D.B. Chernov - Dr.Sc. (Eng.), Chief of Department, Scientific & Research Institute of Standardization and Unification (Moscow). E-mail: nts@niisu.ru

The article considers the main advantages of the thermomechanical actuators made of alloys with "shape memory" for use in automatic regulating systems. The results of testing schemes and the actual test results of NiTi actuators are shown. The principle of operation of thermomechanical actuators is based on using the operating elements of a new group of materials alloys - alloys with a special type of martensitic transformation and has the effect of memorizing and restoring forms. These alloys are often referred to as "smart materials". The article presents the main advantages of thermomechanical devices including: combining in one body a thermosensitive and executive device, compactness, high ratio of useful work per unit mass, design simplicity and reliability, immunity, the absence of acoustic vibrations. Presents an test circuits of the actuators, comprising: severe conditions with generating maximal efforts, "soft" coun-teraction to counterbody meet the real operation of the device and a circuit with a constant load to determine the longterm performance of the actuator. Presents a block diagram of thermomechanical device comprising thermomechanical actuator as main member of the apparatus and some auxiliary systems: initiation system, recovery system, in turn, composed of the phase return systems and return deformation node and a power transmission system for a mechanical impulse to an object of exposure. The possible ways of initiating operating stroke of actuators including an external heating by convection flow sur-rounding environment, heat transmission or incandescent, or direct heating by passing an electric current or an induced current. Presents experimental data on the efficiency of the thermomechanical actuator in the form of a spring made of an alloy of nickel and titanium, for the case of tests on a rigid circuit with a constant load to the number of heating-cooling cycles to 1000. The main conclusions were that the thermo-mechanical devices are promising for a wide range of designs in an emergency, regulating and tracking systems in the one-time and in multicycle version combines tracking and executive functions.

 

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