Self-Healing & Smart Materials

• Self-healing materials, smart materials and aerospace sustainable design are the subject of this information.

Self-Healing Materials: Types and New Technologies

• Self-healing materials return to their original state after damage, cut, or fracture by repairing themselves.
• They are developed from nature based on the regenerative systems of living beings.
• The process of closing the "wound" of the material and restoring it typically lasts minutes to hours.

Types of Self-Healing Materials

• Microcapsule-based materials have microcapsules embedded within them.
• When a material is damaged, the microcapsules break and release compounds to fill the damage.
• This closes the break and returns the material to its original state.
• The material can only heal itself once with this technology.
• Materials with internal vascular circulation are similar to microcapsules.
• Compounds are released to fill in the damage and solidify like in microcapsules.
• Channels are used instead of spheres dispersed inside the material.
• They can be connected to an external tank for a longer-lasting repair.
• The healing agent may travel slower than spread of damage.
• Intrinsically self-healing materials can return to their original shape independently or with external energy, such as light or heat.
• An example is shape-memory material where it returns to its original shape after being bent and released.
• The self-healing behavior is almost infinite as long as they have the necessary conditions for their self-repair process.
• Reversible polymers can transform physical energy into a chemical or physical response to heal the damage.
• This occurs through polymerization and responds to external stimuli to recover initial material properties.
• Tri-layered polymers could better protect astronauts in space

Smart Materials

• Smart materials adapt to their environment and change properties with environmental conditions.
• Dynamic properties and response to stimuli such as light, heat, electricity, or humidity, characterize them.

Types of Smart Materials

• Piezoelectric materials convert electrical energy to mechanical energy and vice versa.
• This offers utility as actuators, sensors, accelerometers, and energy harvesters due to charge generated from motion.
• Magnetostrictive materials respond to magnetic field changes, and are similar to piezoelectric materials.
• They can function as actuators or sensors if deformed and are used in sensors, transformers, and actuators.
• Hydrogels can absorb and hold water or liquids under certain environmental conditions.
• They can be chemically tailored to respond to stimuli, as found in disposable diapers.

Aerospace Sustainable Design

• Morphing wing design involves an airplane wing that can change its geometric shape during flight.
• This optimizes performance based on mission requirements.
• Active flow control for drag reduction is technology where disturbances are introduced into a fluid flow.
• This manipulates the behavior of the flow, reducing aerodynamic or hydrodynamic drag.
• This actively adjusts the flow to minimize resistance and optimize efficiency.
• A blended wing body (BWB), also known as blended body, hybrid wing body (HWB) or a lifting aerofoil fuselage is an aircraft with:
• a fixed-wing design
• with no clear dividing line between the wings and the main body.
• the aircraft's main advantage of the BWB design is the reduction of wetted area and accompanying form drag.
• Electrified Aircraft Propulsion (EAP) involves electrically-powered aircraft that convert electrical energy from batteries to drive an electric motor connected to a propeller.
• This produces propulsive thrust for flight, with systems like the Velis Electro being certified ultralight aircraft.
• Hybrid-electric aircraft (HEA) combine traditional fossil fuel-powered engines and electric motors for propulsion.
• Electric motors are used typically for takeoff and landing, switching to conventional engines in the air.
• The electric motors provide additional power during takeoff and climb, reducing the need for full power from traditional engines.
• The traditional engines take over at cruising altitude, and electric motors are turned off or used to assist.
• Hydrogen-powered aircraft use hydrogen fuel instead of conventional jet fuel to decarbonize the aeronautical sector.
• Combustion hydrogen planes rely on modified engines to use hydrogen fuel, similar to current fuel aircraft with less emissions, and are optimal for bigger, long-distance planes.
• Fuel cell hydrogen planes generate electricity within fuel cells to turn propellers, producing heat and water as by-products, with applications for smaller planes.