"Smartness" can be characterized by self-adaptability, self-sensing, memory, and decision making. Smart vehicles can assess their own health and perform self-repair. They will also know how to fly to a safe haven under emergencies.

Smart vehicle technologies are a blend of smart materials and structures, innovative actuators and sensors, and intelligent flow control strategies—including sonic boom mitigation technologies, revolutionary propulsion ideas, and biologically inspired concepts. The field of smart materials and structures, for example, evolved over the past decades and increased its pace in the 1990s. It has inspired numerous innovative concepts in the United States and abroad.

Major demonstration programs have addressed structural health monitoring, vibration suppression, shape control and multifunctional structural concepts for spacecraft and launch vehicles, aircraft and rotorcraft. The demonstrations have focused on showing potential system-level performance improvements using smart technologies in realistic aerospace systems.

Some recent work related to smart vehicle technology has focused on the development of composite systems with active constituents, of distributed actuation systems, and of fiber optic and compact integrated sensor systems. Current trends aim at the atomic and molecular level to synthesize new materials that are functionally smart. Examples include molecularly imprinted polymers and other materials that contain inherent receptors for information. Other efforts are integrating diverse sensors on a single substrate, and working on practical techniques to fabricate them.

In a concept developed at the University of Illinois at Urbana-Champaign, micro capsules release a healing agent in a smart material.

Self-healing material concepts have received increasing attention in recent years. For example, self-healing plastics use material that has the ability to heal cracks when fracture occurs. Shape memory alloys in composites can stop propagating cracks by imposing compressive forces, resulting from stress-induced phase transformation. Current research aims at developing adaptive, self-repairing materials and structures that can arrest dynamic crack propagation, heal cracks, restore structural integrity and stiffness, and reconfigure themselves to serve more functions.

Controlling fundamental mechanisms in fluids has long been the focus of intense effort. Recent applications of airflow sensing and intelligent control to air vehicles include improving performance by increasing lift or reducing drag generated by a surface and maneuvering through the use of fluidic devices. Current activities aim at understanding the physics associated with the shock wave formation in high-speed flight and developing designer fluid mechanics tools for all types of flow control—flow separation control, vortex control, laminar flow control, turbulent drag reduction, anti-noise, mixing enhancements, combustion control, circulation control, and favorable wave interference.

A suite of high-payoff sonic boom mitigation technologies is being explored for reducing the sonic boom overpressure to an acceptable level to people on the ground (less than 0.3 pounds per square foot). Techniques include airframe shaping, heat addition, particulate injection, leading-edge plasma generation, temporal and spatial variation of lift distribution, and adaptive flow control.

Indirect reduction of sonic boom amplitudes can also be achieved by decreasing vehicle gross weight, or increasing vehicle lift-to-drag ratio by maintaining supersonic laminar flow. In addition, the use of intelligent propulsion control systems is being explored for efficient, reliable operation of the complex supersonic inlet/engine/nozzle system.

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