Aerospace Science and Technology

Journal: Aerospace Science and Technology

Abbreviation

Aerosp. sci. technol.

Publisher

Elsevier

ISSN

1270-9638

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Publications 1 - 10 of 16

Modelling and configuration control of wing-shaped bi-stable piezoelectric composites under aerodynamic loads
Arrieta, Andres F.; Bilgen, Onur; Friswell, Michael I.; et al. (2013)
Aerospace Science and Technology
Bi-stable composites have been considered for morphing applications thanks to their ability to hold two statically stable shapes with no energy consumption. In this paper, the modelling of the dynamic response of cantilevered wing-shaped bi-stable composites is presented. To this end, an analytical model approximating the dynamic response about each statically stable shape of wing-shaped bi-stable composites is derived. Theoretical modal properties are obtained to attain or stabilise a desired configuration following a previously introduced resonant control strategy. The resonant control technique is evaluated for a wing-shaped bi-stable composite subject to aerodynamic loads. Wind tunnel experiments are conducted on a wing-shaped specimen showing the ability of the control strategy to stabilise or attain a desired stable shape under aerodynamic loads.
On maximizing safety in stochastic aircraft trajectory planning with uncertain thunderstorm development
Hentzen, Daniel; Kamgarpour, Maryam; Soler, Manuel; et al. (2018)
Aerospace Science and Technology
Associative parametric CAE methods in the aircraft pre-design
Ledermann, Christof; Hanske, Claus; Wenzel, Jörg; et al. (2005)
Aerospace Science and Technology
The balanced mode decomposition algorithm for data-driven LPV low-order models of aeroservoelastic systems
Iannelli, Andrea; Fasel, Urban; Smith, Roy (2021)
Aerospace Science and Technology
A novel approach to reduced-order modeling of high-dimensional systems with time-varying properties is proposed. It combines the problem formulation of the Dynamic Mode Decomposition method with the concept of balanced realization. It is assumed that the only information available on the system comes from input, state, and output trajectories, thus the approach is fully data-driven. The goal is to obtain an input-output low dimensional linear model which approximates the system across its operating range. Time-varying features of the system are retained by means of a Linear Parameter-Varying representation made of a collection of state-consistent linear time-invariant reduced-order models. The algorithm formulation hinges on the idea of replacing the orthogonal projection onto the Proper Orthogonal Decomposition modes, used in Dynamic Mode Decomposition-based approaches, with a balancing oblique projection constructed from data. As a consequence, the input-output information captured in the lower-dimensional representation is increased compared to other projections onto subspaces of same or lower size. Moreover, a parameter-varying projection is possible while also achieving state-consistency. The validity of the proposed approach is demonstrated on a morphing wing for airborne wind energy applications by comparing the performance against two recent algorithms. Analyses account for both prediction accuracy and closed-loop performance in model predictive control applications.
Review of designs and flight control techniques of hybrid and convertible VTOL UAVs
Ducard, Guillaume J.J.; Allenspach, Mike (2021)
Aerospace Science and Technology
This paper provides a broad perspective and analysis of the work done in control of hybrid and convertible unmanned aerial vehicles (UAVs) for the main existing designs. These flying machines are capable of vertical take off and landing (VTOL) in helicopter mode and able to transition to high-speed forward flight in airplane mode and vice versa. This paper aims at helping engineers and researchers develop flight control systems for VTOL UAVs. To this end, a historical perspective first shows the technological advances in VTOL aircraft over the years. The main VTOL concepts and state-of-art flight control methods for VTOL UAVs are presented and discussed. This study shows both the common parts and the fundamental differences in the modeling, guidance, control, and control allocation for each hybrid-VTOL-UAV type. The open challenges and the current trends in the field are highlighted. These are namely: 1) augmenting or replacing classical controllers with data-driven methods such as neural networks and machine-learning-based controllers; 2) incorporating as much knowledge of the vehicle as possible into the flight controller, for example through model predictive control or model-based nonlinear controllers; 3) a trend towards finding a unified-control approach valid in all flight modes without the need to switch among flight controllers or to perform predefined-gain scheduling, and 4) the need to mitigate control complexity and available computing resources.
Design and development of FOLLY: A self-foldable and self-deployable quadcopter
Tuna, Turcan; Ovur, Salih E.; Gokbel, Etka; et al. (2020)
Aerospace Science and Technology
Reduced basis methods for structurally nonlinear Joined Wings
Teunisse, Nick; Demasi, Luciano; Tiso, Paolo; et al. (2017)
Aerospace Science and Technology
There is currently a large interest towards unconventional aircraft configurations. According to many experts, only revolutionary concepts can meet the demands of a sustainable aviation. Within this scenario, studies and investigations on innovative aircraft layouts have been flourished: Blended Wing Body, Joined Wings and Box Wings are relevant examples of configurations departing from the traditional monoplane. Joined Wings are characterized by strong geometric nonlinear effects, whose complexity is enhanced by the over-constrained layout and the intrinsic relevant bending-torsion coupling. Thus, the application of standard linear analysis tools of routine use in the aerospace industry is neither acceptable nor practical: the preliminary design phase needs a large number of simulations that have to be computationally fast and at the same time preserve an acceptable level of accuracy/fidelity. For this reason, reduced order models are particularly relevant for the design of these systems. However, several reduced order methods applied in the past to Joined Wings did not provide satisfactory accuracy and reliability. The poor performance is mainly due to the very early onset of nonlinear effects, even at very moderate deflections. This work provides an assessment, and an algorithm enhancement when needed, of several existing techniques aimed to build an effective reduction basis for model order reduction. In particular, Vibration Modes, Modal Derivatives, Ritz Vectors, Static Modes, Trial Solutions and Corrections Vectors are critically examined when applied to a representative JW configuration. The results indicate that Ritz Vectors and Modal Derivatives provide excellent accuracy of the reduced solution when compared with the full order solution. Specifically, a drastic increase in the performance of the reduced order model is noticed when ab-initio information regarding Modal Derivatives are included. This highlights and confirms the relevance of nonlinearities even at the early deformation stages. Hence, taking into account nonlinearities since the early design phases seems to be an unavoidable necessity for Joined Wings. As a consequence, efficient and reliable reduced order modeling might play an essential role in the design of such innovative configurations.
Tunable passive control of thermoacoustic instabilities based on a variable geometry combustor outlet nozzle
Blondé, Audrey; Schuermans, Bruno; Dharmaputra, Bayu; et al. (2025)
Aerospace Science and Technology
This paper presents a tunable combustor outlet geometry, which enables control of thermoacoustic instabilities. It is based on a water-cooled conical piston inserted in the outlet orifice. By varying the axial position of the piston, the outlet cross section area can be smoothly adjusted to control the acoustic boundary condition, from strongly reflecting to non-reflecting, over a broad range of frequencies. The classic model of Bechert for the reflection coefficient of an orifice with low Mach bias flow is adapted to account for the non-isothermal nature of the flow at this tunable combustor outlet, and experimentally validated for a wide range of conditions. It is then showed that this broadband tunable passive control enables suppression of high amplitude thermoacoustic limit cycles during operation. The results suggest that this device can be particularly useful for measuring the response of a burner and its flame to acoustic perturbations, because this measurement requires thermoacoustically stable states for a wide range of operating conditions.
Robust aircraft trajectory planning under uncertain convective environments with optimal control and rapidly developing thunderstorms
González-Arribas, Daniel; Soler, Manuel; Sanjurjo-Rivo, Manuel; et al. (2019)
Aerospace Science and Technology
Dynamic CAD objects for structural optimization in preliminary aircraft design
Ledermann, Christof; Ermanni, Paolo; Kelm, Roland (2010)
Aerospace Science and Technology

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