Read Aloud the Text Content

This audio was created by Woord's Text to Speech service by content creators from all around the world.

Text Content or SSML code:

Although, materials in this group do not produce strain upon application of an external stimulus they are some times also referred to as actuator system. Example include the electro- and megneto reheological fluids, which respond with an increase in viscosity upon application of an external electrical or magnetic field. The property that can be altered influences what type of applications smart materials can be used for. The applied driving forces for smart materials can be broadly classified as electrical fields- common materials include piezoelectric ceramics and piezoelectric polymers, thermal fields- materials are mainly shape memory alloys (SMAs), and magnetic fields-common materials include magnetostrictive materials and magnetic shape memory alloys. 1. Piezoelectric materials have two unique properties which are interrelated. When a piezoelectric material is deformed, it gives off a small but measurable electrical discharge. Alternatively, when an electrical current is passed through a piezoelectric material it experiences a significant increase in size (up to a 4% change in volume). Piezoelectric materials are most widely used as sensors in different environments. They are often used to measure fluid compositions, fluid density, fluid viscosity, or the force of an impact. 2. Electro-rheostatic and Magneto rheostatic fluids Electro-rheostatic (ER) and magneto- rheostatic (MR) materials are fluids, which can experience a dramatic change in their viscosity. These fluids can change from a thick fluid (similar to motor oil) to nearly a solid substance within the span or a millisecond when exposed to a magnetic or electric field; the effect can be completely reversed just as quickly when the field is removed. MR fluids experience a viscosity change when exposed to a magnetic field, while ER fluids experience similar changes in an electric field. The most common form of MR fluid consists of tiny iron particles suspended in oil, while ER fluids can be as milk chocolate or cornstarch and oil. Applications The broad but strongly interdisciplinary field of materials seeks to apply multifunctional capabilities to existing and new structures. By definition, smart structures and materials are those which can sense external stimuli, via internal sensing and/or actuation, and respond with active control to that stimuli in real or near real time. Current activities in the field range from the design, fabrication, and test of fully integrated structural systems to enabling research in individual discipline areas i.e., materials, sinking and actuation techniques, control algorithms and architectures, etc. The typical approach to achieving smart structures synthesizes composite materials and structures from known constituents. The active elements are either embedded or ttached to conventional structural materials. Typical smart structure sensors include fiber optics and piezoelectric ceramics and polymers. Embedded sensors can be used in discrete or distributed locations to provide built-in structural quality assessment capabilities, both during composite processing and system operation. In terms of system performance, it is important that the right