Article
Mechanics
Sai Vishal, Ashwad Raaj, Chandan Bose, J. Venkatramani
Summary: This study investigates the synchronization characteristics of a pitch-plunge aeroelastic system under the influence of coupled structural free-play and dynamic stall-induced aerodynamic non-linearities. The results show that free-play nonlinearity plays a dominant role in the dynamical transition when attached flow is present. The onset of dynamic stall is found to be crucial in bifurcation scenarios at high flow speed regimes.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2021)
Article
Acoustics
Peihan Wang, Zhigang Wu, Chao Yang
Summary: The frequency-time domain method is a powerful tool but limited to steady-state solutions. A modified frequency-time domain method is proposed to investigate nonlinear dynamic behaviors with initial conditions. The feasibility is validated through numerical results and compared with the Runge-Kutta algorithm. The sensitivity of parameters and calculation methods of convolution integral contributes to strategies for accuracy.
JOURNAL OF SOUND AND VIBRATION
(2023)
Article
Engineering, Mechanical
Sai Vishal, Ashwad Raaj, Chandan Bose, J. Venkatramani, Grigorios Dimitriadis
Summary: The present study investigates the bifurcation characteristics of a pitch-plunge aeroelastic system with coupled non-smooth nonlinearities in both structural and aerodynamic aspects. The study shows that the freeplay gap plays a key role in combining the effects of structural and aerodynamic nonlinearities. Interesting discontinuity-induced bifurcation scenarios arise at high values of the freeplay gap, which can significantly impact the safety of the aeroelastic system.
NONLINEAR DYNAMICS
(2022)
Article
Engineering, Mechanical
B. E. Saunders, R. Vasconcellos, R. J. Kuether, A. Abdelkefi
Summary: This study focuses on the numerical analysis of a dynamical system with multi-segmented freeplay, which includes four stiffness transitions and five distinct regions in the phase space. The effects of the multi-segmented parameters on bifurcation diagram evolution, multi-stable behavior, and different bifurcations are studied. Various tools such as harmonic balance, basins of attraction, phase planes, and Poincare section analysis are used to investigate these phenomena. Results show that among the three multi-segmented parameters, asymmetry has the strongest effect on the system's response.
NONLINEAR DYNAMICS
(2023)
Article
Chemistry, Multidisciplinary
Liuyue Bai, Zhigang Wu, Chao Yang
Summary: This study provides novel perspectives on the nonlinear aeroelastic characteristics of all-movable fins with freeplay nonlinearities. An unsteady aerodynamic model based on the second-order piston theory considering thickness effects is employed. A discrete scanning method using the describing function method is established for systems with multiple freeplay nonlinearities to solve limit-cycle oscillations (LCOs) and avoid solution loss. The influence of support stiffness and freeplay size ratio on the system's dynamical response is analyzed.
APPLIED SCIENCES-BASEL
(2023)
Article
Mathematics, Interdisciplinary Applications
Davide Martini, Giacomo Innocenti, Alberto Tesi
Summary: This paper investigates Limit Cycle Oscillations (LCOs) in a Pitch & Plunge model of the wing dynamics. The existence of Predicted Limit Cycles (PLCs) is established using the Describing Function (DF) method, with analysis on the influence of wind speed on system behavior, confirming the accuracy of the method.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Engineering, Mechanical
Andrea Iannelli, Mark Lowenberg, Andres Marcos
Summary: This paper investigates the impact of model uncertainty on the nonlinear dynamics of aeroelastic systems, particularly focusing on the scenarios arising in nonlinear flutter analysis when uncertainties in the model are considered. By employing a framework that addresses robustness issues from a nonlinear dynamics perspective, the study quantifies stability information, enhances understanding of Hopf bifurcation mechanisms, and reveals properties of the nominal system that are difficult to detect using traditional numerical approaches.
NONLINEAR DYNAMICS
(2021)
Article
Engineering, Aerospace
Shuaishuai Liu, Rui Zhao, Kaiping Yu, Bowen Zheng
Summary: This paper proposes a backbone-curve-based framework for the identification of folding fins with freeplay nonlinearity. The method is more direct and elegant than most existing nonlinear identification approaches and consists of three steps: obtaining the linear model, solving the backbone curves analytically, and identifying the freeplay parameters through curve fitting. Numerical experiments and a real-life example demonstrate the effectiveness of the proposed method.
CHINESE JOURNAL OF AERONAUTICS
(2022)
Article
Engineering, Aerospace
Yayun Shi, Shun He, Gaowei Cui, Gang Chen, Yan Liu
Summary: This study investigates the quenching of limit cycle oscillation (LCO) in a supercritical airfoil (NLR 7301) considering freeplay in transonic viscous flow. Computational Fluid Dynamics (CFD) based on Navier-Stokes equations is used to calculate transonic aerodynamic forces. A loosely coupled scheme with steady CFD and an efficient graphic method is developed to obtain the aerodynamic preload. The LCO quenching is observed based on nonlinear dynamic aeroelastic response obtained using a time marching approach.
CHINESE JOURNAL OF AERONAUTICS
(2023)
Article
Engineering, Mechanical
Sanuja Jayatilake, Branislav Titurus
Summary: This paper presents a comprehensive model of a nonlinear aeroelastic system to analyze complex aeroelastic phenomena. The structural model is developed using the Rayleigh-Ritz approach and includes a damping model. The aerodynamics of the problem is modeled using the ONERA dynamic stall model. The response of the aeroelastic problem is evaluated through time-marched simulations.
NONLINEAR DYNAMICS
(2022)
Article
Mechanics
Ashwad Raaj, Sirshendu Mondal, Venkatramani Jagdish
Summary: The study explores the possibility of using the concept of Amplitude Death (AD) to suppress oscillatory instabilities in aeroelastic systems, specifically focusing on flutter instability caused by nonlinear fluid-structure interactions. Coupling two airfoils together, the effects of coupling strength and time delay on the regime of AD are systematically varied to investigate their impact on flutter suppression. The findings demonstrate that AD can effectively suppress flutter instability and serve as a potential mechanism for flutter suppression in both deterministic and stochastic input flow scenarios.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2021)
Article
Acoustics
Jose Augusto da Silva, Flavio D. Marques
Summary: Structural nonlinearities are typically present in aeroelastic systems, and this article investigates the effects of various types of concentrated structural nonlinearities on a typical aeroelastic section with trailing edge control surface. The study analyzes different nonlinear scenarios involving cubic hardening stiffness, free play, free play with preload, and slip dry friction in the trailing edge control surface motion.
JOURNAL OF VIBRATION AND CONTROL
(2022)
Article
Engineering, Aerospace
Jonathan Hilger, Markus Raimund Ritter
Summary: The Pazy wing aeroelastic benchmark is a highly flexible wind tunnel model. Static coupling simulations and stability analyses for selected flow velocities and angles of attack were presented, showing a significant change in flutter stability with increasing deflection and influence of modal properties.
Article
Engineering, Mechanical
Yeyin Xu, Yinghou Jiao, Zhaobo Chen
Summary: Independent vibrations in nonlinear systems are advantageous for vibration isolation. In this research, a sequence of odd-order independent subharmonic vibrations in a nonlinear flexible rotor system is studied. The stability and bifurcations of the vibrations are discussed, and it is found that the vibrations can effectively suppress global synchronous vibrations.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Engineering, Aerospace
Bo Sun, Xuerui Wang, Erik-Jan van Kampen
Summary: In this paper, an event-triggered intelligent control scheme with a single critic network is proposed to address the optimal stabilization problem of nonlinear aeroelastic systems. The feasibility and performance of the algorithm are verified through applying it to an optimal stabilization task of a nonlinear aeroelastic system.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Acoustics
Jose Augusto da Silva, Flavio D. Marques
Summary: Structural nonlinearities are typically present in aeroelastic systems, and this article investigates the effects of various types of concentrated structural nonlinearities on a typical aeroelastic section with trailing edge control surface. The study analyzes different nonlinear scenarios involving cubic hardening stiffness, free play, free play with preload, and slip dry friction in the trailing edge control surface motion.
JOURNAL OF VIBRATION AND CONTROL
(2022)
Article
Engineering, Mechanical
W. Yossri, A. Bouma, S. Ben Ayed, R. Vasconcellos, A. Abdelkefi
Summary: The study compares the effects of different aerodynamic formulations on wing-based systems, finding that using unsteady fluid-structure interaction and stall modeling is crucial for continuous wing systems even at small angles of attack and reduced frequency values.
NONLINEAR DYNAMICS
(2022)
Article
Thermodynamics
A. Bouma, E. Le, R. Vasconcellos, A. Abdelke
Summary: This study investigates the design and nonlinear characteristics of a two-degree of freedom piezoaeroelastic energy harvesting system with freeplay and multi-segmented nonlinearities. The analysis explores the nonlinear responses under different conditions and proposes an effective design approach for harvesting energy at low wind speeds.
Article
Engineering, Mechanical
L. G. P. dos Santos, F. D. Marques, R. M. G. Vasconcellos
Summary: Stall flutter, which is commonly encountered in aircraft with flexible wings, has become an increasingly likely condition as the demand for more flexible wings grows. The characterization of the post-flutter dynamical behavior is important due to the involvement of various nonlinearities that can result in complex motion. In this study, the dynamics of an idealized HALE typical section with pitch-plunge motion and nonlinearities in the stall flutter regime were investigated using an aeroelastic state-space formulation and a modified Beddoes-Leishman dynamic stall model. The results show that period-doubling can occur without stall, but chaos arises at discontinuity-induced bifurcations due to dynamic stall. A parametric study was conducted to assess the influence of key parameters on the development of bifurcations and chaos.
NONLINEAR DYNAMICS
(2022)
Article
Mechanics
Myrella V. Cabral, Flavio D. Marques, Antonio J. M. Ferreira
Summary: This study numerically investigates the nonlinear aeroelastic behavior of multibay composite laminate curved panels exposed to cross-stream supersonic flow. Unlike most previous studies, the evaluation of panel flutter in this research is based not only on oscillation amplitudes but also on energy quantification. The results reveal that the interaction between adjacent bays leads to a more complex behavior and higher energetic loss compared to the traditional single panel approach.
COMPOSITE STRUCTURES
(2022)
Article
Acoustics
Carlos Renan dos Santos, Flavio Donizeti Marques
Summary: This study fills the gap in the literature of efficient tools with low computational cost to assess unsteady and nonlinear aerodynamics loads accounting for three-dimensional wing effects. By developing a nonlinear unsteady lifting line model, it investigates finite wing effects on the power generation from stall-induced oscillations. The results reveal that the dynamic behavior of the three-dimensional harvester may differ from the two-dimensional case, resulting in a reduction in harvested power.
JOURNAL OF VIBRATION AND CONTROL
(2023)
Article
Engineering, Civil
H. S. Naveen Kumar, Subhaschandra Kattimani, Flavio D. Marques, T. Nguyen-Thoi, Mehdi Shariati
Summary: This research investigates the geometrically nonlinear behavior of functionally graded saturated porous material (FGSPM) plate under undrained conditions. The refined shear deformation plate theory (RSDPT) is used to model the FGSPM plate with von Karman's nonlinearity, and Biot's linear poroelasticity theory is applied to establish the constitutive equations. The results show that the saturated fluid significantly affects the nonlinear deflection and vibration behavior of the FGSPM plate.
INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS
(2023)
Article
Engineering, Mechanical
Gabriel P. Araujo, Jose Augusto I. da Silva, Flavio D. Marques
Summary: The combination of a rotational NES with EH for vortex-induced vibrations of a cylinder exposed to airflow is investigated in this study. The results show that this combination has the potential to dissipate vibration energy and generate electricity simultaneously, making it suitable for the design of energy extraction devices.
JOURNAL OF FLUIDS AND STRUCTURES
(2022)
Article
Mechanics
Pedro K. Suzuki, Flavio D. Marques, Daniel A. Pereira
Summary: Electric energy is essential worldwide, but current energy matrices may not always be adequate. Wind energy is a viable source, although its use is limited. Centimeter-Scale Wind Turbines (CSWTs) offer a potential solution, but their design lacks a systematic procedure. This study proposes a modified approach to calculate power curves for CSWTs without the need for experimental tests. Three CSWTs were fabricated using a 3D printer and evaluated using wind tunnel testing. Results show that the modified method is well-suited for CSWT analysis, with better outcomes for turbines with more blades.
Article
Engineering, Mechanical
A. Bouma, R. Vasconcellos, A. Abdelkefi
Summary: Modeling and performance investigation is conducted on a three-degree-of-freedom piezoaer-oelastic system with freeplay and multi-segmented stiffness with and without impact. Results show that grazing and grazing/sliding bifurcations may be present, and the response is complex with several transitions as the wind speed is increased. An effective design is determined for a three-degree-of-freedom wing-based energy harvester by selecting the freeplay gap size and multi-segmented nonlinear stiffness in the pitch and control surface and the electrical load resistance.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Engineering, Aerospace
Emanuel A. R. Camacho, Flavio D. Marques, Andre R. R. Silva
Summary: The present study focuses on the importance of leading-edge dynamic incidence in the propulsive performance of flapping airfoils. By adding a pitching leading-edge to a conventional NACA0012 airfoil, the propulsive characteristics can be improved. Numerical results show that the leading-edge pitching amplitude greatly affects the propulsive power and efficiency, providing significant improvements.
Article
Mechanics
E. Mubai, D. P. Mason
Summary: The two-dimensional turbulent thermal classical far wake is investigated in this study. The turbulence is described using the Boussinesq hypothesis for Reynolds stresses and Prandtl's mixing length model for eddy viscosity and eddy thermal conductivity. Two conservation laws are derived for the thermal boundary layer equations using the multiplier method, and two conserved quantities are obtained from the conserved vectors and boundary conditions. Lie point symmetry associated with the momentum and thermal conserved vectors is derived, showing that the momentum and thermal mixing lengths are proportional. An invariant solution is obtained numerically using a shooting method, and analytically when v = 0, kappa = 0.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
Daniel J. Arrigo, Travis C. Chism
Summary: This paper investigates the governing equations for plane stress deformations of isotropic incompressible hyperelastic materials. The authors previously discovered a linearization method for the plane strain case of the Varga material, and in this paper, they further demonstrate that the governing equations for the plane stress case can also be linearized.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
A. P. Chugainova, R. R. Polekhina
Summary: This article numerically investigates the conditions for the decay of a nonlinear wave into a system of waves traveling at different velocities in a viscoelastic weakly anisotropic medium. Solutions of a hyperbolic system of equations are studied in the region of nonuniqueness of parameters, where a solution to the Riemann problem can be constructed with both a single wave and a system of waves corresponding to the same initial data.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
Yu. N. Grigoriev, E. I. Kaptsov, S. V. Meleshko
Summary: This paper studies the mathematical properties of gasdynamics equations with thermochemical nonequilibrium and provides solutions for two different models. The results show that the solutions to the modified system of equations are physically consistent and can describe the effects of thermochemical nonequilibrium.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
Y. Hao, X. Y. Guo, Y. B. Fu
Summary: This paper investigates the nonlinear stochastic dynamic response of a three-degree-of-freedom(3-DOF) airfoil with high substructural nonlinearity under vertical turbulent disturbances. The effects of parameters such as the incoming velocity, turbulence scale and intensity on the stochastic dynamics behavior of the system are clarified.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
T. Flament, J. -F. Deu, A. Placzek, M. Balmaseda, D. -M. Tran
Summary: This paper focuses on the numerical computation of vibrations in geometrically nonlinear structures induced by aeroelastic coupling with fluid flow using reduced order models (ROM). The proposed ROM formulation utilizes projection on a basis of reduced dimension enhanced with dual modes, allowing for the accurate capture of dynamic characteristics and adaptation to unsteady aerodynamic loads. The limitations of the classical Implicit Condensation method are highlighted, while the ROM proposed overcomes these limitations and accurately captures the dynamics.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
Sidhartha Sankar Roy, Kishore Chandra Biswal
Summary: This study investigates the non-linear slosh dynamics of a sloped wall tank with a bottom-mounted object under seismic excitation. The potential flow theory is used to model the liquid domain using a mixed Eulerian-Lagrangian method. The study successfully quantifies the non-linear seismic response of the tank and the influence of the internal object on the hydrodynamic behavior. A parametric investigation is conducted by altering the object's height. Comparison with linear analysis justifies the necessity of non-linear analysis. The developed non-linear finite element model is found to be more effective and can be used in designing structure-coupled sloped wall TLDs.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
Kapil Dev, Om P. Suthar
Summary: This study presents stability analyses of thermosolutal convection in a Newtonian fluid-saturated Darcy porous layer under non-uniform inclined heating, considering the presence of the Soret effect. The results reveal the destabilizing effect of the solutal Darcy-Rayleigh number and Lewis number on the system's stability, while the Soret parameter has a non-monotonic effect depending on the horizontal Rayleigh number.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
Sandhya Maurya, Dia Zeidan, Manoj Pandey
Summary: This paper investigates a two-phase mass flow model governed by gravity, which involves solid particles and a viscous fluid. By utilizing the Lie symmetries admitted by the system, similarity solutions for the (2+1)-dimensional two-phase mass flow model are obtained. Through analytical solutions and numerical analysis, the physical behaviors of the resulting systems are successfully analyzed.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
Longfei Tan, Wei Zhang, Zixun Wang, Bowen Hou, Wei Sun
Summary: This study investigates the factors influencing the stiffness variation characteristics of a bolted joint during service, including macro deviation, micro-topography, and hysteresis characteristics. Through experiments and finite element modeling analysis, it is found that macro deviations and micro-topography on the bearing surface can cause irregular dynamic changes in the stiffness of the bolted joint, significantly affecting the dynamic/static response of the entire structure.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)
Article
Mechanics
Yu Xiao, Ze-Qi Lu, Nan Wu
Summary: This study investigates the characteristics of a magnet-engaged nonlinear piezoelectric energy generator stimulated by friction-induced vibration (FIV) in two distinct design configurations (in parallel and in-series). The results indicate that factors such as decay factor, dynamic friction coefficient, static friction coefficient, and normal force have an effect on the stability of the system and the generation of FIV. The in-parallel systems exhibit a higher charging power within the same operating range, while the in-series systems are more likely to excite FIV with a wider operating range.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2024)