GB2599644A

GB2599644A - Transducer for ultrasonic testing

Info

Publication number: GB2599644A
Application number: GB2015713.7A
Authority: GB
Inventors: Costello Laurie
Original assignee: Creid 7 Ltd
Current assignee: Creid 7 Ltd
Priority date: 2020-10-05
Filing date: 2020-10-05
Publication date: 2022-04-13
Also published as: WO2022074365A1; GB202015713D0

Abstract

The arrangement comprises an ultrasonic transducer 20 adapted to emit ultrasonic waves and/or to receive ultrasonic waves, a chamber housing 30 coupled to the transducer which when the transducer device is placed in contact with the material under investigation defines an exposed area of the material under investigation; and a sealing device 40 interposing the chamber housing and the material under investigation. The chamber housing, sealing device and the exposed area of the material under investigation define a sealed chamber for receiving a coupling fluid 102. The chamber housing 30 may be attached to a rigid scanning frame.

Description

Transducer for Ultrasonic Testing The present invention relates to sensors and transducers used in ultrasonic testing. In particular, but not exclusively, the present invention relates to sensors and transducers used in ultrasonic reflectometry.

In ultrasonic reflectometry (UR), a transducer generates ultrasonic waves which typically propagate through a fluid and then through a material which is being investigated. The waves propagate through the material until they reach an interface in the material. The wave is partially reflected at the interface and partially transmitted onwards. The reflected waves travel back to the transducer via the fluid, then properties of the material can be determined by measuring the amplitude and/or the time of flight of the reflected waves. Typically, the acoustic impedance of the fluid is matched to that of the material under investigation.

There are many practical applications of UR. The most common engineering application is non-destructive testing. However, UR can also be employed to investigate the interface between two surfaces. The closer the impedance matching and/or the greater the contact area, the better that ultrasonic waves are transmitted from one surface to the other. Indeed, the degree of wave transmission can even be used to determine the contact pressure at the interface of the two surfaces.

Known transducers for UR typically include a membrane or bladder that is filled with the fluid in the form of water (often with an additive) to improve the signal transmission into the material body. The membrane, when placed in contact with the material under investigation, provides a contact surface but this constitutes an additional interface which could cause reflection of ultrasonic waves. Furthermore, as the thickness of the material under investigation increases, there is a point where the second reflection from the interface and the first reflection from the back wall of the material overlap. This represents a limitation of existing devices. An example of this type of transducer is a wheel probe which allows rolling contact of the transducer with a surface. The membrane of this transducer is similar to a tyre. Another example is a wedge probe which includes a trapezoidal shaped membrane.

Typically, known UR methods involve using a form of couplant to effectively fill the air gap between the contact surface of the transducer device and the material under investigation. This is to avoid a large portion of the signal being reflected at the contact surface interface and not transmitted as intended. The couplant may be a water spray or more viscous water and oil based gels. However, the couplant can dry out or change constituency through time, which may impact the signal and the repeatability of the measurement.

According to a first aspect of the present invention there is provided an ultrasonic transducer device comprising: a transducer adapted to emit ultrasonic waves and/or to receive ultrasonic waves; a chamber housing coupled to the transducer and having a first opening 15 which, when the transducer device is placed in contact with the material under investigation, defines an exposed area of the material under investigation; and a sealing device interposing the chamber housing and the material under investigation, wherein the chamber housing, sealing device and the exposed area of the material under investigation define a sealed chamber for receiving a fluid.

Optionally, the chamber housing includes one or more side walls for partly defining the chamber.

Optionally, the chamber housing has a second opening for mounting the transducer.

Optionally, the second opening is at an opposite end of the chamber housing to the first opening.

The chamber housing may be substantially tubular.

The orientation of the transducer relative to the chamber housing may be variable to allow the emitting of ultrasonic waves at variable angle relative to the material under investigation.

The chamber housing may be conical or frusto-conical.

The sealing device may be formed from a gel or another semi-solid material.

The sealing device may be adapted to adhere to the material under investigation.

Alternatively, the sealing device may be sealingly attached to the material under investigation, such as using an adhesive.

The sealing device may be formed from a viscoelastic material.

The transducer device may include a plurality of transducers which are coupled to the chamber housing.

Optionally, the transducer device includes pressure reducing means for reducing the internal pressure of the chamber.

Optionally, the pressure reducing means comprises a vacuum pump or the like.

Optionally, the transducer device includes a scanning frame comprising one or more rigid support members.

Optionally, the scanning frame, when placed in contact with the material under investigation, is adapted to maintain a consistent distance between the transducer and the material under investigation.

The transducer device may be in the form of a pipe clamp for UR investigation of a pipe, pipe coupling or the like.

According to a second aspect of the present invention there is provided a method of performing ultrasonic measurement, the method comprising: providing a transducer device comprising: a transducer adapted to emit ultrasonic waves and/or to receive ultrasonic waves; a chamber housing coupled to the transducer and having a first opening which, when the transducer device is placed in contact with the material under investigation, defines an exposed area of the material under investigation; and a sealing device interposing the chamber housing and the material under investigation; placing the sealing device in contact with a material under investigation such 10 that the chamber housing, sealing device and the exposed area of the material under investigation define a sealed chamber for receiving a fluid; filling the chamber with a fluid.

Optionally, the method includes mounting the transducer to the chamber housing such that the orientation of the transducer relative to the chamber housing can be varied to allow the emitting of ultrasonic waves at variable angle relative to the material under investigation.

Optionally, the method includes forming the sealing device from a gel or another semi-solid material.

Optionally, the method includes adapting the sealing device to adhere to the material under investigation.

Alternatively, the method may include sealingly attaching the sealing device to the material under investigation, such as by using an adhesive.

Optionally, the method includes reducing the internal pressure of the chamber.

Optionally, the method includes using a scanning frame to maintain a consistent distance between the transducer and the material under investigation.

The invention will be described below, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of (a) a wheel probe and (b) a wedge probe in accordance

s with the prior art;

Figure 2 is a sectional side view of a transducer device in accordance with a first embodiment of the invention; Figure 3 is a sectional side view of the transducer device of Figure 2 with the transducer orientated at an oblique angle; Figure 4 is a side view of the transducer device of Figure 2 on an uneven surface; Figure 5 is a side view of the transducer device of Figure 2 and including a scanning frame; and Figure 6 is a side view of a transducer device in accordance with a second embodiment of the invention.

Figure 1 shows examples of prior art transducer devices. Figure 1 (a) shows a wheel probe 110 in which a centrally located transducer 112 is surrounded by a circular membrane 114 filled with fluid. The transducer 112 emits ultrasonic waves through the fluid 102 and then the membrane 114 and then into a material 100 under investigation and receives reflected ultrasonic waves. The membrane 114 can rotate relative to the transducer 112. This provides rolling contact of the wheel probe 110 with the surface of the material 100, which in this case is a circular surface such as that of a pipe.

Figure 1 (b) shows a wedge probe 120. A transducer 122 is mounted to a trapezoidal shaped membrane 124 filled with fluid 102. The orientation of the transducer 122 is adjustable and the shape of the membrane 124 allows ultrasonic waves to be emitted at an oblique angle to the plane of the material 100.

Figure 2 shows an ultrasonic transducer device 10 according to a first aspect of the invention. The device 10 includes an active transducer 20 which is adapted to emit ultrasonic waves and to receive reflected ultrasonic waves. However, the invention may also relate to passive transducers. Also, although one one transducer is shown, the device could include a number of sensors (some of which may be passive and some of which may be active).

The device 10 also includes a chamber housing 30. The housing 30 is tubular and conical, having a small opening 32 for mounting the transducer 20 at one end and another, larger, opening 34 at the other end. Located at this opening 34 is an annular sealing device 40. When the transducer device 10 is placed in contact with a material 100 under investigation, this defines an exposed area of the material 100. With the sealing device 40 contacting the material 100 at the boundary of the area.

The chamber housing 30, sealing device 40 and the exposed area of the material 100 define a sealed chamber for receiving a fluid 102.

The sealing device 40 is formed from a viscoelastic gel and is adapted to adhere to the material 100 to create a seal between the sealing device 40 and the material 100. An example material for this gel is Raytech Magic GeITM. Other examples include!so GeITM and Gurosil GeITM. These low viscosity and high dielectric materials are conventionally used primarily at sealants in electrical connectors and cables.

The mounting of the transducer 20 to the opening 32 is such that the orientation of the transducer 20 relative to the chamber housing 30 is variable. This allows the emitting of ultrasonic waves at variable angle relative to the plane of the material 100. The conical shape of the chamber housing 30 facilitates more oblique angle. Figure 3 shows the device with the transducer 20 at an oblique angle.

The chamber housing 30 includes a fluid inlet 50 and an air vent 52. Once the device has been placed in contact with the material 100 and the sealed chamber formed, the chamber is filled with fluid which enters at the fluid inlet 50. The air in the chamber is evacuated via the air vent 52.

The transducer device 10 includes pressure reducing means in the form of a vacuum pump (not shown) for reducing the internal pressure of the chamber. This promotes adherence of the device 10 to the material 100 as well as helping to maintain the seal to prevent fluid leaking from the chamber.

Before setting, the viscous nature of the material of the sealing device 40 allows it to flow and take up the contours of the material 100 under investigation. This means that the sealing device material is highly advantageous when the device 10 is being used to investigate materials with highly irregular surfaces. This is shown in Figure 4.

Although the material of the sealing device 40 adheres to the material 100 under investigation, it does not permanently bond to it. If it is desirable to move the device 10 to a new location to investigate a different portion of the material 100, this can be done. The device can be pulled upwards (which stretches the material of the sealing device 40) and then slid laterally to the new location.

It is common to carry out repeated measurements on the same material 100. It is zo desirable that all the measurements are performed in a consistent manner. To assist with this, the transducer device 10 includes a scanning frame 60 as shown in Figure 5. The frame 60 comprises a number of rigid support members 62 which are also placed in contact with the material 100. The transducer 20 is coupled to the frame 60. This ensures that a consistent distance between the transducer and the material 100 is maintained.

The coupling of the transducer 20 to the frame can be motorised for precise adjustment of the orientation of the transducer 20. Also, the adjustment of the transducer 20 can be automated to perform a predetermined scanning pattern.

Figure 6 shows a second embodiment of the invention and like features are given like reference numbers.

In this embodiment, the transducer device 10 is in the form of a pipe clamp for UR investigation of a pipe, pipe coupling or the like. The device 10 encircles the pipe. However, as before, a sealed chamber is created and acoustic waves are transmitted through the fluid and directly into the material of the pipe (without passing through an additional membrane). Furthermore, there is no requirement to use an additional couplant which can dry out.

Pipework, pipe coupling and so on typically are provided in standard sizes. Different variations of the device of this embodiment can be provided which accommodate these different standard sizes.

Figure 6 shows only one transducer 20. This allows a measurement at one circumferential location. In other embodiments, the device 10 can include multiple transducers 20 to allow simultaneous measurement at multiple circumferential locations.

Alternatively, as with the first embodiment of the invention, it is possible to move the device 10 to a new location. This can be by rotating the device 10 about the longitudinal axis of the pipe or coupling. This can be done multiple times to effectively investigate the full circumference of the pipe or coupling. The device can also be moved longitudinally to investigate different longitudinal sections of the pipe or coupling.

Various modifications and improvements can be made to the above without departing from the scope of the invention.

Claims

CLAIMS1. An ultrasonic transducer device comprising: a transducer adapted to emit ultrasonic waves and/or to receive ultrasonic waves; a chamber housing coupled to the transducer and having a first opening which, when the transducer device is placed in contact with the material under investigation, defines an exposed area of the material under investigation; and a sealing device interposing the chamber housing and the material under investigation, wherein the chamber housing, sealing device and the exposed area of the material under investigation define a sealed chamber for receiving a fluid.
2. A device as claimed in Claim 1, wherein the chamber housing includes one or more side walls for partly defining the chamber.
3. A device as claimed in Claim 1 or 2, wherein the chamber housing has a second opening for mounting the transducer.
4. A device as claimed in Claim 3, wherein the second opening is at an opposite end of the chamber housing to the first opening.
5. A device as claimed in any preceding claim, wherein the chamber housing is substantially tubular.
6. A device as claimed in any preceding claim, wherein the orientation of the transducer relative to the chamber housing is variable to allow the emitting of ultrasonic waves at variable angle relative to the material under investigation.
7. A device as claimed in any preceding claim, including a plurality of transducers which are coupled to the chamber housing.
8. A device as claimed in any preceding claim, wherein the chamber housing is conical or frusto-conical.
9. A device as claimed in any preceding claim, wherein the sealing device is formed from a gel or another semi-solid material.
10. A device as claimed in any preceding claim, wherein the sealing device is adapted to adhere to the material under investigation.
11. A device as claimed in any preceding claim, wherein the sealing device is formed from a viscoelastic material.
12. A device as claimed in any preceding claim, including pressure reducing means for reducing the internal pressure of the chamber.
13. A device as claimed in Claim 12, wherein the pressure reducing means 15 comprises a vacuum pump.
14. A device as claimed in any preceding claim, wherein the transducer device includes a scanning frame comprising one or more rigid support members.
15. A device as claimed in Claim 14, wherein the scanning frame, when placed in contact with the material under investigation, is adapted to maintain a consistent distance between the transducer and the material under investigation.
16. A device as claimed in any preceding claim, wherein the transducer device is in the form of a pipe clamp for UR investigation of a pipe or a pipe coupling
17. A method of performing ultrasonic measurement, the method comprising: providing a transducer device comprising: a transducer adapted to emit ultrasonic waves and/or to receive ultrasonic waves; a chamber housing coupled to the transducer and having a first opening which, when the transducer device is placed in contact with the material under investigation, defines an exposed area of the material under investigation; and a sealing device interposing the chamber housing and the material under investigation; placing the sealing device in contact with a material under investigation such that the chamber housing, sealing device and the exposed area of the material under investigation define a sealed chamber for receiving a fluid; filling the chamber with a fluid.
18. A method as claimed in Claim 17, including mounting the transducer to the chamber housing such that the orientation of the transducer relative to the chamber housing can be varied to allow the emitting of ultrasonic waves at variable angle relative to the material under investigation.
19. A method as claimed in Claim 17 or 18, including forming the sealing device from a gel or another semi-solid material.
20. A method as claimed in any of Claims 17 to 19, including adapting the sealing device to adhere to the material under investigation.
21. A method as claimed in any of Claims 17 to 20, including reducing the internal pressure of the chamber.
22. A method as claimed in any of Claims 17 to 21, including using a scanning zo frame to maintain a consistent distance between the transducer and the material under investigation.