Magnetostrictive transducers for compressive force using ferrite

A transducer for compressive force using Mn-Mg and Ni-Zn ferrite is offered in this paper, based on the magnetomechanical effect that the magnetic characteristics of the material are influenced by mechanical stress. They can be realized by applying a Royer´s and Marzolf´s circuit. The input to the transducer is pressure, and the output is an oscillator frequency. The change of the magnetic characteristics caused by repeated application and removal of 1.8 kg/mm²pressure can be reversible. With a Marzolf type transducer, at low pressure the input-output characteristic shows a hysteresis till 0.9 kg/mm², but at higher pressure than 0.9 kg/mm²the characteristics are completely linear. With a Royer type transducer the characteristics are almost linear, although a little hysteresis is found over the range from 0 to 1.8 kg/mm². The experimental results show that at low pressure the characteristics are nonlinear, including the hysteresis, and the influence of the temperature is 1.2%/°C over the range from 18 to 30°C. The method is also useful in the case of investigating the flux reversal mechanism under various stress conditions.