SU1582118A1 - Acousto-emissive method inspecting articles - Google Patents

Abstract

This invention relates to non-destructive testing of materials and products. The aim of the invention is to increase the reliability of control of products consisting of two elements bonded by bolted or riveted joints by comparing the coordinates of acoustic emission sources (AE) and the absolute values of emission times of AE signals recorded by transducers installed on both elements of the product. If for both groups of transducers the coordinates of the AE sources or the absolute emission times of the AE signals are different, then they conclude that the AE signal came from a defect, and is not the noise caused by the friction of the rivet or bolt. 1 il.

Description

The invention relates to non-destructive testing of materials and products and can be used to control developing defects in products with bolted and riveted joints by acoustic emission signals (A3).

The aim of the invention is to increase the reliability of control of products consisting of two elements bonded by bolted or riveted joints, by comparing the coordinates of AE sources and the absolute values of the emission times of AE signals recorded by the transducers installed on both elements of the products.

The drawing shows the functional, flax diagram of the device that implements the method of control products.

The device contains at least six channels of reception and amplification of AE signals, each of which contains series-connected electro-acoustic transducer 1-6, preamplifier 7-12 and amplifier with filter 13-18, blocks 19,20 determining the arrival times of AE signals, generator 21, coordinates determining blocks 22,23, comparison block 24.

The outputs of the amplifiers 13-15 are connected to the corresponding inputs of the block 19 for determining the arrival times of signals, and the outputs of the amplifiers 16-18 are connected (by the corresponding inputs of the block 20 for determining the signal arrival times. The fourth inputs of the blocks 19.20 for determining the signal arrival times are connected to the output of the generator 21 pr masp

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to

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coal pulses, and the outputs of blocks 19,20 determine the arrival times - with the corresponding inputs of blocks 22, 23 determine the coordinates, the outputs of which are connected to the input of block 24 comparison

The method of control products is as follows.

On the elements of the controlled product Q, bolted or riveted, two groups of electroacoustic transducers 1 to 6 are placed, each group (converters 1 to 3 and transducers 4 to 6) 15 represent an acoustic antenna,

Each antenna is placed on the corresponding element of the product. The signals A3 are received by receiving converters 1-6, amplified and filtered out in blocks 7 - FROM. Blocks 19, 20 determine the arrival times of AE signals at receiving transducers 1-6. The arrival times are determined by signals from a generator of 21 rectangular pulses. Counting the number of pulses arriving from the generator 21, is performed on the first signal AE, which came to

any of the transducers 1-6. Therefore, blocks 19, 20 of determining the arrival times JQ of signals begin to work simultaneously, which makes it possible to calculate and compare the absolute times of radiation of the sources of signals A3. The contents of the RAM of blocks 19, 20 Dg determine the times of arrival arrive at Q: Cathery calculates the coordinates and absolute times of radiation of AE signal sources. In block 24, the comparison compares the computed coordinates and absolute emission times of the AE signals of two groups of transducers 1-6, and excludes AE signals with matching emission times and source coordinates of the AE signals, If for both antennas or / coordinates, or the absolute emission times of the AE signals are different, then V concludes that the AE signal arrived, Q from the defect, and is not the noise caused by the friction of the rivet or bolt. When inspecting a product consisting of elements of the same design, the gain factors from transducers 1 to 3 located on the element being monitored are larger than that of transducers 4 to 6 placed on the second element to which

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fasten the first element. In this case, both noise signals and signals from defects are fixed on the monitored element, and only noise signals on the second element.

AE signals, caused by friction of bolts and rivets, will be fixed by both antennas, since rubbing a rivet or a bolt will cause oscillations in both elements simultaneously. If a crack starts to develop from any hole of one of the elements, the AE signals arising in this element will propagate along it, and the signals A3 will be transmitted to the other element with a large attenuation due to poor acoustic contact of bolted or riveted elements. connection.

Thus, this method allows to increase the reliability of monitoring riveted or bolted connections by using an additional group of AE converters and comparing the parameters of AE signals of two groups of converters.

Claims (1)

Invention Formula An acoustic emission method of controlling products, which consists in placing a group of electroacoustic transducers on the surface of a product element, loading the product, accepting acoustic emission signals, determining their parameters and the arrival time differences on the transducers, judging by the signal parameters and arrival time differences coordinates of sources of acoustic emission and defectiveness of the product, characterized in that, in order to increase the reliability of control of products consisting of two elements bonded by oh bolted or riveted connections, place the second group of transducers on the second element of the product, determine the coordinates of the acoustic emission sources by the second group of transducers, determine the absolute values of the arrival times of signals on one of the transducers of both the first and second groups, according to the coordinates of the sources and the absolute values of the arrival times of the signals are determined by the absolute values of the emission times of the acoustic emission signals, and the registered signals are considered to be received in 511582П8 shorter from a defect, if for both groups i or the absolute arrival times of the signal generators, the coordinates of the sources of fishing are different. / J /four 2 uh $ 15 and  $ Jff eleven one 17 "  S J8 79 yy one 21 -tl 2 J 20 23