Correlations Between UM/NAST Nonlinear Aeroelastic Simulations and the Pre-Pazy Wing Experiment

Riso, Cristina; Cesnik, Carlos E. S.

doi:10.2514/6.2021-1712

Cited by 13 publications

(10 citation statements)

References 25 publications

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“…Ref. [46] describes the development of the equivalent beam model for its use in UM/NAST (University of Michigan Nonlinear Aeroelastic Simulation Toolbox) using their Enhanced FEM2Stick (EF2S) framework. UM/NAST employs 4-by-4 equivalent sectional stiffness and mass matrices are obtained along a beam reference line (located at 44.1% chord).…”

Section: B Model Reductionmentioning

confidence: 99%

“…For consistency between the baseline models, the MRM structural model was based on a coupled 6-by-6 beam model built in Matlab with the stiffness coefficients from [46] and, like in SHARPy, infinitely rigid shear terms. Twenty mode shapes were extracted from 100 FE nodes along the beam and interpolated to 400 segments along the reference line over the wingspan.…”

Section: B Model Reductionmentioning

confidence: 99%

“…A modal analysis of the unloaded Pre-Pazy wing has been performed to validate the sectional coefficients of the equivalent beam models against the full 3D FEM in which the frequencies are compared. Tables 1 and 2 show the original FEM, UM/NAST [46], SHARPy and MRM frequencies. Since the SHARPy and MRM models are derived from the UM/NAST model it is this data that we use to compare our models against.…”

Section: Modal Analysismentioning

confidence: 99%

“…Since the SHARPy and MRM models are derived from the UM/NAST model it is this data that we use to compare our models against. For a performance evaluation of the one-dimensional beam model compared to the full 3D FEM the reader is referred to [46], although the good agreement between the full 3D FEM and the one-dimensional beam model justifies its use. Turning to the models used herein, the SHARPy and MRM models, with maximum errors of 0.7% against the UM/NAST model in the 3rd out-of-plane (OOP3) bending mode can be considered acceptable.…”

Section: Modal Analysismentioning

confidence: 99%

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Flutter Predictions for Very Flexible Wing Wind Tunnel Test

Goizueta¹,

Wynn²,

Palacios³

et al. 2022

Journal of Aircraft

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The stability boundaries of a very flexible wing are sought to inform a wind-tunnel flutter test campaign. The objective is twofold: to identify via simulation the relevant physical processes to be explored while ensuring safe and non-destructive experiments, and to provide a benchmark case for which computational models and test data are freely available. Analyses have been independently carried out using two geometrically nonlinear structural models coupled with potential flow aerodynamics. The models are based on a prototype of the wing for which static load and aeroelastic tests are available, and the experimental results have been successfully reproduced numerically. The wing displays strong geometrically nonlinear effects with static deformations as high as 50% of its span. This results in substantial changes to its structural dynamics, which display several mode crossings that cause the flutter mechanisms to change as a function of deformation. Stability characteristics depend on both the free-stream velocity and the angle of attack. A fast drop of the flutter speed is observed as the wing deforms as the angle of attack is increased, while a large stable region is observed for wing displacements over 25%. The corresponding wind tunnel dynamic tests have validated these predictions.

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Section: B Model Reductionmentioning

confidence: 99%

Section: B Model Reductionmentioning

confidence: 99%

Section: Modal Analysismentioning

confidence: 99%

Section: Modal Analysismentioning

confidence: 99%

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Flutter Predictions for Very Flexible Wing Wind Tunnel Test

Goizueta¹,

Wynn²,

Palacios³

et al. 2022

Journal of Aircraft

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“…It is 550 mm in span and 100 mm in chord; it consists of an aluminum spar within a Nylon 3D printed chassis with a NACA0018 airfoil profile ribs to which an Oralight film skin gives its aerodynamic shape. A one-dimensional beam model of the wing has been derived by Riso et al in [35] where a 3D finite element model has been reduced to sectional coefficients such that it can be used in tools such as SHARPy. The Pazy wing is capable of undergoing large deformations (approximately 50% of span) and in previous work by the authors, the wing has shown a complex stability envelope driven by its deformation [14].…”

Section: Case Study: Pazy Wingmentioning

confidence: 99%

Fast flutter evaluation of very flexible wing using interpolation on an optimal training dataset

Goizueta

Wynn

Palacios

2022

AIAA SCITECH 2022 Forum

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Machine learning strategies can be efficiently used to accelerate the exploration of the design space or flight envelope of highly flexible aeroelastic systems. In this paper, we explore the use of interpolation between parametric state-space realizations to, with few true systems sampled in the parameter space, produce with adequate accuracy a state-space model anywhere in the parameter space. The location of the sampling points is shown to be decisive thus the selection of these points takes the focus in this work. Several approaches are explored, putting emphasis on adaptive schemes that locate the optimal points in the parameter space that are needed to capture the changing system dynamics. Since the evaluation of the true system is costly, optimization techniques based on statistical surrogate models are sought, which need to be trained but are effective in locating the best locations to use as sampling data. A novel method inspired by Bayesian optimization is used to make the most out of a limited number of known state-spaces by taking different combinations as training and testing data of the statistical surrogate, leading to not only an accurate interpolation framework but also to a reduction of 50% of the number of costly full system evaluations compared to a standard Bayesian optimization set-up. These methods are demonstrated on the Pazy wing, a very flexible wing with a complex stability envelope, whereby we produce a very accurate representation of the flutter envelope at a reduced computational cost.

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