SU1597673A1 - Sample for testing piezoelectric materials for mechanical strength - Google Patents

Abstract

This invention relates to testing the mechanical strength of piezoelectric materials. The aim of the invention is to increase the reliability of the tests. The sample contains a cylindrical piezoelectric element with a radius of R and height H with collector electrodes 1 and 2, on the side surface of the sample made in the form of a cylinder, there is a conductive track 3, made in the form of a spiral. The track and electrodes are interconnected by switching electrodes 4 and 5. The spiral is applied at an angle α determined from the ratio α≥ARCTG [3 (1-5H) / 20ϕR], and the number of turns N is determined from the condition N≥10H / (3 -5H). when tested while the conductor track is intact, the charges at the ends are mutually canceled. In the event of a defect and a rupture of the track, an uncompensated charge appears, which is recorded with a high degree of confidence by the measuring apparatus. 1 il.

Description

The invention relates to the field of controlling the mechanical strength of piezoelectric materials and can be used in the process of their manufacture and testing.

The aim of the invention is to increase the reliability of tests in determining the mechanical strength of piezoelectric materials.

The drawing shows a diagram of the sample.

The sample consists of a cylindrical piezoelectric element with a radius of R and a height of N. On its ends there are applied pull-down electrodes 1 and 2, and on the lateral forming surface - a conductive track 3, filled in the form of a spiral. The conductor track 3 and the collector electrodes 1 and 2 are connected by segments of switching electrodes 4 and 5.

The application of the conductive path 3 can be accomplished by any of the traditional methods, for example, by firing metal-containing pastes, by spraying or by chemical deposition. Thereafter, the sample is polarized to give it piezoelectric properties and the subsequent electrical connection of the conductive track 3 and the current collecting electrodes 1 and 2 with the sections of the switching electrodes 4 and 5, which are cold-applied (for example, by deposition) in order to prevent sample. There are other varisd with |

0 h

SAE

Samples are manufactured, for example, the application of collector electrodes, polarization, and the simultaneous cold deposition of a conductor path and switching electrodes. Depending on the geometric dimensions of the sample, the walkway is applied so that the angle of inclination of the coil / arctg is:; -, where -

/ rk

interwinding distance of the track. This allows for a given geometrical dimensions of the sample and the track to obtain an IL

maximum number of turns N, -

+ n

It was established experimentally that at forces reaching about 60% of the sample mechanical strength limit, micro-cracks appear and fragments with a linear size of 1 0.3 mm fall from the surface. Their orientation is directed along the direction of the applied force.

After applying the track in this way, you can detect defects, linear size 1 of which is not less than +1.5 h. In order to increase the reliability, it is necessary to minimize the inter-jitter H-position. Then the parameters of the conductive path should satisfy the following conditions:

with

with

0 5

P

five

The collector electrodes 1 and 2 are connected to measuring equipment, such as an oscilloscope or a voltmeter. As long as the sample is intact, the electric charges arising on the current-body electrodes are mutually canceled (as the electrodes are shorted by a conductive path),

V

Damage, which with a high degree of probability begins on the surface of the sample, due to the increased sensitivity of brittle materials to surface defects, is directed along the direction of mechanical stresses and leads to rupture of the conductive path and the appearance of uncompensated charge on current-collecting electrodes, which with a high degree of confidence is recorded by the measuring apparatus.

Claims (1)

Invention Formula A sample for mechanical testing of piezoelectric materials, made in the form of a polarized cylinder with collector electrodes at the ends, characterized in that, in order to increase the reliability of the tests, a connecting current collector was applied to the side surface of the cylinder. electrodes conductive track in the form of a spiral with an angle of inclination c / and number of turns N, satisfying the ratios Samples were tested as follows. After fabrication, the sample is placed in a tensile testing machine. mechanical strength tests under static loads or on a shaker (impact test bench) for testing under dynamic loads. 40 , .. “, .. 3Iiz5 |). 45 N U / Yun 3-5h where h is the width of the conductive path, mm; R is the radius of the sample, m; H - sample height, mm. Editor A. Shandor Compiled by E. Karpilovska Tehred M. Hodanić Order 3046 Circulation 503 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology 113035, Moscow, Zh-35, 4/5, Raushsk nab. . Corrector O. Tsiple Subscription