herein referred to as a "fully coupled" and "decoupled" methods are implemented to investigate the influence of multi-physics interaction on the 3 D stress state and fatigue response of a turbine blade. In the fully-coupled approach, the solutions of the fluid-flow and the solid-domain finite element problem are obtained concurrently, while in the decoupled approach, the independently computed aerodynamic forces are unilaterally transferred as boundary conditions in the subsequent finite element solution. In both cases, a three-dimensional unsteady stator-rotor aerodynamic configuration is modelled to depict a forced-vibration loading of high-cycle failure mode. Also analyzed is the low-cycle phenomenon which arises due to the mean stresses of the rotational load of the rotating turbine wheel. The coupling between the fluid and solid domains (fully-coupled approach) provides a form of damping which reduces the amplitude of fluctuation of the stress history, as opposed to the decoupled case with a resultant higher amplitude stress fluctuation. While the stress amplitude is higher in the decoupled case, the fatigue life-limiting condition is found to be significantly influenced by the higher mean stresses in the fully-coupled method. The differences between the two approaches are further explained considering three key fatigue parameters;mean stress, multiaxiality stress state and the stress ratio factors. The study shows that the influence of the coupling between the fluid and structures domain is an important factor in estimating the fatigue stress history.
In this paper, a new take on the concept of an active subspace for reducing the dimension of the design parameter space in a multidisciplinary analysis and optimization (MDAO) problem is proposed. The new approach is ...
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In this paper, a new take on the concept of an active subspace for reducing the dimension of the design parameter space in a multidisciplinary analysis and optimization (MDAO) problem is proposed. The new approach is intertwined with the concepts of adaptive parameter sampling, projection-based model order reduction, and a database of linear, projection-based reduced-order models equipped with interpolation on matrix manifolds, in order to construct an efficient computational framework for MDAO. The framework is fully developed for MDAO problems with linearized fluid-structure interaction constraints. It is applied to the aeroelastic tailoring, under flutter constraints, of two different flight systems: a flexible configuration of NASA's Common Research Model;and NASA's Aeroelastic Research Wing #2 (ARW-2). The obtained results illustrate the feasibility of the computational framework for realistic MDAO problems and highlight the benefits of the new approach for constructing an active subspace in both terms of solution optimality and wall-clock time reduction.
Purpose The purpose of this exhaustive experimental study is to investigate the fluid-structure interaction in the flexible membrane wings over a range of angles of attack for various Reynolds numbers. Design/methodol...
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Purpose The purpose of this exhaustive experimental study is to investigate the fluid-structure interaction in the flexible membrane wings over a range of angles of attack for various Reynolds numbers. Design/methodology/approach In this paper, an experimental study on fluid-structure interaction of flexible membrane wings was presented at Reynolds numbers of 2.5 x 10(4), 5 x 10(4) and 7.5 x 10(4). In the experimental studies, flow visualization, velocity and deformation measurements for flexible membrane wings were performed by the smoke-wire technique, multichannel constant temperature anemometer and digital image correlation system, respectively. All experimental results were combined and fluid-structure interaction was discussed. Findings In the flexible wings with the higher aspect ratio, higher vibration modes were noticed because the leading-edge separation was dominant at lower angles of attack. As both Reynolds number and the aspect ratio increased, the maximum membrane deformations increased and the vibrations became visible, secondary vibration modes were observed with growing the leading-edge vortices at moderate angles of attack. Moreover, in the graphs of the spectral analysis of the membrane displacement and the velocity;the dominant frequencies coincided because of the interaction of the flow over the wings and the membrane deformations. Originality/value Unlike available literature, obtained results were presented comparatively using the sketches of the smoke-wire photographs with deformation measurement or turbulence statistics from the velocity measurements. In this study, fluid-structure interaction and leading-edge vortices of membrane wings were investigated in detail with increasing both Reynolds number and the aspect ratio.
Analytical solution for vibration analysis of orthotropic and FGM submerged cylindrical shell containing a surface crack of variable angular orientation is presented in this work. The governing equations in terms of t...
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Analytical solution for vibration analysis of orthotropic and FGM submerged cylindrical shell containing a surface crack of variable angular orientation is presented in this work. The governing equations in terms of transverse deflection of cracked-submerged shell have been derived using classical shell theory. The fluid forces associated with its inertial effects are added in the governing differential equation to incorporate the fluid-structure interaction effect. The line spring model (LSM) is used to formulate the crack coefficients to accommodate the effect of crack in the governing equation. Furthermore, the governing equation is solved using Donell-Mushtari-Vlasov (DMV) theory to get the fundamental frequency. The results are presented for frequency by giving the input parameters as crack length, crack orientation, and shell's physical properties such as radius, thickness, and length of the *** by Wei-Chau Xie
In this paper, the modelling strategies of fluid-structure interaction impact simulation between amphibious aircraft float structure and water are investigated. fluid-structure interaction in the form of constant velo...
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In this paper, the modelling strategies of fluid-structure interaction impact simulation between amphibious aircraft float structure and water are investigated. fluid-structure interaction in the form of constant velocity hydrodynamic impact was numerically modelled using finite element software by employing the coupled Eulerian-Lagrangian method. Four types of modelling strategies of the float, i.e., (1) full shell, (2) full solid, (3) multi-stage multi-scale, and (4) concurrent multi-scale modelling, are implemented and compared to obtain the most accurate model to obtain stress distribution on the float structure components. The modelling procedure and the advantages and disadvantages of each strategy are discussed comprehensively. The results show that the simulation using the structure modelled as shell elements is the most accurate strategy to obtain stress distribution on the float structure components while the solid elements model is the worst since the stresses predicted by using this model is lower than that of the shell elements model, especially when insufficient elements in the thickness direction is used. The multi-stage multi-scale in terms of shell-to-solid sub-modelling can be an alternative strategy since the results are similar to that using the shell geometry model. The concurrent multi-scale modelling, on the other hand, predicts acceptable stress values with a reasonable computational resource while maintaining computational accuracy and efficiency.
In this work, we present a new monolithic finite element strategy for solving fluid-structure interaction problems involving a compressible fluid and a hyperelastic structure. In the Lagrangian limit, the time-steppin...
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In this work, we present a new monolithic finite element strategy for solving fluid-structure interaction problems involving a compressible fluid and a hyperelastic structure. In the Lagrangian limit, the time-stepping strategy that we propose conserves the total energy, and linear and angular momenta. Detailed proofs with numerical validations are provided. We use a displacement-based Lagrangian formulation for the structure, and a velocity-based arbitrary Lagrangian-Eulerian mixed formulation with appropriately chosen interpolations for the various field variables to ensure stability of the resulting numerical procedure. A hybrid formulation is used to prevent locking of thin structures. Apart from physical variables such as displacement, velocity, and so forth, no new variables are introduced in the formulation. The use of the exact tangent stiffness matrix ensures that the algorithm converges quadratically within each time step. A number of benchmark examples have been solved to illustrate the good performance of the proposed method.
Recirculation in venovenous extracorporeal membrane oxygenation (VV ECMO) leads to reduction in gas transfer efficiency. Studies of the factors contributing have been performed using in vivo studies and computational ...
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Recirculation in venovenous extracorporeal membrane oxygenation (VV ECMO) leads to reduction in gas transfer efficiency. Studies of the factors contributing have been performed using in vivo studies and computational models. The fixed geometry of previous computational models limits the accuracy of results. We have developed a finite element computational fluid dynamics model incorporating fluid-structure interaction (FSI) that incorporates atrial deformation during atrial filling and emptying, with fluid flow solved using large eddy simulation. With this model, we have evaluated an extensive number of factors that could influence recirculation during two-site VV ECMO, and characterized their impact on recirculation, including cannula construction, insertion depth and orientation, VV ECMO configuration, circuit blood flow, and changes in volume, venous return, heart rate, and blood viscosity. Simulations revealed that extracorporeal blood flow relative to cardiac output, ratio of superior vena caval (SVC) to inferior vena caval (IVC) blood flow, position of the SVC cannula relative to the cavo-atrial junction, and orientation of the return cannula relative to the tricuspid valve had major influences (>20%) on recirculation fraction. Factors with a moderate influence on recirculation fraction (5%-20%) include heart rate, return cannula diameter, and direction of extracorporeal flow. Minimal influence on recirculation (<5%) was associated with atrial volume, position of the IVC cannula relative to the cavo-atrial junction, the number of side holes in the return cannula, and blood viscosity.
We consider a loosely-coupled algorithm for fluid-structure interaction based on a Robin interface condition for the fluid problem (explicit Robin-Neumann scheme). We study the dependence of the stability of this meth...
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We consider a loosely-coupled algorithm for fluid-structure interaction based on a Robin interface condition for the fluid problem (explicit Robin-Neumann scheme). We study the dependence of the stability of this method on the interface parameter in the Robin condition. In particular, for a model problem we find sufficient conditions for instability and stability of the method. In the latter case, we find a stability condition relating the time discretization parameter, the interface parameter, and the fluid and structure densities. Numerical experiments confirm the theoretical findings and highlight optimal choices of the interface parameter that guarantee accurate solutions.
Atherosclerotic plaque in the femoral is the leading cause of peripheral artery disease (PAD), the worse consequence of which may lead to ulceration and gangrene of the feet. Numerical studies on fluid-structure inter...
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Atherosclerotic plaque in the femoral is the leading cause of peripheral artery disease (PAD), the worse consequence of which may lead to ulceration and gangrene of the feet. Numerical studies on fluid-structure interactions (FSI) of atherosclerotic femoral arteries enable quantitative analysis of biomechanical features in arteries. This study aims to investigate the hemodynamic performance and its interaction with femoral arterial wall based on the patient-specific model with multiple plaques (calcified and lipid plaques). Three types of models, calcification-only, lipid-only and calcification-lipid models, are established. Hyperelastic material coefficients of the human femoral arteries obtained from experimental studies are employed for all simulations. Oscillation of WSS is observed in the healthy downstream region in the lipid-only model. The pressure around the plaques in the two-plaque model is lower than that in the corresponding one-plaque models due to the reduction of blood flow domain, which consequently diminishes the loading forces on both plaques. Therefore, we found that stress acting on the plaques in the two-plaque model is lower than that in the corresponding one-plaque models. This finding implies that the lipid plaque, accompanied by the calcified plaque around, might reduce its risk of rupture due to the reduced the stress acting on it.
Aortic valve replacement(AVR)remains a major treatment option for patients with severe aortic valve *** outcome of AVR is strongly dependent on implanted prosthetic valve ***-structureinteraction(FSI)aortic root mode...
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Aortic valve replacement(AVR)remains a major treatment option for patients with severe aortic valve *** outcome of AVR is strongly dependent on implanted prosthetic valve ***-structureinteraction(FSI)aortic root models were constructed to investigate the effect of valve size on hemodynamics of the implanted bioprosthetic valve and optimize the outcome of AVR *** models with 4 sizes of bioprosthetic valves(19(No.19),21(No.21),23(No.23)and 25 mm(No.25))were *** ventricle outflow track flow data from one patient was collected and used as model flow *** Mooney–Rivlin models were used to describe mechanical properties of aortic valve *** flow pressure,velocity,systolic valve orifice pressure gradient(SVOPG),systolic cross-valve pressure difference(SCVPD),geometric orifice area,and flow shear stresses from the four valve models were *** results indicated that larger valves led to lower transvalvular pressure gradient,which is linked to better post AVR *** SVOPG,mean SCVPD and maximum velocity for Valve No.25 were 48.17%,49.3%,and 44.60%lower than that from Valve No.19,*** orifice area from Valve No.25 was 52.03%higher than that from Valve No.19(1.87 cm2 vs.1.23 cm2).Implantation of larger valves can significantly reduce mean flow shear stress on valve *** initial results suggested that larger valve size may lead to improved hemodynamic performance and valve cardiac function post *** patient studies are needed to validate our findings.
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