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In-Plane Dynamic Analysis of Complex-Shaped Laminated Cracked Plates with Irregular Holes

AIAA JOURNAL 2023年第7期61卷 3172-3189页

作者： Zhong, Rui Wang, Qingshan Huang, Zhou Chen, Longting Shao, Wen Shuai, Cijun Cent South Univ Coll Mech & Elect Engn Changsha 410083 Peoples R China China Acad Engn Phys Inst Syst Engn Mianyang 621999 Peoples R China Jiangxi Univ Sci & Technol Ganzhou 341000 Peoples R China

This paper reports the unified in-plane vibration solutions of irregular laminated cracked plates having complex holes under various boundary restrictions. According to the geometric features of the studied structure, an irregular plate with/without the dropoff ply is decomposed into a variety of intact triangular and quadrilateral laminated elements. These elements are then mapped to two-dimensional regular square plates for deriving the unified formulations of the element energy integral. Simultaneously, the boundary restrictions at the external edge of the plate and fully rigid connections between the substructures are emulated through in-plane translational springs. The in-plane variables of intact plate elements are characterized by Chebyshev element expansions. Thus, the in-plane modal and harmonic response solutions are extracted by performing the general Rayleigh-Ritz procedures. Some in-plane vibration tests and finite element simulations concerning cracked plates with built-in holes are further executed. The applicability and accuracy of the proposed dynamic model are validated by comparison with the experimental data and those computed by finite element models (FEM). Also, some parametric cases are presented to investigate the influence of structural parameters, laminated configurations, and the dropoff ply effect on the in-plane dynamic characteristics of complex-shaped plates, which may provide useful benchmarks for structural design and damage detection of engineering structures.

关键词： Mechanical and structural Vibrations structural Composite Materials Laminated Structure structural dynamics and characterization Irregular Plates Dynamic Model Analysis

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Transonic Flutter Dips of the AGARD 445.6 Wing

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JOURNAL OF AIRCRAFT 2024年第2期61卷 515-522页

作者： Stanford, Bret K. Jacobson, Kevin E. NASA Langley Res Ctr Aeroelast Branch Hampton VA 23681 USA

The AGARD 445.6 configuration is the most popular validation test case for transonic flutter predictions, but the actual extent of truly nonlinear transonic flow for this case is unclear, due to the sparsity of the experimental data and the thin profile of the wing. This work utilizes a combination of mesh adaptation and the linearized frequency-domain method to obtain high-quality viscous and inviscid flutter predictions;these solutions show a double flutter dip through the transonic Mach range driven by complex shock growth across the wing. A single experimental flutter point lies in this flutter dip area, which is not enough to assess the accuracy of these transonic flutter predictions. Modeling the boundary layer of the wind tunnel wall (as opposed to the commonly assumed symmetry wall assumption) has a very large impact on the predicted flutter boundary, though the size of the boundary layer during the original experiment is uncertain.

关键词： Boundary Layer Thickness Incompressible Flow Signal Processing Wind Tunnel Models Aerodynamic Force Unsteady Reynolds Averaged Navier Stokes Aircraft Wing Components CFD Codes Aeroelastic Analysis structural dynamics and characterization

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Modeling and Estimation of Continuous Flexible Structure Using Theory of Functional Connections

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JOURNAL OF GUIDANCE CONTROL AND dynamics 2024年第10期47卷 2103-2119页

作者： Lombardi, Carlo Bevilacqua, Riccardo Mortari, Daniele Embry Riddle Aeronaut Univ Dept Aerosp Engn Daytona Beach FL 32114 USA Texas A&M Univ Dept Aerosp Engn College Stn TX 77843 USA

This paper presents a novel method for modeling and estimating the dynamics of a continuous structure based on a limited number of noisy measurements. The goal is reached using a Kalman filter in synergy with the recently developed mathematical framework known as the Theory of Functional Connections (TFC). The TFC allows deriving a functional expression capable of representing the entire space of the functions that satisfy a given set of linear and, in some cases, nonlinear constraints. The proposed approach exploits the possibilities offered by the TFC to derive an approximated dynamical model for the flexible system using the Lagrangian mechanics. The result is a representation of the structural dynamics using a finite number of states, in contrast to the infinite-dimensional model that would be obtained by application of the traditional continuum mechanics models that are based on sets of partial differential equations. The limited number of states enables the application of the well-known Kalman filter framework to improve the estimation of the displacements and displacement velocities. In addition, the continuous displacement field of the structure can be reconstructed with high fidelity. The theoretical development of the method is presented in relation to the case of an Euler-Bernoulli beam. Finally, the obtained model is used to carry out a simulation campaign aimed at assessing the accuracy, efficiency, and robustness of the proposed method.

关键词： Flexible and Active Structures Unscented Kalman Filter Euler Bernoulli Beam Theory structural dynamics and characterization Continuum Mechanics

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Toward an Efficient Method for F-16 Limit Cycle Oscillation Prediction

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JOURNAL OF AIRCRAFT 2024年第2期61卷 558-569页

作者： Kariv, Daniel Kunz, Donald L. Iovnovich, Michael Israeli Air Force Aircraft Programs & Engn Ctr Tel Aviv Israel Air Force Inst Technol Wright Patterson AFB OH 45433 USA

This study presents the development and validation of a computationally efficient prediction framework for the well-known nonlinear F-16 limit cycle oscillation (LCO) phenomenon. The framework relies on a simple physical working model that has been suggested and demonstrated in the past according to which LCO is primarily a flutter instability that is bounded by the existence of nonlinear structural damping (NSD), although potentially affected by nonlinear aerodynamic effects as well. In the framework developed herein, the NSD model is derived and calibrated using a novel method that simplifies the process and allows applicability of the derived NSD models for multiple aircraft download cases. Good LCO prediction capabilities are obtained using the suggested method in terms of LCO levels and trends with flight conditions, as demonstrated using four F-16 test configurations. This framework also allows several practical benefits, which makes it particularly suitable for industrial-level applications.

关键词： structural dynamics and characterization Unsteady Aerodynamics Computational Fluid dynamics Aeroelasticity Limit Cycle Oscillation

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Numerical Optimization of Metasurface Cells for Acoustic Reflection

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AIAA JOURNAL 2024年第3期62卷 1136-1147页

作者： Palma, Giorgio Centracchio, Francesco Burghignoli, Lorenzo Cioffi, Ilaria Iemma, Umberto Roma Tre Univ Dept Civil Comp Sci & Aeronaut Technol Engineerin Via Vito Volterra 62 I-00146 Rome Italy

Metamaterials and metasurfaces disclosed new degrees of freedom in controlling the acoustic field. Exploiting the generalized Snell law and the generalized law of reflection, the assembly of subwavelength unit cells is able to achieve extraordinary refraction and reflection by means of a controlled phase delay introduced in the field by the treated boundaries. The space-coiling design is one of the most powerful for cells in this metadevice class, providing effective low-thickness metasurfaces. However, space-coiling suffers from a narrow frequency operating range due to the intrinsic connection between the design operating wavelength and the characteristic dimensions of the metasurface. This work defines a procedure based on numerical optimization for designing space-coiling cells for modular acoustic metasurfaces, extending the frequency range in which the metasurface is effective. The set comprises eight different unit cells, each introducing a tailored phase shift in the reflected field that can be arranged to produce the desired acoustic effect. The broadband design is obtained by minimizing the dependency on the operating frequency of phase delay introduced by the cells, keeping the overall thickness below a quarter of the design wavelength. Results are shown for the benchmark problem of a metasurface modifying the reflection angle from a boundary.

关键词： Mathematical Optimization Acoustic Metamaterial Finite Element Method Acoustic Wave Particle Swarm Optimization structural dynamics and characterization Mechanical and structural Vibrations Numerical Simulation Simulation Based Design Optimization Metasurfaces

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Including Blade Elasticity into Frequency-Domain Propeller Whirl Flutter Analysis

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JOURNAL OF AIRCRAFT 2024年第3期61卷 774-784页

作者： Koch, Christopher Koert, Benedikt DLR German Aerosp Ctr Inst Aeroelast Dept Aeroelast Simulat Bunsenstr 10 D-37073 Gottingen Germany

Whirl flutter as an aeroelastic instability can be a limiting factor in the design and certification of turboprop aircraft configurations, especially for the engine suspension. Whirl flutter prediction for these configurations is currently done in the frequency domain using rigid propeller aerodynamic derivatives. Blade flexibility is neglected in this process, although it is known to have an impact on whirl flutter predictions. This paper uses frequency-domain transfer matrices for the propeller hub loads identified from a time-domain multibody simulation model of an isolated turboprop propeller and included into a frequency-domain flutter analysis to study the impact of blade elasticity on propeller whirl flutter. Results demonstrate a significantly stabilizing effect of blade elasticity on propeller whirl flutter due to a reduction of the destabilizing pitch-yaw cross-coupling moment. The method demonstrated in this paper is applicable to arbitrary time-domain propeller models and compatible with standard frequency-domain flutter processes, allowing for increased fidelity in the flutter prediction process.

关键词： Frequency Response Functions Propeller Analysis structural dynamics and characterization Multibody Simulation Aircraft Components and Structure Aeroelastic Instability Whirl Flutter Turboprop Aircraft

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High-Fidelity Aerostructural Optimization with a Geometrically Nonlinear Flutter Constraint

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AIAA JOURNAL 2023年第6期61卷 2430-2443页

作者： Gray, Alasdair C. Riso, Cristina Jonsson, Eirikur Martins, Joaquim R. R. A. Cesnik, Carlos E. S. Univ Michigan Dept Aerosp Engn Ann Arbor MI 48109 USA Georgia Inst Technol Daniel Guggenheim Sch Aerosp Engn Atlanta GA 30332 USA

When designing aircraft, avoiding dynamic aeroelastic instabilities such as flutter is a key requirement. One way to meet this requirement is to use a multidisciplinary design optimization subject to a flutter constraint. Flutter-constrained design optimizations have used geometrically linear detailed models, which do not accurately predict flutter for very flexible aircraft, or geometrically nonlinear low-order models, which do not accurately trade off cruise range and structural mass. This paper presents a framework for integrating a geometrically nonlinear, subsonic flutter constraint that captures the large in-flight deflections of very flexible aircraft into high-fidelity gradient-based aerostructural optimization. The cruise range and stress constraints are computed accurately with detailed aerostructural analyses, which use a built-up finite element model coupled to Reynolds-averaged Navier-Stokes computational fluid dynamics. The detailed model is condensed to a low-order aeroelastic model to compute the geometrically nonlinear flutter constraint and its adjoint derivatives with computational cost and robustness suitable for optimization. The framework is demonstrated by maximizing the cruise range of a subsonic high-aspect-ratio wing with respect to panel thicknesses, sweep, and span. The impact of the geometrically nonlinear flutter constraint highly depends on the in-flight deformation level. At low deflection levels, sweeping the wing backward is the most effective flutter prevention method, and the flutter constraint has little impact on the achievable cruise range. At high deflection levels, shortening the wing span is necessary to suppress flutter, reducing the achievable cruise range by up to 5.9%. This work is a step toward making multidisciplinary design optimization a practical tool for designing the energy-efficient, very flexible aircraft of the future, which require geometrically nonlinear flutter analyses early in the design cycle to prevent f

关键词： Finite Element Modeling Multidisciplinary Design Optimization Computational Fluid dynamics Nonlinear Aeroelastic Systems Aircraft Wing Design structural dynamics and characterization Flutter Analysis Aircraft Flutter structural Optimization Shape Optimization

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Data-Driven Bayesian Inference for Stochastic Model Identification of Nonlinear Aeroelastic Systems

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AIAA JOURNAL 2024年第5期62卷 1889-1905页

作者： McGurk, Michael Lye, Adolphus Renson, Ludovic Yuan, Jie Univ Strathclyde Aerosp Ctr Excellence Glasgow G1 1XJ Scotland Natl Univ Singapore Singapore Nucl Res & Safety Initiat Singapore 138602 Singapore Imperial Coll London Dynam Grp South Kensington Campus London SW7 2AZ England Univ Southampton Comp Engn Design Grp Southampton SO17 1BF England

The objective of this work is to propose a data-driven Bayesian inference framework to efficiently identify parameters and select models of nonlinear aeroelastic systems. The framework consists of the use of Bayesian theory together with advanced kriging surrogate models to effectively represent the limit cycle oscillation response of nonlinear aeroelastic systems. Three types of sampling methods, namely, Markov chain Monte Carlo, transitional Markov chain Monte Carlo, and the sequential Monte Carlo sampler, are implemented into Bayesian model updating. The framework has been demonstrated using a nonlinear wing flutter test rig. It is modeled by a two-degree-of-freedom aeroelastic system and solved by the harmonic balance methods. The experimental data of the flutter wing is obtained using control-based continuation techniques. The proposed methodology provided up to a 20% improvement in accuracy compared to conventional deterministic methods and significantly increased computational efficiency in the updating and uncertainty quantification processes. Transitional Markov chain Monte Carlo was identified as the optimal choice of sampling method for stochastic model identification. In selecting alternative nonlinear models, multimodal solutions were identified that provided a closer representation of the physical behavior of the complex aeroelastic system than a single solution.

关键词： Nonlinear Aeroelastic Systems Uncertainty Quantification structural dynamics and characterization Applied Mathematics Aerospace Engineering Surrogate Model Bayesian model updating Nonlinear Aeroelasticity Limit cycle oscillation

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Time-Varying Aeroelastic Modeling and Analysis for a Morphing Wing

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AIAA JOURNAL 2024年第10期62卷 3825-3840页

作者： Yu, Shijie Zhou, Xinghua Huang, Rui Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Aerosp Struct Nanjing 210016 Peoples R China

The paper presents a novel time-varying aeroelastic modeling approach for the morphing wing with the process of camber changing. The time-varying modeling methodology includes structural dynamics modeling, unsteady aerodynamic modeling, and interpolation for fluid-structure coupling. Firstly, the morphing wing is modularized and divided into fixed and variable parts by the floating frame of reference formulation. It is combined with the Craig-Bampton method to reduce order and eliminate nonindependent degrees of freedom. Then, the unsteady vortex-lattice method is used to calculate the transient, unsteady aerodynamic force for time evolution. Furthermore, the above time-varying structural dynamics modeling and a fluid-structure coupling interpolation are integrated to construct overall aeroelastic modeling, obtaining a set of differential-algebraic equations. Finally, these equations are numerically solved by the generalized-alpha method. The proposed approach provides an innovative idea to deal with the incredible complexity of the aeroelastic effect as structural characteristics change over time. It can efficiently and accurately analyze the morphing wing's transient response or flutter property. To verify and utilize the time-varying aeroelastic modeling approach, numerical calculations and comparative studies were carried out regarding the time-varying characteristics of the structural modes, aerodynamic calculations, and flutter prediction of the morphing wing.

关键词： Aeroelastic Stability Unsteady Aerodynamic Modeling structural dynamics and characterization Aerodynamic Performance Time-varying Aeroelasticity System Variable Camber Wing Floating Frame of the Reference Formulation Craig-Bampton Method Unsteady Vortex-lattice Method Flutter

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Reduced-Order Identification of Aeroelastic Systems with Constrained and Imposed Poles

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JOURNAL OF GUIDANCE CONTROL AND dynamics 2023年第6期46卷 1038-1051页

作者： Fournier, Hugo Massioni, Paolo Pham, Minh Tu Bako, Laurent Vernay, Robin Airbus Operat SAS F-31060 Toulouse France Univ Lyon Ecole Cent Lyon UMR5005 INSA LyonUniv Claude Bernard Lyon 1CNRSAmpere F-69621 Villeurbanne France Univ Lyon Univ Claude Bernard Lyon 1 Ecole Cent Lyon CNRSAmpereUMR5005INSA Lyon F-69130 Ecully France

This work investigates the identification of reduced-order state-space models from aeroelastic simulations of the interaction of a built-in structural finite element model and a linear aerodynamic model using unsteady potential theory. The objective is to propose and compare different new frequency-based identification methods operating on frequency response associated to the inputs and outputs of interest. The first methods considered are the Loewner interpolation method and a subspace algorithm. Subsequently, the paper introduces the possibility to apply stability constraints and to impose a certain number of poles estimated beforehand by the p-k method in order to make the identified models closer to the true aeroelastic physics. To achieve this goal, new dedicated techniques are developed and subsequently validated on data generated by random state-space models of various orders, and on aeroelastic data obtained from structural and aerodynamic aircraft models.

关键词： Aeroelastic Response Aerodynamic Force Singular Value Decomposition Mathematical Optimization structural dynamics and characterization Aeroservoelasticity Model Order Reduction System Identification Control Theory Aircraft dynamics

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