RU1774237C - Method of calibration of flaw detectors of dielectric part surface foliation - Google Patents

Abstract

Usage: the invention relates to a measurement technique with regard to defectometry of composite dielectric materials. SUMMARY OF THE INVENTION: on the way of flat electromagnetic waves to a defect-free sample, plates of various thicknesses are made on props, made, like props, of the same material as the defect-free sample. By changing the thickness of the plates and using props of various heights, unambiguous dependences are obtained in the form of reference hodographs of the reflection coefficient on the thickness and location of surface delaminations. 2 ill. Ј

Description

The invention relates to a control and measuring technique and can be used to create flaw detectors for electromagnetic monitoring of the thickness and location of surface defects in the form of plane delaminations in composite dielectric materials.

A known method for calibrating a flaw detector of the depth in articles made of dielectrics is that from one or two microwave oscillators are directed normal to the surface of the test object, after interacting with it, the reflected signal is recorded and the signal is detected by changing the signal the presence of a defect and its depth.

The known method allows reliable detection of various types of defects, in

including the most dangerous for polymer composite materials - delamination, it is not possible to simultaneously determine their location - the depth and delamination thickness

This method is the closest to the proposed and is taken as a prototype

The purpose of the invention is to simplify the calibration of a flaw detector for the thickness and depth of a surface bundle.

This goal is achieved in that in the method of calibrating a flaw detector of surface delaminations in products made of dielectrics, which consists in irradiating the reference sample with an electromagnetic wave, measuring the reflection coefficient and determining the dependence of the coefficient

|

-ch4

4 GO

with

s |

reflection from the depth and thickness of the delamination, a defect-free sample is used as a reference sample, on the surface of which plates of different thickness are mounted on supports that are made of the same material as the defect-free sample, and the dependence of the reflection coefficient on the depth and depth of separation is determined by irradiating plates of various thicknesses and changing the height of the supports respectively.

In FIG. 1 and 2 show a diagram of one embodiment of a device that implements the proposed method and example hodographs for a typical monitoring object.

The device consists of a microwave oscillation generator 1, a separation unit 2 of the emitted and received signals, a receiving and emitting antenna 3, a dielectric lens 4, plates 5 of various thicknesses, props 6, a defect-free sample 7, a dielectric substrate 8, a recording unit 9.

Electromagnetic waves of the microwave range from the generator 1 are sent to the separation unit 2 of the emitted and received signals and then to the receiving-emitting antenna 3, in the aperture of which there is a lens 4, transforming them into a flat front. Then the waves fall on the plates 5 located on the supports 6 of a fixed height d. By moving plates of different thicknesses along the wave path, it is possible to obtain different depths of the location of the bundle h. Reflected from the system: plates 5, airspace, defect-free sample 7 and substrate 8, electromagnetic waves enter the antenna 3 through the lens 4 and then to the separation unit 2, after which they are registered in block 9.

and

By way of illustration in FIG. Figure 2 shows the hodographs of the complex reflection coefficient V (ReV and ImV - its real and imaginary components)

5 with a perpendicular sounding of a 40 GHz plane electromagnetic wave of a dielectric plate 2 cm thick in a defect-free state located on a thick dielectric substrate 10. The relative permittivities and tangents of the loss angle of the plate and substrate are as follows: Ј1 4; Ј2 5; tgdi 0.02; 0.5. Near-surface delaminations of thickness d lie in the plate at depths h varying from 0.25 to 2.25 mm. The obtained hodographs, as well as hodographs for other cases show that for near-surface thin bundles it is possible to obtain unambiguous information about the depth and thickness of the bundles.

Claims (1)

SUMMARY OF THE INVENTION A method for calibrating a flaw detector with 25 surface delaminations in dielectric products, comprising irradiating a reference sample with an electromagnetic wave, changing the reflection coefficient and determining the dependence of the reflection coefficient 30 on the depth and thickness of the delamination, characterized in that, in order to simplify the method, as The reference sample uses a defect-free sample, on the surface of which plates of various thicknesses on supports made of the same material are installed. the series, as the defect-free sample, and the dependence of the reflection coefficient on the depth and thickness of the delamination 40 is determined by irradiating plates of various thicknesses and changing the height of the props, respectively. 1.5 -0  & 8.75m. Jmv -0.4 Fie. 2.