Magnetostrictive transducers

Nickel is being used ia magnetostrictive transducers ia some ultrasonic devices, eg, solderiag irons and ultrasonic cleaners, because of its moderate magnetostriction and availabiUty. This market, however, is dominated by piezoelectric transducers of lead zirconate—titanate (PZT) (see Ultrasonics). 

Magnetostriction is the dimensional change (strain) which accompanies the domain movement and rotation of magnetization. When the magnetio field vibrates so does mag-netostriotion, and as a result ultrasonic waves are produced. A magnetostrictive transducer (MART) is a transducer in a non-contact US instrument where the coated sample... 

The preceding studies were mainly carried out under free field conditions at high frequencies. Weber and Chon [35] carried out similar measurements at low frequency (21.5 kHz) under restricted field conditions. Their experimental device, similar to that used by Timmerhaus and Fogler [36], is illustrated in Figure 13. The emitter is a magnetostrictive transducer with base area 16 cm2 attached by epoxy to the bottom of a 600 cm3 beaker filled with water as coupling fluid. A tube... 

The kinetics and mechanism of the electrodeposition of indium from acid electrolytes in the presence of an ultrasonic field was studied by Kadyrov and Rakhmatullaev [67] in the early 1980s. They studied the mechanism of the electrodeposition of In from different baths in an ultrasonic field in cells as a means of intensifying the process. They carried out experiments on baths containing various concentrations of Indium (i) In2(S04)3 30g/L, (ii) In2(S04)3 70g/L, (iii) In(N03)3 30g/L, and (iv) InCl3 30 g/L at a pH 2.5 and a temperature of 20 °C. The ultrasonic vibrations were created by a magnetostrictive transducer with frequency of 17.5 kHz fed by a 800-W generator. They found that ultrasound greatly influenced the... 

Chin, G. Y. (1971). Processing control of magnetic properties of magnetostrictive transducer applications. Journal of Metals, 23, 42. 

For selected irradiation, using magnetostriction transducers, which are preferable to piezo-ceramics, is effective in changing processing parameters. 

Among the magnetostrictive transducers it is more expedient to use those, which in their construction allows them to be used inside the extrusion head. The installation of transducers in the body of the forming tool, reduces the impact of the ultrasonic oscillations on the polymer. 

The design improved the continuous extrusion profile process and increased the output of the extrusion head. This improvement is achieved by using an ultrasonic horn within a many stream extrusion head. The magnetostrictive transducer horn is located in the extrusion channel and is cooled. The charmels of the profile section are formed between the profile section and the horn (Figure 5.1). 

To produce a high quality surface (10-12), it is necessary to avoid a discontinuous flow of the melt through the profiling channel. A high quality profile with a polished surface is produced with degradation of the polymer surface as a consequence of the effect of the magnetostrictive transducer. The ultrasonic oscillations reduce the toughness of the polymer and the resistance of the wall affect the melt flow at the channel boundary. 

II - choke 12 - choke 13 - magnetostrictive transducer 14 - source of ultrasonic oscillations 15 - channels for chilling 16 - choke... 

The experiments used an industrial extruder ATL-45. The extrusion installation included a forming unit composed of a forming head to produce a square section 45 x 45 mm. Ultrasonic oscillations were produced in the forming head by two standard magnetostrictive transducers PMC-6-2 ultrasonic USF-1-4 oscillations. 

Magnetostrictive transducers are electromechanical devices which use magnetostriction, an effect found in some ferromagnetic materials, e.g. nickel. Such materials reduce in size when placed in a magnetic field and... 

As a property of anomalously high magnitude in cubic Laves phase compounds of rare earth metals such as Fe2(Tbo.3Dyo.7), which are the basis of magnetostrictive materials serving as magnetostrictive transducers and sensors [3.3]. 

Piezoelectric, electrostrictive and magnetostrictive transducers are able to transform electrical energy into mechanical energy and vice versa, almost without any delay. This property is the base for self-sensing solid-state actuators. 

The resulting force Fg on the mechanical side, analogous to (6.47), is approximated by the sum of the force F of the magnetostrictive transducer... 

Analog to the piezoelectric transducer, the mechanical behaviour can be described by a spring with the mass m and the stiffness cm. The amplitude response I/Fg of the magnetostrictive transducer has a definite lower cutoff frequency /u and a mechanically determined natural frequency fo for a short-circuit electrical port (Vg = 0), and the amplitude response s/J has a mechanically determined natural frequency fo for an open mechanical port... 

Fig. 6.133. Typical hysteretic characteristics of a magnetostrictive transducer for different mechanical loads with marked operating region and operating point...

The inherent sensor effect in active materials allows, in combination with proper measurement and signal processing methods, the simultaneous use of piezoelectric or magnetostrictive transducers as both sensors and actuators. At present there exists two different methods, a state quantity-related and a parameter-related for using these inherent sensor effects [336]. In both cases the mechanical values of F and s must be reconstructed from the measured electrical quantities. 

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