SU503603A1 - Piezoelectric sensor - Google Patents

Description

1 (54) PIEZOELECTRIC SENSOR

one

The invention relates to acoustics and can be used to determine the physical characteristics of various materials by measuring the propagation parameters of shear and longitudinal waves.

A component piezoelectric sensor is known that simultaneously detects several types of deformations. The sensor contains a system of glued piezoplates, the plates of which are electrically isolated from one another and connected to the recording device through an adder, which outputs the sum and difference of the electrical signals taken from each plate by means of their sequential phase and phase. In this case, a signal is received from one recorder input, caused by bending deformation (compression deformation is compensated), and to another input, a signal caused by compressing deformation (deformation of bending is compensated).

However, in the pulsed mode of operation with: ignal caused by compression deformation.

not compensated due to differences in the amplitude-frequency characteristics of the individual plates constituting the component sensor. The difference in the amplitudes of the signal is not linear and for each value of the frequency has a different value, in contrast to the continuous mode, when at one given frequency the permanent difference can be eliminated by introducing attenuators.

Thus, the presence of several piezoplates does not allow the sensor to be used in a pulsed measurement mode. The purpose of the invention is simultaneous.

registration of longitudinal and shear deformations using pulsed measurement mode.

For this purpose, the device proposed on the top face of the piezoplates has two electrically insulated electrodes, each of which is divided by area, and one opposite electrode, connected to the KOMNtyTaTopy, the output of which is connected to the inputs recorded, is applied to the opposite face.

devices.

The drawing shows a block diagram of the proposed device.

The sensor consists of a piezoplast 1, the polarization vector of which is perpendicular to electrodes 2, 3 and 4. Electrode 2 is deposited on the lower edge of the sensor, and on the bottom edge of the sensor, i.e. in the face there are two electrodes 3 and 4, equal in raft, di and electrically isolated.

The electrodes 2, 3, and 4 of the piezoplates 1 are connected to a switch 5, the output of which is connected to the inputs of a recording device 6, for example, a two-beam oscilloscope. Piezoplastina 1 registers the longitudinal A and shear (transverse) B strain.

When measuring shear strain; At the first input of the recording device 6, through the switch 5, a signal is taken from electrodes 3 and 4. The measured deformation causes the bending deformation in the piezoplate 1, the material of the piezoplate adjacent to the electrode 3 (4) undergoes a deformation stretching, and simultaneously another part of the piezoplate , under the electrode 4 (3), undergoes a compression deformation, with the result of What between the electrodes 3 and 4 ratios of potentials arise.

When measuring the longitudinal composition of acoustic oscillations, a signal is taken from the electrode 2 and connected in parallel to the $ 3 electrode 4 and 4 via switch 5 to the second input of the recording device 6.

The longitudinal deformation of the piezoplast 1 excites the potentials of the same sign on the electrodes 3 and 4, since the areas of the electrodes 3 and 4 are equal and, therefore, the potential difference caused by the longitudinal deformation is zero in this case.

Claims (1)

Invention Formula A piezoelectric sensor comprising a piezoelectric plate with electrodes and a recording device, characterized in that, in order to simultaneously detect longitudinal and shear deformations; in the pulsed measurement mode, two electrically isolated electrodes of equal size are applied to one face of the piezoplates, and one electr. electrode connected to a switch, the output of which is connected to the inputs of a recording device, is placed on the opposite face.