مواد کامپوزیتی پیزوالکتریک

Piezoelectric Composite Materials

مواد کامپوزیتی پیزوالکتریک

ABSTRACT

A piezoelectric Composite is a combination of a piezoelectric ceramic and/or polymer and a nonpiezoelectric polymer constituting a new version of piezoelectric material . In general terms , piezoelectric composite applies to any piezoelectric material resulting from combining a piezoelectric  polymer or ceramic with other nonpiezoelectric materials including air-filled voids . Earlier versions of piezoelectric  composite synthesized include barium titanate embedded polymer matrix and lead zirconate- titanate (PZT) ceramic Powder dispersed in a polymeric receptacle .Subsequent development are : (i)  Flexible piezoelectric composites using PbTiO₃ or PZT plus synthetic rubber ; (ii) PVD-based pyroelectric composites ; (iii) woven PZT ceramic/polymer composites

 

مواد هوشمند الکترو مغناطیس

Electromagnetic smart Material

مواد هوشمند الکترو مغناطیس

ABSTRACT

smart materials refer to a class of materials and/or composite media having inherent intelligence together with self-adaptive capabilities to external stimuli . Also known as intelligent materials they constitute a few subsets of the material family that “ manifest their own functions intelligently depending on environmental changes” . Electromagnetic (EM) smart materials are specific subsets of smart materials wich can adaptively change their EM characteristics when an external stimulus is applied proportional to a sensed EM response.Classically such intelligent material systems have been conceived in the development of mechanical structures which contain their own sensors actuators and self-assessing computational feasibilities so as to modify their structural (elastic) behavior via feedback control capabilities .

مواد جاذب امواج الکترومغناطیسی

Electromagnetic wave Absorbing Materials

مواد جاذب امواج الکترومغناطیسی

ABSTRACT

For specific application there is a need for materials which absorb the electromagnetic energy incident on them . These nonreflective electromagnetic wave (EM) absorbing materials are useful as radar absorbing materials (RAMs) as surface coverings in electromagnetic anechoic chambers etc . Their primary function is to absorb and dissipate the electromagnetic energy to which they are exposed so that the reflected and/or scattered electromagnetic component is significantly small. In RAM applications when a target is surface-treated with an absorbing material the radar echo is minimized facilitating an electronic countermeasure technique of low probability of detection of the target by the radar.

کنترل استاتیک مواد

Static Control Materials

کنترل استاتیک مواد

ABSTRACT

Static control materials are those which are useful to prevent or minimize the buildup of electrostatic charges on conducting and/or noconducting bodies . These materials are essentially of three typses : (1) Antistatic materials ; (2) static dissipative materials and (3) static conductive materials . Antistatic materials (or antistats ) act as the static control media in three different ways :First , they reduce the coefficient of friction to help minimize the frictional ( triboelectric ) Static charge generation .  Second, they increase surface resistivity to dissipate ( or bleed off ) the charges . third, they interact with the environmental factors to neutralize the generated charges .

مواد الکترو اپتیک

Electrooptic Materials

مواد الکترو اپتیک

ABSTRACT

The term electrooptic effect refers  to a change in the refractive index of a transparent substance induced by an applied electric field , usually at a frequency below the optic vibrational resonance of the lattice or the molecules involved . the linear and quadratic electrooptic effects are known as the Pockels and kerr effects, respectively . The linear electrooptic ( or Pockels ) effect refers to a change in relative optical dielectric impermeability (B_ij) proportional to an applied electric field E_k whos highest frequencies are below the lattice resonance of a crystal .Refractive index of a crystal : Considering light propagation through a crystal the electromagnetic energy stored in a unit volume of dielectric is represented by an ellipsoid whit a geometry that reflects the symmetry of the crystal .

مواد هوشمند الکترو مغناطیس

Electromagnetic smart Material

مواد هوشمند الکترو مغناطیس

ABSTRACT

smart materials refer to a class of materials and/or composite media having inherent intelligence together with self-adaptive capabilities to external stimuli . Also known as intelligent materials they constitute a few subsets of the material family that “ manifest their own functions intelligently depending on environmental changes” . Electromagnetic (EM) smart materials are specific subsets of smart materials wich can adaptively change their EM characteristics when an external stimulus is applied proportional to a sensed EM response.Classically such intelligent material systems have been conceived in the development of mechanical structures which contain their own sensors actuators and self-assessing computational feasibilities so as to modify their structural (elastic) behavior via feedback control capabilities .

مواد دارای تغییر شکل در اثر الکتریسیته

Electroheological Materials

مواد دارای تغییر شکل در اثر الکتریسیته (Electrorheological)

ABSTRACT

The electroheological effect refers to the abrupt change in viscosity in certain colloidal sols when subjected to an electric field . The phenomenon of electroheology (ER) was first reported by w . M. Winslow in 1947 and therefor is also known as the Winslow effect . An ER fluid changes is flow characteristics ( due to the viscosity changes ) in the presence of a high voltage low current electric field and if the strength of the electric field is sufficient the fluid behaves much like a solid . The adaptive response of an ER fluid ( which takes only milliseconds )is in the from of progressive gelling which is proportional to the field strength . In the absence of electric field the fluid flows freely like water .

مواد چیرال الکترومغناطیس

Electromagnetic chiral Material

مواد چیرال الکترومغناطیس

ABSTRACT

A special class of electromagnetic (EM) material referred to as chiral materials are emerging in engineering application . A chiral medium is one whose electric and magnetic fields are cross-coupled . The characteristic aspect of such materials is the intrinsic handedness (right or left ) present in their physical structure . Optically active natural  materials exhibit mirror-asymmetric molecular structure(s) and have been originally known as chiral materials ,Natural chiral structurs include a diverse array of sugars amino acids DNA and certain mollusks as well as winding vegetation while the man-made versions encompass such objects as a helix a Mobius strip or an irregular tetrahedron.

مواد فانتوم الکترومغناطیس

Electromagnetic Phantom Material

مواد فانتوم الکترومغناطیس

ABSTRACT

A state-of-the-art intrest in electromagnetic research is to elucidate and characterize the interaction between nonionizing radiations versus living systems . The purpose is three fold : (1) To understand the mechanism(s) of interactions involved  (۲) to investigate any deleterious effects which many result from such interactions and (3) to consider the possibilities of such interactions  inducing beneficial effects in the living systems. A subset of relevant studies refers to electromagnetic dosimetry and hyperthermia considerations .In both cases it is of interest to know the extent of absorption of nonionizing radiation by living systems . Nonionizing radiation in general refers to electromagnetic (EM) waves from the  quasistatic region to the end of visible radiation .

 

مواد سرامیکی و پلیمری دارای مواد رسانا

Conductor-Loaded Polymeric and ceramic Material

مواد سرامیکی و پلیمری دارای مواد رسانا (دارای ذرات تقویت کننده رسانا)

ABSTRACT

Conductor-filled polymers and ceramic are specific subsets of the conductor-Loaded dielectrics . The primary reason for adding conducting particles in polymers plastics or ceramics is to enhance the electrical conductance of the medium . In general polymers and ceramics when loaded with conductors become very good conductors of electricity and are useful in a wide range of electromagnetic applications. However inclusion of a metallic constituent in a polymer matrix may affect the low density and high strength or impact resistance properties of the plastics or the ceramics .