Flexible High Aspect Ratio Wing: Low Cost Experimental Model and Computational Framework

Abstract

Aircraft concepts of tomorrow, such as high aspect ratio wing aircraft, are far more integrated between technical disciplines and thus require multi-disciplinary design approaches. Design tools able to predict associated dynamics need to be developed if such wing concepts are to be matured for use on future transport aircraft. The Cranfield University Beam Reduction and Dynamic Scaling (BeaR D S ) Programme provides a framework that scales a conceptual full size aircraft to a cantilevered wing model of wind tunnel dimensions, such that there is similitude between the static and dynamic behaviour of the model and the full size aircraft. This process of aeroelastically scaled testing combines the technical disciplines of aerodynamics, flight mechanics and structural dynamics, to provide a means by which future concept aircraft can be de-risked and explored. Data acquisition from wind tunnel testing can then be used to validate fluid-structure interaction frameworks that model the aeroelastic effect on the flight dynamics of the aircraft. This paper provides an overview of the BeaR D S methodology, and focuses on the Phase I of the programme, being the development of a reduced Cranfield A-13 aircraft cantilevered wing, to mitigate risk associated with the manufacturing and instrumentation approach. It is shown that a low cost acquisition system of commercial Inertial Measurement Units (IMUs) can measure the response of the wing within the desired frequency range. Issues associated with the Phase I testing are discussed, and methods are proposed for the Phase II programme that allow these problems to be resolved for a larger scale flexible wing with active control surfaces.

The Teager-Kaiser Energy Cepstral Coefficients as an Effective Structural Health Monitoring Tool

“…This is representative of historical masonry buildings, which noteworthy often present several structural problematics and require proper monitoring [30], especially in the case of high-rise medieval structures [31,32]. The second case study regards the spar of the high-aspect-ratio (HAR) prototype wing XB-1 studied in [33]. This case also presents its own difficulties, arising from the high flexibility of the cantilevered structure.…”

Aeroelastic Scaling for Flexible High Aspect Ratio Wings

“…However, the trend in the aerospace design shifts towards a more integrated concept [3] requiring a close link between each discipline. This is especially important for a high aspect ratio wing that brings the aeroelastic frequency closer to the frequency of the rigid-body dynamics [4].…”

“…For a high aspect ratio scaled wing, Spada [12] suggested the rib and spar design with balsa wood as the skin cover. However, these methods bring some disadvantages, such as buckling of the skin due to high deflection [15], which consequently changes the aerodynamic profile. One of the solutions to the buckling is by building the aerodynamic profile into several sections and leave a small gap between each section.…”

“…Because of these implications, B R D S makes use of a different manufacturing methodology. The skin adopts the PolyJet technology that allows printing of multi-materials continuously along the span [15]. B R D S is applying this technology by printing rigid and elastic parts repeatedly.…”

“…By doing so, the B R D S skin adds negligible stiffness to the spar while at the same time allows the model to bend without any buckling issue. As PolyJet technology is relatively new in this area, B R D S was planned as a two-phase programme (see Fig.1a) [15]. Phase 1 (XB-1) has been conducted to assess the risk of using the modular design and manufacturing using PolyJet technology while at the same time testing an off-the-shelf in-house built instrumentation system [15].…”