Manufacturing and characterisation of 3D printed thermoplastic morphing skins

Abstract

Morphing aircraft are one promising solution to reducing the aviation industry's environmental impact because they can make aircraft more aerodynamically efficient, thereby reducing greenhouse gas emissions. The design of morphing skins is inherently challenging due to the competing design constraints of needing to be stiff out-of-plane to resist pressure loads while being compliant in-plane to minimise actuation energy. Previous work by these authors introduced the novel concept of Geometrically Anisotropic Thermoplastic Rubber (GATOR) morphing skins that take advantage of multi-material 3D printing and structural scaling laws to allow for better compromises between these competing design constraints. In this work, multi material Fused Filament Fabrication (FFF) methods were used to 3D print the proposed GATOR sandwich panels from two different stiffnesses of thermoplastic polyurethane to demonstrate the manufacturing process and experimentally quantify the performance of some simple embodiments of the GATOR concept. The panels were mechanically tested to determine their flexural and extensional stiffnesses. Results show that the panels can be extended to a stretch ratio of λ = 1.6 with a linear response at low stretch ratios. The results from the flexural experiments show that the flexible face sheets are capable of withstanding some compression before buckling, which results in a linear behaviour at small forces. These results show the promise of the GATOR skin concept and motivate future development of designs that further exploit the underlying principles of the concept.

Cycle deformation behavior of 3D‐printed CF/PEEK honeycomb metamaterials with zero Poisson's ratios

“…The experimental span was 32 mm and the crosshead loading speed was 1 mm/min. The total distance of the crosshead loading was 12 mm 8 …”

“…(3) Out‐of‐plane load carrying capacity 13–15 : Resistance to aerodynamic loads is required to prevent deformation and damage to the airfoil during flight. (4) Recyclable 8 : Able to be used stably for a certain period to enhance the reliability of morphing aircraft. (5) Adaptable to the high‐temperature environment: During high‐speed flight, the wing is heated by friction with the air.…”

“…The corrugated structure can reach approximately 26% deformation at 85% fracture stress, but the mechanical properties decrease significantly after the cyclic loading. Heeb et al 8 prepared ZPR honeycomb sandwich metamaterials by 3D printing two different components of TPU elastomeric materials, respectively. The tensile and flexural properties of the sandwich metamaterials were tested under quasi‐static loading.…”

“…The application of flexible morphing wings for variable span and chord length is becoming a growing area of research. To meet the practical needs of morphing aircraft, flexible morphing wings need to satisfy the following conditions: (1) zero Poisson's ratio (ZPR) metastructure [8][9][10][11] : To realize one-dimensional deformation in the span or chord length direction, while remaining constant in the remaining directions. (2) Large in-plane deformation: Currently considered in-plane deformation range is: 20 of swept back angle, 200% of span chord ratio, and 50% of wing area.…”

A three-dimensional constitutive equation for shape memory polymer composites considering energy dissipation under single loading–unloading condition

“…Most of the existing studies have used elastomers as surface materials due to their stretchable and repeatable strain behaviors. 2,3 However, the elastomers require continuous force to maintain their extended configurations. This requirement can bring about problems such as deterioration of structural durability and high power consumption.…”