Nauka i Obrazovanie (Jan 2017)
Intelligent Materials Used in Hydraulic, Fuel, and Rudder Control Systems of Aircrafts
Abstract
The device is really intelligent, only if it is capable to respond to changing external conditions. The devices, which "feel" the external environment and can change their characteristics, have many advantages compared to the conventional devices: they are more efficient, wear out more slowly, and have lower operating costs.The scope of smart products is truly infinite. Alloys with memory effect also apply to intellectual content. Natural piezoelectric crystals such as silicon dioxide (intellectual material) have been known for over a hundred years. They have greater stiffness and can be used at high operating frequencies. Due to the direct piezoelectric effect, they have been successfully used as a strain gage. Later came artificial ceramic piezoelectric materials; they are used as mechanical transducers. Thus, an inverse piezoelectric effect is usually used. It consists in the change of dimensions when an electric field is applied. Control of intellectual structure can be provided by heat fluxes, electromagnetic, hydraulic or piezoelectric forces and through application of electro-rheological, and magneto-rheological fluids. The article examines the intellectual materials and technologies that are already in place or will find its application in aviation hydraulic and fuel systems and control systems of rudders (CSR) of aircrafts in the near future.The paper considers in detail the shape memory effect alloys (SMEA) as "intelligent" materials. Actuators made from SMEA have a number of advantages: high working power; large recoverable deformation; different types of strain (tensile, compressive, bending and torsional); most specific value of the work per unit mass. All the SMEA advantages may be well used for the so-called thermo-mechanical connections (TMС) of pipelines where SMEA drawbacks in this application, practically, do not affect the quality of TMC. In aircraft engineering the TMC were first used in hydraulic systems of the aircraft TU204.The paper also considers piezoelectric transducers, which are based on the reverse piezoelectric effect that converts electrical power into mechanical strain or displacement. The use of piezoelectric effect in hydraulic systems, rudder control systems, fuel systems of aircrafts will allow significant improving the static and dynamic characteristics of amplifiers (precision, speed, dynamic sensitivity, bandwidth, weight, etc.)
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