performance index of piezoelectric ceramics
Publish Time: 2018-11-13 Origin: Site
Piezoelectric constant d33 of piezoelectric ceramics is a linear response coefficient that reflects the mutual coupling between the mechanical quantity (stress or strain) and the electrical quantity (electrical displacement or electric field). When a compressive stress T3 is applied along the polarization direction (z-axis) of the piezoelectric ceramic, and a charge is generated on the electrode surface, there is a relationship: where d33 is a piezoelectric constant, and the first number in the foot indicates the direction of the electric field. Or the vertical direction of the electrode surface, the second number refers to the stress or strain direction; T3 is the stress; D3 is the electric displacement. It is the proportional constant of a piezoelectric medium that converts mechanical energy (or electrical energy) into electrical energy (or mechanical energy), reflecting the relationship between stress (T), strain (S), electric field (E), or electrical displacement (D). It reflects the coupling relationship of the electromechanical properties of the material and the strength of the piezoelectric effect, which leads to the piezoelectric equation. There are four common constants of Pzt4 material piezoelectric disc: dij, gij, eij, hij. 2 Electromechanical coupling coefficient Kp, electromechanical coupling coefficient K is a physical quantity that comprehensively reflects the coupling relationship between mechanical energy and electrical energy of piezoelectric ceramics, and is a reflection of piezoelectric-electric energy conversion capability of piezoelectric materials. The definition of electromechanical coupling coefficient is:
Mechanical quality factor Qm
Piezoelectric ceramics of consume energy in order to overcome internal friction when is vibrating. The mechanical quality factor Qm is a parameter that reflects the amount of energy consumption. The larger the Qm, the smaller is the energy consumption. The definition of the mechanical quality factor Qm is where fr is the resonant frequency of the piezo ceramic bimorph, fa is the anti-resonant frequency of the piezoelectric vibrator, R is the minimum impedance Zb min (resonant resistance) at the resonant frequency, C0 is the static capacitance of the piezoelectric vibrator, and C1 is the piezoelectric vibrator resonant capacitor.
Frequency constant N
For a piezoelectric vibrator, the probability of the resonant frequency and the length of the vibrator vibration direction is a constant, that is, the frequency constant. N=fr×l where: fr is the resonant frequency of the piezoelectric vibrator; and l is the length of the vibrating direction of the piezoelectric ceramics ring transducers. Radial vibration of thin disc: Np=fr×D (D is the diameter of the disc) Thin plate thickness stretching vibration: Nt=fr×t (t is the thickness of the thin plate) Slender rod K33 vibration: N33=fr×l(l For the length of the rod) Thin plate shear K15 vibration: N15 = fr × lt (lt is the thickness of the thin plate)