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Smart Material Types

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Smart material types
    Explain the types and Properties of smart material ? Types of Smart Materials Piezoelectrics : Piezoelectric materials convert electrical energy to mechanical energy, and vice versa. They offer a wide range of utility and can be used as actuators (provide a voltage to create motion), sensors, such as many accelerometers, and energy harvesters since the charge generated from motion can be harvested and stored. Common applications for  piezo materials are BBQ igniters and actuators for inkjet printer heads. Midé has successfully commercialized energy harvesters, haptic actuators, piezo valve actuators, and flow control devices. Shape Memory Alloys: The most commonly available Shape Memory Alloy is Nitinol, which was srcinally developed by the Naval Ordinance Laboratory. SMA’s have the ability to change phase as a function of temperature, and in that pro cess generate a force or motion. They are capable of relatively high energy but move slowly. Typically applications include morphing structures, thermal triggers, and some high strain energy absorbing applications. Advanced materials still under development include magnetically activated shape memory alloys. Magnetostrictive: Similar to piezoelectric materials that respond to changes in electrical fields, this class of materials responds to changes in magnetic fields and can perform as an actuator, or sensor if deformed. While they can work well, they exhibit a large hysteresis which must be compensated when using the material in sensor applications. Shape Memory Polymers: Shape Memory Polymers (SMP) are similar to Shape Memory Alloys except the obvious fact they are made from a  polymer matrix. They possess much greater recoverable strains than the alloys, but typically under lower forces. Morphing structures has been the area of greatest use to date for SMP’s.      Hydrogels: Hydrogels can be tailored to absorb and hold water, or other liquids, under certain environmental conditions. Hydrogels have been around for a long time, specifically in disposable diapers. A key feature however is the gels can be tailored chemically to respond to different stimuli. Midé has also patented a method to embed the gels into a foam which enables systems to be built with the gels, such as the Hydrogel Activated Bulkhead Shaft Seals. Electroactive Polymers: There are many forms of electroactive polymers and many are still being refined. They have great potential as the flexibility of how they can be used provide advantages over some of the metals and ceramics mentioned above. Most typically applications include energy harvesting and sensing (see Stretchsense development kit) however some researchers are looking at high voltage, low current actuators. Bi-Component Fibers: Adaptive thermal insulation can enable smart clothing that can change its thermal properties based on the environment. Midé has developed bi-component fiber technology where two different materials are co-extruded together to enable shape change depending on ambient temperature. What are the applications of smart Material? SMART MATERIALS IN AUTOMOBILE INDUSTRY Here are a few ways in which GENERAL MOTORS have used smart materials in automobile.To control of the airflow into the engine, a shape memory alloy-activated louver system will be used. This smart material functions to reduce the cooling airflow into the engine compartment and reduces aerodynamic drag. The result is improved aerodynamics and drag reduction and rapid warm-up during cold engine start up. While air dams are frequently damaged by low-speed impacts during parking situations and certain objects like ramps, snow, and ice, GM developed an active air dam that is activated by a shape memory alloy. The active air dam can monitor vehicle speed, and with the use of 4-wheel drive (4WD) configuration, the vehicle lowers or raises the air    dam to improve the vehicle's aerodynamic drag. Lastly, GM also developed and tested a grab handle that also uses shape memory alloys to move into position by using a temperature-activated shape memory combined with the changes in the handle's stiffness. All of these three newly developed auto parts features a shape memory alloy. Other examples include novel aluminum forming processes that provide enhanced body panels and light weighting,  polymer Nano composites that provide superior mechanical properties at lower cost, and magneto rheological fluids for improved chassis systems. The properties inherent in shape memory alloys and polymers have the potential to  be game-changers in the automotive advanced materials field, eventually leading to vehicle subsystems that can self-heal in the event of damage, or that can be designed to change color or appearance. Smart materials also could be used in sensors that can configure the safety systems of the car after detecting the  physical characteristics of the passengers. Some ‘true’ smart materials - electrochromic materials - are being used in automatic light and heat control in the automotive industry (e.g. self-dimming mirrors and rear windows). A further application of smart materials in the automotive sector is the use of shape memory polymers in the so- called ‘fender bender’, w here deformations as a result of minor collisions can be removed by treatment with a heat gun. SMART MATERIALS IN AIRCRAFT INDUSTRY The changes which occur due to changes in flight speed, altitude, and changes in weight due to consumption of fuel could be compensated by wing camber variations, to pursue optimal geometry for any flight condition, thus improving aerodynamic and structural performance. Existing aircraft cannot change shape without aerodynamic gaps, something that can be solved with Smart Intelligent Structures. By ensuring the detailed consideration of structural needs throughout the entire lifetime of an aircraft and focusing on the structural integration of needed past capabilities, Smart Intelligent Aircraft Structures will allow aircraft designers to seriously consider conformal morphing technologies. The reduced drag during take-off, cruise and landing for future and ecologically improved civil aircraft wings can be achieved Through naturally laminar wing technology, by incorporating a gapless and deformable leading edge device with lifts providing capability. Such a morphing structure typically consists of a flexible outer skin and an internal driving mechanism. Current aircraft designs already employ winglets aimed at increasing the cruise flight efficiency by induced drag reduction. Smart intelligent Structures propose a state of the    art technology that incorporates a wingtip active trailing edge, which could be a means of reducing winglet and wing loads at key flight conditions. Another component of an “intelligent” aircraft structure is the ability to sense and diagnose potential threats to its structural integrity. This differs from conventional non-destructive testing (NDT) by the fact that Structural Health Monitoring (SHM) uses sensors that are permanently bonded or embedded in the structure. MULTIFUNCTIONAL MATERIALS IN AIRCRAFT By increasing the relative fraction of composite components within new aircraft, challenges regarding electrical conductivity have arisen such as lightning strike protection, static discharge, electrical bonding and grounding, interference shielding and current return through the structure. These drawbacks can be solved by the use of emerging technologies such as Nano composites, which combine mechanical, electrical and thermal properties.  Nanoparticle reinforced resins have been found to offer two distinct advantages over current resin systems. First of all, they are able to provide an increase in fracture toughness of up to 50% for older liquid resin infusion (LRI) resins and 30% in more advanced systems. Secondly, percolated nanoparticles drastically improve resin conductivity, turning it from a perfect isolator into a semiconductor. While improved damage tolerance properties could directly lead to structural weight savings, the exploitation of electrical properties could also enable a simpler, and hence cheaper, Electrical Structure Network (ESN). Biopolymer Membrane: The cabin's bionic structure will be coated with a biopolymer membrane, which controls the amount of natural light, humidity and temperature, providing opacity or transparency on command and eliminating the need for windows. This smarter structure will make the aircraft lighter and more fuel- efficient while giving passengers 360 degree views of the skies. Bionic Structures
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