Flutter Boundary Prediction in a Global Stochastic Framework

2021 ◽  
pp. 1-11
Author(s):  
Wenjing Gu ◽  
Li Zhou
Keyword(s):  
Stochastic Framework ◽  
Flutter Boundary

scholarly journals Analysis of a Nonlinear Aeroelastic System with Parametric Uncertainties Using Polynomial Chaos Expansion

2010 ◽  
Vol 2010 ◽  
pp. 1-21 ◽  
Author(s):  
Ajit Desai ◽  
Sunetra Sarkar
Keyword(s):  
Polynomial Chaos ◽  
Polynomial Chaos Expansion ◽  
Stochastic Bifurcation ◽  
Parametric Uncertainties ◽  
Chaos Expansion ◽  
Aeroelastic Stability ◽  
Aeroelastic System ◽  
Important Concern ◽  
Stochastic Framework ◽  
Flutter Boundary

Aeroelastic stability remains an important concern for the design of modern structures such as wind turbine rotors, more so with the use of increasingly flexible blades. A nonlinear aeroelastic system has been considered in the present study with parametric uncertainties. Uncertainties can occur due to any inherent randomness in the system or modeling limitations, and so forth. Uncertainties can play a significant role in the aeroelastic stability predictions in a nonlinear system. The analysis has been put in a stochastic framework, and the propagation of system uncertainties has been quantified in the aeroelastic response. A spectral uncertainty quantification tool called Polynomial Chaos Expansion has been used. A projection-based nonintrusive Polynomial Chaos approach is shown to be much faster than its classical Galerkin method based counterpart. Traditional Monte Carlo Simulation is used as a reference solution. Effect of system randomness on the bifurcation behavior and the flutter boundary has been presented. Stochastic bifurcation results and bifurcation of probability density functions are also discussed.

Uncertainty Quantification and Bifurcation Behavior of an Aeroelastic System

2010 ◽  
Author(s):  
Ajit Desai ◽  
Sunetra Sarkar
Keyword(s):  
Uncertainty Quantification ◽  
Polynomial Chaos ◽  
Stochastic Bifurcation ◽  
Chaos Expansion ◽  
Aeroelastic System ◽  
Aeroelastic Response ◽  
Important Concern ◽  
Stochastic Framework ◽  
Flutter Boundary ◽  
Bifurcation Behavior

Aeroelastic stability remains an important concern for the design of modern structures such as wind turbine rotors, more so with the use of increasingly flexible blades and military aircrafts with increasing maneuvering capabilities etc. A nonlinear aeroelastic system has been considered in the present study with parametric uncertainties. The analysis has been put in a stochastic framework and the propagation of system uncertainties have been quantified in the aeroelastic response. A spectral uncertainty quantification tool called Polynomial Chaos Expansion has been used. A projection based non-intrusive Polynomial Chaos approach is compared to its classical Galerkin based counterpart, and proven to be more efficient as order of chaos expansion increases. Effect of system randomness on the bifurcation behavior and the flutter boundary has been significant. Stochastic bifurcation results and bifurcation of probability density functions are presented here.

Stochastic framework for peak demand reduction opportunities with solar energy for manufacturing facilities

2021 ◽  
pp. 127891
Author(s):  
Miguel A. Peinado-Guerrero ◽  
Jesus R. Villalobos ◽  
Patrick E. Phelan ◽  
Nicolas A. Campbell
Keyword(s):  
Solar Energy ◽  
Peak Demand ◽  
Demand Reduction ◽  
Stochastic Framework ◽  
Manufacturing Facilities

scholarly journals High-Fidelity Fin–Actuator System Modeling and Aeroelastic Analysis Considering Friction Effect

2021 ◽  
Vol 11 (7) ◽  
pp. 3057
Author(s):  
Jin Lu ◽  
Zhigang Wu ◽  
Chao Yang
Keyword(s):  
System Modeling ◽  
Past Research ◽  
High Fidelity ◽  
Aeroelastic Stability ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Flutter Boundary ◽  
Actuator System ◽  
Friction Models ◽  
Comparison Of The Results

Both the dynamic characteristics and structural nonlinearities of an actuator will affect the flutter boundary of a fin–actuator system. The actuator models used in past research are not universal, the accuracy is difficult to guarantee, and the consideration of nonlinearity is not adequate. Based on modularization, a high-fidelity modeling method for an actuator is proposed in this paper. This model considers both freeplay and friction, which is easy to expand. It can be directly used to analyze actuator characteristics and perform aeroelastic analysis of fin–actuator systems. Friction can improve the aeroelastic stability, but the mechanism of its influence on the aeroelastic characteristics of the system has not been reported. In this paper, the LuGre model, which can better reflect the friction characteristics, was integrated into the actuator. The influence of the initial condition, freeplay, and friction on the aeroelastic characteristics of the system was analyzed. The comparison of the results with the previous research shows that oversimplified friction models are not accurate enough to reflect the mechanism of friction’s influence. By changing the loads, material, and geometry of contact surfaces, flutter can be effectively suppressed, and the power loss caused by friction can be minimized.

scholarly journals A Stochastic Model to Describe the Scattering in the Response of Polysilicon MEMS

2021 ◽  
Vol 2 (1) ◽  
pp. 95
Author(s):  
Luca Dassi ◽  
Marco Merola ◽  
Eleonora Riva ◽  
Angelo Santalucia ◽  
Andrea Venturelli ◽  
...  
Keyword(s):  
Silicon Film ◽  
Micro Fabrication ◽  
Micro Electro Mechanical Systems ◽  
Local Fluctuations ◽  
Stochastic Framework ◽  
On Line ◽  
Chip Testing ◽  
On Chip ◽  
Time Required ◽  
Polycrystalline Silicon Film

The current miniaturization trend in the market of inertial microsystems is leading to movable device parts with sizes comparable to the characteristic length-scale of the polycrystalline silicon film morphology. The relevant output of micro electro-mechanical systems (MEMS) is thus more and more affected by a scattering, induced by features resulting from the micro-fabrication process. We recently proposed an on-chip testing device, specifically designed to enhance the aforementioned scattering in compliance with fabrication constraints. We proved that the experimentally measured scattering cannot be described by allowing only for the morphology-affected mechanical properties of the silicon films, and etch defects must be properly accounted for too. In this work, we discuss a fully stochastic framework allowing for the local fluctuations of the stiffness and of the etch-affected geometry of the silicon film. The provided semi-analytical solution is shown to catch efficiently the measured scattering in the C-V plots collected through the test structure. This approach opens up the possibility to learn on-line specific features of the devices, and to reduce the time required for their calibration.

Ground Flutter Simulation Test Based on Reduced Order Modeling of Aerodynamics by CFD/CSD Coupling Method

2019 ◽  
Vol 11 (01) ◽  
pp. 1950008
Author(s):  
Binwen Wang ◽  
Xueling Fan
Keyword(s):  
Aerodynamic Force ◽  
Test System ◽  
Simulation Test ◽  
Robust Controller ◽  
Test Technique ◽  
Reduced Order ◽  
Aerodynamic Model ◽  
Flutter Boundary ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Flutter is an aeroelastic phenomenon that may cause severe damage to aircraft. Traditional flutter evaluation methods have many disadvantages (e.g., complex, costly and time-consuming) which could be overcome by ground flutter test technique. In this study, an unsteady aerodynamic model is obtained using computational fluid dynamics (CFD) code according to the procedure of frequency domain aerodynamic calculation. Then, the genetic algorithm (GA) method is adopted to optimize interpolation points for both excitation and response. Furthermore, the minimum-state method is utilized for rational fitting so as to establish an aerodynamic model in time domain. The aerodynamic force is simulated through exciters and the precision of simulation is guaranteed by multi-input and multi-output robust controller. Finally, ground flutter simulation test system is employed to acquire the flutter boundary through response under a range of air speeds. A good agreement is observed for both velocity and frequency of flutter between the test and modeling results.

scholarly journals Mixed H 2 / H ∞ Control in a Stochastic Framework

1992 ◽  
Vol 25 (21) ◽  
pp. 108-111
Author(s):  
M.A. Peters ◽  
A.A. Stoorvogel
Keyword(s):  
Stochastic Framework

Flutter of Perforated Metallic Plates Repaired with Cross-Ply Composite Patches

2009 ◽  
Vol 417-418 ◽  
pp. 709-712
Author(s):  
Ali Amin Yazdi ◽  
Jalil Rezaeepazhand
Keyword(s):  
Laminated Composite ◽  
Material Anisotropy ◽  
Perforated Plates ◽  
Closed Form Solutions ◽  
Finite Element Software ◽  
Composite Patch ◽  
Numerical Studies ◽  
Flutter Analysis ◽  
Flutter Boundary ◽  
Metallic Plates

This study investigates the application of laminated composite patches for enhancement of flutter behavior of perforated metallic plates repaired with an external composite patch. Due to material anisotropy and discontinuity in geometry involved in flutter analysis of repaired plates, closed form solutions are practically unobtainable. Numerical studies using commercial finite element software were conducted to investigate the effects of variation in lamination parameters on the flutter boundary of perforated plates repaired with cross-ply composite patches. Both ply-level and sub-laminate level configurations are investigated. Presented results illustrate that flutter boundaries of perforated plates can be changed by choosing proper stacking sequence for composite patches.

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