Span Morphing using the Compliant Spar

RM Ajaj (University of Southampton), EI Saavedra Flores (Universidad de Santiago de Chile, Chile), MI Friswell (Swansea University) & FA Diaz de la O (University of Liverpool)

Journal of Aerospace Engineering, Vol. 28, No. 4, July 2015, paper 04014108


This paper develops and models the Compliant Spar concept that allows the wing span to be varied to provide roll control and enhance the operational performance for a medium altitude long endurance (MALE) UAV. The wing semi-span is split into morphing partitions and the concept maybe incorporated in each partition; however only the tip partition is considered here. The Compliant Spar is made of compliant joints arrange in series to allow the partition to be flexible under axial (spanwise) loads but at the same time stiff enough to resist bending loads. Each compliant joint consists of two concentric overlapping AL 2024-T3 tubes joined together using elastomeric material. Under axial (spanwise) loading, the elastomeric material deforms in shear allowing the overlapping distance between the tubes to vary and hence the length (in the spanwise direction) of the joint/spar to vary. High fidelity modelling of the concept is performed. Then, structural design optimisation studies are performed to minimise the axial stiffness and the structural mass of the concept for various design constraints. The flexible skin and actuation system to be used are also addressed.

Paper Availability

This material has been published in the Journal of Aerospace Engineering, Vol. 28, No. 4, July 2015, paper 04014108. Unfortunately the copyright agreement with ASCE does not allow for the PDF file of the paper to be available on this website.

Link to paper using doi: 10.1061/(ASCE)AS.1943-5525.0000442

Link to the Journal of Aerospace Engineering website