Ultrasonic targets for nondestructive testing.

Abstract

To provide an ultrasonic target including a main reflector.SOLUTION: An ultrasonic target 1 includes a main reflector 10, the main reflector including three main faces 11-13 extending from a main vertex S10, the main faces forming a main trirectangular trihedron, the main reflector defining a main base plane that faces the main vertex and forms a base of the main trirectangular trihedron. The target includes at least one auxiliary reflector 20-40 fastened to the main reflector, each auxiliary reflector including three auxiliary faces 21-23, 31-33, 41-43 extending from an auxiliary vertex S20-S40, the auxiliary faces forming an auxiliary trirectangular trihedron, the auxiliary reflector defining an auxiliary base plane that faces the auxiliary vertex and forms a base of the auxiliary trirectangular trihedron.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The technical field of the present invention relates to ultrasonic non-destructive testing, and in particular to testing of equipment located in harsh environments. [Background technology]

[0002] Certain industrial facilities are subject to periodic inspections to check the integrity of equipment or structures. These inspections are carried out to meet regulatory requirements and / or to satisfy safety demands. It may be a matter of checking the integrity of structures or components or performing inspections or dimensional inspections of their location.

[0003] However, certain environments are not suitable for visual inspection techniques based on conventional image sensors. These include, for example, facilities with very high temperatures or irradiation levels. These environments may also be submerged in opaque liquids or covered by opaque shields, such as metal shields. Such situations can be encountered in the nuclear industry, for example, in fast neutron reactors cooled by liquid sodium or liquid lead, or even in facilities with tanks that may contain internal equipment related to the nuclear fuel cycle that cannot be seen from the outside.

[0004] Ultrasonic inspection techniques can overcome these types of difficulties in this type of equipment, allowing the equipment to be monitored during operation, during routine inspections, or before maintenance or demolition work, by utilizing the propagation of ultrasonic waves through various media, whether liquid or solid.

[0005] The principle of such measurements is well known: an incident sound wave is transmitted by a transmitter in the direction of the equipment or structure being inspected. The latter reflects the incident wave. A portion of the reflected wave is then detected by a detector. To perform this type of measurement, an ultrasonic transducer is typically used, acting as both a transmitter and a receiver. The incident wave generally takes the form of a pulsed wave or a short wave train. The reflected wave, i.e., the wave that propagates back to the detector, is conventionally called an "echo." Acoustic measurements are advantageous because of the maturity of instrumentation and the high performance of the associated imaging software. The amplitude and time of flight of the reflected sound wave are typically utilized. The time of flight corresponds to the time interval between the transmission of the incident sound wave and the detection of the reflected sound wave (echo).

[0006] However, transmitted or reflected sound waves are typically attenuated between the transmitting or receiving transducer and the device being tested. This is especially true when a shield, such as a metal thickness, is placed between the transducer and the device under test. To increase the strength of the reflected waves propagating toward the transducer, targets called triangular corner reflectors can be placed on the testing device.

[0007] The principle of operation of triangular corner reflectors is well known, especially in the field of optics, since the problem is the fundamental principle of reflection and refraction. AA is composed of three orthogonal planes as shown in Figure 1. A triangular corner reflector, usually called a "cube corner", is i When exposed to an incident sound wave propagating parallel to the axis of the incident wave, r This is due to three successive reflections of the sound wave from various orthogonal faces of the target. This characteristic is observed when the angle of incidence is limited to approximately 25°-30° relative to the normal of the target's bottom major surface. The intensity of the reflected wave varies with the area of ​​the target and the axis of incidence Δ i The magnitude of the echo increases with the centrality of the target. Thus, a target is qualified as echogenic because it produces an echo that is stronger than the echo produced by specular reflection from a plane wall.

[0008] The use of targets for reflecting sound waves has already been described, for example, in EP 2192593. In the latter case, the target is placed on a piece of equipment, in this case a pump for a nuclear reactor. The target is planar or formed from two orthogonal planes. It is used as an ultrasonic reflector for inspecting the vibrations of the equipment, regardless of whether the vibration amplitude or frequency is being inspected. JP 56-004006 A1 describes the use of triangular corner reflectors for reflecting sound waves.

[0009] EP 2937711 A1 describes the use of various triangular reflective targets placed at different positions on the same equipment, the problem being to reflect electromagnetic waves for the purpose of testing vibrations. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] European Patent Application Publication No. 2192593 [Patent Document 2] Japanese Patent Application Publication No. 56-004006 [Patent Document 3] European Patent Application Publication No. 2937711 Summary of the Invention [Problem to be solved by the invention]

[0011] None of the above-mentioned documents describe the use of a triangular corner reflector that is fixed to a device and intended to be used as a sole acoustic reflector to quantitatively estimate the device's motion. The invention described below addresses this problem. It allows quantitative estimation of the motion, particularly in two or three dimensions, of a device with a fixed target that acts as an ultrasonic reflector. The motion can be estimated with a single target. [Means for solving the problem]

[0012] The first subject of the invention is an ultrasonic target equipped with a main reflector, said main reflector comprising: having three principal faces extending from the principal vertex and forming a principal right trihedron; defining a major base that faces the major vertex and forms a base of the major right trihedron; The target comprises at least one sub-reflector fixed to the main reflector, the or each sub-reflector comprising: It has three auxiliary faces extending from the auxiliary vertex and forming an auxiliary right-angled trihedron; An auxiliary base is defined that faces the auxiliary vertex and forms the base of the auxiliary right trihedron.

[0013] Preferably, the target has the or each auxiliary base parallel to the main base.

[0014] The primary reflector and each secondary reflector are configured to reflect incident ultrasonic waves propagating along an incident axis to produce reflected waves propagating along a reflection axis parallel to the incident axis, the incident axis preferably being positioned over a range of incident angles extending up to an angle of 25° or 30° relative to a normal to the base major surface.

[0015] The reflector and each sub-reflector form a monolithic target, the target being of one unitary construction, so that the position of each sub-reflector is fixed relative to the main reflector.

[0016] According to one embodiment, the or each auxiliary vertex is positioned at a distance relative to said major base that is different from the distance between said main vertex and said major base, said distance being measured perpendicular to said major base.

[0017] According to one embodiment, the target comprises at least two or at least three auxiliary reflectors fixed to the main reflector. Each auxiliary vertex may be positioned at the same distance from the main base in a direction perpendicular to the main vertex. At least two auxiliary vertices may be positioned at different distances from the main vertex, the distances being measured perpendicular to the main base.

[0018] Each reflector defines a volume defined by a surface forming the reflector and a base surface of the reflector. The target may be one in which the volumes defined by at least two reflectors selected from the primary reflector and the secondary reflector are different from each other.

[0019] According to one embodiment, two adjacent major faces are separated by a ridge extending from said major vertex; at least one auxiliary vertex of one auxiliary reflector, called an inner auxiliary reflector, is located on the ridge; The internal auxiliary reflector is the adjacent main surfaces forming the auxiliary surfaces of the auxiliary reflector; a transverse auxiliary surface extending between the adjacent major surfaces and parallel to the major surface opposite the adjacent auxiliary surface; is defined by

[0020] The target may comprise a plurality of secondary reflectors, each of which may be an internal reflector.

[0021] According to one embodiment, the primary reflector defines an interior space located between the major surface and the bottom major surface; At least one auxiliary reflector is disposed outside the interior space.

[0022] A second subject of the present invention is a method for estimating the movement of a target according to the first subject of the present invention, comprising, in the examination step, a) exposing the target to incident acoustic waves emitted by an acoustic radiation source, the incident acoustic waves propagating along an axis of incidence, the axis of incidence being inclined at an angle of less than 30° with respect to a normal axis of the base major surface of the target; b) subsequent to step a, detecting acoustic waves reflected by the target, the reflected acoustic waves propagating along a reflection axis parallel to the incidence axis; c) determining a position of the target based on the acoustic waves detected in step b, the position including a location and / or an orientation of the target; d) considering a reference position including a reference position and / or a reference orientation of said target; e) comparing the target position obtained in step c with the reference position; Includes:

[0023] The method comprises: f) estimating the movement of the target relative to the reference position based on the comparison result obtained in step e); may include:

[0024] The reference position may be estimated by performing steps a), b) and c) prior to the inspection stage. The reference position may be determined based on a drawing or a three-dimensional model.

[0025] The target may be fixed to an instrument or component, and the method includes estimating the movement of the instrument or structural element relative to a reference configuration. The reference configuration may unambiguously correspond to a nominal configuration of the instrument or structural element. The method may be intended to be used to check whether the instrument or structural element is in the reference configuration. [Brief explanation of the drawings]

[0026] The invention will be better understood upon reading the description of the exemplary embodiments set forth in the remainder of the description with reference to the figures listed below. [Figure 1] FIG. 1 shows a target according to the prior art. [Figure 2A] FIG. 2A shows a first embodiment of the present invention. [Figure 2B] FIG. 2B shows a first embodiment of the present invention. [Figure 2C] FIG. 2C shows a first embodiment of the present invention. [Figure 2D] FIG. 2D illustrates the movement of a target according to the present invention. [Figure 2E] FIG. 2E illustrates the movement of a target according to the present invention. [Figure 3A] FIG. 3A shows a second embodiment of the present invention. [Figure 3B] FIG. 3B shows a third embodiment of the present invention. [Figure 4A] 4A shows a C-scan map generated by placing a transducer facing a target according to a first embodiment. In this configuration, the acoustic waves transmitted by the transducer propagate perpendicular to the bottom major surface of the target. [Figure 4B] 4B shows a C-scan map generated by placing the transducer facing the target according to the first embodiment. In this configuration, the acoustic waves transmitted by the transducer propagate perpendicular to the bottom major surface of the target. [Figure 4C] FIG. 4C is a timing diagram illustrating the detection of echoes reflected by auxiliary reflectors on a target. [Figure 4D] FIG. 4D is a timing diagram illustrating the detection of echoes reflected by the target's main reflector. [Figure 4E] FIG. 4E is a timing diagram showing the detection of echoes reflected by the instrument, in this case the target being a fixed plate. [Figure 5A]5A shows a C-scan map generated by placing a transducer facing a target according to a first embodiment. In this configuration, the acoustic waves transmitted by the transducer propagate at an angle relative to the normal to the bottom major surface of the target. [Figure 5B] 5B shows a C-scan map generated by placing the transducer facing the target according to the first embodiment. In this configuration, the acoustic waves transmitted by the transducer propagate at an angle relative to the normal to the bottom major surface of the target. [Figure 5C] FIG. 5C shows the rotation of the target about an axis perpendicular to the base of the main reflector and passing through the main vertex. [Figure 6] FIG. 6 shows the main steps of a method for implementing the invention for the purpose of testing equipment. DETAILED DESCRIPTION OF THE INVENTION

[0027] 2A to 2E show a first example of a reflective ultrasound target 1 according to the present invention. The target 1 comprises a primary reflector 10 formed from three planar orthogonal surfaces 11, 12, and 13. The three planar orthogonal surfaces intersect and form a primary vertex S 10 The Cartesian coordinate system X, Y, and Z is shown. The surfaces 11, 12, and 13 are each located on an orthogonal plane P xz , P yz , P xy It is located in.

[0028] In the example shown, the primary reflector 10 is an isosceles right trihedron. Each face is an isosceles right triangle, with its right angles at the primary vertices S 10 Each face is located at the main vertex S 10 In the example shown, the opposite boundary is 11 b , 12 b , and 13 b The boundary is coplanar and has a major base P 10 The base of a trihedron is the triangle with the height H of the triangle. 10means a plane perpendicular to the major vertex S 10 It is measured from the main base P 10 and height H 10 is shown in Figure 2C.

[0029] The main reflector 10 is the same as the target 1 described in relation to the prior art. AA The incident sound wave has the same characteristics as the incident axis Δ i When the incident wave propagates along the axis Δ r It generates a reflected wave that reflects along the incident axis Δ i The effect of reflection parallel to the principal base P 10 This occurs in the incident angle range Ω of ±25° or 30° relative to the direction perpendicular to the laser.

[0030] The surfaces of the main reflector are rigid and have a roughness small compared to the wavelength of the ultrasonic waves used. They are preferably made of a material with good properties for the reflection of ultrasonic waves at the interface with the surrounding medium, for example a stainless steel surface intended for immersion in water or liquid metal. The main bottom surface P 10 along the boundary 11 b , 12 b , and 13 b The portion defined by is preferably open to facilitate propagation of sound waves through the bottom major surface, or may comprise a rigid material with a small thickness.

[0031] The reflective target 1 is provided with at least one secondary reflector. In this embodiment, the reflective target 1 is provided with three secondary reflectors 20, 30 and 40, which is the preferred configuration.

[0032] Each of the secondary reflectors 20, 30, and 40 is securely fixed to the primary reflector 10. The target is intended to be placed relative to an instrument for testing the instrument using an acoustic testing modality. Prior to placement relative to the instrument, the target is a monolithic component of one-piece construction. As described below, the secondary reflectors 20, 30, and 40 may be positioned within an interior space defined by the primary reflector 10 or may be coupled to the primary reflector with mounts. Thus, when the target 1 moves, the movement affects the primary reflector 10 and each of the secondary reflectors.

[0033] Like the primary reflector 10, each secondary reflector is an isosceles right trihedron. Each secondary reflector 20, 30, and 40 is formed by three planar secondary faces at right angles to one another, whose intersections form vertices called the secondary vertices. Each secondary face is in the shape of an isosceles right triangle, with the triangle forming right angles at the secondary vertices. Each secondary face extends from the secondary vertex to a boundary. The boundaries of the secondary faces of each secondary reflector define a secondary base, which may be coplanar. The secondary base forms the base of the secondary trihedron. The base is a plane perpendicular to the height of the secondary trihedron, and its height is measured from the secondary vertex. Figure 2C shows the vertex S of the primary reflector 10. 10 , and the vertex S of the auxiliary reflector 20 20 Height H extending from 10 , H 20 2C shows the major base P 10 and the auxiliary bottom surface P of the auxiliary reflector 20 also shows.

[0034] Figure 2A shows First auxiliary vertex S 20 a first auxiliary reflector 20 extending between a first auxiliary surface 21, a second auxiliary surface 22, and a third auxiliary surface 23 around the Second auxiliary vertex S 30 a second auxiliary reflector 30 extending between a first auxiliary surface 31, a second auxiliary surface 32, and a third auxiliary surface 33 around the Third auxiliary vertex S 40a third auxiliary reflector 40 extending between a first auxiliary surface 41, a second auxiliary surface 42, and a third auxiliary surface 43 around the This shows:

[0035] In this first example, each auxiliary reflector is aligned with the primary vertex S 10 and the main base P 10 , and are located in the space defined by the main reflector 10. Such an auxiliary reflector is called an "internal reflector". The reflective target 1 is then particularly compact. More precisely, each auxiliary reflector 20, 30, and 40 is a first auxiliary surface and a second auxiliary surface, each corresponding to a portion of two adjacent major surfaces of the primary reflector, the portion extending from a boundary between the adjacent major surfaces; a third auxiliary surface extending parallel to a major surface of the main reflector, said major surface facing said adjacent major surface; is defined by

[0036] therefore, The auxiliary surfaces 21 and 22 of the first auxiliary reflector 20 are two portions of the main surfaces 11 and 12 of the main reflector, said portions being located between the two boundaries 11 and 12 of the main reflector. b and 12 b The other auxiliary surface 23 of the first auxiliary reflector 20 extends parallel to the other main surface 13. The auxiliary surfaces 31 and 33 of the second auxiliary reflector 30 are two portions of the main surfaces 11 and 13 of the main reflector, said portions being located between the two boundaries 11 and 13 of the main reflector. b and 13 b The other auxiliary surface 32 of the second auxiliary reflector 30 extends parallel to the other main surface 12. The auxiliary surfaces 42 and 43 of the third auxiliary reflector 40 are two portions of the main surfaces 12 and 13 of the main reflector, said portions being located between the two boundaries 12 of the main reflector. b and 13 b The other auxiliary surface 41 of the third auxiliary reflector 40 extends parallel to the other main surface 11.

[0037] According to the first embodiment, the intersection line between two adjacent main faces of the main reflector 10 is formed by the ridge 10 of said main reflector. a In each of the auxiliary reflectors 20, 30, and 40, Auxiliary vertex S 20 , S 30 , and S 40 is located on the ridge of the main reflector, The auxiliary reflector is two adjacent main surfaces (e.g., main surfaces 11, 12 for the auxiliary reflector 20), parts of which form auxiliary surfaces (e.g., auxiliary surfaces 21, 22 for the auxiliary reflector 20); other auxiliary surfaces 23, called transverse auxiliary surfaces, which extend between the adjacent main surfaces parallel to the main surface facing the adjacent main surface (for example, main surface 13 for reflector 20); is defined by

[0038] 2B shows another three-dimensional view of the target according to the first embodiment. In the first embodiment, the bases of the main reflector and each of the secondary reflectors are coincident. More generally, the bases of the main reflector 10 and each of the secondary reflectors 20, 30, 40 are parallel.

[0039] A plane acoustic wave 100 is incident on the axis Δ i When the beam propagates along the axis of reflection Δ r 2D shows how the reflected wave propagates along the a main reflected wave 101 reflected by the main reflector; Auxiliary reflected waves 102, 103, and 104 are reflected by the three auxiliary reflectors, respectively; This shows:

[0040] Due to the spatial offset between the various reflectors, the auxiliary reflected waves 102, 103, 104 are shifted in time relative to the main reflected wave 101, resulting in a temporal phase shift. In the example shown in Figure 2D, the main reflected wave 101 is delayed relative to the auxiliary reflected waves.

[0041] In Figure 2E, the target 1 is positioned facing the transducer 50, as described above. The transducer 50, which may be, for example, a piezoelectric transducer, acts as a transmitter and receiver of acoustic waves and is placed far enough from the target so that the angle of incidence of the incident acoustic waves can be considered the same for all parts of the target. The transducer 50 transmits the incident acoustic waves 100 propagating towards the target along an axis of incidence Δ i Under the influence of reflections from the various reflectors that make up the target, four reflected waves 101, 102, 103, and 104 are formed in the direction of the transducer, propagating parallel to the axis of incidence. Due to the spatial offset between the various reflectors, the auxiliary reflected waves 102, 103, and 104 are shifted in time with respect to the main reflected wave 101.

[0042] Depending on the angle of incidence, the auxiliary reflected waves may be shifted relative to one another. The angle of incidence depends on the position of the transducer 50 relative to the target 1. According to a first embodiment, assuming a plane incident sound wave, the auxiliary reflected waves are shifted relative to one another at an angle of incidence Δ i is the main base P 10 In the first embodiment, the signals are synchronized when they are orthogonal to each other, i.e., they are not shifted in time from each other. 10 Considering the distance measured perpendicular to each auxiliary vertex S 20 , S 30 , and S 40 is the main vertex S 10 due to the fact that they are equidistant from

[0043] As mentioned above, each of the reflected waves 101, 102, 103, and 104 has a reflection axis Δ r The incident axis Δ iThe effect of parallel reflection occurs when the range of angles of incidence Ω relative to the normal to the base of each reflector is ±25° or ±30°. The geometry of the three right-angled trihedrons maximizes the angular range Ω over which "parallel reflection" occurs. Furthermore, the fact that the bases of each reflector are parallel to one another allows the angular range Ω to be the same for all reflectors forming the target, whether they are primary or secondary reflectors.

[0044] Normal incidence, i.e., incidence axis Δ i When the reflector's base is perpendicular to the reflector's base, the intensity of each reflected wave is maximized, which corresponds to the desired configuration. When the reflectors' bases are parallel, the angular response of each reflector is similar. Angular response refers to the relative intensity of the reflected wave to the intensity of the incident wave as a function of the angle of incidence.

[0045] Figure 3A shows a second embodiment, in which the vertex of each auxiliary reflector 20, 30, 40 is joined to the boundary of the main reflector 10. According to this embodiment, each auxiliary reflector is located outside the interior space defined by the main reflector. In the embodiment shown in Figure 3A, as in the first embodiment, the bottom surface of each auxiliary reflector is parallel to the bottom surface of the main reflector. Figure 3A shows an instrument E, in this case a plate, on which a target 1 is fixed.

[0046] It should also be noted that, considering the distance measured along an axis perpendicular to the major base, the vertex of each auxiliary reflector is equidistant from the vertex of the main reflector, as in the first embodiment. Such equidistance is not essential. In a third embodiment shown in FIG. 3B, the vertices of auxiliary reflectors 30 and 40 are coupled to the boundary of the main reflector 10 by holders 35, 45, each of which may be, for example, a rod. Each holder forms one mount of the target. The length of each holder is different. In this embodiment, each auxiliary vertex S 20 , S 30 , S 40 and the main vertex S 10 The distances between each are different.

[0047] According to this embodiment, similarly to the second embodiment, Each auxiliary reflector is located outside an interior space defined by the primary reflector; The base of each sub-reflector is parallel to the base of the main reflector.

[0048] In both embodiments, the target 1 is intended to be fixed to equipment that requires periodic inspection using an acoustic modality, in which the equipment is exposed to incident acoustic waves 100. As explained in relation to the prior art, this may involve equipment immersed in an opaque medium that is difficult to visually inspect. One target application is, for example, the inspection of equipment immersed in liquid lead or liquid sodium in fast neutron reactors.

[0049] Due to their geometric configuration, each reflector forming a target is particularly echogenic and generates a reflected wave that is stronger than the sound waves reflected by a flat surface. By using a target with various reflectors, strong and time-shifted reflected waves can be obtained following target illumination, where time-shifted means that the sound waves reflected by the main reflector are shifted in time relative to the sound waves reflected by the secondary reflectors or each sound wave. Each reflected wave is conventionally referred to by the term "echo." The target 1 generates a main echo and at least one, preferably more than one, secondary echo. The time shift between each secondary echo and the main echo allows the main echo to be easily distinguished from each secondary echo.

[0050] Furthermore, the amplitude of each echo depends on the dimensions of the reflector. In the above-described embodiment, the main reflector 10 has a larger dimension than each of the auxiliary reflectors. Therefore, the main reflector can generate stronger echoes than the auxiliary reflectors, which also makes it easier to distinguish the main echo from the auxiliary echoes. Therefore, when each reflector defines a volume contained between each face and the bottom of the reflector, it is preferable that the volumes defined by the two different reflectors are different. For example, the volume of the main reflector may be larger or smaller than the volume of each of the auxiliary reflectors.

[0051] In any embodiment, the length of the ridge of the main reflector may be comprised between 2 cm and several tens of cm, for example 30 or 40 cm. The length of the ridge of each sub-reflector is preferably equal to or greater than the length of the ridge of the main reflector. a The length is between 0.25 and 4 times the length of the

[0052] By detecting and identifying the echoes generated by each reflector, it is possible to obtain information about the position of each reflector in space using methods known in the field of ultrasonic non-destructive testing, and thus to deduce the position of the target in space, which can refer to, for example, its distance relative to the ultrasonic transducer and / or its orientation relative to the axis of incidence.

[0053] In the above-described embodiments, each face of each auxiliary reflector is parallel to one face of the main reflector. However, this is not required. In these embodiments, the faces of the auxiliary reflectors do not have to be parallel to the faces of the main reflector.

[0054] FIG. 4A shows a C-scan map obtained experimentally using a target according to the first embodiment. In this example, the acoustic transducer described above was used to transmit incident acoustic waves and detect reflected acoustic waves. The transducer was placed 25 cm from the bottom major surface of the target. The incident acoustic waves were transmitted at a center frequency of 2.25 MHz, with the axis of incidence perpendicular to the bottom surface of the target. The acoustic transducer was 1 / 2 inch wide, the target was placed underwater, and the propagation velocity of the acoustic waves was 1490 m.s. -1 is.

[0055] The term C-scan is known to those skilled in the art. It corresponds to a map of the maximum amplitude of acoustic echoes, which are detected along a detection plane scanned by an acoustic transducer. The detection plane may preferably be perpendicular to the incident axis. Thus, the grayscale levels represent the amplitude of the echoes. In the case of Figure 4A, the C-scan map is therefore obtained on a detection plane parallel to the major base of the target. The incident axis Δ i is perpendicular to the detection plane. A strong echo 101 (referenced by the letter a) is observed emanating from the main reflector 10, and three echoes 102, 103, and 104 (referenced by the letter b) of smaller amplitude, corresponding to the secondary reflectors 20, 30, and 40. Outside the main reflector, an echo is observed emanating from plate E, also referenced by the letter c.

[0056] Figure 4B shows a C-scan map showing the time-of-flight of the detected echoes, i.e., the time between the transmission of the incident sound wave and the detection of the echo, rather than the spatial amplitude distribution. Thus, the grayscale levels indicate the time-of-flight and, therefore, the distance between each reflector and the ultrasonic sensor. It can be seen that the time-of-flight of the auxiliary echoes 102, 103, and 104 is smaller than that of the main echo 101. This is because the auxiliary reflectors are closer to the detection plane than the main reflector. In this configuration, the detection plane is parallel to the base of each target reflector, and because all the auxiliary reflectors share a common base, the time-of-flight of each auxiliary echo is equal, within the measurement uncertainty.

[0057] While FIG. 4A provides two-dimensional spatial information parallel to the detection plane, FIG. 4B provides access to depth information (ranging measurements) perpendicular to the detection plane.

[0058] 4A and 4B in combination estimates the position of the target in space. By position, we mean the location and / or orientation of the target. It is advantageously compared to a reference position of the target. By comparing the target position with the reference position during the examination phase, any movement of the target can be detected. The reference position may be established using a reference ultrasound measurement performed in a reference phase before (or preceding) the examination phase. It may be obtained theoretically, for example based on a three-dimensional model or drawing, and / or via other measurement modalities.

[0059] Figures 4C, 4D, and 4E show timing diagrams of the detected echoes reflected by the auxiliary reflector, the main reflector, and the plate E on which the target is fixed, respectively. In Figures 4C to 4E, the x-axis corresponds to time (in microseconds, μs), while the y-axis corresponds to amplitude (in arbitrary units). Figures 4C and 4E show The order of detection of reflected sound waves, where the echo of the secondary reflector (Figure 4C) is detected before the echo of the main reflector (Figure 4D), which is detected before the echo of the plate (Figure 4E). the difference in intensity between the various echoes, where it may be seen that the intensity of the echo of the auxiliary reflector is smaller than that of the main reflector or plate; can be observed.

[0060] Figures 5A and 5B are amplitude and time-of-flight C-scan maps, respectively, obtained by tilting the transducer transmit / detect face relative to the bottom surface of each reflector, which corresponds to a slight rotation of the target relative to the transducer transmit / detect face. In these figures, only the echoes of the secondary reflectors are shown. In these figures, The maximum amplitudes Amax of echoes 102, 103, and 104 are 0.273, 0.269, and 0.308, respectively. The times of flight t of echoes 102, 103, and 104 are 313.1 μs, 312.9 μs, and 312.3 μs, respectively. You can be sure of this.

[0061] Based on the wave speed in water, it is estimated that a 1 μs shift in time of flight corresponds to a distance of 0.7 mm.

[0062] It can be concluded that the secondary reflector 20 from which echo 102 originates is far from the transmitting / detecting plane (long time of flight), while the secondary reflector 40 from which echo 104 originates is closer.

[0063] Figure 5C illustrates the rotation of the target between a reference position, where each secondary reflector is represented by a black disk, and a measurement position, where each secondary reflector is represented by a ring, as adopted during the inspection phase. In this figure, the transmitting / detecting faces of the transducers are assumed to be parallel to the base of the main reflector. Comparison of the positions shows the rotation of the target between the reference and measurement positions about an axis of rotation perpendicular to the base of each reflector and passing through the apex of the main reflector.

[0064] Figure 6 shows the main steps of the implementation of a target as described above: the target is fixed to the equipment E whose position it is desired to inspect. The equipment in question may be, for example, an equipment of a nuclear reactor cooled by liquid sodium or liquid lead.

[0065] In step A, the transducer 50 is positioned facing the target 1, and incident sound waves are transmitted toward the target. 10 0° to the normal (the incident axis is the bottom surface P 10 The term "angle of incidence" refers to an angular range extending from the incident plane (perpendicular to the target) to ±25° or 30°. The smaller the angle of incidence, the stronger the echo. Preferably, the sound wave is a plane wave by the time it reaches the target. For sound waves, typically ultrasound, the acoustic frequency is between 20 kHz and 10 MHz.

[0066] In step B, the echoes generated by the target's main reflector and each of its secondary reflectors are detected. In this example, the detection is performed by the same transducer 50 acting as a transmitter in step A and as a receiver in step B.

[0067] In step C, the position (location and / or orientation) of the target 1 is estimated based on the echoes detected in step B. Typically, step C is performed by a processing unit using the measurements of the transmitting / receiving transducers 50. According to the principle of time-of-flight ranging, taking into account the propagation speed of sound waves, the distance between the transducers 50 and each reflector can be estimated by measuring the time-of-flight (the time interval between the transmission of an incident wave and the detection of a reflected wave). The processing unit is programmed to execute an algorithm for processing the acoustic signals.

[0068] In step D, the target position is compared to a reference position to estimate the target's motion between the reference position and the position estimated from the echoes measured in step B. The reference position may have been established by performing steps A, B, and C in a previous phase, called the referencing phase. Alternatively, the reference position may be established based on a drawing or a three-dimensional model.

[0069] According to one possibility, in step D, the distance between the transducer 50 and each reflector (main and secondary reflectors) is compared with a reference distance established for each reflector. If the measured distance does not match the reference distance, the processing unit generates an anomaly signal. The target position is then updated.

[0070] The present invention utilizes the echogenic characteristics of the target, facilitating the experimental determination of its position in space. Based on the comparison results in step D, it can be concluded whether the device to which the target is fixed has moved relative to the reference configuration. In particular, since the target is a paired structure and fixed to the device, the movement of the target reflects the movement of the device to which it is placed.

[0071] In all embodiments, the target comprises at least a primary reflector and at least one secondary reflector, and preferably the target comprises at least three secondary reflectors.

[0072] The number of auxiliary reflectors may vary depending on the number of degrees of freedom in which the target is considered to be able to move and / or on bulk constraints.

[0073] The invention can be used to inspect instruments or structures immersed in an opaque medium or that cannot be illuminated, and in particular instruments or structures submerged in a liquid, in particular an opaque liquid. The instrument in question may be covered by an opaque shield, which may be made of, for example, metal or plastic.

[0074] More generally, the invention can be applied to environments incompatible with conventional imaging means. For example, the environment in question may be one where temperatures or radiation levels are very high and remote operation is essential. The invention may also be used in the nuclear industry to inspect the integrity of structures. It may also be relevant in other industrial sectors where opaque fluids or complex equipment are used, such as the food processing industry, the chemical or oil and gas industry, or the aviation industry.

Claims

1. An ultrasonic target (1) comprising a main reflector (10), said main reflector comprising: It has three main faces (11, 12, 13) extending from a main vertex (S10) and forming a main right-angled trihedron; A major base (P10) is defined facing the major vertex and forming the base of the major right trihedron, The target comprises at least one sub-reflector (20, 30, 40) fixed to the main reflector (10), each sub-reflector comprising: The three auxiliary faces (21, 22, 23, 31, 32, 33, 41, 42, 43) extend from the auxiliary vertices (S20, S30, S40) and form an auxiliary right-angled trihedron; Auxiliary bases (P20, P3) facing the auxiliary vertices and forming the bases of the auxiliary right trihedron ０ , P ４０ ) has been established, The target is such that each auxiliary bottom surface is parallel to the main bottom surface (P １０ ) is parallel to Two adjacent main faces (11, 12) are connected by a ridge (10) extending from the main vertex (S10). ａ ) are divided into the at least one auxiliary reflector is an internal auxiliary reflector; The auxiliary vertex (S ２０ ) is located on the ridge, The internal auxiliary reflector is the adjacent main surfaces (11, 12) forming the auxiliary surfaces (21, 22) of the internal auxiliary reflector; a transverse auxiliary surface (23) extending between the adjacent main surfaces and parallel to the main surface (13) facing the adjacent main surfaces; is defined by target.

2. the or each auxiliary vertex (S20, S30, S40) is located at a distance relative to said major base (P10) that is different from the distance between said main vertex (S10) and said major base, said distance being measured perpendicular to said major base; The target of claim 1 .

3. at least two auxiliary reflectors fixed to the main reflector; A target according to claim 1 or 2.

4. Each auxiliary vertex (S20, S30, S40) is located at a position perpendicular to the main base. １０ ) are placed at the same distance from each other. A target according to any one of claims 1 to 3.

5. At least two auxiliary vertices (S20, S30, S40) are located at two different distances from the main vertex (S10), the distances being measured in a direction perpendicular to the main base. The target of claim 2.

6. Each reflector defines a volume defined by a surface forming the reflector and a bottom surface of the reflector, and the target is one in which the volumes defined by at least two reflectors selected from the main reflector (10) and one auxiliary reflector (20, 30, 40) are different. A target according to any one of claims 1 to 5.

7. a plurality of auxiliary reflectors (20, 30, 40), each of which is an internal reflector; A target according to any one of claims 1 to 6.

8. The main reflector (10) has the main surfaces (11, 12, 13) and the main bottom surface (P1 ０ ) defining an interior space located between the At least one auxiliary reflector (20, 30, 40) is arranged outside the interior space. A target according to any one of claims 1 to 6.

9. at least two auxiliary reflectors fixed to the main reflector, each auxiliary reflector being positioned outside the interior space; The target of claim 8.

10. 10. A method for detecting the movement of a target (1) according to any one of claims 1 to 9, wherein in the examination step: a) exposing the target to incident acoustic waves (100) emitted by an acoustic radiation source (50), the incident acoustic waves propagating along an axis of incidence (Δi), the axis of incidence being inclined at an angle of less than 30° with respect to a normal axis of the bottom surface of the target; b) following step a), detecting the acoustic waves (101, 102, 103, 194) reflected by the target, the reflected acoustic waves having a reflection axis (Δ ｒ ), and c) determining a position of the target based on the acoustic waves detected in step b), the position including a location and / or an orientation of the target; Including, d) considering a reference position including a reference position and / or a reference orientation of said target; e) comparing the target position obtained in step c) with the reference position; A detection method comprising:

11. f) estimating the movement of the target relative to the reference position based on the comparison result of step e); The detection method of claim 10, comprising:

12. The reference position is estimated by performing steps a), b) and c) before the inspection stage. The detection method according to claim 10 or 11.

13. The reference position is determined based on a drawing or a three-dimensional model. The detection method according to claim 10 or 11.

14. the target is fixed to an instrument or a structural element (E), and the method includes estimating the movement of the instrument or the structural element relative to a reference configuration; The detection method according to any one of claims 10 to 13.

Images