A method and system for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials

Abstract

The present invention provides a method and system for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials. The technical solution of the present invention sets a gasket between standard samples of epoxy composite materials, obtains the change of ultrasonic longitudinal wave waveform by moving the gasket, obtains the position corresponding to the gasket when the ultrasonic longitudinal wave waveform disappears, measures the distance between the upper surface of the gasket and the upper surface of the standard sample, and obtains the maximum propagation depth of ultrasonic longitudinal waves in epoxy composite materials. After replacing probes of different frequencies, repeat the operation steps to obtain the maximum propagation depth of ultrasonic longitudinal waves of different frequencies; the detection system includes: a variable angle longitudinal wave probe for transmitting longitudinal waves, a variable angle longitudinal wave probe for receiving longitudinal waves, a probe connecting line, an ultrasonic pulse generator and receiver, a signal transmission line, and an oscilloscope. The technical solution of the present invention can measure the propagation depth of ultrasonic longitudinal waves of different frequencies in epoxy composite materials, and the operation process is simple.

Description

Technical Field

[0001] The invention relates to the field of nondestructive testing of power transmission and transformation insulation equipment, and in particular to a method and system for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials. Background Art

[0002] Gas-insulated metal-enclosed switchgear (GIS) is widely used in urban high-voltage power grids or power systems in complex terrain and small areas due to its high reliability and strong safety. The large-size insulation parts of GIS combined electrical appliances are key components of GIS, and their performance will directly affect the reliable operation of GIS.

[0003] GIS large-size insulating parts are cast from epoxy composite materials. During the manufacturing process, due to unsatisfactory quality control of the casting process, large residual stress will be generated inside, which will deteriorate the performance of GIS large-size insulating parts and thus threaten the safe and reliable operation of GIS. Therefore, the detection of residual stress of GIS large-size insulating parts plays a vital role in ensuring the safe operation of the power grid.

[0004] The ultrasonic critical refraction longitudinal wave method is suitable for the detection of residual stress of large-size insulation parts of GIS due to its good directivity, easy on-site operation and non-destructive testing. During the stress detection process, when the ultrasonic critical refraction longitudinal wave propagates in the epoxy composite material, the propagation depth is related to its frequency.

[0005] However, there is currently no detection method that can directly measure the propagation depth of ultrasonic critical refraction longitudinal waves of different frequencies in epoxy composite materials, which to a certain extent limits the application of ultrasonic critical refraction longitudinal wave method in residual stress detection of large-size insulating parts of GIS. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method and system for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials.

[0007] The present invention provides a method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials, and the specific steps include:

[0008] (1) placing a gasket between two standard specimens, the two standard specimens clamping the gasket, the two standard specimens and the gasket being both epoxy composite materials;

[0009] (2) fixing a variable angle longitudinal wave probe for transmitting longitudinal waves on the surface of one of the standard samples, and fixing a variable angle longitudinal wave probe for receiving longitudinal waves on the same surface of another standard sample;

[0010] (3) moving the gasket downward to obtain ultrasonic longitudinal wave waveform information, and obtaining the corresponding position of the gasket when the ultrasonic longitudinal wave waveform information disappears;

[0011] (4) obtaining the distance between the upper end of the gasket and the upper surfaces of the two standard specimens at the corresponding position of the gasket when the ultrasonic longitudinal wave waveform information disappears, which is the maximum propagation depth of the ultrasonic longitudinal wave in the epoxy composite material;

[0012] (5) Replace the probe with a different frequency and repeat steps (2) to (4).

[0013] Preferably, the casting process of the gasket and the two standard samples is the same.

[0014] Preferably, placing the gasket between two standard specimens, wherein the two standard specimens clamp the gasket, specifically includes: the upper end of the gasket and the upper surfaces of the two standard specimens are at the same height plane.

[0015] Preferably, fixing the ultrasonic longitudinal wave transmitting probe and the ultrasonic longitudinal wave receiving probe on the two standard samples specifically includes: using tape to fix the ultrasonic longitudinal wave transmitting probe and the ultrasonic longitudinal wave receiving probe located on the same side to the surface of the standard sample respectively.

[0016] Preferably, the downward movement of the gasket specifically includes: the gasket extends out of the standard sample, and the extended portion of the gasket is manually controlled to move the gasket slowly vertically between the standard samples.

[0017] Furthermore, the method of obtaining the distance between the upper end of the gasket and the upper surfaces of the two standard specimens specifically includes: at the corresponding position of the gasket when the ultrasonic longitudinal wave waveform information disappears, measuring the distance between the upper surface of the gasket and the upper surfaces of the two standard specimens, which is the maximum propagation depth of the ultrasonic longitudinal wave in the epoxy composite material corresponding to the frequency of the ultrasonic longitudinal wave probe.

[0018] Furthermore, coupling agent is applied between the ultrasonic longitudinal wave probe and the two standard samples, and between the two standard samples and the gasket.

[0019] A system for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials, comprising:

[0020] A variable angle longitudinal wave probe for transmitting longitudinal waves, a variable angle longitudinal wave probe for receiving longitudinal waves, a probe connecting line, an ultrasonic pulse generator and receiver, a signal transmission line, and an oscilloscope;

[0021] One end of the probe connecting line is connected to the variable angle ultrasonic probe that transmits longitudinal waves, and the other end is connected to the output end of the ultrasonic pulse generator receiver; one end of another probe connecting line is connected to the variable angle ultrasonic probe that receives longitudinal waves, and the other end is connected to the receiving end of the ultrasonic pulse generator receiver; one end of the signal transmission line is connected to the synchronization end of the ultrasonic pulse generator receiver, and the other end is connected to the oscilloscope.

[0022] Furthermore, it also includes a computer for acquiring ultrasonic longitudinal wave waveform data information, performing data processing, and accurately acquiring the moment when the waveform disappears.

[0023] More preferably, the variable angle longitudinal wave probe for transmitting longitudinal waves and the variable angle longitudinal wave probe for receiving longitudinal waves are longitudinal wave piezoelectric contact probes, using rectangular composite material piezoelectric wafers, the bottom surface of the probe is a flat rectangle, the probe is designed as a narrow strip, and the angle of longitudinal wave emission can be adjusted between 0° and 90°;

[0024] More preferably, the ultrasonic pulse generator-receiver is a pulse generator-receiver with negative square wave excitation, adjustable square wave amplitude and width, low noise response, and adjustable gain;

[0025] More preferably, the oscilloscope is a four-channel high-performance digital storage oscilloscope with a bandwidth of 100 MHz, a maximum sampling rate of 2.5 GS / s, and high input impedance;

[0026] More preferably, the probe connection line is a signal line that matches the ultrasonic pulse generator and receiver with the variable-angle longitudinal wave ultrasonic probe that transmits longitudinal waves or receives longitudinal waves;

[0027] More preferably, the signal transmission line is a transmission line with a stray inductance less than 1 mH and a resistance less than 5 mΩ.

[0028] It can be seen from the above technical solutions that the present invention has the following advantages:

[0029] The present invention provides a method and system for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials. The technical solution of the present invention is to set a gasket between standard samples of epoxy composite materials, and to obtain the change of ultrasonic longitudinal wave waveform by moving the gasket, and to obtain the corresponding position of the gasket when the ultrasonic longitudinal wave waveform disappears, and to measure the distance between the upper surface of the gasket and the upper surface of the standard sample, so as to obtain the maximum propagation depth of ultrasonic longitudinal waves in epoxy composite materials, and to obtain the maximum propagation depth of ultrasonic longitudinal waves of different frequencies by repeating the operation steps after replacing probes of different frequencies, and the operation process is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 A schematic flow chart of a method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials provided in a specific embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a system for implementing a method for measuring the propagation depth of ultrasonic longitudinal waves of different frequencies in epoxy composite materials provided in a specific embodiment of the present invention;

[0033] Explanation of the reference numerals: ultrasonic pulse generator and receiver 1, oscilloscope 2, variable-angle longitudinal wave probe for transmitting longitudinal waves 3, variable-angle longitudinal wave probe for receiving longitudinal waves 4, signal transmission line 5, standard sample A6, gasket 7, standard sample B8, probe connecting line 9, computer 10. DETAILED DESCRIPTION

[0034] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the term "on" or the like is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0036] Unless otherwise clearly specified and limited, the terms "connection", "fixation" and "setting" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, an indirect connection through an intermediate medium, or a connection between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] The embodiment of the present invention provides a method and system for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials. For details, please refer to Figure 1 to Figure 2 .

[0038] In this embodiment, a method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials comprises the following specific steps:

[0039] (1) placing a gasket between two standard specimens, the two standard specimens clamping the gasket, the two standard specimens and the gasket being both epoxy composite materials;

[0040] (2) fixing a variable angle longitudinal wave probe for transmitting longitudinal waves on the surface of one of the standard samples, and fixing a variable angle longitudinal wave probe for receiving longitudinal waves on the same surface of another standard sample;

[0041] (3) moving the gasket downward to obtain ultrasonic longitudinal wave waveform information, and obtaining the corresponding position of the gasket when the ultrasonic longitudinal wave waveform information disappears;

[0042] (4) obtaining the distance between the upper end of the gasket and the upper surfaces of the two standard specimens at the corresponding position of the gasket when the ultrasonic longitudinal wave waveform information disappears, which is the maximum propagation depth of the ultrasonic longitudinal wave in the epoxy composite material;

[0043] (5) Replace the probe with a different frequency and repeat steps (2) to (4).

[0044] Specifically, the materials and casting processes of the two standard samples and the gasket selected in step (1) are the same. According to the needs of testing large-size GIS insulating parts, the same materials and casting processes as the tested large-size GIS insulating parts can also be selected. The two standard samples are two groups of identical rectangular parallelepipeds, and the overall dimensions of each group are 70mm×60mm×90mm in length×width×height. The overall dimensions of the gasket are 70mm×30mm×2mm in length×width×height.

[0045] Specifically, in step (1), the gasket is clamped between two ultrasonic longitudinal wave probes, an object with a horizontal lower surface is placed on the upper surfaces of standard samples A6, standard samples B8 and gasket 7, and gasket 7 is moved upward until it can no longer be moved upward. At this time, the upper end of gasket 7 is in the same height plane as the upper surfaces of standard samples A6 and standard samples B8; when gasket 7 is clamped between two standard samples, static friction can keep the gasket from being displaced, and the gasket will only move when it is moved manually. Therefore, after keeping the gasket 7 at the same height as the upper surfaces of standard samples A6 and standard samples B8, no action is required to keep the height of the gasket and the upper surfaces of the standard samples unchanged.

[0046] Specifically, in step (2), the variable angle longitudinal wave probe 3 for transmitting longitudinal waves is fixed on the upper surface of the standard sample A6 by using tape, and the variable angle longitudinal wave probe 4 for receiving longitudinal waves is correspondingly fixed on the upper surface of the standard sample B8. The angles of the two variable angle longitudinal wave probes are determined according to the Snell principle. The tape is pasted on the front and back surfaces of the two standard samples so that the two probes are located on the same side to facilitate the reception of ultrasonic longitudinal waves. The two probes are kept fixed on the surface of the standard samples during the test.

[0047] Specifically, in step (3), the longitudinal wave emitted by the variable angle longitudinal wave probe is refracted on the probe wedge and the surface of the standard sample A6, generating an ultrasonic critical refracted longitudinal wave in the standard sample A6, and the ultrasonic critical refracted longitudinal wave is transmitted from the standard sample A6 to the standard sample B8 through the gasket 7, and is received by the variable angle longitudinal wave probe 4 on the surface of the standard sample B8; the two ends of the gasket 7 extend out of the standard sample by 5 mm respectively, and the extended parts of the two ends of the gasket 7 are manually controlled to move the gasket 7 slowly up and down between the standard sample A6 and the standard sample B8; at the beginning of the test, the upper end of the gasket 7 is kept at the same height as the upper surfaces of the standard samples A6 and B8, and the waveform graphic information on the oscilloscope is observed, while the gasket is moved downward, and the waveform on the oscilloscope changes with the movement of the gasket; when the waveform disappears, the gasket is stopped from being moved, and the gasket 7 is fixed at the corresponding position when the waveform disappears.

[0048] Specifically, in step (4), since the standard sample A6 and the standard sample B8 are placed on the same horizontal plane, the upper surface of the two standard samples is the upper surface of the standard sample A6 or the standard sample B8; if the standard sample A6 is placed horizontally higher than the standard sample B8, the upper surface of the two standard samples is the upper surface of the standard sample A6; in this embodiment, after the gasket 7 is fixed at the position corresponding to when the waveform disappears, the distance between the upper surface of the gasket 7 and the upper surface of the standard sample A6 or the standard sample B8 is measured, which is the maximum depth range of the ultrasonic longitudinal wave of this frequency propagating in the epoxy composite material.

[0049] Specifically, in step (5), the variable angle longitudinal wave probes of different frequencies are replaced, and steps (2) to (4) are repeated to complete the measurement of the propagation depths of ultrasonic longitudinal waves of different frequencies in the epoxy composite material, thereby obtaining the propagation depths of ultrasonic longitudinal waves of different frequencies in the epoxy composite material.

[0050] In a more preferred embodiment, in order to increase the coupling effect, coupling agent is applied between the two ultrasonic longitudinal wave probes and the two standard samples, and between the standard sample and the gasket.

[0051] In this embodiment, a system for implementing a method for measuring the propagation depth of ultrasonic critical refracted longitudinal waves of different frequencies in epoxy composite materials comprises: an ultrasonic pulse generator and receiver 1, an oscilloscope 2, a variable angle longitudinal wave probe 3 for transmitting longitudinal waves, a variable angle longitudinal wave probe 4 for receiving longitudinal waves, a signal transmission line 5, and a probe connection line 9;

[0052] One end of the probe connecting line 9 is connected to the variable angle ultrasonic probe 3 for transmitting longitudinal waves, and the other end is connected to the output end of the ultrasonic pulse generator receiver 1; one end of another probe connecting line 9 is connected to the variable angle ultrasonic probe 4 for receiving longitudinal waves, and the other end is connected to the receiving end of the ultrasonic pulse generator receiver 1; one end of the signal transmission line 5 is connected to the synchronization end of the ultrasonic pulse generator receiver 1, and the other end is connected to the oscilloscope 2.

[0053] In a more preferred embodiment, it also includes a computer 10, which obtains the ultrasonic longitudinal wave waveform data information of the oscilloscope 2 through data transmission, performs data processing, and accurately obtains the moment when the waveform disappears.

[0054] In a more preferred embodiment, the variable-angle longitudinal wave probe 3 for emitting longitudinal waves and the variable-angle longitudinal wave probe 4 for receiving longitudinal waves are longitudinal wave piezoelectric contact probes, using rectangular composite material piezoelectric chips, the bottom surface of the probe is a flat rectangle, the probe is designed as a narrow strip, and the angle of longitudinal wave emission can be adjusted between 0° and 90°.

[0055] In a more preferred embodiment, the ultrasonic pulse generator-receiver is a pulse generator-receiver with negative square wave excitation, adjustable square wave amplitude and width, low noise response, and adjustable gain. Its transmitting circuit is composed of a high-performance square wave pulse generator and a high-voltage circuit, and the receiving circuit has the characteristics of low noise and wide bandwidth, thereby ensuring the quality of ultrasonic generation and receiving signals.

[0056] In a more preferred embodiment, the oscilloscope 2 is a four-channel high-performance digital storage oscilloscope with a bandwidth of 100 MHz, a maximum sampling rate of 2.5 GS / s, and high input impedance, which displays the received ultrasonic signal in real time.

[0057] In a more preferred embodiment, the probe connecting line 9 is a signal line that matches the ultrasonic pulse generator receiver and the variable-angle longitudinal wave ultrasonic probe that transmits longitudinal waves or receives longitudinal waves. It has the characteristics of low noise and strong anti-interference ability, ensuring that the output electrical signal of the ultrasonic pulse generator receiver can be received by the variable-angle longitudinal wave probe with high quality. At the same time, it ensures that the electrical signal converted from the ultrasonic signal received by the variable-angle longitudinal wave probe is returned to the receiving end of the ultrasonic pulse generator receiver with high quality.

[0058] In a more preferred embodiment, the signal transmission line 5 is a transmission line with a stray inductance less than 1mH and a resistance less than 5mΩ, which shortens the phase delay of the high-frequency signal during the transmission process, ensures that the electrical signal received by the oscilloscope and the electrical signal at the signal output end of the ultrasonic pulse generator and receiver are at the same potential and phase in real time, greatly reduces the detection error, and ensures the detection accuracy.

[0059] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials, characterized in that: The specific steps include: (1) placing a gasket between two standard specimens, the two standard specimens clamping the gasket, the two standard specimens and the gasket being both epoxy composite materials; (2) fixing a variable angle longitudinal wave probe for transmitting longitudinal waves on the surface of one of the standard samples, and fixing a variable angle longitudinal wave probe for receiving longitudinal waves on the same surface of another standard sample; (3) moving the gasket downward to obtain ultrasonic longitudinal wave waveform information, and obtaining the corresponding position of the gasket when the ultrasonic longitudinal wave waveform information disappears; (4) obtaining the distance between the upper end of the gasket and the upper surfaces of the two standard specimens at the corresponding position of the gasket when the ultrasonic longitudinal wave waveform information disappears, which is the maximum propagation depth of the ultrasonic longitudinal wave in the epoxy composite material; (5) Replace the probe with a different frequency and repeat steps (2) to (4); The casting process of the gasket and the two standard samples is the same.

2. A method and system for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials according to claim 1, characterized in that: Placing the gasket between two standard specimens, wherein the two standard specimens clamp the gasket, specifically comprises: The upper end of the gasket is at the same height plane as the upper surfaces of the two standard specimens.

3. The method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials according to claim 1, characterized in that: Fixing an ultrasonic longitudinal wave transmitting probe and an ultrasonic longitudinal wave receiving probe on the two standard samples specifically includes: The ultrasonic longitudinal wave transmitting probe and the ultrasonic longitudinal wave receiving probe located on the same side are fixed to the surface of the standard sample by using adhesive tape.

4. The method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials according to claim 1, characterized in that: The step of moving the gasket downwards specifically includes: The gasket extends out of the standard sample, and the extended portion of the gasket is manually controlled to make the gasket move vertically slowly between the standard samples.

5. The method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials according to claim 4, characterized in that: The obtaining of the distance between the upper end of the gasket and the upper surfaces of the two standard specimens specifically includes: At the corresponding position of the gasket when the ultrasonic longitudinal wave waveform information disappears, the distance between the upper surface of the gasket and the upper surfaces of the two standard specimens is measured, which is the maximum propagation depth of the ultrasonic longitudinal wave in the epoxy composite material corresponding to the frequency of the ultrasonic longitudinal wave probe.

6. The method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials according to claim 5, characterized in that: Coupling agent is applied between the ultrasonic longitudinal wave probe and the two standard samples, and between the two standard samples and the gasket.

7. A system for implementing the method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials according to any one of claims 1 to 6, characterized in that: include: A variable angle longitudinal wave probe for transmitting longitudinal waves, a variable angle longitudinal wave probe for receiving longitudinal waves, a probe connecting line, an ultrasonic pulse generator and receiver, a signal transmission line, and an oscilloscope; One end of the probe connecting line is connected to the variable angle ultrasonic probe that transmits longitudinal waves, and the other end is connected to the output end of the ultrasonic pulse generator receiver; one end of another probe connecting line is connected to the variable angle ultrasonic probe that receives longitudinal waves, and the other end is connected to the receiving end of the ultrasonic pulse generator receiver; one end of the signal transmission line is connected to the synchronization end of the ultrasonic pulse generator receiver, and the other end is connected to the oscilloscope.

8. The system of the method for measuring the propagation depth of ultrasonic longitudinal waves in epoxy composite materials according to claim 7, characterized in that: It also includes a computer for acquiring ultrasonic longitudinal wave waveform data information, performing data processing, and accurately acquiring the moment when the waveform disappears.

9. The system of claim 8, wherein: The variable angle longitudinal wave probe for transmitting longitudinal waves and the variable angle longitudinal wave probe for receiving longitudinal waves are longitudinal wave piezoelectric contact probes, which use rectangular composite material piezoelectric wafers, the bottom surface of the probe is a flat rectangle, the probe is designed as a narrow strip, and the longitudinal wave emission angle can be adjusted between 0° and 90°; The ultrasonic pulse generator receiver is a pulse generator receiver with negative square wave excitation, adjustable square wave amplitude and width, low noise response, and adjustable gain; The oscilloscope is a four-channel high-performance digital storage oscilloscope with a bandwidth of 100MHz, a maximum sampling rate of 2.5GS / s, and high input impedance; The probe connection line is a signal line that matches the ultrasonic pulse generator and receiver with the variable angle longitudinal wave ultrasonic probe that transmits longitudinal waves or receives longitudinal waves; The signal transmission line is a transmission line with a stray inductance less than 1 mH and a resistance less than 5 mΩ.

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