阅读说明：本技术 用于无损测试的布置及其测试方法 (Arrangement for non-destructive testing and testing method thereof ) 是由 范峥 丹尼洛·里瑟维奇 余旭东 于 2019-02-01 设计创作，主要内容包括：一种用于组件部件的无损测试的布置,该布置可包括第一端面和第二相对端面。该布置可包括：多个分立压电换能元件,按照圆形阵列来布置在第一端面上；以及电波信号发射和接收单元,电耦合到压电换能元件。电波信号发射和接收单元可以能够生成电激励波信号,并且接收电响应波信号。压电换能元件可在电激励波信号施加时以与第一端面平行的同相剪切运动并且以相对圆形阵列的相应切线方向变形,以便在组件部件中在组件部件的第一端面生成对应结构承载波,使得所述结构承载波能够在组件部件中传播。(An arrangement for non-destructive testing of a component part may include a first end face and a second opposing end face. The arrangement may include: a plurality of discrete piezoelectric transducing elements arranged in a circular array on the first end face; and an electric wave signal transmitting and receiving unit electrically coupled to the piezoelectric transducing element. The electric wave signal transmission and reception unit may be capable of generating an electric excitation wave signal and receiving an electric response wave signal. The piezoelectric transducing element is deformable upon application of an electrical excitation signal with an in-phase shear motion parallel to the first end face and with a respective tangential direction relative to the circular array so as to generate a corresponding structural carrier wave in the assembly member at the first end face of the assembly member such that the structural carrier wave is capable of propagating in the assembly member.)

1. An arrangement for non-destructive testing of a component part, the arrangement comprising:

the component part to be tested comprises a first end face and a second end face opposite to the first end face;

a plurality of discrete piezoelectric transducing elements arranged in a circular array on said first end face of said assembly member; and

an electrical wave signal transmitting and receiving unit electrically coupled to the plurality of discrete piezoelectric transducing elements and capable of generating and applying an electrical excitation wave signal to the piezoelectric transducing elements and capable of receiving an electrical response wave signal from the piezoelectric transducing elements and processing the electrical response wave signal,

wherein the piezoelectric transducing elements are configured and arranged to deform in-phase shear motion parallel to the first end face and in respective tangential directions relative to the circular array upon application of the electrical excitation wave signal so as to generate in the assembly component a corresponding structural carrier wave at the first end face of the assembly component such that the structural carrier wave can propagate from the first end face to the second end face for reflection by the second end face and return from the second end face to the first end face as a response wave which can be received by the piezoelectric transducing elements and correspondingly converted into the electrical response wave signal for reception and processing by the electrical wave signal transmission and reception unit.

2. The arrangement of claim 1, wherein said electrical wave signal transmission and reception unit is configured to generate said electrical excitation wave signal having a frequency such that the correspondingly created structural carrier wave is an ultrasonic wave.

3. The arrangement of claim 1 or 2, wherein the piezoelectric transducing elements each comprise a mating surface, and the electrical excitation signal is applied in a direction perpendicular to the mating surfaces via a corresponding electrical potential across the respective piezoelectric transducing element so as to deform the respective piezoelectric transducing element in a respective shear motion, wherein the mating surfaces are in contact with the first end face of the assembly component.

4. An arrangement according to claim 3, wherein said piezoelectric transducing elements each comprise at least one pair of planar electrodes to receive said electrical potential, one of said planar electrodes being provided on said mating surface and a second of said planar electrodes being provided on the other surface of said respective piezoelectric transducing element opposite said mating surface.

5. The arrangement of claim 3 or 4, wherein the mating surface of the respective piezoelectric transducing element is parallel to the first end face of the assembly component.

6. The arrangement according to any one of claims 1 to 5, wherein the plurality of discrete piezoelectric transducing elements are coupled electrically in parallel with each other so as to be collectively deformed in a synchronized manner upon application of the electrical excitation wave signal.

7. The arrangement of any one of claims 1 to 6, wherein the piezoelectric transducing element is coupled to the first end face of the assembly component via an adhesive or bonding or mechanical fixation together with application of an ultrasound transmissive couplant therebetween.

8. The arrangement of any one of claims 1 to 7, wherein the piezoelectric transducing elements are each trapezoidal shaped piezoelectric transducing elements, and wherein the respective trapezoidal shaped piezoelectric transducing elements are oriented with their respective shorter bases pointing towards the center of the circular array.

9. The arrangement of claim 8, wherein the first end face of the assembly member includes an annularly shaped surface.

10. The arrangement according to claim 9, wherein a ratio of a perpendicular distance between the shorter and longer bases of the respective trapezoidal shaped piezoelectric transduction elements to a difference between a radius of an outer circumference of the ring shaped surface and a radius of an inner circumference of the ring shaped surface is between 0.8 and 0.9.

11. The arrangement according to claim 10, wherein the length of the longer base of the respective trapezoidal shape piezoelectric transducing element is obtained via the pythagoras theorem using the radius of the outer circumference of the ring shape surface as an oblique side, the sum of the perpendicular distance of the respective trapezoidal shape transducing element as a first side and the radius of the inner circumference of the ring shape surface, and half the length of the longer base of the respective trapezoidal shape transducing element as a second side.

12. The arrangement of claim 11, wherein the sum of the lengths of the shorter bases of all the trapezoidal shape piezoelectric transducing elements is smaller than a reference circumference, and the sum of the lengths of the longer bases of all the trapezoidal shape piezoelectric transducing elements is larger than the reference circumference, and wherein the radius of the reference circumference is half of the sum of the radius of the inner circumference of the ring shape surface and the radius of the outer circumference of the ring shape surface.

13. The arrangement of any one of claims 1 to 12, wherein the assembly component comprises a solid cylinder.

14. The arrangement of any one of claims 1 to 13, wherein the arrangement forms a structural connection assembly, wherein the assembly component is an elongate component, optionally a bolt, the component extending along a longitudinal axis, and wherein the first and second end faces are formed by first and second axial end faces of the elongate component.

15. A non-destructive testing method, comprising:

arranging a plurality of discrete piezoelectric transduction elements in a circular array on a first end face of a cylindrical assembly component to be tested, the cylindrical assembly component including a first end face and a second end face opposite the first end face; and

operating an electrical wave signal transmitting and receiving unit electrically coupled to the plurality of discrete piezoelectric transducing elements to generate an electrical excitation wave signal and applying the electrical excitation wave signal to the piezoelectric transducing elements in a manner causing the piezoelectric transducing elements to move in phase shear motion parallel to the first end face and to deform in respective tangential directions relative to the circular array so as to generate in the assembly component a corresponding structural carrier wave at the first end face of the assembly component such that the structural carrier wave is capable of propagating from the first end face to the second end face for reflection by the second end face and returning as a response wave from the second end face back to the first end face, the response wave being capable of being received by the piezoelectric transducing elements and correspondingly converted into the electrical response wave signal for reception and processing by the electrical wave signal transmitting and receiving unit, wherein the structural carrier wave is generated in the form of a fundamental torsional guided wave.

16. The non-destructive testing method of claim 15, wherein the electrical excitation signal has a frequency such that the correspondingly created structural carrier wave is an ultrasonic guided wave.

17. The nondestructive testing method according to claim 15 or 16, further comprising determining, via the electric wave signal transmitting and receiving unit, a position of a defect along the length of the cylindrical component part based on an elapsed time of a corresponding response wave of the defect.

Technical Field

Various embodiments are generally directed to an arrangement for non-destructive testing and a method of non-destructive testing. In particular, various embodiments relate generally to arrangements for non-destructive testing and methods of non-destructive testing of component parts (e.g., structural bolts).

Background

Bolted joints are one of the most common connecting elements used in engineering structural applications, primarily providing structural continuity and transfer of internal loads from one component to another. Due to their widespread use in the industry, bolt types, material choices, dimensions and other specifications have been documented in various international standards. However, under fluctuating load conditions, structural bolts are susceptible to fatigue failure. Cracks can initiate in high stress areas of the bolt and can grow to critical sizes that withstand sustained cyclic loading, causing complete separation of the fastening structural components. Furthermore, in bolted joints comprising a plurality of bolts, once one of them fails, the remaining bolts must withstand a redistribution load during their service life, wherein fatigue cracking can easily be introduced further. It is therefore essential to periodically monitor the health of bolts during service use in order to detect them in time in the event that cracking or corrosion may propagate deep in the material and ultimately lead to catastrophic failure of the entire structure.

Typical non-destructive testing (NDT) methods of inspecting structural bolts include magnetic particle inspection, dye penetrant, radiography, eddy current, and ultrasonic testing. These approaches can be adapted to identify defects in the bolt that may occur during the manufacturing process or during use in service.

In the magnetic particle test, a test specimen must be magnetized, and magnetic particles in dry or wet suspension form are then applied to the surface of the bolt. Due to the leakage of magnetic flux at the discontinuity of the structure, powder particles will accumulate in the defect region, thus forming a visual indication. This technique is easy to implement and has high sensitivity to even very small defects, but is only applicable to ferromagnetic materials and can only detect surface and subsurface defects. Dye penetrants are another economical method of bolt inspection, where the entire surface of the test assembly will be covered with penetrants. At sufficient dwell time, excess penetrant is removed, and then developer is applied, so that the defect indication is visible to the inspector under ultraviolet or white light. This approach may be applicable to all non-ferrous and ferrous materials, but only to surface fracture defects. In addition, performing tests on rough surfaces (e.g., threads) or on porous materials would make it difficult to remove any excess penetrant and may cause false damage indications. However, these two low cost but effective NDT techniques require direct access to the entire bolt structure. Thus, they can only be used for in-process control and end-product inspection, but are difficult to use for in-service maintenance as field inspections because installed bolts cannot be frequently removed from the joint structure to provide the required reveal. Other NDT methods (e.g., radiography and eddy current testing) are also time consuming and costly for such field inspection of bolted joints.

Among the available NDT techniques, conventional ultrasonic testing methods may be most suitable for bolt inspection during in-service use because they are portable, free of removing bolts from installed locations, and have high penetration depth and good sensitivity to small defects. The test may be performed with a single transducer in pulse-echo mode or with two transducers in transmission mode. Typically, an ultrasonic transducer is placed in direct contact with one end of the bolt, and the transmitted ultrasonic waves propagate along the bolt. A defect occurring in the propagation path will act as a reflector reflecting a part of the energy propagating in the medium and the location of the defect can be determined by the arrival time of the reflected wave and the wave speed in the material.

Conventional ultrasonic testing is based on local inspection and can only inspect a single row along the axis of the bolt, which requires scanning the transducer point by point across the bolt end in order to achieve sufficient coverage of the region of interest. Thus, such tests are time consuming and tedious for damage detection, and interpretation of the received signals has proven difficult in the presence of geometric echoes (e.g., bolt threads, back wall), mode transitions, and reflections by cracks. However, conventional ultrasonic testing can provide sufficient accuracy in measuring bolt length.

In recent years, advanced ultrasound phased array technology has also been used in bolt inspection, where an array probe (with or without a normal beam wedge coupled) is mounted in a custom fixture on the bolt head, and a small angle sector scan (also referred to as an azimuth scan or a sweep scan) is performed to obtain structural information in the beam plane. The coded rotation of the probe is then applied to cover the entire circumference of the bolt. Coded phased array testing can provide increased detectability compared to conventional ultrasonic testing, but its performance is inadequate when long bolts are encountered, where a larger beam steering angle would be required for full length coverage.

Accordingly, there is a need for a more practical and efficient arrangement for non-destructive testing and a non-destructive testing method.

Disclosure of Invention

According to various embodiments, an arrangement for non-destructive testing of a component part is provided. The arrangement may include a component part to be tested, which may include a first end face and a second end face opposite the first end face. The arrangement may further comprise a plurality of discrete piezoelectric transducing elements arranged in a circular array on the first end face of the assembly member. The arrangement may further comprise an electrical wave signal transmitting and receiving unit electrically coupled to the plurality of discrete piezoelectric transducing elements. The electric wave signal transmission and reception unit may be capable of generating an electric excitation wave signal and applying the electric excitation wave signal to the piezoelectric transducing element. The electric wave signal transmission and reception unit may be capable of receiving the electric response wave signal from the piezoelectric transducing element and processing the electric response wave signal. According to various embodiments, the piezoelectric transducing element may be configured and arranged to deform in-phase shear motion parallel to the first end face and in respective tangential directions relative to the circular array upon application of the electrical excitation wave signal so as to generate in the assembly member a corresponding structural carrier at the first end face of the assembly member such that the structural carrier is capable of propagating from the first end face to the second end face so as to be reflected by the second end face and returning as a response wave from the second end face to the first end face. The response wave can be received by the piezoelectric transducing element and correspondingly converted into an electrical response wave signal for reception and processing by the electrical wave signal transmitting and receiving unit.

According to various embodiments, a non-destructive testing method is provided. The method may include arranging a plurality of discrete piezoelectric transducing elements in a circular array on a first end face of a cylindrical component part to be tested. The cylindrical component part to be tested may include a first end surface and a second end surface opposite to the first end surface. The method may further comprise operating an electrical wave signal transmission and reception unit (which is electrically coupled to the plurality of discrete piezoelectric transducing elements) to generate an electrical excitation signal and apply said electrical excitation signal to the piezoelectric transducing elements by deforming the piezoelectric transducing elements with in-phase shear motion parallel to the first end face and with respective tangential directions relative to the circular array so as to generate in the component part corresponding structural bearers at the first end face of the component part such that said structural bearers can propagate from the first end face to the second end face for reflection by the second end face and return as a response wave from the second end face to the first end face. The response wave can be received by the piezoelectric transducing element and correspondingly converted into an electrical response wave signal for reception and processing by the electrical wave signal transmitting and receiving unit. The structural carrier wave may take the form of a fundamental torsional guided wave.

Drawings

In the drawings, like reference numerals generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments are described with reference to the following drawings, in which:

FIGS. 1A and 1B show dispersion curves for guided modes in a cylindrical rod waveguide, where the phase or group velocity of the modes is a function of the product of frequency and radius;

FIGS. 2A and 2B illustrate an arrangement of piezoelectric transducing elements on a component of an assembly, in accordance with various embodiments;

FIG. 2C schematically illustrates an arrangement for non-destructive testing of component parts, in accordance with various embodiments;

FIG. 3 illustrates a poled piezoelectric ceramic plate having electrodes on a top surface and a bottom surface, in accordance with various embodiments;

fig. 4A and 4B illustrate the configuration and size of a trapezoidal-shaped piezoelectric transduction element used in various embodiments;

FIG. 5A illustrates example inspection data from an original bolt using the arrangement of FIG. 2C, in accordance with various embodiments; and

fig. 5B illustrates example inspection data from a damaged bolt using the arrangement of fig. 2C, in accordance with various embodiments.

Detailed Description

The embodiments described below in the context of the apparatus are similarly valid for the respective methods, and vice versa. Further, it will be understood that the embodiments described below may be combined, e.g., a portion of one embodiment may be combined with a portion of another embodiment.

It will be understood that the terms "upper", "above", "top", "bottom", "lower", "side", "rear", "left", "right", "front", "lateral", "side", "up", "down", and the like, when used in the following description, are used for convenience and to aid in the understanding of the relative position or orientation, and are not intended to limit the orientation of any device or structure or any portion of any device or structure. In addition, the singular terms "a", "an", and "the" include plural references unless the context clearly dictates otherwise. Similarly, the word "or" is intended to include "and" unless the context clearly indicates otherwise.

Various embodiments are generally directed to an arrangement for non-destructive testing and a method of non-destructive testing. In particular, various embodiments relate generally to arrangements for non-destructive testing and methods of non-destructive testing of component parts (e.g., structural bolts). The assembly member may be a structural assembly member. According to various embodiments, an arrangement and method for non-destructive testing (NDT) of component parts (e.g., structural bolts) using ultrasonic guided waves is provided.

According to various embodiments, ultrasonic guided wave testing can be a valid alternative to field inspection of component parts (e.g., long structural bolts) because it can potentially allow rapid screening for effective distances from fixed transducers and remote inspection of difficult to acquire structures. It may achieve 100% thickness coverage of the waveguide (e.g., assembly component) and thus may be able to detect primary detection occurring anywhere in the structure (e.g., assembly component). There has been successful commercial deployment of guided waves for remote inspection of pipelines and tracks, although such guided wave techniques have not been commercialized for bolt inspection (or inspection of component parts). This may be due to the limited transducer position (or limited area of the end face of the component part) provided by the bolt head and legs (e.g. socket head bolts), which is detrimental to the efficient generation of guided wave modes. More importantly, the main problems to be overcome are dispersion and the presence of multiple modes in the guided wave. The guided wave is generally dispersive, meaning that its phase or group velocity changes with frequency. The phase velocity of the guided waves represents the rate at which the individual vertices of the wave move, while the group velocity describes the propagation velocity of a guided wave packet (or envelope) having components of similar frequency. Fig. 1A and 1B show dispersion curves for guided modes in a cylindrical rod waveguide (or cylinder or cylindrical structure) where the phase or group velocity of the mode is a function of the product of frequency and radius. Dispersion curves can be used to predict the extent to which dispersion will occur for a given wavelength division group. Any excitation wave of a finite time period has a certain frequency bandwidth and each frequency component in a wave packet may propagate at a different group velocity. If the difference in velocity is large for the frequency range of interest, different frequency components may arrive at different times, which will cause distortion in the shape of the wave packet as it propagates. In contrast, if the group velocity is very close to the generated frequency range, the wave packet may remain similarly shaped throughout its propagation.

In practical remote non-destructive testing (NDT)/Structural Health Monitoring (SHM) applications, the advantageous steering modes should be minimally dispersive, so that interpretation of the detected signal can be simpler. Guided waves in cylindrical systems can be classified into three types of modes according to the wave structure. The longitudinal (L) mode is a longitudinal axisymmetric mode; the torsional (T) mode has primarily circumferential particle displacement; the flexural (F) mode is a non-axisymmetric bending mode. Among these modes, the fundamental torsional guided wave mode T (0,1) is completely non-dispersive, which makes post-processing of the signal less complex than other dispersive modes. At the same time, there is only one torsional axisymmetric mode at low frequencies, making transduction less complex than L or F modes, where the transducer system must be carefully designed to suppress unwanted concurrent excitation of other modes in the same wave series.

For the reasons described above, various embodiments can use fundamental torsional guided waves to detect damage in component parts (e.g., long structural bolts, etc.).

Various embodiments may be particularly useful for field damage detection in installed assembly components (e.g., structural bolts), which may require access to only one end of the bolt for transduction, and may eliminate the need to disassemble the bolt from the fastener joint.

Various embodiments may be particularly well suited for remote inspection of assembly components (e.g., bolts). According to various embodiments, the transmitted guided wave itself may be able to propagate a significant distance in the assembly component (e.g., bolt), thereby achieving complete coverage of the entire assembly component such that major defects occurring anywhere in the assembly component may be detected.

Further, in various embodiments, an ultrasonic transducer (which may include an ultrasonic sensor or a piezoelectric transducing element) may be permanently attached to the end of the assembly component (e.g., bolt), which may facilitate real-time Structural Health Monitoring (SHM) of the installed assembly component or bolted joint. According to various embodiments, the arrangement for non-destructive testing may form a structural connection assembly, wherein the assembly component is an elongated component (optionally a bolt) extending along a longitudinal axis, and wherein the assembly component has first and second end faces formed by first and second axial end faces of the elongated component. Furthermore, the ultrasonic transducer may be permanently arranged on the end face of the assembly component.

According to various embodiments, there is provided an apparatus for ultrasonic non-destructive testing of component parts (e.g., structural bolts), the apparatus may comprise:

a circular array of trapezoidal shaped piezoelectric elements (or piezoelectric transducing elements) that can produce pure shear motion in the circumferential direction subject to an applied electric field; and

an ultrasonic pulser/receiver unit (or an electric wave signal transmitting and receiving unit) generates a pulse-like excitation signal (or an electric excitation wave signal) at a desired frequency, and receives a reflected wave of the distal end of the bolt and the defect (or an electric response wave signal converted by the trapezoidal-shaped piezoelectric transducer element from a response wave received from the structural component part and/or the defect in the structural component part).

According to various embodiments, the array of piezoelectric elements (or piezoelectric transducing elements) may be coupled to a head (or foot) of a structural assembly component (e.g., a structural bolt). They may be positioned in a circular configuration and each trapezoidal patch (or piezoelectric transducing element) may preferably be configured with optimized dimensions to maximize the contact area between the piezoelectric element (or piezoelectric transducing element) and the planar surface of one end of the assembly member (or bolt end), particularly when a hexagon socket bolt head may be encountered. All of these patches (or piezoelectric transducing elements) can be connected in parallel so that they can generate in-phase shear motion when an electric field is applied, and discrete shear motion in the circumference of the component part (or bolt) can constructively cause the generation of torsional guided waves.

According to various embodiments, ultrasonic signals for NDT/SHM purposes may be transmitted in a substantially non-dispersive manner such that accurate timing measurements may be made (i.e., so that an accurate location of a defect may be determined). The generated fundamental torsional mode can propagate along the assembly member (or bolt) without exhibiting dispersion, so that the received signal can maintain the same shape as the incident wave. At the same time, the torsional mode may have little attenuation, which may enable an effective inspection distance.

According to various embodiments, the ultrasonic generator assembly (or ultrasonic transducer) may be adaptable to different geometries of the end face of the assembly member (or bolt head geometry). Thus, the ultrasonic transducer may comprise a plurality of discrete piezoelectric patches (or piezoelectric transducing elements) arranged along the circumference of the end face of the assembly member (or bolt). According to various embodiments, each patch (or piezoelectric transducing element) may be sized to achieve sufficient contact area and optimal transmission efficiency. In addition, according to various embodiments, the number of piezoelectric patches (or piezoelectric transducing elements) used may suppress the flexural mode (which may be excited along with the fundamental torsional mode).

According to various embodiments, the piezoelectric element (or piezoelectric transducing element) may be coupled to the end face (or bolt end) of the assembly member by any of the following means: (i) jointing connection; and (ii) a mechanical fixation and ultrasound transmission couplant. According to various embodiments, such coupling between the ultrasonic transducer and the accessible end of the waveguide (i.e., the assembly member) may facilitate efficient energy transfer therebetween. Bonding connections according to various embodiments may include adhesive bonding, welding, soldering, and other bonding techniques. The coupled ultrasound transducer may operate in a pulse-echo configuration such that the piezoelectric element (or piezoelectric transducing element) may function as a transmitter as well as a receiver. The received signal (or electrical response wave signal) may then be retrieved and analyzed by the ultrasonic pulser/receiver unit (or electrical wave signal transmitting and receiving unit) to give an indication of structural integrity.

Various embodiments may allow installed component parts (or structural bolts) to be periodically inspected during life for SHM purposes. To accomplish this, the array of piezoelectric elements (or piezoelectric transducing elements) may be permanently attached to the end face of the assembly component or to the bolt head (e.g., by adhesive bonding) and the associated lead ends made accessible from a remote location. Thus, multiple data collections from the same sensor at the same location can be compared and analyzed to capture changes in the periodically monitored assembly components (or bolts) by connecting only the pulser/receiver units (or electrical wave signal transmitting and receiving units) to those wires. Various embodiments may also allow for more accurate separation of environmental effects (e.g., ambient temperature variations, stress and liquid loading) from actual defects. Furthermore, such tests may be performed by untrained personnel (requiring only a fully qualified inspector when the sensor or transducer is first installed).

Various embodiments will be described herein by examining example assembly components in the form of structural bolts with reference to the drawings.

Various embodiments use ultrasonic torsional guided waves for damage detection in component parts, such as structural bolts. As previously described, various embodiments can be implemented without scanning the ultrasound probe point-by-point over the region of interest, and the transmitted guided waves can be used to quickly screen the component parts (or bolts) to achieve 100% coverage of the component part thickness (or bolt thickness) as compared to conventional ultrasound testing. Furthermore, the selected twisted guided mode may be non-dispersive in its propagation, making interpretation of the received signal simpler.

From a hardware perspective, commercially available transducers cannot provide sufficient contact with the end face (or bolt head) of a component part of a complex shape (e.g., having an inner hexagon), and thus guided wave modes may be difficult to generate. Various embodiments use discrete piezoelectric elements (or piezoelectric transducing elements) to generate in-phase shear motions to match the cross-sectional particle displacement (i.e., mode shape) of the fundamental torsional mode so that the mode can be efficiently excited in the assembly member (or bolt). Without loss of generality, such an ultrasonic sensor or transducer configuration may provide flexibility in transducer configuration, and if the applied stress is perfectly aligned with the associated mode shape, a particular steering mode may be initiated in a structure having component parts with an even more complex accessible geometry.

Furthermore, conventional ultrasonic testing as well as the use of commercial transducers makes it difficult to achieve SHM objectives. Various embodiments allow the feasibility of permanent attachment of sensors or transducers to in-service component parts (or structural bolts) and the ease of periodic data retrieval to periodically monitor the health condition of the component parts (or bolts).

Various embodiments use fundamental torsional guided waves for remote inspection of component parts (or structural bolts). Fig. 1A and 1B show the phase and group velocity dispersion curves of guided modes in a cylindrical steel rod. The phase and group velocity dispersion curves of the cylindrical steel rod are shown in fig. 1A and 1B as a function of the frequency-radius product. As shown, below 1MHz-mm, only three modes can propagate in the rod: l (0,1) mode (the lowest order longitudinal mode with extended behavior), F (1,1) mode (the substantially flexible mode with non-axisymmetric bending motion), and T (0,1) mode (the lowest order torsional mode with particle displacement primarily in the circumferential direction). These patterns may be associated with S in the plate, respectively₀(symmetrical) A₀(antisymmetric) and SH₀The (shared-level) mode is similar. To track patterns that exist in cylindrical systems, dual index naming is often used. The first index represents the circumferential order of the modes, describing the integer number of wavelengths around the circumference of the cylinder, and the second index is a counter variable indicating the sequential order of the modes in its wave series.

As can be seen from fig. 1A and 1B, the F (1,1) mode is highly dispersive and therefore not advantageous for NDT/SHM purposes, whereas the L (0,1) mode handles less dispersion at lower frequencies, and the T (0,1) mode is completely non-dispersive at all frequencies. Thus, the L (0,1) mode can have an inspection that is used in a relatively very dispersive regime below 0.8 MHz-mm. These low frequencies may suffer little attenuation and, therefore, may propagate long axial distances without significant loss of signal strength. At the same time, fewer propagating guided modes exist at low frequency regimes, which may make excitation of selected guided modes easier without exciting other unwanted wave modes that may significantly complicate the received signal. The T (0,1) mode may have similar advantages to the L (0,1) mode in terms of ease of excitation and may propagate at much lower phase velocities, which means that the T (0,1) mode may have a shorter wavelength than the L (0,1) mode at a given frequency, generally making it more sensitive to defects. Furthermore, the non-dispersive nature of the T (0,1) mode may provide a wider frequency range over which operation may be performed, in practical tests with wavelengths as small as possible. Thus, various embodiments may use the basic torsional mode T (0,1) for assembly component (or bolt) inspection.

Various embodiments use a spatial annular array of piezoelectric patches (or piezoelectric transducing elements) to excite the desired fundamental torsional mode. Fig. 2A and 2B illustrate an arrangement of piezoelectric transducing elements 220 on an assembly member 210, wherein an array of piezoelectric elements 220 (or piezoelectric transducing elements) may be attached to an end face 212 (or bolt head) of the assembly member 220 using a socket head 214, according to various embodiments. The piezoelectric transducing element 220 may be a trapezoidal shape piezoelectric transducing element. All piezoelectric transducing elements 220 may be connected in parallel and may generate in-phase shear motion subject to an applied electric field across each piezoelectric transducing element 220. Torsional guided waves can thus be generated and propagate through the body 216 of the assembly component 210 (or the threaded root and shank region of the bolt) by aligning torsional stresses on the end face 212 (or bolt head) of the assembly component 210. In fig. 2A, the shearing motion of the corresponding piezoelectric transducing element 220 is illustrated by arrows 229.

Figure 2C schematically illustrates an arrangement 200 for non-destructive testing of a component part 210, in accordance with various embodiments (or embodiments of an ultrasonic guided wave system for bolt inspection). As previously mentioned, the transducer 221, which transducer 221 comprises a piezoelectric transducing element 220 and may be coupled to the end face 212 of the assembly member 210 (or a test bolt head), may be driven by an electrical wave signal transmitting and receiving unit 230 (or an ultrasonic pulser/receiver unit), which electrical wave signal transmitting and receiving unit 230 may be operated in a pulse-echo configuration. Due to the non-dispersive nature, the excited fundamental twisted guided mode (or structural carrier) may be at a constant group velocity V along the assembly member 210 (or bolt structure)_grAnd (5) spreading. A defect occurring at the surface of the assembly member 210 (or bolt) or deep inside thereof may reflect part of the wave energy, and the reflected wave (or response wave) may be captured by the same transducer 221. The user interface 240 may then visualize the recorded time trace to determine the time of arrival (t) of the reflected wave (or response wave)_arr) And the distance between the defect and the end face 212 of the component part 210 (or bolt head) may be regarded as d ═ V_grt_arr2 obtainingAnd (4) obtaining.

As shown, an arrangement 200 for trialling component parts 210 may include a component part 210 to be tested, in accordance with various embodiments. According to various embodiments, the assembly member 210 may be a structural connection assembly member or a structural bolt or bolt. Accordingly, the assembly member 210 may be an elongated member extending along a longitudinal axis. According to various embodiments, the assembly member 210 may comprise a solid cylinder. According to various embodiments, the assembly member 210 may include a first end face 212 and a second end face 213 opposite the first end face 212. Accordingly, the face 212 and the second end face 213 of the assembly member 210 may be formed by extending the respective first and second axial end faces of the member.

According to various embodiments, the arrangement 200 includes a plurality of discrete piezoelectric transducing elements 220, the piezoelectric transducing elements 220 being arranged in a circular array 222 on the first end face 212 of the assembly member 210. Accordingly, a plurality of discrete piezoelectric transducing elements 220 may be arranged at the first axial end face of the elongated member. According to various embodiments, the circular array 222 may take the shape of a ring by placing or arranging a plurality of discrete piezoelectric transducing elements 220 as follows: such that the last element is placed next to the first element such that the plurality of discrete piezoelectric transducing elements 220 are arranged in a continuous circular closed loop.

According to various embodiments, the arrangement 200 may further comprise an electrical wave signal transmitting and receiving unit 230 electrically coupled or connected to the plurality of discrete piezoelectric transducing elements 220. Accordingly, the electrical wave signal transmitting and receiving unit 230 may be in electrical communication with the plurality of discrete piezoelectric transducing elements 220. According to various embodiments, the electric wave signal transmission and reception unit 230 may be capable of generating an electric excitation wave signal and applying the electric excitation wave signal to the piezoelectric transduction element 220. Accordingly, the electric wave signal transmission and reception unit 230 may transmit an electric excitation wave signal to the piezoelectric transducing element 220 to excite the piezoelectric transducing element 220. According to various embodiments, the electric wave signal transmission and reception unit 230 may be capable of receiving the electric response wave signal from the piezoelectric transducing element 220 and processing the electric response wave signal. Accordingly, the piezoelectric transducing element 220 may return the electrical response wave signal to the electrical wave signal transmitting and receiving unit 230 for processing.

According to various embodiments, the electrical wave signal transmission and reception unit 230 may be understood as any kind of electronic device or circuit configured to generate an electrical excitation wave signal and/or configured to receive and process an electrical response wave signal. The electric wave signal transmission and reception unit 230 may include a combination of two or more functional circuits (e.g., a power supply circuit, an oscillator circuit, an amplifier circuit, a signal processing circuit, etc.).

According to various embodiments, the piezoelectric transducing element 220 may be configured and arranged to deform in an in-phase shearing motion parallel to the first end face 212 of the assembly member 210 and in a corresponding tangential direction relative to the circular array 222 upon application of an electrical excitation signal. Accordingly, each piezoelectric transducing element 220 may be configured to shear when excited by an electrical excitation wave signal. The piezoelectric transducing elements 220 may also be arranged such that the respective directions of the respective shearing motions may be parallel to the first end face 212 of the assembly member 210. Further, the respective direction of the respective shear motion of each piezoelectric transducing element 220 may be tangential to the respective position of the respective piezoelectric transducing element 220 along the circumference of the circular array 222. According to various embodiments, the deformation of the piezoelectric transducing element 220 may generate corresponding structural carriers at the first end face 212 of the assembly member 210 such that the structural carriers can propagate from the first end face 212 to the second end face 213, be reflected by the second end face 213, and return to the first end face 212 as a response wave from the second end face 213. Accordingly, the shear motion of the piezoelectric transduction element 220 may convert the electrical excitation wave signal into wave energy in the form of structurally-carried waves that propagate through the assembly member 210 from the first end face 212 to the second end face 213, guided by and confined within the geometric boundaries of the assembly member 210. At least a portion of the structural carrier wave may then be reflected by the second end face 213 of the component part 210 as a response wave that passes from the second end face 213 of the component part 210 back to the first end face 212 of the component part. According to various embodiments, the assembly member 210 may be an elongated member. Accordingly, the structural carrier wave may propagate along the length of the elongate member from the first axial end face of the elongate member to the second axial end face of the elongate member, and the response wave may propagate along the length of the elongate member back from the second axial end face of the elongate member to the first axial end face of the elongate member.

According to various embodiments, the response wave may be received by the piezoelectric transducing element 220 and correspondingly converted into an electrical response wave signal for reception and processing by the electrical wave signal transmitting and receiving unit 230. Accordingly, the response wave may be received by the piezoelectric transducing element 220 through the first end face 212 of the assembly member 210. In addition, the piezoelectric transduction element 220 may convert wave energy of the response wave into an electric response wave signal, which is then received by the electric wave signal transmission and reception unit 230.

According to various embodiments, imperfections in the assembly member 210 may cause a small portion of the structural carriers to be reflected earlier than the remaining structural carriers reflected by the second end face 213 of the assembly member 210. Accordingly, the response wave may also include wave energy reflected by defects in the assembly member 210. Due to the difference in the reflection timing, the response wave from the defect can be returned earlier than the response wave from the second end face 213 of the component part 210.

According to various embodiments, the electrical wave signal transmission and reception unit 230 may be configured to generate an electrical excitation wave signal having a frequency such that the correspondingly created structural carrier wave is an ultrasonic wave. Accordingly, the ultrasonic guided waves can be propagated by the piezoelectric transducer element 220 through the assembly member 220 for testing of the assembly member 220.

According to various embodiments, the plurality of discrete piezoelectric transducing elements 220 may be electrically coupled or connected to each other so as to be collectively deformed in a synchronized manner upon application of an electrical excitation wave signal. According to various embodiments, a plurality of discrete piezoelectric transducing elements may be coupled electrically in parallel or connected electrically in parallel with each other. Accordingly, an electrical excitation signal may be applied to all piezoelectric transducing elements 220 simultaneously such that in-phase shear motion of a plurality of discrete piezoelectric transducing elements 220 may be achieved.

According to various embodiments, the piezoelectric transducing element 220 may be coupled to the first end face 212 of the assembly member 210 via an adhesive or bonding or mechanical fixation together with the application of an ultrasound transmissive couplant therebetween. Accordingly, efficient energy transfer between the piezoelectric transducing element 220 and the assembly member 210 can be facilitated through the connection.

FIG. 3 shows a view along x₃The piezoelectric ceramic plate 308 is polarized in the direction in which the electrodes 307, 309 are provided on the top and bottom surfaces of the piezoelectric ceramic plate 308. As shown, x₃The orientation is in a plane parallel to the top and bottom surfaces to which the electrodes 307, 309 are attached. According to various embodiments, a thickness shear mode PZT-5H wafer may be used, the wafer having a high d₁₅Piezoelectric coupling coefficient (subject to IEEE standard on piezoelectricity) so as to be along x₁A pure shear motion is generated when an electric field is applied in a direction. As shown, x₁Oriented perpendicular to the top and bottom surfaces of the piezoceramic plate 308. According to various embodiments, the piezoceramic plate 308 may then be cut into trapezoids of a desired size to serve as the piezoelectric transducing element 220.

According to various embodiments, the piezoelectric transducing elements 220 may each include a reference surface, and the electrical excitation signal may be applied in a direction perpendicular to the reference surface via a corresponding electrical potential across the corresponding piezoelectric transducing element 220 so as to deform the corresponding piezoelectric transducing element 220 with a corresponding shear motion. Accordingly, an electric potential may be applied from the respective reference surface through the respective piezoelectric transducing element 220 to a corresponding other surface of the respective piezoelectric transducing element 220, which is opposite to the respective reference surface.

According to various embodiments, the piezoelectric transducing elements 220 may each include at least one pair of electrical contact structures to receive an electrical potential, and one of the electrical contact structures may be disposed on the reference surface. Accordingly, at least one pair of electrical contact structures may be provided to each piezoelectric transducing element 220 such that an electrical potential may be applied to the respective piezoelectric transducing element 220.

According to various embodiments, the pair of electrical contact structures may comprise a pair of planar electrodes (e.g., electrodes 307, 309). Accordingly, each piezoelectric transducing element 220 may include at least one pair of planar electrodes. According to various embodiments, one of the planar electrodes may be disposed on the reference surface of the corresponding piezoelectric transducing element 220, and a second of the planar electrodes may be disposed on the other surface of the corresponding piezoelectric transducing element 220 opposite to the reference surface. Accordingly, at least one pair of planar electrodes of the respective piezoelectric transducing elements 220 may be on opposite surfaces of the respective piezoelectric transducing elements 220 so as to sandwich the piezoelectric material therebetween.

According to various embodiments, the reference surface of the respective piezoelectric transducing element 220 may be parallel to the first end face 212 of the assembly member 210. Accordingly, the electrical potential applied across the respective piezoelectric transducing element 220 can be perpendicular to the first end face 212 of the assembly member 210. According to various embodiments, the pair of electrical contact structures of the respective piezoelectric transducing element 220 may be disposed on a surface of the respective piezoelectric transducing element 220, which is parallel to the first end face 212 of the assembly member 210. According to various embodiments, the pair of planar electrodes on the respective piezoelectric transducing elements 220 may be parallel to the first end face 212 of the assembly member 210.

According to various embodiments, the reference surface of the respective piezoelectric transducing element 220 may be a mating surface of the respective piezoelectric transducing element 220 that is attached or adhered or fixed or bonded to the first end face 212 of the assembly member 210 so as to be in direct contact with the first end face 212 of the assembly member 210. According to various embodiments, a first one of the planar electrode pairs of the respective piezoelectric transducing element 220 may be disposed on a mating surface of the respective piezoelectric transducing element 220. Accordingly, the respective piezoelectric transducing element 220 can be attached or adhered or secured or bonded to the first end face 212 of the assembly component 210 with a first of the planar electrode pairs in direct contact with the first end face 212 of the assembly component 210. According to various embodiments, a second one of the planar electrode pairs of the respective piezoelectric transducing element 220 may be disposed on a surface of the respective piezoelectric transducing element 220 opposite to a mating surface of the respective piezoelectric transducing element 220. Accordingly, a second one of the planar electrode pairs may be exposed and directed away from the first end face 212 of the assembly member 210. According to various embodiments, an electrical excitation signal may be applied in a direction perpendicular to the mating surfaces via corresponding electrical potentials across a planar electrode pair across the respective piezoelectric transducing element 220 so as to deform the respective piezoelectric transducing element 220 in a respective shear motion.

Referring again to fig. 2A and 2B, according to various embodiments, the piezoelectric transducing elements 220 may each be a trapezoidal shaped piezoelectric transducing element 224. Accordingly, each piezoelectric transducing element 220 can be a 4-sided planar shape having a pair of opposing parallel sides 225, 226 and two other sides 227, 228 that are not parallel to each other. The pair of opposing parallel edges 225, 226 may have different lengths. Accordingly, the shorter side of the opposing parallel pair of sides may be the shorter base 225 and the longer side of the opposing parallel pair of sides may be the longer base 226. According to various embodiments, the respective trapezoidal shaped piezoelectric transducing elements 224 may be oriented with their respective shorter bases 225 pointing towards the center 223 of the circular array 222. According to various embodiments, the piezoelectric transducing element 220 may include other shapes, such as a rectangle, a square, a triangle, a parallelogram, a rhombus, an arrow shape, or any other suitable shape.

According to various embodiments, the number of piezoelectric transduction elements 220 (or piezoelectric ceramic patches) used and the size of each piezoelectric transduction element 220 (or patch) may be determined so as not to affect the purity of the excitation wave mode and the wave transmission efficiency. According to various embodiments, a plurality of piezoelectric transducing elements 220 (or piezoelectric ceramic patches) along the circumference may tangentially press the end face 212 (or bolt head) of the assembly member 210 and may fully excite the fundamental torsional mode only when the applied stress fully matches its cross-sectional mode shape.

Fig. 4A and 4B illustrate the configuration and size of the trapezoidal shape piezoelectric transducing element 224 used in the respective embodiments. As shown, the transduction zone may be bounded by circular inner and outer boundaries, with radii R, respectively_iAnd R_o. The number (N) of trapezoidal shaped piezoelectric transducing elements 224 (or piezoelectric transducing elements or piezoelectric patches or piezoelectric elements) used to discretize the circle may be determined by the separation angle (θ): n2 pi/θ. If too few trapezoidal shaped piezoelectric transducing elements 224 are used for excitation (e.g., N ≦ 4), the flexural guided mode may be readily generated along with the expected torsional mode, which may complicate post-processing of the received signals and determination of damage or defects in the assembly components 210 (or bolts). However, if the transducer includes too many trapezoidal shaped piezoelectric transducing elements 224, correlation is madeThe fabrication process, assembly, coupling, and circuitry can become more complex. Thus, according to various embodiments, the number N of trapezoidal shaped piezoelectric transduction elements 224 may be configured or selected to achieve an optimal tradeoff between assembly complexity and overall performance.

According to various embodiments, upon determination of the number (or patch number) N of trapezoidal shaped piezoelectric transducing elements 224, the dimensions of the respective trapezoidal shaped piezoelectric transducing elements 224 may primarily affect the transmission efficiency of the selected wave mode. In general, the larger the trapezoidal shaped piezoelectric transducing element 224 used, the higher amplitude of the T (0,1) mode can be transmitted. Accordingly, the contact area between the trapezoidal shaped piezoelectric transducing element 224 and the first end face 212 (or the bolt head) of the assembly member 210 can be maximized so as to achieve the highest transmission amplitude for a given excitation voltage. In various embodiments, the following criteria may be recommended for selecting appropriate height (h) and base length (a and b) of the trapezoidal shape piezoelectric transducing element (or trapezoidal piezoelectric ceramic element) in terms of geometrical relationships:

(i)h≤ξ(R_o-R_i) Wherein ξ is 0.8-0.9 is a gap correction factor;

(ii)

(iii)a<π(R_o-R_i)/N<b。

according to various embodiments, these criteria may facilitate achieving a balanced and robust configuration of the trapezoidal shaped piezoelectric element 224.

Referring to fig. 2A, 2B, and 4A, according to various embodiments, the first end face 212 of the assembly member 210 may include an annularly shaped surface. Accordingly, the first end face 212 of the assembly member 210 may include a central cavity or socket (e.g., an internal hexagonal socket) such that the first end face 212 may have an annularly shaped surface.

Referring to the above criterion (i) and referring to fig. 4A and 4B, according to various embodiments, the perpendicular distance between the shorter base 225 and the longer base 226 of the corresponding trapezoidal-shaped piezoelectric transducing element 224 and the radius R of the outer circumference of the ring-shaped surface_oAnd inner circumference of surface of annular shapeRadius R_iThe ratio of the difference between may be between 0.8 and 0.9.

Referring to the above criterion (ii) and referring to fig. 4A and 4B, according to various embodiments, the length ('B') of the longer base 226 of the corresponding trapezoidal-shaped piezoelectric transducing element 224 may use the radius R of the outer circumference of the ring-shaped surface as the hypotenuse_oThe perpendicular distance of the corresponding trapezoidal shape transducer element 224 as the first side and the radius R of the inner circumference of the ring-shaped surface_iAnd half of the length ('b') of the longer base 226 of the corresponding trapezoidal shaped transducer element as the second side is obtained via the pythagoras theorem.

Referring to criterion (iii) above and to fig. 4A and 4B, according to various embodiments, the sum of the lengths ('a') of the shorter bases 225 of all the trapezoid-shaped piezoelectric transducing elements 224 may be smaller than the reference circumference 231, and the sum of the lengths ('B') of the longer bases 226 of all the trapezoid-shaped piezoelectric transducing elements 224 may be larger than the reference circumference 231. According to various embodiments, the reference circumference 231 may be a radius R of an inner circumference having a ring-shaped surface_iRadius R from the outer circumference of the ring-shaped surface_oThe circumference of a circle of radius in between. According to various embodiments, the radius of the reference circle 231 may be the radius R of the inner circumference of the annularly shaped surface_iRadius R from the outer circumference of the ring-shaped surface_oHalf of the sum of.

According to various embodiments, the geometric constraint may be relaxed slightly when the piezoelectric transducing element 220 (or piezoelectric ceramic element) is first bonded to the matching layer before being coupled to the first end face 212 (or bolt head) of the assembly member 210. Additionally, in various embodiments, an engagement template (having a desired number of cuts, such as trapezoidal cuts) may be used to ensure accurate positioning of the piezoelectric transducing element 220 (such as the trapezoidal shaped piezoelectric transducing element 224) when engaged to the first end face 212 (or bolt head) of the assembly member 210 or to the matching layer. Once the bonding layer is fully cured, the mold plate may be removed and the wires may then be bonded to the electrical contact structures (e.g., electrodes) of the respective piezoelectric transducing elements 220.

According to various embodiments, the piezoelectric transduction element 220 (or piezoelectric element) can be combined with appropriate matching layers and backing materials and associated electrodes and wires to form a sealed transducer that can be used to transmit and receive guided wave modes in a common cylindrical structure. According to various embodiments, such transducers may be developed for discrete NDT purposes.

Various embodiments may be packaged including permanently attached piezoelectric transducing elements 220 (or sensors or transducers), electrical wave signal transmitting and receiving units 230 (or ultrasonic pulser/receiver units), associated circuit hardware, wireless data transmission, signal processing to create a remote monitoring system to periodically assess and record the health conditions of the bolt in service of other cylindrical assemblies in the industry.

FIG. 5A shows an example time trace received from an original bolt (diameter: 27 mm; length: 435mm), and FIG. 5B shows an example time trace received from a damaged bolt (circumferential crack length: 13 mm; crack depth: 2 mm; located in the middle of the bolt) at an excitation frequency of 150kHz using an arrangement 200 for non-destructive testing in accordance with various embodiments. By way of example, two independent steel bolts in raw and cracked states are screened through the arrangement 200 (or ultrasonic guided wave system) for non-destructive testing in accordance with various embodiments. Both bolts share the same geometry (length: 435 mm; diameter: 27mm) and material properties, and a 13mm wide circumferential crack with a constant 2mm depth is formed in the middle of one bolt. In this embodiment, eight trapezoidal piezo ceramic elements are coupled to the bolt head and are excited at a center frequency of 150kHz and fully launch the fundamental torsional guided mode. The recorded time traces of the two test bolts are shown in fig. 5A and 5B. As shown, in the original bolt, only the incident wave and the back wall echo are recognizable, and the reflected wave by the crack is easily captured in the time trace measured by the head of the damaged bolt. Thus, according to various embodiments, the location of cracks in a bolt may be determined, thereby demonstrating the defect detectability of various embodiments.

As illustrated by the above example with reference to fig. 5A and 5B, in accordance with various embodiments, a non-destructive testing method is provided. The non-destructive testing method may include arranging a plurality of discrete piezoelectric transducing elements in a circular array on a first end face of a cylindrical component part to be tested. The cylindrical assembly member may include a first end face and a second end face opposite the first end face. According to various embodiments, the method may further comprise operating an electrical wave signal transmission and reception unit (which is electrically coupled to the plurality of discrete piezoelectric transducing elements) to generate an electrical excitation signal and apply said electrical excitation signal to the piezoelectric transducing elements by deforming the piezoelectric transducing elements with in-phase shear motion parallel to the first end face and with respective tangential directions relative to the circular array so as to generate in the assembly member corresponding structural carriers at the first end face of the assembly member such that said structural carriers can propagate from the first end face to the second end face for reflection by the second end face and return as a response wave from the second end face to the first end face. According to various embodiments, the response wave may be received by the piezoelectric transduction element and correspondingly converted into an electrical response wave signal for reception and processing by the electrical wave signal transmission and reception unit, wherein the structural carrier wave is generated in the form of a fundamental torsional guided wave.

According to various embodiments, the electrical excitation signal may have a frequency such that the correspondingly created structural carrier wave is an ultrasonic wave.

According to various embodiments, the method may further include determining, via the electrical wave signal transmitting and receiving unit, a location of the defect along the length of the cylindrical assembly member based on an elapsed time of a corresponding response wave of the defect. According to various embodiments, the electrical wave signal transmitting and receiving unit may include a user interface from which the location of the defect may be determined.

The following relates to various embodiments.

According to various embodiments, there is provided an arrangement for non-destructive testing of a component part, the arrangement comprising:

the device comprises a component to be tested, a first testing component and a second testing component, wherein the component to be tested comprises a first end face and a second end face opposite to the first end face;

a plurality of discrete piezoelectric transducing elements arranged in a circular array on the first end face of the assembly member; and

an electrical wave signal transmitting and receiving unit electrically coupled to the plurality of discrete piezoelectric transducing elements and capable of generating and applying an electrical excitation wave signal to the piezoelectric transducing elements and capable of receiving an electrical response wave signal from the piezoelectric transducing elements and processing the electrical response wave signal,

wherein the piezoelectric transducing elements are configured and arranged to deform in-phase shear motion parallel to the first end face and in respective tangential directions relative to the circular array upon application of the electrical excitation wave signal so as to generate in the assembly member a corresponding structural carrier at the first end face of the assembly member such that said structural carrier can propagate from the first end face to the second end face for reflection by the second end face and return from the second end face to the first end face as a response wave which can be received by the piezoelectric transducing elements and correspondingly converted into an electrical response wave signal for reception and processing by the electrical wave signal transmission and reception unit.

According to various embodiments, the electrical wave signal transmission and reception unit may be configured to generate an electrical excitation wave signal having a frequency such that the correspondingly created structural carrier wave is an ultrasonic wave.

According to various embodiments, the piezoelectric transducing elements may each comprise a reference surface, and the electrical excitation signal may be applied in a direction perpendicular to the reference surface via a corresponding electrical potential across the corresponding piezoelectric transducing element so as to deform the corresponding piezoelectric transducing element in a corresponding shear motion.

According to various embodiments, the piezoelectric transducing elements may each comprise at least one pair of electrical contact structures to receive an electrical potential, and one of said electrical contact structures is arranged on said reference surface.

According to various embodiments, the pair of electrical contact structures may comprise a pair of planar electrodes. One of the planar electrodes may be disposed on the reference surface, and a second of the planar electrodes may be disposed on the other surface of the corresponding piezoelectric transducing element opposite to the reference surface.

According to various embodiments, the reference surface of the respective piezoelectric transducing element may be parallel to the first end face of the assembly member.

According to various embodiments, the reference surface may be a mating surface of the respective piezoelectric transducing element.

According to various embodiments, the piezoelectric transducing elements may each comprise a mating surface, and the electrical excitation signal may be applied in a direction perpendicular to the mating surfaces via a corresponding electrical potential across the corresponding piezoelectric transducing element so as to deform the corresponding piezoelectric transducing element in a corresponding shear motion, wherein the mating surfaces may be in contact with the first end face of the assembly member.

According to various embodiments, the piezoelectric transducing elements may each include at least one pair of planar electrodes to receive an electric potential, one of the planar electrodes may be disposed on the mating surface, and a second of the planar electrodes may be disposed on the other surface of the corresponding piezoelectric transducing element which may be opposite to the mating surface.

According to various embodiments, the mating surface of the respective piezoelectric transducing element may be parallel to the first end face of the assembly member.

According to various embodiments, a plurality of discrete piezoelectric transducing elements may be coupled electrically in parallel or connected electrically in parallel with each other so as to be collectively deformed in a synchronized manner upon application of an electrical excitation signal.

According to various embodiments, the piezoelectric transducing element may be coupled to the first end face of the assembly member via bonding or mechanical fixation together with application of an ultrasound transmissive couplant therebetween.

According to various embodiments, the piezoelectric transducing elements may each be a trapezoidal shaped piezoelectric transducing element. According to various embodiments, respective trapezoidal shaped piezoelectric transducing elements may be oriented with their respective shorter bases pointing toward the center of the circular array.

According to various embodiments, the first end surface of the assembly member may comprise an annularly shaped surface.

According to various embodiments, a ratio of a perpendicular distance between the shorter base and the longer base of the respective trapezoidal shape piezoelectric transduction elements to a difference between a radius of the outer circumference of the ring-shaped surface and a radius of the inner circumference of the ring-shaped surface may be between 0.8 and 0.9.

According to various embodiments, the length of the longer base of the corresponding trapezoidal shape piezoelectric transducing element can be obtained via the pythagoras theorem using the radius of the outer circumference of the ring shape surface as the hypotenuse, the sum of the perpendicular distance of the corresponding trapezoidal shape transducing element as the first side and the radius of the inner circumference of the ring shape surface, and half the length of the longer base of the corresponding trapezoidal shape transducing element as the second side.

According to various embodiments, the sum of the lengths of the shorter bases of all the trapezoidal shape piezoelectric transduction elements may be smaller than the reference circumference, and the sum of the lengths of the longer bases of all the trapezoidal shape piezoelectric transduction elements may be larger than the reference circumference, wherein the radius of the reference circumference may be half of the sum of the radius of the inner circumference of the ring-shaped surface and the radius of the outer circumference of the ring-shaped surface.

According to various embodiments, the assembly member may comprise a solid cylinder.

According to various embodiments, the arrangement may form a structural connection assembly. According to various embodiments, the assembly member may be an elongated member (optionally a bolt) that may extend along the longitudinal axis. According to various embodiments, the first and second end surfaces may be formed by first and second axial end surfaces of the elongated member.

According to various embodiments, there is provided a non-destructive testing method, the method comprising:

arranging a plurality of discrete piezoelectric transducing elements in a circular array on a first end face of a cylindrical assembly component to be tested, the cylindrical assembly component comprising a first end face and a second end face opposite the first end face; and

operating an electrical wave signal transmission and reception unit, which is electrically coupled to a plurality of discrete piezoelectric transducing elements, to generate an electrical excitation wave signal and apply the electrical excitation wave signal to the piezoelectric transducing elements, by deforming the piezoelectric transducing element with in-phase shear motion parallel to the first end face and with respective tangential directions relative to the circular array, for generating in the component part a corresponding structural carrier wave at the first end face of the component part, such that said structural carrier wave can propagate from the first end face to the second end face for reflection by the second end face and return as a response wave from the second end face to the first end face, the response wave can be received by the piezoelectric transducing element and correspondingly converted into an electrical response wave signal, for reception and processing by electrical wave signal transmission and reception units, wherein the structural carrier wave is generated in the form of a fundamental torsional guided wave.

According to various embodiments, the electrical excitation signal may have a frequency such that the correspondingly created structural carrier wave may be an ultrasonic guided wave.

According to various embodiments, the method may further include determining, via the electrical wave signal transmitting and receiving unit, a location of the defect along the length of the cylindrical assembly member based on an elapsed time of a corresponding response wave of the defect.

Various embodiments provide arrangements and methods that can be used to detect and locate damage that occurs in component parts (e.g., structural bolts) during use in service. Through detected damage in installed component parts (e.g., structural bolts), they can be replaced in a timely manner to avoid the damage extending into a catastrophic failure of the overall system.

While the invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes, modifications, variations in form and details may be made therein without departing from the scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.