Structural soundness diagnostic system, diagnostic method, and aircraft structure

Abstract

The present invention relates to a structural soundness diagnosis system, a diagnosis method, and an aircraft structure, and aims to reduce constraints in structural soundness diagnosis of a structure and improve defect detection accuracy. A structural soundness diagnosis system of an embodiment performs structural soundness diagnosis of a structure having a plate-shaped first inspection area without a bent portion and a second inspection area including a bent plate-shaped portion, and includes: an ultrasonic transducer that oscillates ultrasonic waves in the first inspection area; an ultrasonic sensor that detects a waveform of at least one of a transmission wave of the ultrasonic wave that passes through the first inspection area and a reflected wave of the ultrasonic wave that is reflected in the first inspection area; a strain sensor that detects a strain amount in the second inspection area; and a signal processing unit that obtains an index representing the soundness of the structure including the first inspection area and the second inspection area based on the waveform detected by the ultrasonic sensor and the strain amount detected by the strain sensor.

Description

Technical Field

[0001] Embodiments of the present invention relate to a structural soundness diagnosis system, a structural soundness diagnosis method, and an aircraft structure. Background Art

[0002] At present, as one of the structural health monitoring (SHM) technologies for checking the health of structures such as aircraft structures, buildings, windmills, bridges, or pipelines, there is a known technology using ultrasound (for example, see Patent Documents 1, 2, and 3). In SHM using ultrasound, an exciter for oscillating ultrasound and an ultrasonic sensor such as an optical fiber for detecting the ultrasound waveform are installed on the structure, and by analyzing the change in the ultrasound waveform, it is diagnosed whether a defect such as damage has occurred in the structure and the degree of the defect.

[0003] On the other hand, as one of the SHM technologies, there is a known technology that detects the strain amount of a structure by using a strain sensor such as a strain gauge or an optical fiber sensor, analyzes the change in the strain amount, thereby monitoring the load borne on the structure and diagnosing whether defects such as damage have occurred in the structure (for example, refer to Patent Documents 4 and 5).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-173336

[0007] Patent Document 2: Japanese Patent Application Publication No. 2017-173191

[0008] Patent Document 3: International Publication No. 2017 / 175692

[0009] Patent Document 4: International Publication No. 2018 / 055827

[0010] Patent Document 5: Japanese Patent Application Publication No. 2018-146368 Summary of the invention

[0011] Problems to be solved by the invention

[0012] The current SHM method based on ultrasonic waveform changes has the following disadvantages: when ultrasonic waves are not oscillating, the structure cannot be inspected, and the structure part with a shape that does not propagate ultrasonic waves cannot be inspected. On the other hand, the current SHM method based on strain amount changes has the disadvantages of low sensitivity compared to ultrasonic waveform changes and the need to include a strain sensor in the inspection area.

[0013] Therefore, various restrictions are imposed in any case of adopting the SHM method using ultrasonic waves or the SHM method using strain sensors. As a result, there has been no progress in the practical application of the SHM technology, which has a wide inspection area and targets aircraft structures having complex shapes. In particular, in the case of aircraft structures made of fiber reinforced plastics (FRP: Fiber Reinforced Plastics) such as glass fiber reinforced plastics (GFRP: Glass Fiber Reinforced Plastics) or carbon fiber reinforced plastics (CFRP: Carbon Fiber Reinforced Plastics), although it is expected to detect abnormalities such as damage caused by collisions during the flight of the aircraft, all inspections are performed visually by inspectors before and after the flight.

[0014] Therefore, an object of the present invention is to reduce the constraints in SHM of a structure and improve the detection accuracy of defects.

[0015] Technical solutions to solve problems

[0016] A structural soundness diagnostic system according to an embodiment of the present invention performs structural soundness diagnosis of a structure having a first plate-shaped inspection area without a bent portion and a second plate-shaped inspection area including a bent portion, wherein the system comprises: an ultrasonic vibrator that oscillates ultrasonic waves in the first inspection area; an ultrasonic sensor that detects a waveform of at least one of a transmission wave of the ultrasonic wave that passes through the first inspection area and a reflection wave of the ultrasonic wave that is reflected in the first inspection area; a strain sensor that detects a strain amount in the second inspection area; and a signal processing unit that obtains an index representing the soundness of the structure including the first inspection area and the second inspection area based on the waveform detected by the ultrasonic sensor and the strain amount detected by the strain sensor.

[0017] Furthermore, the above-mentioned structural soundness diagnostic system is mounted on the aircraft structure according to the embodiment of the present invention.

[0018] Furthermore, the structural soundness diagnostic method according to the embodiment of the present invention performs structural soundness diagnosis of the structure using the above-mentioned structural soundness diagnostic system.

[0019] In addition, a structural soundness diagnosis method of an embodiment of the present invention performs structural soundness diagnosis of a structure having a first plate-shaped inspection area without a bent portion and a second plate-shaped inspection area including a bent portion, wherein the following steps are included: an ultrasonic vibrator oscillates ultrasonic waves in the first inspection area; an ultrasonic sensor detects a waveform of at least one of a transmission wave of the ultrasonic wave that passes through the first inspection area and a reflected wave of the ultrasonic wave that is reflected in the first inspection area; a strain sensor detects a strain amount in the second inspection area; and based on the waveform detected by the ultrasonic sensor and the strain amount detected by the strain sensor, an indicator representing the soundness of the structure including the first inspection area and the second inspection area is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a block diagram of a structural soundness diagnostic system according to an embodiment of the present invention.

[0021] Figure 2 Indicated by Figure 1 The illustrated diagram is a diagram of a first arrangement example of ultrasonic transducers and ultrasonic sensors when the ultrasonic inspection unit detects both a transmitted wave of an ultrasonic wave that has transmitted through a first inspection region and a reflected wave of an ultrasonic wave that has been reflected in the first inspection region.

[0022] Figure 3 Indicated by Figure 1 The illustrated diagram is a diagram of a second example of arrangement of ultrasonic transducers and ultrasonic sensors when the ultrasonic inspection unit detects both a transmitted wave of an ultrasonic wave that has transmitted through a first inspection region and a reflected wave of an ultrasonic wave that has been reflected in the first inspection region.

[0023] Figure 4 Indicated by Figure 1 The illustrated diagram is a diagram of a third arrangement example of ultrasonic transducers and ultrasonic sensors when the ultrasonic inspection unit detects both a transmitted wave of an ultrasonic wave that has transmitted through a first inspection region and a reflected wave of an ultrasonic wave that has been reflected in the first inspection region.

[0024] Figure 5 A circuit diagram showing an example of an optical signal circuit for outputting a physical quantity measured by an optical fiber sensor as an optical signal of transmitted light.

[0025] Figure 6 A circuit diagram showing an example of an optical signal circuit for outputting a physical quantity measured by an optical fiber sensor as an optical signal of reflected light.

[0026] Figure 7 A perspective view showing an example in which an ultrasonic transducer, an ultrasonic sensor, and a strain sensor are mounted on an aircraft structure.

[0027] Figure 8This is a plan view showing another example in which an ultrasonic transducer, an ultrasonic sensor, and a strain sensor are mounted on an aircraft structure.

[0028] Fig. 9 yes Figure 8 A side view of the aircraft structure is shown.

[0029] Fig.10 Indicates the use Figure 1 The structural soundness diagnosis system shown is a flowchart of an example of a flow when performing SHM of a structure. DETAILED DESCRIPTION

[0030] A structural soundness diagnostic system, a structural soundness diagnostic method, and an aircraft structure according to embodiments of the present invention will be described with reference to the accompanying drawings.

[0031] (Structural Soundness Diagnostic System)

[0032] Figure 1 It is a block diagram of a structural soundness diagnostic system according to an embodiment of the present invention.

[0033] The structural soundness diagnosis system 1 is a system for performing SHM on a structure O, which has a first inspection area I1 in a plate shape without a bent portion and a second inspection area I2 including a bent plate-like portion. The first inspection area I1 and the second inspection area I2 may overlap each other partially, or may be areas that do not overlap each other at all. Therefore, the first inspection area I1 and the second inspection area I2 may be areas that do not overlap at least partially including a bent plate-like portion.

[0034] As an example of a structure O having a plate-shaped first inspection area I1 without a bent portion and a second inspection area I2 including a bent plate-shaped portion, there can be cited an aircraft structure in which a reinforcement member composed of at least one of a longitudinal beam (longitudinal through-material), a spar (cross beam), a rib (wing rib), and a frame is attached to a panel (outer panel). Therefore, the structural soundness diagnostic system 1 is attached to a structure O such as an aircraft structure having a structure in which a panel is reinforced by a reinforcement member.

[0035] The structural soundness diagnosis system 1 is configured to perform SHM of the first inspection area I1 and the second inspection area I2 by performing ultrasonic inspection of the first inspection area I1 and measuring the strain amount in the second inspection area I2. Therefore, the structural soundness diagnosis system 1 includes an ultrasonic inspection unit 2 for performing ultrasonic inspection of the first inspection area I1, a strain amount detection unit 3 for measuring the strain amount of the second inspection area I2, and a signal processing unit 4.

[0036] The ultrasonic inspection unit 2 is composed of an ultrasonic vibrator 5 such as piezoelectric ceramics that oscillates ultrasonic waves in the first inspection area I1, an ultrasonic sensor 6 that detects the waveform of at least one of the transmitted wave of the ultrasonic wave that passes through the first inspection area I1 and the reflected wave of the ultrasonic wave reflected in the first inspection area I1, and a control circuit 7 that controls the ultrasonic vibrator 5 and includes a circuit such as a pulse device that oscillates ultrasonic waves in the first inspection area I1. On the other hand, the strain amount detection unit 3 has a strain sensor 8.

[0037] When ultrasonic inspection of a plate is performed, Lamb waves are particularly preferred from the viewpoint of improving the signal-to-noise ratio (SNR) and accuracy. Therefore, it is preferred that the ultrasonic vibrator 5 of the ultrasonic inspection unit 2 oscillates Lamb waves as ultrasonic waves. Lamb waves are waves that propagate in a thin plate that are less than half the wavelength of ultrasonic waves and are waves that mix symmetric modes and asymmetric modes.

[0038] In the case where the ultrasonic sensor 6 detects only the transmitted wave of the ultrasonic wave that passes through the first inspection area I1, the ultrasonic vibrator 5 and the ultrasonic sensor 6 are arranged opposite to each other with the first inspection area I1 sandwiched therebetween so that the ultrasonic wave oscillated from the ultrasonic vibrator 5 and propagated in the first inspection area I1 can be received by the ultrasonic sensor 6. In the case where the ultrasonic sensor 6 detects only the reflected wave of the ultrasonic wave reflected in the first inspection area I1, for example, the ultrasonic vibrator 5 and the ultrasonic sensor 6 can be arranged at positions close to each other so that the reflected ultrasonic wave oscillated from the ultrasonic vibrator 5 and reflected in the first inspection area I1 can be received by the ultrasonic sensor 6. Alternatively, the ultrasonic vibrator 5 can be used as the ultrasonic sensor 6, and the ultrasonic vibrator 5 and the ultrasonic sensor 6 can also be composed of a common ultrasonic vibrator.

[0039] When detecting both the transmitted wave of the ultrasound wave penetrating the first inspection area I1 and the reflected wave of the ultrasound wave reflected in the first inspection area I1, multiple ultrasonic sensors 6 may be configured for each ultrasonic vibrator 5, or vice versa, multiple ultrasonic vibrators 5 may be configured for each ultrasonic sensor 6.

[0040] Figure 2 It means that Figure 1 The illustrated diagram is a first arrangement example of the ultrasonic transducers 5 and the ultrasonic sensors 6 when the ultrasonic inspection unit 2 detects both the transmitted wave of the ultrasonic wave that has passed through the first inspection region I1 and the reflected wave of the ultrasonic wave that has been reflected in the first inspection region I1 .

[0041] like Figure 2As shown, if the ultrasonic vibrator 5 and the first ultrasonic sensor 6A are arranged opposite to each other with the first inspection area I1 sandwiched therebetween, and the second ultrasonic sensor 6B is arranged side by side near the ultrasonic vibrator 5, the transmitted wave of the ultrasonic wave that passes through the first inspection area I1 can be detected by the first ultrasonic sensor 6A, and on the other hand, the reflected wave of the ultrasonic wave reflected in the first inspection area I1 can be detected by the second ultrasonic sensor 6B.

[0042] Figure 3 It means that Figure 1 The illustrated diagram is a second example of arrangement of the ultrasonic transducers 5 and the ultrasonic sensors 6 when the ultrasonic inspection unit 2 detects both the transmitted wave of the ultrasonic wave that has passed through the first inspection region I1 and the reflected wave of the ultrasonic wave that has been reflected by the first inspection region I1 .

[0043] like Figure 3 As shown, if the first ultrasonic vibrator 5A and the ultrasonic sensor 6 are arranged opposite to each other with the first inspection area I1 sandwiched therebetween, and the second ultrasonic vibrator 5B is arranged side by side near the ultrasonic sensor 6, the ultrasonic sensor 6 can detect the ultrasonic wave that oscillates from the first ultrasonic vibrator 5A and passes through the first inspection area I1, and on the other hand, the ultrasonic sensor 6 can detect the ultrasonic wave that oscillates from the second ultrasonic vibrator 5B and is reflected from the first inspection area I1.

[0044] Figure 4 It means by Figure 1 The illustrated diagram is a diagram of a third arrangement example of the ultrasonic transducer 5 and the ultrasonic sensor 6 when the ultrasonic inspection unit 2 detects both the transmitted wave of the ultrasonic wave that has passed through the first inspection region I1 and the reflected wave of the ultrasonic wave that has been reflected in the first inspection region I1.

[0045] like Figure 4 As shown, the first ultrasonic vibrator 5A and the second ultrasonic vibrator 5B can be arranged opposite to each other with the first inspection area I1 sandwiched therebetween. In this way, the ultrasonic wave oscillated from one of the first ultrasonic vibrator 5A and the second ultrasonic vibrator 5B and transmitted through the first inspection area I1 can be detected by the other of the first ultrasonic vibrator 5A and the second ultrasonic vibrator 5B. That is, the other of the first ultrasonic vibrator 5A and the second ultrasonic vibrator 5B can be used as the ultrasonic sensor 6.

[0046] In addition, if the first ultrasonic vibrator 5A is used as the ultrasonic sensor 6, the ultrasonic wave oscillated from the first ultrasonic vibrator 5A and reflected in the first inspection area I1 can be detected by the first ultrasonic vibrator 5A also functioning as the ultrasonic sensor 6. Similarly, if the second ultrasonic vibrator 5B is used as the ultrasonic sensor 6, the ultrasonic wave oscillated from the second ultrasonic vibrator 5B and reflected in the first inspection area I1 can be detected by the second ultrasonic vibrator 5B also functioning as the ultrasonic sensor 6.

[0047] When the first inspection area I1 is wide, a plurality of ultrasonic transducers 5 and a plurality of ultrasonic sensors 6 may be arranged so as to be able to divide one first inspection area I1 into a plurality of sub-areas to cover the first inspection area I1. In other words, a plurality of first inspection areas I1 may be overlapped with each other, and at least one ultrasonic transducer 5 and at least one ultrasonic sensor 6 may be arranged in each first inspection area I1. In this case, ultrasonic inspection can be performed based on the waveforms of a plurality of ultrasonic waves obtained from the overlapping common areas.

[0048] As the ultrasonic sensor 6, in addition to an ultrasonic transducer capable of transmitting and receiving ultrasonic waves, an optical fiber sensor that does not oscillate ultrasonic waves but only detects ultrasonic waves can also be used. Examples of optical fiber sensors include FBG sensors and phase-shifted FBG (PS-FBG: Phase-shifted FBG) sensors. In addition, PS-FBG is an FBG that introduces a local phase shift into the periodic variation of the refractive index.

[0049] When an optical fiber sensor is used as the ultrasonic sensor 6, a light source for irradiating laser light to the optical fiber sensor and necessary optical elements are connected to the optical fiber sensor. The signal representing the ultrasonic waveform detected by the optical fiber sensor may be transmitted light or reflected light of the optical fiber sensor.

[0050] Figure 5 1 is a circuit diagram showing an example of an optical signal circuit when the physical quantity measured by the optical fiber sensor 10 is output as an optical signal of transmitted light.

[0051] like Figure 5 As shown in FIG. 1 , when an optical fiber sensor 10 such as an FBG sensor or a PS-FBG sensor is mounted on an object, the wavelength distribution of the transmitted light from the optical fiber sensor and the wavelength distribution of the reflected light change according to the displacement generated on the object. Therefore, if a light source 11 is connected to one end of the optical fiber sensor 10 and a light detector 12 is connected to the other end of the optical fiber sensor 10, the displacement of the object can be detected as the wavelength change of the transmitted light from the optical fiber sensor 10 detected by the detector 12. That is, the displacement of the object is converted into the wavelength change of the transmitted light from the optical fiber sensor 10, and an optical signal is output from the optical fiber sensor 10 as the transmitted light with a changed wavelength.

[0052] Therefore, if the optical fiber sensor 10 is arranged at the ultrasonic wave detection position, the vibration of the micro displacement of the structure O caused by the ultrasonic wave is converted into the vibration of the wavelength of the transmitted light, and the ultrasonic wave waveform can be detected as the waveform of the wavelength vibration of the transmitted light from the optical fiber sensor 10. Of course, a desired optical element such as an optical filter for removing noise of the optical signal can also be connected.

[0053] Figure 6 1 is a circuit diagram showing an example of an optical signal circuit when the physical quantity measured by the optical fiber sensor 10 is output as an optical signal of reflected light.

[0054] like Figure 6 As shown in FIG. 1 , if an optical circulator 13 is connected to one end of the optical fiber sensor 10, a light source 11 is connected to the input port of the optical circulator 13, and a light detector 12 is connected to the output port of the optical circulator 13, the reflected light of the optical fiber sensor 10 can be detected by the light detector 12. Therefore, the displacement amount of the object can be detected as the wavelength change amount of the reflected light from the optical fiber sensor 10 detected by the light detector 12. That is, the displacement amount of the object is converted into the wavelength change amount of the reflected light from the optical fiber sensor 10, and the optical signal is output from the optical fiber sensor 10 as the reflected light with a changed wavelength.

[0055] Therefore, if the optical fiber sensor 10 is arranged at the ultrasonic wave detection position, the vibration of the micro displacement of the structure O caused by the ultrasonic wave is converted into the vibration of the wavelength of the reflected light, and the ultrasonic wave waveform can be detected as the waveform of the wavelength vibration of the reflected light from the optical fiber sensor 10. Of course, a desired optical element such as an optical filter for removing noise of the optical signal can also be connected.

[0056] In this way, in the ultrasonic inspection unit 2, the ultrasonic sensor 6 such as the optical fiber sensor 10 detects the waveform of the ultrasonic wave in the first inspection region I1, while the strain amount detection unit 3 measures the strain amount in the second inspection region I2.

[0057] The strain amount detection unit 3 is composed of a strain sensor 8 for detecting the strain amount of the second inspection area I2 and necessary circuit elements corresponding to the type of the strain sensor 8. As the strain sensor 8, a strain gauge may be used, but the above-mentioned optical fiber sensor 10 can be used as a highly sensitive strain sensor 8.

[0058] That is, if the optical fiber sensor 10 is installed in the second inspection area I2, since the optical transmission characteristics and optical reflection characteristics of the optical fiber sensor 10 change according to the amount of strain in the second inspection area I2, the amount of strain in the second inspection area I2 can be output as an optical signal of transmitted light or reflected light from the optical fiber sensor 10. In this case, if the following known methods such as using a wide-band laser, connecting in series a plurality of optical fiber sensors 10 that transmit or reflect light in different wavelength bands, and multiplexing optical signals output from the plurality of optical fiber sensors 10 are adopted, an optical signal indicating the position and amount of strain generated in the second inspection area I2 can be obtained.

[0059] As described above, in the ultrasonic inspection unit 2, the ultrasonic inspection is performed on the plate-shaped first inspection area I1 without a bent portion. Therefore, the ultrasonic vibrator 5 and the ultrasonic sensor 6 of the ultrasonic inspection unit 2 are installed in the plate-shaped first inspection area I1 without a bent portion. On the other hand, the strain amount in the second inspection area I2 including the bent plate-shaped portion is measured by the strain amount detection unit 3. Therefore, the strain sensor 8 of the strain amount detection unit 3 is installed in the second inspection area I2 including the bent plate-shaped portion.

[0060] The reason why the first plate-shaped inspection area I1 without a bent portion is subjected to ultrasonic inspection and the second inspection area I2 including a bent plate-shaped portion is subjected to strain measurement is because of the following two disadvantages and advantages: On the one hand, since ultrasonic waves such as Lamb waves propagate over a wide range, a wide area can be inspected compared to strain inspection. On the other hand, if the medium is not flat or has a very small curvature, ultrasonic waves cannot propagate with sufficient intensity. Therefore, parts with complex shapes cannot be inspected with sufficient accuracy. On the other hand, the strain sensor 8 can detect the strain of objects with complex shapes. On the other hand, compared to ultrasonic inspection, the strain can only be detected within a narrow range.

[0061] Therefore, based on the characteristics of Lamb waves and the variation characteristics of the strain amount, a plate-like area that is wider than the second inspection area I2 and has no bent part is determined as the first inspection area I1. On the other hand, determining the area including the bent plate-like part as the second inspection area I2 is a reasonable method for determining the inspection area using the characteristics of each physical quantity, wherein the above-mentioned characteristics of Lamb waves refer to: especially when Lamb waves are used as ultrasonic waves, they propagate over a wide range compared to the variation of the strain amount, whereas at the bent plate-like part, the attenuation of the amplitude is large compared to the variation of the strain amount; the above-mentioned variation characteristics of the strain amount refer to: compared with the Lamb wave, the attenuation of the amplitude at the bent plate-like part is small, whereas, compared with the Lamb wave, it propagates over a narrow range.

[0062] Figure 7 It is a perspective view showing an example of attaching the ultrasonic transducer 5 , the ultrasonic sensor 6 , and the strain sensor 8 to the aircraft structure O1 .

[0063] like Figure 7For example, an ultrasonic oscillator 5, an ultrasonic sensor 6, and a strain sensor 8 can be installed on an aircraft structure O1 obtained by strengthening a panel O2 with a hat-shaped stringer O3 having a hat-shaped cross section. The panel O2 has a flat or slightly curved plate-like structure. Therefore, the ultrasonic oscillator 5 and the ultrasonic sensor 6 are installed on the panel O2 so that ultrasonic inspection can be performed on the first inspection area I1 of the panel O2. On the other hand, the hat-shaped stringer O3 has a complex shape including a bent plate-like portion. Therefore, the strain sensor 8 is installed on the hat-shaped stringer O3 so that the strain amount can be measured with respect to the second inspection area I2 of the hat-shaped stringer O3.

[0064] In Figure 7 In the example shown, a first fiber optic sensor 10A is installed on the panel O2 as the ultrasonic sensor 6, and a second fiber optic sensor 10B is installed on the hat-shaped stringer O3, which is subjected to a load larger than that of the panel O2, as the strain sensor 8. In addition, since a part of the panel O2 also exists inside the hat-shaped stringer O3, the ultrasonic oscillator 5 and the ultrasonic sensor 6 are arranged for ultrasonic inspection.

[0065] Of course, not limited to the hat-shaped stringer O3, the ultrasonic oscillator 5, the ultrasonic sensor 6, and the strain sensor 8 are installed on an aircraft structure O1 obtained by installing variously shaped stiffeners such as I-shaped stringers or T-shaped stringers on the panel O2, and both ultrasonic inspection and strain amount measurement can be performed.

[0066] Figure 8 FIG. is a plan view showing another example of installing the ultrasonic oscillator 5, the ultrasonic sensor 6, and the strain sensor 8 on the aircraft structure O1. Fig. 9 is Figure 8 a side view of the aircraft structure O1 shown.

[0067] As Figure 8 and Fig. 9 For example, the aircraft structure O1 constituting the fuselage of a typical aircraft has a structure in which a plurality of frames O4 and a plurality of stringers O5 are installed on the panel O2. Therefore, a plurality of plate-like regions surrounded by adjacent frames O4 and stringers O5 are formed on the aircraft structure O1 constituting the fuselage.

[0068] In the aircraft structure O1 constituting such a fuselage, the strain sensor 8 is installed on each frame O4 and each stringer O5 that are subjected to a load and have a complex shape. On the other hand, the ultrasonic oscillator 5 and the ultrasonic sensor 6 can be installed on a part of the panel O2 surrounded by the frame O4 and the stringer O5.

[0069] In Figure 8In the example shown, a first optical fiber sensor 10A is installed as an ultrasonic sensor 6 on the portion of the panel O2 surrounded by the frame O4 and the longitudinal beam O5, and a second optical fiber sensor 10B is installed as a strain sensor 8 on the upper surface of the frame O4 and the longitudinal beam O5 having an inverted T-shaped cross section.

[0070] In this way, by installing the strain sensor 8 on the reinforcement member such as the longitudinal beam, wing spar, rib or frame, and installing the ultrasonic vibrator 5 and the ultrasonic sensor 6 on the panel, the SHM of the aircraft structure O1 including the first inspection area I1 and the second inspection area I2 can be performed by ultrasonically inspecting the panel including the first inspection area I1 and measuring the strain amount of the reinforcement member including the second inspection area I2. The same is true for the structure O other than the aircraft structure O1.

[0071] In addition, when SHM is performed on a structure O having a structure with a reinforcement member installed on a panel, the method is not limited to bonding the strain sensor 8 to the surface of the reinforcement member. For example, as described in Japanese Patent Application Laid-Open No. 2017-173191, the strain sensor 8 can also be installed on the reinforcement member by embedding it in the reinforcement member and clamping it between the reinforcement member and the panel. In addition, when a strain sensor 8 such as an optical fiber sensor 10 is sandwiched between the reinforcement member and the panel, the strain sensor 8 can also be embedded on the panel side to measure the strain amount of the reinforcement. In this case, the strain amount of both a part of the reinforcement member and a part of the panel can be measured by the strain sensor 8, so the area including a part of the reinforcement member and a part of the panel can also be set in the second inspection area I2.

[0072] The SHM of the structure O can be performed by obtaining an index indicating the soundness of the structure O. The signal processing unit 4 is a signal processing circuit that obtains an index indicating the soundness of the structure O including the first inspection area I1 and the second inspection area I2 based on the waveform of the ultrasonic wave from the first inspection area I1 detected by the ultrasonic sensor 6 and the strain amount of the second inspection area I2 detected by the strain sensor 8.

[0073] The detection signal of the ultrasonic waveform is outputted from the ultrasonic sensor 6 as an electrical signal or an optical signal. On the other hand, the detection signal of the strain amount of the second inspection area I2 is also outputted from the strain sensor 8 as an electrical signal or an optical signal. Figure 5 and Figure 6 The signal processing unit 4 is composed of a photodetector 12 for converting an optical signal into an electrical signal, an A / D (analog-to-digital) converter for converting an analog electrical signal into a digital electrical signal, and a computer for processing the digital electrical signal. In addition, an optical element such as an optical filter for processing the optical signal may be provided in the signal processing unit 4.

[0074] Specific examples of indices useful for the soundness of the SHM of the structure O include indices indicating whether damage has occurred in the structure O, whether cracks have occurred in the structure O, whether peeling has occurred in the FRP constituting the structure O, and the degree of defects generated in the structure O. Therefore, in the signal processing unit 4, at least one of these indices can be obtained.

[0075] The signal processing unit 4 performs desired signal processing on the waveform signal of the ultrasonic wave detected from the first inspection region I1 and the strain amount of the second inspection region I2, thereby obtaining inspection information including SHM, which is an index indicating soundness.

[0076] For example, if the waveform of the ultrasonic wave detected from the first inspection area I1 is analyzed and abnormal waveform changes of the ultrasonic wave are detected, the presence or absence of defects such as damage, cracks or peeling in the first inspection area I1 can be detected. As a more specific example, the signal waveform obtained by averaging the waveform signal of the ultrasonic wave detected from the first inspection area I1 (averaging processing), filtering processing such as LPF (Low Pass Filter) or HPF (High Pass Filter) for removing noise, envelope detection processing, Fourier transform processing, and frequency analysis processing such as wavelet transform are compared with a reference waveform equivalent to the signal waveform when there is no defect in the first inspection area I1. When the signal waveform detected from the first inspection area I1 deviates from the reference waveform by more than a threshold value, it is determined that a defect has occurred in the first inspection area I1, and the waveform of the ultrasonic wave passing through the first inspection area I1 has changed due to the influence of the generated defect.

[0077] In addition, if the waveform of the reflected wave of the ultrasonic wave is detected from the first inspection area I1, the position of the defect can be inferred by notifying the signal processing unit 4 from the control circuit 7 of the ultrasonic vibrator 5 when the ultrasonic wave is oscillated from the ultrasonic vibrator 5 toward the first inspection area I1, and measuring the elapsed time from the moment when the ultrasonic vibrator 5 oscillates the ultrasonic wave to the peak moment of the reflected wave detected by the ultrasonic sensor 6.

[0078] When the structure O is an aircraft structure O1, the first inspection area I1 is subjected to aerodynamic loads and vibrates during the flight of the aircraft. The vibration mode of the first inspection area I1 during the flight of the aircraft changes dynamically according to various flight conditions such as the speed and altitude of the aircraft that change moment by moment.

[0079] Therefore, a feature quantity representing the vibration of the first inspection area I1 corresponding to the flight conditions of the aircraft is obtained in advance, and signal processing is performed to remove the vibration of the first inspection area I1 caused by the aircraft flight from the ultrasonic vibration, thereby enabling ultrasonic inspection during the aircraft flight. The vibration according to the flight conditions of the aircraft varies according to the flight conditions, so it is not limited to simulation and experiment, and can also be obtained statistically by machine learning. This is also the case when the structure O is a mobile body other than the aircraft structure O1 such as an automobile.

[0080] On the other hand, if the change in the strain amount of the second inspection area I2 is analyzed, it is possible to detect the presence or absence of defects such as damage, cracks, or peeling in the second inspection area I2. As a more specific example, the measured value of the strain amount in the second inspection area I2 is compared with the reference value of the strain amount when there is no defect in the second inspection area I2. When the measured value of the strain amount deviates from the reference value of the strain amount by exceeding a threshold value, it can be determined that a defect has occurred in the second inspection area I2, and the strain amount in the second inspection area I2 has increased due to the influence of the generated defect.

[0081] When the structure O is an aircraft structure O1, the second inspection area I2 is deformed by the aerodynamic load during the flight of the aircraft, and the strain amount of the second inspection area I2 changes. The strain amount of the second inspection area I2 during the flight of the aircraft also changes dynamically according to various flight conditions such as the speed and altitude of the aircraft that change every moment, similar to the vibration mode in the first inspection area I1.

[0082] Therefore, the variation of the strain amount in the second inspection area I2 corresponding to the flight conditions of the aircraft is obtained in advance, and by performing signal processing to remove the variation of the strain amount in the second inspection area I2 caused by the flight of the aircraft from the strain amount in the second inspection area I2 measured by the strain sensor 8, the strain amount in the second inspection area I2 caused only by the defect can be extracted during the flight of the aircraft. The variation of the strain amount in the second inspection area I2 obtained according to the flight conditions of the aircraft varies according to the flight conditions, just like vibration, and therefore is not limited to simulation and experiment, and can also be obtained statistically by machine learning. This is also the case when the structure O is a mobile body other than the aircraft structure O1 such as an automobile.

[0083] In the case where the strain sensor 8 is an optical fiber sensor 10, the measured value of the strain amount in the second inspection area I2 is obtained by analyzing the waveform signal representing the wavelength spectrum of the transmitted light or reflected light from the optical fiber sensor 10 output from the optical detector 12. That is, the measured value of the strain amount in the second inspection area I2 is expressed as the change in the peak wavelength of the signal waveform representing the wavelength spectrum of the transmitted light or reflected light output from the optical fiber sensor 10. Therefore, it is also possible to perform signal processing such as averaging processing, filtering processing, and frequency analysis processing similar to the signal processing performed on the waveform signal of the ultrasonic wave on the signal output from the optical detector 12.

[0084] In addition, when multiple strain gauges are arranged at different positions or when the optical fiber sensor 10 detects the strain amount at multiple positions, the strain amount at multiple positions in the second inspection area I2 is measured. Therefore, based on the strain amount in the second inspection area I2, not only the presence or absence of defects but also the location of the defects can be obtained. In addition, if the change in the strain amount over time is measured, the degree of progress of the defect can also be understood.

[0085] When the second inspection area I2 to be the object of strain measurement is very close to the defect generated in the first inspection area I1 to be the object of ultrasonic inspection, the measured value of the strain in the second inspection area I2 also changes slightly due to the influence of the defect generated in the first inspection area I1. Therefore, based on the measured value of the strain in the second inspection area I2, it is possible to infer not only whether there is a defect in the second inspection area I2, but also whether there is a defect in the first inspection area I1.

[0086] Therefore, the signal processing unit 4 can be provided with a function of determining whether a defect is likely to occur in the first inspection area I1 based on the measured value of the strain amount in the second inspection area I2 detected by the strain sensor 8. Specifically, when a slight change in the strain amount to the extent that it is determined that no defect occurs in the second inspection area I2 is detected by threshold processing, it can be determined that a defect is likely to occur in the first inspection area I1 close to the position where the slight change in the strain amount is detected.

[0087] When the optical fiber sensor 10 is used as the strain sensor 8, Figure 7 and Figure 8 For example, in order to measure the strain amount in a wider second inspection area I2 by a common optical fiber sensor 10, the length of the optical fiber sensor 10 is sometimes lengthened so that only a part of the optical fiber sensor 10 is near the first inspection area I1, and sometimes multiple parts of the optical fiber sensor 10 are near different first inspection areas I1. This is also the case when multiple strain gauges are arranged at different positions as the strain sensor 8.

[0088] Therefore, by dividing the second inspection region I2 into a plurality of regions, it is possible to determine whether a defect is likely to occur in the first inspection region I1 based on the strain amount in the region closest to the first inspection region I1 among the plurality of regions.

[0089] As a specific example, Figure 7 As shown, if a common optical fiber sensor 10 is arranged in a Z shape along the ridgelines of two convex fold sides (mountain fold sides) and two concave fold sides (valley fold sides) on the outside of the cap-shaped longitudinal beam O3, then two portions of the optical fiber sensor 10 arranged along the ridgelines of the two concave fold sides are respectively adjacent to portions of the panel O2 on both sides of the cap-shaped longitudinal beam O3 and portions of the panel O2 on the inside of the cap-shaped longitudinal beam O3.

[0090] Therefore, the second inspection area I2 can be divided into a first area R1 along the ridgeline of one concave fold side of the cap-shaped longitudinal beam O3, a second area R2 along the ridgeline of the other concave fold side, and another area R3. Furthermore, when the strain amount in either of the first and second areas R1 and R2 along the ridgeline of the concave fold side increases to such an extent that it cannot be determined that a defect has occurred in the first and second areas R1 and R2, it can be determined that either of the first inspection area I1 set in the panel O2 close to the side of the cap-shaped longitudinal beam O3 and the first inspection area I1 set in the panel O2 on the inner side of the cap-shaped longitudinal beam O3 may have a defect.

[0091] As another specific example, Figure 8 As shown, if a single or multiple optical fiber sensors 10 are arranged in a grid shape, the second inspection area I2 set in the multiple frames O4 and the multiple longitudinal beams O5 can be divided into multiple areas at the positions where the optical fiber sensors 10 intersect each other. In addition, when the strain amount increases to such an extent that it cannot be determined that a defect has occurred in one of the multiple areas constituting the second inspection area I2, it can be determined that a defect may occur in at least one of the two first inspection areas I1 set in the rectangular area of ​​the panel O2 formed on both sides of the frame O4 or the longitudinal beam O5 where the strain amount increases.

[0092] The measurement of the strain amount by the optical fiber sensor 10 can be continued as long as light is incident on the optical fiber sensor 10 from the light source 11. In addition, the measurement of the strain amount by the resistance strain gauge that detects the strain amount as a change in resistance can be continued as long as a voltage is applied to the strain gauge from a power supply. Therefore, the inspection such as the detection of defects in the second inspection area I2 caused by the measurement of the strain amount in the second inspection area I2 and the determination of whether defects may occur in the first inspection area I1 can be continued by setting the strain sensor 8 to the working state.

[0093] On the other hand, in order to perform ultrasonic inspection of the first inspection area I1, it is necessary to oscillate ultrasonic waves from the ultrasonic vibrator 5. As long as the oscillation interval of the ultrasonic waves is set short and the ultrasonic waves are oscillated intermittently at a certain interval, the ultrasonic inspection can be continued intermittently. However, in order to reduce power consumption, it is desirable to set the oscillation interval of the ultrasonic waves to be longer.

[0094] Therefore, the oscillation of ultrasonic waves is not manually performed by operating the input device 7A connected to the control circuit 7 of the ultrasonic vibrator 5, or is automatically performed at a certain interval determined in a manner to reduce power consumption. Instead, the determination of whether a defect is likely to occur in the first inspection area I1 can be continued by measuring the strain amount in the second inspection area I2. In addition, when it is determined that a defect is likely to occur in the first inspection area I1, the ultrasonic inspection of the first inspection area I1 can be performed. Thus, the disadvantage of ultrasonic inspection that requires energy for continuous inspection can be compensated by the inspection of the strain amount that can be easily continued.

[0095] The ultrasonic inspection in the first inspection area I1 can be automatically started based on the measurement result of the strain amount in the second inspection area I2. In this case, in the signal processing unit 4, when it is determined that a defect may occur in the first inspection area I1 based on the strain amount of the second inspection area I2 detected by the strain sensor 8, the control circuit 7 of the ultrasonic vibrator 5 can be controlled by the signal processing unit 4 to control the ultrasonic vibrator 5 to oscillate ultrasonic waves in the first inspection area I1. That is, the determination result in the signal processing unit 4 that a defect may occur in the first inspection area I1 is used as a trigger to oscillate ultrasonic waves from the ultrasonic vibrator 5 in the first inspection area I1.

[0096] As a specific example, if Figure 7 If the strain of the cap-shaped longitudinal beam O3 shown in FIG. 1 is slightly increased, it is determined that at least one of the panels O2 on both sides is suspected of being defective, and ultrasonic inspection of one or both of the panels O2 on both sides can be performed. Figure 8 When the strain of the frame O4 or longitudinal beam O5 shown in the figure increases slightly locally, it is determined that at least one of the rectangular portions of the panel O2 on both sides of the portion where the strain increases is suspected to be defective, and ultrasonic inspection of the rectangular portions of the panel O2 on both sides can be performed.

[0097] As described above, in the case of ultrasonic inspection based on the ultrasonic reflected wave reflected in the first inspection area I1, the position of the defect in the first inspection area I1 can be calculated based on the peak time and sound speed of the ultrasonic reflected wave, etc. In contrast, in the case of ultrasonic inspection based only on the waveform of the ultrasonic wave that passes through the first inspection area I1, it is difficult to find the position of the defect in the first inspection area I1 unless a plurality of ultrasonic transducers 5 and ultrasonic sensors 6 are closely arranged.

[0098] However, as described above, the amount of strain in the second inspection area I2 is sometimes affected by the defect generated in the first inspection area I1 that is the target of ultrasonic inspection and changes. It is believed that the distribution of the amount of strain that changes in the second inspection area I2 changes depending on the position of the defect generated in the first inspection area I1. Specifically, it is believed that the closer the position in the second inspection area I2 is to the position of the defect generated in the first inspection area I1, the greater the change in strain.

[0099] Therefore, regardless of whether it is determined in advance that a defect is likely to occur in the first inspection area I1 based on the strain amount in the second inspection area I2, the result of the ultrasonic inspection with the first inspection area I1 as the object is: in the signal processing unit 4, when it is determined that a defect has occurred in the first inspection area I1 based on the waveform of the ultrasonic wave detected by the ultrasonic sensor 6, the defect generation area in the first inspection area I1 can be estimated based on the distribution of the strain amount of the second inspection area I2 detected by the strain sensor 8.

[0100] As a specific example of easy analysis based on strain distribution, the following process can be cited: the defect generation region is narrowed down to a region within the first inspection region I1 whose position is closest to the position of the second inspection region I2 where the strain amount becomes a peak value compared with other positions within the second inspection region I2. In this case, for example, a region having a fan-shaped shape or a region in which a part of the fan is cut off is extracted from the first inspection region I1 as the defect generation region.

[0101] As a specific example of complex analytical processing based on strain distribution, the following processing can be cited: repeated simulations and experiments are performed to obtain the relationship between the position of the defect in the first inspection area I1 and the distribution of the strain amount in the second inspection area I2, and the relationship is stored in a storage device as a table or function, and the defect generation area is estimated based on the reference information stored in the storage device and the distribution of the strain amount actually measured. In this case, the estimation accuracy can be improved by machine learning methods, etc.

[0102] (Structural Soundness Diagnosis Method)

[0103] Next, a structural soundness diagnostic method for performing SHM of the structure O using the structural soundness diagnostic system 1 will be described.

[0104] Fig.10 It means use Figure 1 The structural soundness diagnostic system 1 shown is a flowchart of an example of a flow when performing SHM of a structure O.

[0105] First, in step S1, ultrasonic inspection is performed in a first plate-shaped inspection area I1 without a bent portion and strain measurement is performed in a second plate-shaped inspection area I2 including a bent portion. Figure 1 The ultrasonic inspection unit 2 shown obtains at least one of the waveform of the ultrasonic wave transmitted through the first inspection region I1 and the waveform of the ultrasonic wave reflected by the first inspection region I1. Meanwhile, the strain detection unit 3 measures the strain amount in the second inspection region I2.

[0106] More specifically, an electrical signal is applied from the control circuit 7 of the ultrasonic inspection unit 2 to the ultrasonic vibrator 5 manually or automatically at regular intervals by operating the input device 7A. Figures 7 to 9 For example, an ultrasonic wave is oscillated from an ultrasonic transducer 5 disposed in a structure O such as an aircraft structure O1. The oscillated ultrasonic wave propagates in a plate-shaped first inspection area I1 having no bent portion, such as a panel O2 of the aircraft structure O1. Figures 2 to 4 For example, at least one of the waveform of the ultrasonic wave transmitted through the first inspection area I1 and the waveform of the ultrasonic wave reflected from the first inspection area I1 is determined by Figure 7 Or the first optical fiber sensor 10A shown in 8 or the ultrasonic sensor 6 for detection.

[0107] The ultrasonic sensor 6 is Figure 5 or Figure 6 In the case of the optical fiber sensor 10 shown in the example, a broadband laser or the like is emitted from the light source 11 to the optical fiber sensor 10. In addition, an ultrasonic waveform signal is output from the optical fiber sensor 10 as an optical signal. Figure 4 In the case of an ultrasonic transducer, the ultrasonic waveform signal is output as an electrical signal. The ultrasonic waveform signal detected by the ultrasonic sensor 6 is output from the ultrasonic sensor 6 to the signal processing unit 4 .

[0108] On the other hand, through Figure 1 The strain sensor 8 of the strain amount detection unit 3 shown in FIG. 1 measures the strain amount in the second inspection area I2. As a specific example, Figures 7 to 9 For example, the strain sensor 8 such as the second optical fiber sensor 10B disposed in the structure O such as the aircraft structure O1 measures the strain amount in the second inspection area I2 including the bent plate-like portion such as the cap-shaped stringer O3 or the frame O4 and stringer O5.

[0109] The strain sensor 8 is Figure 5 or Figure 6 In the case of the optical fiber sensor 10 shown in the example, a broadband laser or the like is emitted from the light source 11 to the optical fiber sensor 10. Then, a detection signal of the strain amount is outputted from the optical fiber sensor 10 as an optical signal. On the other hand, in the case where the strain sensor 8 is a resistive strain gauge, a detection signal of the strain amount is outputted as an electrical signal. The detection signal of the strain amount detected by the strain sensor 8 is outputted from the strain sensor 8 to the signal processing unit 4.

[0110] In this way, the signal processing unit 4 obtains an index indicating the soundness of the structure O including the first inspection area I1 and the second inspection area I2 based on the waveform of the ultrasonic wave detected by the ultrasonic sensor 6 and the strain amount of the second inspection area I2 detected by the strain sensor 8. As a specific example, whether a defect occurs in the first inspection area I1 and the second inspection area I2 can be obtained as an index indicating the soundness.

[0111] Therefore, in step S2, it is determined whether the strain amount of the second inspection area I2 has changed relative to the strain amount that serves as the reference. In the case where it is determined that the strain amount of the second inspection area I2 has not changed relative to the strain amount that serves as the reference, in step S3, it is determined whether the ultrasonic waveform obtained from the first inspection area I1 has changed relative to the ultrasonic waveform that serves as the reference. In addition, in the case where it is determined that the strain amount of the second inspection area I2 has changed relative to the strain amount that serves as the reference, in step S4, it is determined whether the ultrasonic waveform obtained from the first inspection area I1 has changed relative to the ultrasonic waveform that serves as the reference. In addition, the order of determining whether the ultrasonic waveform has changed and determining whether the strain amount has changed is arbitrary, and the order can be reversed or performed simultaneously through parallel processing.

[0112] Furthermore, when it is determined that the ultrasonic waveform obtained from the first inspection area I1 and the strain amount of the second inspection area I2 have not changed from the waveform that serves as the reference and the strain amount that serves as the reference, it can be determined that there is no defect in both the first inspection area I1 and the second inspection area I2. In addition, when it is determined that the ultrasonic waveform obtained from the first inspection area I1 has changed from the waveform that serves as the reference, it can be determined that there is a defect in the first inspection area I1, and when it is determined that the strain amount in the second inspection area I2 has changed from the strain amount that serves as the reference, it can be determined that there is a defect in the second inspection area I2. Therefore, when it is determined that the ultrasonic waveform obtained from the first inspection area I1 and the strain amount of the second inspection area I2 have changed from the waveform that serves as the reference and the strain amount that serves as the reference, it can be determined that there are defects in both the first inspection area I1 and the second inspection area I2.

[0113] (Effect)

[0114] The structural soundness diagnostic system 1 and the structural soundness diagnostic method described above classify the structure O into an area for ultrasonic inspection and an area for strain measurement according to the shape of the structure O, and perform SHM based on both changes in ultrasonic waveform and changes in strain.

[0115] Therefore, according to the structural soundness diagnostic system 1 and the structural soundness diagnostic method, compared with the case where SHM is performed only by ultrasonic inspection or the case where SHM is performed only by measuring the amount of strain, the constraints in SHM can be reduced and the inspection accuracy can be improved.

[0116] That is, even if the strain sensor 8 is not configured in a comprehensive manner, SHM can be performed by ultrasonic inspection for the first plate-shaped inspection area I1 without a bent portion. In other words, it is possible to reduce the detection omission of defects caused by insufficient configuration of the strain sensor 8. On the contrary, for the second inspection area I2 of the plate-shaped portion including a bent portion, SHM is performed based on the strain amount, thereby reducing the detection omission of defects caused by the ultrasonic wave not being propagated with sufficient strength for defect detection.

[0117] That is, defects that cannot be detected by SHM performed by measuring only the amount of strain and defects that cannot be detected by ultrasonic inspection alone can be detected, and usage restrictions existing in existing SHM systems can be reduced.

[0118] In addition, compared with the conventional SHM that measures only the amount of strain, it is not necessary to configure a plurality of strain sensors 8 in the plate-shaped first inspection area I1 without a bent portion, so the number of strain sensors 8 and the amount of data of the measured amount of strain and the amount of signal processing can be significantly reduced. In particular, if the structure O is an aircraft structure O1, it is possible to achieve lightweighting, which is very important for aircraft, by reducing the number of strain sensors 8 and the scale of the signal processing circuit.

[0119] (Other Embodiments)

[0120] The above describes a specific embodiment, but the described embodiment is only an example and does not limit the scope of the invention. The new method and device described herein can be embodied in various other ways. In addition, in the method and device described herein, various omissions, substitutions and changes can be made without departing from the scope of the invention. The scope of the added claims and their equivalents are included in the scope and purpose of the invention, including such various modes and modifications.

[0121] Explanation of symbols

[0122] 1Structural soundness diagnostic system

[0123] 2Ultrasonic inspection unit

[0124] 3Strain detection unit

[0125] 4Signal Processing Unit

[0126] 5.5A,5B Ultrasonic vibrator

[0127] 6.6A, 6B ultrasonic sensors

[0128] 7. Control Circuit

[0129] 7A input device

[0130] 8 Strain Sensors

[0131] 10, 10A, 10B fiber optic sensors

[0132] 11 Light Source

[0133] 12 light detectors

[0134] 13 Light Circulator

[0135] I1 First inspection area

[0136] I2 Second inspection area

[0137] O structure

[0138] O1 Aircraft Structure

[0139] O2 Panel

[0140] O3 cap-shaped longitudinal beam with brim

[0141] O4 Framework

[0142] O5 Stringer

[0143] R1, R2, R3 areas.

Claims

1. A structural soundness diagnosis system for performing structural soundness diagnosis of a structure, wherein the structure has a first inspection area in the form of a plate without a bent portion and a second inspection area in the form of a plate having a bent portion, the structural soundness diagnosis system comprising: an ultrasonic vibrator installed in the first inspection area and oscillating ultrasonic waves in the first inspection area; an ultrasonic sensor installed in the first inspection area and detecting a waveform of at least one of a transmission wave of the ultrasonic wave that transmits the first inspection area and a reflection wave of the ultrasonic wave that is reflected in the first inspection area; a strain sensor installed in the second inspection area and detecting a strain amount of the second inspection area; as well as A signal processing unit is configured to obtain an index indicating the soundness of the structure including the first inspection region and the second inspection region based on the waveform detected by the ultrasonic sensor and the strain amount detected by the strain sensor.

2. The structural integrity diagnostic system according to claim 1, wherein: The signal processing unit obtains, as the index, at least one of an index indicating whether damage occurs in the structure, whether cracks occur in the structure, whether peeling occurs in the fiber reinforced plastic constituting the structure, and the degree of defects occurring in the structure.

3. The structural integrity diagnostic system according to claim 2, wherein: The signal processing unit determines whether a defect is likely to occur in the first inspection region based on the strain amount in the second inspection region detected by the strain sensor.

4. The structural integrity diagnostic system according to claim 3, wherein: The signal processing unit divides the second inspection region into a plurality of regions, and determines whether a defect is likely to occur in the first inspection region based on the strain amount in a region closest to the first inspection region among the plurality of regions.

5. The structural integrity diagnostic system according to claim 3 or 4, wherein: The signal processing unit further includes a control circuit that controls the ultrasonic transducer to oscillate ultrasonic waves in the first inspection region when determining that a defect may occur in the first inspection region based on the strain amount detected by the strain sensor.

6. The structural soundness diagnostic system according to any one of claims 1 to 4, wherein: When the signal processing unit determines that a defect has occurred in the first inspection region based on the waveform detected by the ultrasonic sensor, the signal processing unit estimates a region where the defect has occurred based on the amount of strain detected by the strain sensor.

7. An aircraft structure, equipped with the structural soundness diagnostic system according to any one of claims 1 to 6.

8. A method for diagnosing structural integrity, wherein: The structural soundness diagnosis of the structure is performed using the structural soundness diagnosis system according to any one of claims 1 to 6.

9. A structural soundness diagnosis method for diagnosing the structural soundness of a structure having a first plate-shaped inspection area without a bent portion and a second plate-shaped inspection area including a bent portion, wherein: The structural integrity diagnosis method comprises the following steps: oscillating ultrasonic waves in the first inspection area by an ultrasonic transducer installed in the first inspection area; detecting, by an ultrasonic sensor installed in the first inspection area, a waveform of at least one of a transmission wave of the ultrasonic wave that passes through the first inspection area and a reflection wave of the ultrasonic wave that is reflected in the first inspection area; detecting a strain amount of the second inspection area by a strain sensor installed in the second inspection area; and An index indicating the soundness of the structure including the first inspection region and the second inspection region is obtained based on the waveform detected by the ultrasonic sensor and the strain amount detected by the strain sensor.

10. The structural soundness diagnosis method according to claim 8 or 9, wherein: The strain sensor is installed on the reinforcement of the aircraft structure obtained by installing the reinforcement composed of at least one of the longitudinal beam, the wing beam, the rib and the frame on the panel. On the other hand, the ultrasonic vibrator and the ultrasonic sensor are installed on the panel to perform a structural soundness diagnosis of the aircraft structure having both the panel including the first inspection area and the reinforcement including the second inspection area.

11. The structural soundness diagnosis method according to claim 8 or 9, wherein: The ultrasonic wave is an oscillating Lamb wave.

12. The structural soundness diagnostic method according to claim 11, wherein: Based on the characteristics of Lamb waves and the variation characteristics of the strain amount, a plate-like region wider than the second inspection region and without a bent portion is determined as the first inspection region, and on the other hand, a region including a bent plate-like portion is determined as the second inspection region, The Lamb wave has the characteristic that it propagates over a wide range compared to the change in strain, and on the other hand, in the bent plate-like portion, the attenuation of the amplitude is large compared to the change in strain. The change characteristics of the strain amount mean that the attenuation of the amplitude at the bent plate-shaped portion is smaller than that of the Lamb wave, and on the other hand, it propagates in a narrower range than that of the Lamb wave.

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