KRISTINA: Kinematic rib-based structural system for innovative adaptive trailing edge

Abstract

Nature teaches that the flight of the birds succeeds perfectly since they are able to change the shape of their wings in a continuous manner. The careful observation of this phenomenon has re-introduced in the recent research topics the study of "metamorphic" wing structures; these innovative architectures allow for the controlled wing shape adaptation to different flight conditions with the ultimate goal of getting desirable improvements such as the increase of aerodynamic efficiency or load control effectiveness. In this framework, the European research project SARISTU aimed at combining morphing and smart ideas to the leading edge, the trailing edge and the winglet of a large commercial airplane (EASA CS25 category) while assessing integrated technologies validation through high-speed wind tunnel test on a true scale outer wing segment. The design process of the adaptive trailing edge (ATED) addressed by SARISTU is here outlined, from the conceptual definition of the camber-morphing architecture up to the assessment of the device executive layout. Rational design criteria were implemented in order to preliminarily define ATED structural layout and the general configuration of the embedded mechanisms enabling morphing under the action of aerodynamic loads. Advanced FE analyses were then carried out and the robustness of adopted structural arrangements was proven in compliance with applicable airworthiness requirements.

Static and Dynamic Performance of a Morphing Trailing Edge Concept with High-Damping Elastomeric Skin

“…The load-bearing capability of a morphing trailing edge, as well as its ability to reproduce target shapes under the action of aerodynamic and inertial loads, was already discussed in previous works [33,34]. Similar investigations of a more conventional and segmented skin suitable for a morphing aileron were detailed in [35].…”

“…The detailed modelling of a morphing system involves a proper schematization of several components and subassembly items, such as the ribs, connected by spherical and cylindrical joints, the actuator chains, including motor shaft, the skin and the spars, among the others. All elements are fastened and must be compliant with the operative and safety loads (Limit and Ultimate Loads) [33,34]. In this work, the load-bearing actuation system is not covered by the analyses in order to characterize the single contribution of the skin on the generalized stiffness of the morphing structure.…”

Electro-Actuation System Strategy for a Morphing Flap

“…A first remarkable distinction within the adaptive systems can be made according to two macro-groups of interest: mechanized and compliant architectures. The first one implements morphing through rigid roto-translation of linkages interconnected by kinematic chains, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The sizing is led so that each kinematic sub-component withstands the external stresses foreseen in the real operating conditions; the actuators and the transmission lines must allow the correct kinematic behavior of the system, ensuring the achievement of target shape-configurations.…”

“…Fewer actuators are typically required to control the morphing process which expected benefit expected at system level drives the definition of additional mass, volume, force, and power required by the actuation system. In force of this consideration, it naturally follows that the adoption of mechanized structures becomes quite mandatory when dealing with large aircraft applications [3,4,6,8] and/or when multi-modal morphing functionalities have to be assured, [17]. European research projects such as JTI (Joint Technology Initiative)-Clean Sky [2] and GRA-ITD (Green Regional Aircraft-Integrated Technological Demonstration) have been important occasions to demonstrate technological achievements to be integrated into future green open-rotor aircraft (EASA, European Aviation Safety Agency, CS-25 category, [37]).…”

Description of Position Control Laws for Functionality Test of a Bi-modal Morphing Flap

“…Morphing is a bio-inspired concept; the critical and met iculous observation of the elegance of birds' flight has always inspired man [1]. Th is has led aerospace engineers to focus on meta morphic, or adaptive, wing structures capable of adapting their shape in a continuous manner for the entire flight envelope [2].…”