Preliminary failure analysis of an innovative morphing flap tailored for large civil aircraft applications

Abstract

Aircraft wings are usually optimized for a specific mission design point. However, since they operate in a wide variety of flight conditions, some of these have conflicting impacts on aircraft design process, as a single configuration may be efficient in one instance but perform poorly in others. A shape-shifting surface, or usually referred as 'morphing', potentially enables transport aircraft to reach maximum performance in any flight conditions. Within the framework of the Joint Technology Initiative Clean Sky (JTI-CS) project, and during the first phase of the Green Regional Aircraft Integrated Technological Demonstration (GRA-ITD), the authors focused on the design and technological demonstration of an innovative bi-modal morphing outer wing flap to be installed on the next generation open rotor green regional aircraft. A novel active rib layout was designed to enable the articulation of the entire flap structure by means of multi-box arrangement. In order to prove structural load-carrying capabilities with the reference to a relevant environment, the full-scale morphing flap was properly analyzed by means of detailed finite element model analysis. To the authors' knowledge, there is no morphing concept in literature based on a similar architecture based on distributed servo-mechanical actuators. Hence, a rational review of the potential problems associated with actuators off-design conditions has been conducted to investigate the maturity of the concept and safety issues concerning the flap ground static test. In addition, useful insights have been provided to effectively detect potential failure conditions in service

Electro-Actuation System Strategy for a Morphing Flap

“…Moreover, a distributed sensor system based on relative encoder generated the signals for the appropriate feedback actions and, at the same time, monitored possible faults inside the actuation mechanism. Eight controllers (ServoOne Jr. by LTI ® motion, https://www.lti-motion.com, Figure 12a, [14,15]) were mounted in the first four bays of the leading edge in order to drive the actuation groups. Encoders for relative rotation measurement were placed at the hinges H1, H2, and H3 of the ribs at stations 1, 4, and 8.…”

“…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.…”

The Effect of Maneuver Load Alleviation Strategies on Aircraft Performance Indicators

“…Rising environmental concerns nowadays are drawing more attention to the quest towards energy-efficient aircraft. According to European aviation goals, a drastic reduction in current pollutant and noise emissions is sought before the year 2050, aiming at a 75% and 90% reduction of CO 2 and NO x , respectively, together with a 65% cutback in noise level [1]. Such an ambitious goal endorses deeper research towards greener aircraft, featuring a reduction in fuel burn.…”

Aeroelastic Stability Analysis of a Wind Tunnel Wing Model Equipped with a True Scale Morphing Aileron

“…Within the framework of the JTI-Clean Sky project, Green Regional Aircraft "Low Noise Configuration" domain, design and technological demonstration of an innovative flap architecture for CS-25 category regional aircraft was provided [4].…”