SU873107A1 - Method of determination of acoustic emission source coordinates in sheet material articles - Google Patents

Description

(54) METHOD FOR DETERMINING COORDINATES OF SOURCES OF ACOUSTIC EMISSION SIGNALS IN PRODUCTS FROM SHEET

I

The invention relates to a continuous drying control and can be used to control the quality of sheet products such as pressure vessels.

The known method of determining two coordinates in sheet products consists in loading the product, receiving acoustic emission signals, measuring the triangulation parameters of the signals, which determine the coordinates of the source to

The disadvantage of this method is that it does not allow to determine the location of the source by the thickness of the sheet.

The closest to the technical essence of the invention is a method for determining the coordinates of the sources of acoustic emission signals in products made from sheet materials, which consists in loading the product and receiving signals from acoustic materials.

These emissions, their triangulation parameters are determined, the two coordinates of the center of the signal source are determined, the transducers that receive the signal first and last are determined, and the time interval between these events {.21 is measured.

The disadvantage of this method is that it is not possible to determine the depth of the defect.

10 with one-way access to the product.

The chain of the invention is the determination of the depth of the location of a material defect with unilateral access to the product.

IS

This goal is achieved by the fact that in the zone defined by two coordinates, additional transducers are placed, mechanically interconnected, covering this zone

Claims (2)

M and located at equal distances from each other, define additional transducers that receive the signal first and last, and measure the time interval (AT) between these events, and the depth of the position of the defect from the surface of the product is determined from the ratio (s): where r / - is the distance between additional converters; C is the speed of signal propagation in the material. Figure 1 shows the placement of the transducer on the product for determining the two coordinates in FIG. 2, a schematic diagram for determining the depth of the location of the defect. The method is as follows. On the surface of the product of sheet material (see Fig.1) place the transducers 1-4. The latter accept acoustic emission signals and convert them to electrical ones. An electronic device (not shown) measures the time intervals of LT between the instants of signal occurrence in the channels, including for the converters that receive the signal first and last (in this case, 3 and 1). It also determines where these transducers are located. According to the obtained measurement results, the coordinates X.- + ah and y- ± ayi of the center of the signal source are determined. Then in this zone (Additional converters are placed on the surface of the sheet, mechanically interconnected, for example, placed on a template, and at equal distances from each other ot each other. Placement can be not only rectangular, but also in the form of concentric circles around central electroacoustic transducer. But in any form of placement, the covered area must be exceeded (to cover the signal source area. The distance between the transducers is related to measurement error, What will be discussed below: Acoustic emission signals from source A (see Fig. 2) reach the surface of the sheet on which additional transducers are placed. 7 The first signal is received by the transducer & C (the rest is not shown.) The depth of the defect thickness of the material is determined by the ratio of i-e-c; g dT-c. Formula of the invention A method for determining the coordinates of the sources of acoustic emission signals in sheet products is that the product is loaded, the acoustic emission signals are received, their triangulation parameters are determined, the two coordinates of the center of the signal source are determined, the transducers that received the signal first and last are determined, and the time interval between these events is different In order to determine the depth of the defect with one-way access to the product, additional transducers mechanically interconnected are located in the zone defined in two coordinates. covering this zone and located at equal distances from each other, define additional transducers that received the signal first and last, and: measure the time interval (AT) between these events, and the depth of the defect from the surface of the product is determined from correlated 2 LT-O where 6 is the distance between the additional converters C is the signal propagation speed in the material. Sources of information taken into account during the examination 1. USSR author's certificate 8o application No. 2530536/28, cl. G 01 N 29/04, 1977. 2. USSR author's certificate for application number 2604201/28, cl. G 01 N 29/04, 1978 (prototype).  X IIIIIIIWMIB) | k yz gi ± & y. J Elf / / / fig.g