Basis Vector Quantification of Flutter Analysis Structural Modes

Northington, Jay S.

doi:10.2514/1.42591

Cited by 8 publications

(4 citation statements)

References 6 publications

(7 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A relationship between the gAIC of the baseline and modified structures is required. An orthogonal basis can be used such as that obtained by an application of the Gram-Schmidt procedure [35,36] to the baseline modes. On the other hand, it is sometimes advantageous to use a nonorthogonal basis, for example, the use of linear normal modes as bases for a nonlinear structure [37][38][39][40].…”

Section: Aerodynamic Relationship Between the Baseline And Modified Structuresmentioning

confidence: 99%

Economical Unsteady High Fidelity Aerodynamics in a Structural Optimization with a Flutter Constraint

Bartels

Stanford

2017

35th AIAA Applied Aerodynamics Conference

View full text Add to dashboard Cite

Structural optimization with a flutter constraint for a vehicle designed to fly in the transonic regime is a particularly difficult task. In this speed range, the flutter boundary is very sensitive to aerodynamic nonlinearities, typically requiring high-fidelity Navier-Stokes simulations. However, the repeated application of unsteady computational fluid dynamics to guide an aeroelastic optimization process is very computationally expensive. This expense has motivated the development of methods that incorporate aspects of the aerodynamic nonlinearity, classical tools of flutter analysis, and more recent methods of optimization. While it is possible to use doublet lattice method aerodynamics, this paper focuses on the use of an unsteady high-fidelity aerodynamic reduced order model combined with successive transformations that allows for an economical way of utilizing high-fidelity aerodynamics in the optimization process. This approach is applied to the common research model wing structural design. As might be expected, the high-fidelity aerodynamics produces a heavier wing than that optimized with doublet lattice aerodynamics. It is found that the optimized lower skin of the wing using high-fidelity aerodynamics differs significantly from that using doublet lattice aerodynamics.

show abstract

Section: Aerodynamic Relationship Between the Baseline And Modified Structuresmentioning

confidence: 99%

Economical Unsteady High Fidelity Aerodynamics in a Structural Optimization with a Flutter Constraint

Bartels

Stanford

2017

35th AIAA Applied Aerodynamics Conference

View full text Add to dashboard Cite

show abstract

“…This work also established different strategies to model this free-play induced flutter. Although, there has been extensive research work done [3][4][5][6] to gain an understanding of aeroelastic instability (flutter), the literature on understanding the energy connection in this phenomenon is very sparse.…”

Section: Introductionmentioning

confidence: 99%

Understanding Energy Transfer in Aeroelastic Flutter

Deshpande

Kelkar

2016

34th AIAA Applied Aerodynamics Conference

View full text Add to dashboard Cite

This paper presents a fundamental study aimed at understanding energy transfer phenomenon involved in dynamics of flutter of an aeroelastic lifting surface. The study is focused on unraveling the mechanism of energy exchange that takes place between two coupled sub-systems-aero and structure, assessing qualitatively and quantitatively the characteristics of energy transfer during different phases of dynamic response. For the purpose of this study, a lifting surface having NACA 0012 airfoil is considered. A high fidelity fully coupled computational dynamic model of this configuration is developed using Ansys Workbench. The lifting surface configuration was chosen to model the physical prototype that was built for the wind tunnel testing for a Navy project for flutter studies. The computational model is built maintaining the same geometrical and modal characteristics of the physical model. Considering the computational limitations, actual 3D coupled simulation is performed on a smaller section of this model to establish the concept of energy transfer. Previous work of authors showed a 2D aeroelastic system and energy analysis involved in a single cycle of a motion as a proof of concept. This paper presents the analysis of energy transfer across boundary during stable (damped), marginally stable (LCO), and unstable (diverging) phases of the dynamic response of the coupled aeroelastic system using experimental results. Computational results are showed for a configuration where magnetostrictive material is used to harness the energy from the sustained stable oscillations. This basic understanding of energy flow in and out of structure will not only facilitate better designs of lifting surfaces for desired flutter characteristics but also give deeper insights into potential for harvesting energy extracted from flow field by structure during marginally stable and unstable phases of the motion.

show abstract

“…The type of LCO, in this case typical LCO on the F-16, extracts energy from the airstream permitting a bounded structural response beyond the flutter/LCO onset velocity up to a predetermined maximum allowable limit. 3 Denegri 4 shows that flutter/LCO mechanism in the F-16 is not caused by high energy extracting classical 1st bending and 1st torsion modes, but by forward wing and aft wing bending modes. The forward wing and aft wing bending modes dominant in the coupled aero-structural LCO/flutter mechanism extract lower amounts of energy from the airstream 4 than 1st bending and 1st torsion modes.…”

Section: Introductionmentioning

confidence: 99%

Fluid-Structure Interaction Evaluation of F-16 Limit Cycle Oscillations

Lechniak

Bhamidipati

2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

View full text Add to dashboard Cite

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release A: distribution is unlimited. SUPPLEMENTARY NOTESCA: Air Force Flight Test Center Edwards AFB CA CC: 012100 ABSTRACTApplication of high-fidelity computational science and engineering (CSE) tools providebetter data for decisions to enhance weapon systems acquisition, testing, and support. Fluid structure interaction (FSI) simulation is being evaluated to quantify aero-structural dynamic mechanisms that bound F-16 limit cycle oscillations (LCO). The intent of the research objectives is to provide a better understanding of flight-test aero-structural observations through the utilization of CSE tools. Validation of results provided by CSE tools using experimental testing as the truth source, allows for development of methods and processes to accurately determine coupled-field physical characteristics of full fighter aircraft configurations. Specifically for F-16 LCO, the response frequency, coupled mode response, and flutter/LCO onset velocity are evaluated for comparison of CSE tool results against flight test results. SUBJECT TERMS

show abstract

Basis Vector Quantification of Flutter Analysis Structural Modes

Cited by 8 publications

References 6 publications

Economical Unsteady High Fidelity Aerodynamics in a Structural Optimization with a Flutter Constraint

Economical Unsteady High Fidelity Aerodynamics in a Structural Optimization with a Flutter Constraint

Understanding Energy Transfer in Aeroelastic Flutter

Fluid-Structure Interaction Evaluation of F-16 Limit Cycle Oscillations

Contact Info

Product

Resources

About