Study On Electromechanical Resonance Frequency Of Magnetic Field Controlled Piezoelectric/Magnetic Resonant Composite Oscillator

The piezoelectric transducer usually is designed though a fixed resonance frequency method; however, in the process of long-using, due to the influence of environmental factors such as temperature, transducer resonance frequency tends to change away from the work frequency designed, and further affecting the output efficiency of the transducer. In addition, when needed a different working frequency, we must design a new transducer. In this paper, we propose a method by controlling the magnetic fields to regulate the resonance frequency of piezoelectric vibrator. The method is based on the magnetic-force-electric coupling effect of magnetoelectric composite materials. Magnetoelectric composite material composed of piezoelectric vibrator and magnetostrictive material. In a single DC magnetic field, the magnetoelectric coupling effect make the electric mechanical resonance frequency of piezoelectric body changes. To obtain field control the resonant frequency of the piezoelectric vibrator, we provide new method for piezoelectric transducer controllable frequency.This paper based on the AE effect of magnetostrictive material, by using the effective elastic modulus of magnetoelectric composite materials changing with the magnetic field, the resonance frequency shift of the thought of mechanical and electrical. Using the method of elastic mechanics, by using the constitutive equations of magnetostrictive and piezoelectric body, numerical calculation of the piezoelectric capacitance (dielectric constant) and the function relation between magnetic field, frequency, and to simulate the change of the relationship between the mechanical resonance frequency with magnetic field.Magnetoelectric composite come from the compounding of piezoelectric material and magnetostrictive materials in some way, Under the function of the magnetostriction and piezoelectric effect, pass the magnetostriction stress to piezoelectric body though interface, to obtain product of the magnetoelectric properties coupling. In the study of the structure of the magnetoelectric coupling,layered magnetoelectric composite materials are in the majority. Layered composite piezoelectric and magnetostrictive phase function is through the shear stress between the couplings. In this paper, we choose article-ring magnetoelectric composite materials. The effects of piezoelectric and magnetostrictive phase are mediated by normal stress coupling, And make the "leap" of magnetostrictive phase effect, make its magnetron resonant frequency deviation of the magnetic field significantly reduced, and improved the magnetic resonance frequency sensitivity.(1) Using the circular piezoelectric vibrator (PZT) and strip magnetostrictive (TDF) to constitute a magnetoelectric composite structure, the controlling of piezoelectric vibrator capacitance theory model is established by magnetic pressure, the piezoelectric constitutive equation, the elastic dynamics equation, according to the boundary conditions of magnetic field, in which the phase magnetostrictive coefficient of elasticity soft change with magnetic field is the key of consideration of the magnetic control resonance, according to this to research of magnetic control of piezoelectric vibrator resonant characteristics. We used magnetostrictive "jumping effect" to simulate the material capacitance, frequency, and the changes of the external magnetic field. The experimental study the magnetic control law of resonant frequency offset. and the basic theory and experiment is identical. Experiments show that the sensitivity of magnetic tuning respectively is 45Hz/Oe (low frequency) and 133Hz/Oe (high frequency).(2) On the basis of the above theory and experiment, we designed the magnetoelectric composite structure constitute circular piezoelectric vibrator (PZT) and cylinder of magnetostrictive (TDF). Using cylindrical coordinates, magnetic field control of piezoelectric vibrator capacitance theory model is set up by the constitutive equations of piezoelectric and magnetostrictive phase, the elastic dynamics equation. We numerical simulated the material capacitance and frequency, and the changes of the external magnetic field, experimental research and theoretical results are basically identical. Experiments show that the sensitivity of magnetic tuning respectively is 18Hz/Oe (low frequency) and 47Hz/Oe (high frequency).