SU1516954A1 - Method of determining the location of fatigue cracks by signals of acoustic emission - Google Patents

Abstract

The invention relates to non-destructive testing of acoustic emission signals (AE) and can be used to determine the location of developing fatigue cracks in pressure vessels made of sheet materials. The purpose of the invention is to improve the accuracy of determining the location of cracks by increasing the number of measured triangulation parameters of AE signals. Electroacoustic transducers (EAP), equally located in antennas, are electrically respectively combined, except for one in each antenna. From among the unassociated EAPs, the EAP that received the signal first is determined. Triangulation parameters are determined for all EAP antennas. 3 il.

Description

The invention relates to non-destructive testing of acoustic emission (AE) signals and can be used to locate the development of fatigue cracks in pressure vessels from sheet materials.

The aim of the invention is to improve the accuracy of determining the location of cracks by increasing the number of measured triangulation parameters of AE signals.

Fig. 1 shows the layout of electroacoustic transducers (EAC) on the surface of a controlled product, the first option; Fig. 2 is a block diagram of an apparatus for implementing a method for determining the location of fatigue cracks from AE signals; Fig. 3 shows the layout of the EAP on the surface of the tested item, the second option.

The device contains n groups of EAP. the first group includes the first 1, the second 2, the third 3 and the fourth 4 of the EAP, the n-th group includes the first 5, the second 6, the third 7 and the fourth 8 of the EAP. The device also contains the first 9, second 10, and third 11 channel combining units, respectively, the first 12, second 13, and third 14 amplifier drivers connected to each of the amplifier drivers 12–14, the coordinate determination unit 15 connected to its output is a memory block 16, the fourth and nth amplifiers-formers 17 and 18, the circuit OR 19, connected to the corresponding outputs of the fourth and nth amplifiers-formers 17 and 18, block 20 of determining the first signal, whose inputs are connected to the outputs fourth and nth y silica-formers 17 and 18, and out

O) QD

cl

four

dm - according to the second group of inputs of the block 16 to us, the outputs after / pego are connected to the registration unit (not zhzhazan). The output cxeNibi 19 is connected to the fourth input of the coordinate detection unit 15.

The method of determining the location of fatigue cracks by the signaling elements of the LE (ecTBJiHercH in the following 1M manner.

On products 1 and 21 in the region of the first support 22 and the n-th support 23, HALL 1-8 are placed in groups, thereby forming the same acoustic antennas of a quadrangular configuration. JAII placement options are possible. HanjMiMep, on the product 21 without placing the same antenna in the form of a centered triangle. ELI, equally located and antennas, electrically corresponding to P1o are combined, except for one in each antenna: the first CRP 1 and 5 of all groups are connected to the inputs of the first block 9 of the channels, the second CRC 2 and 6 are connected to the channels, the third ELIs 3 and 7 are to the input of the third block 1 1 about kayaloz, not combined by ELP 4 and 8, podkzpochayut respectively to the inputs of the fourth and cth yc iJl-formatters 17 and 18. The LE signals emitted by the developing crack, located for example in the area of support 22 , take EBT 1-4 (ELP of the first antenna) into the appropriate time and convert the LE signals into electrical ones. EBD 1-3 signals are supplied by blocks 9–11 OBG of an electrical channel, the CRT screen 4 is fed to the first non-mediated booster 17, the square-shaped signal generated at its output is fed through the OR circuit 19 to the coordinate determining unit 15. Signals with o (:: tal 1st CRP 1 -3 to amplifier x-formers 12–14, from which outputs and UIls are also fed into block 15, are assigned to a similar form.

measure the time intervals between the signals in the channels and then determine the coordinates of the crack within the surface area of the product 21, controlled by one acoustic antenna (without determining the number of the acoustic antenna). Simultaneously, in block 20 of determining the first

The Q signals determine the EAP number to which the signal arrived first. The memory block 16 simultaneously provides information about the location of the first antenna, which received the signal first, and the coordinates

5 cracks.

Thus, the proposed method makes it possible to increase the accuracy of control by using all EAS in an acoustic antenna (including an additional EAP) for triangular calculation of the coordinates of defects.

Claims (1)

The invention method for determining the location 5 fatigue cracks by acoustic emission signals, which consist in placing electro-acoustic transducers on the product, combining them into antennas, transducers that are equally spaced; In antennas, JA, respectively, combine, except for one in each antenna, receive acoustic emission signals, from among the non-coupled transducers, determine the transducer that received the signal first, and determine the antenna in the zone where the crack is located, determine the arrival time differences signals to the combined transducers and from them calculate the coordinates of the crack, and the location of the crack is determined by the converter that received the signal first, and the calculated coordinates, with the fact that, in order to improve accuracy, the differences in arrival times of signals for all non-coupled converters of each antenna are additionally determined and taken into account when determining the 0 ordinates cracks that P Vkeda y ./t P / x