23-02-2010, 11:43 PM
hi plz send me this topic pdf and ppt
23-02-2010, 11:43 PM
hi plz send me this topic pdf and ppt
12-04-2010, 11:46 AM
please read https://seminarproject.net/Thread-smart-materials for getting more about smart material information
22-04-2010, 10:39 AM
plese send ppt& text of recent trde in ic engine
07-10-2010, 11:41 AM
SMART MATERIALS.doc (Size: 302.5 KB / Downloads: 262) This article is presented by: Shivani Rawat STRUCTRAL APPLICATION OF SMART MATERIALS
INTRODUCTION The development of durable and cost effective high performance construction materials is important for the economic well being of a country. Assorted developments are being made these days to increase the strength and durability of these structures and make them accustomed to various natural changes. The technology now addresses the growing needs for strengthening aging structures , rehabilitating damaged structures and designing new structures to more severe requirements and for longer service life. Innovations are being made in structural materials and to develop superior products that have positive impact on our cost-effective competitiveness, national security and quality of life. In order to achieve the above requirements evaluation of structure is essential. Figure(1) shows the evaluation components of structure. Engineers have to use three main criteria to select materials: desired properties, availability of manufacturing technology, economic feasibility. One of the latest development in this context is the development of smart material. WHAT ARE SMART MATERIALS? “Smartness” of a material is characterized by self-adaptability, self sensing memory and decision making. Smart materials are the materials that respond with shape or other property change upon application of externally applied driving forces (electrical, magnetic and thermal). In other words, smart materials refer to materials that can undergo controlled transformations through physical interactions and are structured with multi-functionality. They have they are able to respond to slight variation in temperature, moisture, pH, electric or magnetic fields by changing their appearance, state and properties. They are exemplified as boon in tackling the problem of deteriorating civil infrastructure and they had influenced the life cost of these structures by reducing the upfront construction cost as they allow reduced safety factors in initial design. SHAPE MEMORY ALLOYS (SMA): The term shape memory refers to the ability of certain alloys to undergo large strains, while recovering their original configuration at the end of the deformation process impulsively or by heating without any residual deformation. This is due to their two unique properties: pseudo-elasticity and shape memory effect. It had been found that these shape memory alloys first bridges the structure and then on application of heat, changes shape and clamp both sides of the crack together. The most efficient and widely used alloys include NiTi (Nickel-Titanium), CuZnAl and CuAlNi.
26-10-2010, 04:34 PM
main semnar.doc (Size: 2.1 MB / Downloads: 236) smart materials ABSTRACT Smart materials obtain their unique properties by the deliberate introduction of multi-functionality. This can enable the material, or the structure from which it is made, to diagnose its condition or environment, change shape, self-repair, or other functions as developing technology allows. It is argued that any of these functions are only viable if both the costs and benefits are considered on a system-wide basis. Some of the particular requirements and challenges for a number of example applications are considered and some general requirements suggested. It is concluded that such system-wide approach to optimization is a challenge for both designers and for those developing smart materials but it is necessary if the full advantages of smart materials are to be realized
06-05-2014, 04:51 PM
SMART MATERIALS SMART MATERIALS.pdf (Size: 225.42 KB / Downloads: 23) INTRODUCTION The world has recently undergone two materials ages, the plastics age and the composite age. In the midst of these two ages a new era has developed. This is the smart materials era. According to early definitions, smart materials are ma- terials that respond to their environments in a timely manner.1–4 The definition of smart materials has been expanded to materials that receive, transmit, or process a stimulus and respond by producing a useful effect that may include a signal that the materials are acting upon it. Some of the stimuli that may act upon these materials are strain, stress, temperature, chemicals (in- cluding pH stimuli), electric field, magnetic field, hydrostatic pressure, different types of radiation, and other forms of stimuli. PIEZOELECTRIC MATERIALS tromechanical systems (MEMS), vibration control, sound control, shape control, product health or lifetime monitoring, cure monitoring, intelligent processing, active and passive controls, self-repair (healing), artificial organs, novel indicat- ing devices, designed magnets, damping, aeroelastic stability, and stress distri- butions. Smart structures are found in automobiles, space systems, fixed- and rotary-wing aircrafts, naval vessels, civil structures, machine tools, recreation, and medical devices.5,6 Another feature that is important about smart materials and structures is that they encompass all fields of science and engineering. Thus when searching for information on smart materials and structures, there are numerous sources, web sites, and professional societies that deal with the technology. PIEZOELECTRIC MATERIALS The simplest definition of piezoelectric materials can be obtained by first break- ing the word into piezo and electric. Piezo is from the Greek word piezein that means to press tightly or squeeze. Combining piezein with electric we have ‘‘squeeze electricity.’’ And that to the first estimation is a very good definition. The history of piezoelectric materials is relatively simple and only the high- lights will be presented. In 1880, Pierre and Paul-Jean Curie showed the pie- zoelectric effect in quartz and Rochelle salt crystals. Their first observations were made by placing weights on the faces of particular crystal cuts, like the X cut quartz plate, detecting charges on the crystal surfaces, and demonstrating that the magnitude of charge was proportional to the applied weight. This phenom- enon has become to be known as the direct pressure electric piezoelectric effect. In 1881 G. Lippmann made the prediction that a crystal such as quartz would develop a mechanical strain when an electric field was applied. ELECTROSTRICTIVE MATERIALS based upon this technology.12,13 In this application the impulse ink jet is produced using a cylindrical transducer that is tightly bound to the outer surface of a cylindrical glass nozzle with an orifice ranging from mils to microns in diameter. In addition to this application several industrious researchers have expanded upon this technique by using a printer as a chemical delivery system for the application of doped polymers for organic light-emitting displays. A group of researchers from Princeton University has used a color ink jet printer based upon piezoelectric technology with a resolution of 640 dots per line and simply re- placed the inks with polymer solutions.14 This technique has also been applied to the manufacture of color filters for liquid-crystal displays. MAGNETOSTRICTIVE MATERIALS Magnetorestrictive materials have the material response of mechanical defor- mation when stimulated by a magnetic field. Shape changes are the largest in ferromagnetic and ferrimagnetic materials. The repositioning of domain walls that occur when these solids are placed in a magnetic field leads to hysteresis between magnetization and an applied magnetic field. When a ferromagnetic material is heated above its Curie temperature, these effects disappear. The mi- croscopic properties of a ferromagnetic solid are different than a ferrimagnetic solid. The magnetic dipoles of a ferromagnetic solid are aligned parallel. The alignment of dipoles in a ferrimagnetic solid can be either parallel or in other directions. ELASTORESTRICTIVE MATERIALS This class of smart materials is the mechanical equivalent to electrorestrictive and magnetorestrictive smart materials. These smart materials exhibit high hys- teresis between stress and strain. The motion of ferroelastic domain walls causes the hysteresis. This motion of the ferroelastic domain walls is very complicated and complex near a martensitic phase transformation. At this phase change, two types of crystal structural changes occur. One is induced by mechanical stress and the other is by domain wall motion. Martensitic shape memory alloys have wide, diffuse phase changes and the ability to exist in both high- and low- temperature phases. The domain wall movements disappear with total change to the high-temperature phase.5,19,20 The elastorestrictive smart material family is in its infancy. |
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