Morphing Systems — An Overview

Background on Morphing Systems

The desire for multi-mission capability in military and civil air vehicle systems has created a need for technologies that allow for drastic wing shape changes during flight. Since most current aircraft are fixed-geometry, they represent a design compromise between conflicting performance requirements in mission segments such as high-speed cruise, low-speed loiter, and low turn radius maneuver. If a hybrid aircraft is designed to combine several flight profiles, the wing design must maximize overall efficiency of the anticipated mission. Through morphing, the aerodynamics of the aircraft can be adapted to optimize performance in each segment by changing areas such as the camber of the airfoils and the twist distribution along the wing.

Adapting the shape of wings in flight allows an air vehicle to perform multiple, radically different tasks by dynamically varying its flight envelope. The wing can be adapted to different mission segments, such as cruise, loitering, and high-speed maneuvering by sweeping, twisting, and changing its span, area, and airfoil shape. Morphing wing technology is considered to be a key component in next-generation unmanned aeronautical vehicles (UAVs) for military and civil application.

CRG successfully demonstrated the self-deploying capabilities of its Veritex™ (Veriflex®-based composite) material in the fabrication and deployment of a sub-scale, carbon fiber reinforced wing. The sub-scale wing was heated, collapsed, and rolled up into a tight package. Once cooled, the structure maintained the rolled up configuration until it was heated and deployed to achieve the memorized wing shape, as shown in the center of the figure below.

A Veritex morphing wing prototype developed by CRG. In the figure, the process begins at the top and proceeds clockwise around to the center. Under thermal stimulus, the wing quickly unfolds and expands to its appropriate chord and shape.

Biological Inspiration

Understanding how birds perform by making their wings morph, or change shape in flight is one step in CRG research efforts to dramatically increase the efficiency and maneuverability of aircraft. Flight capabilities in nature provide a demonstration of feasibility and proof-of-concept for man-made morphing architecture. In fact, the morphology of a pterodactyl’s wings and body shape provides an excellent model for morphing mechanisms and adaptable air vehicle systems.

Compared with the subtle capabilities of a common bird’s wings, mechanical flaps and slats and pivoting wings are heavy, complex and inefficient. While the result of clever ingenuity and years of engineering design, they increase the radar cross-section of a plane and can’t operate at high flight speeds. The ability to substantially change a wing’s shape seamlessly in flight through the use of CRG’s SMP technology will produce aircraft that can fly both fast and slowly, with optimal efficiency at every speed. These vehicles will burn less fuel, run more quietly, fly longer, take off and land in shorter distances, and maneuver more quickly and with greater agility.

In programs with the Air Force Research Laboratories (AFRL), the Defense Advanced Research Projects Agency (DARPA), the Army, Lockheed Martin Skunkworks, and other commercial companies, as well as through internal R&D, CRG scientists are exploring technologies that could one day liberate aircraft from flaps, slats, and ailerons so that they more closely emulate the astonishing adaptability and control of bird flight.

Novel Design Principles

The ultimate goal of research in these morphing programs is to develop new design principles for fully adaptable systems. These design principles would consist of integrated systems using morphing mechanisms, propulsion systems, control systems, structures and materials. In the meantime, CRG has demonstrated feasibility in all these areas. For example, the figure below demonstrates one of the company’s completely new designs for the underlying structure of a morphing aircraft wing.

A “sliding rib” concept for the underlying structure of a morphing wing. This represents a new design philosophy for wing structures. Morphing wing design requires the integration of mechanical structure, seamless skin, and actuators.

In the interest of developing entirely new systems to incorporate shape-changing technologies, CRG’s engineering research for morphing wings consists of a selection of actuators, design of morphing mechanisms and skin, integration of these components into a wing structure, experimental verification of aerodynamic and structural performance of a wing segment, and incorporating the adaptable wing into a complementary morphing air vehicle. CRG’s research in shape memory polymers and morphing structural design has contributed significantly to the development of adaptive wings.

The Veriflex Family of Materials and Morphing Technology – An Ideal Match

Shape memory polymer’s list of applications continues to grow as researchers and customers experiment with it and CRG helps integrate the new technology into existing systems. In fact, application demand for Veriflex is so high that the resin as a material system is now available for sale to the general public through our spin-off company, CRG Industries.

Morphing applications in particular benefit from the capabilities of shape memory materials. CRG has demonstrated feasibility for adaptable systems in manufacturing, military applications, space systems, aerostructures, and propulsion. An overview of some of those applications is outlined below:

Morphing, adaptable systems increase the usefulness and capabilities of a wide range of applications, and CRG has taken a leadership role in research involving morphing technologies. Through the use of innovative smart materials, process engineering, and integration into real-world systems, the results of this research are already revolutionizing the way we design aircraft, build manufacturing systems, equip multipurpose vehicles, and deploy space mirrors.

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