JP6682913B2 - Damage evaluation device and damage evaluation method - Google Patents

Description

  The present invention relates to a damage evaluation device and a damage evaluation method for evaluating the damage level of an inspection target using ultrasonic waves.

  Conventionally, as a method of evaluating the degree of damage due to creep damage of an inspection target, a technique has been proposed in which parameter values such as temperature, strain, and stress are measured, and the damage degree is estimated based on the measured parameter values (for example, Patent Document 1).

Japanese Patent No. 4067811

  However, in the above method, the damage level of the inspection object is estimated by indirect parameter values such as temperature, strain, and stress. Therefore, if an unexpected phenomenon occurs, the damage level will have an estimation error. However, there is a problem that the damage degree cannot be evaluated accurately.

  On the other hand, it is also possible to stop the operation of the inspection object or the device connected to the inspection object and periodically measure the damage level of the inspection object. There is a problem in that the measurement condition changes such as an error occurring at the measurement position, and the damage degree cannot be evaluated accurately.

  The present invention has been made in view of the above problems, and an object thereof is to provide a damage evaluation device and a damage evaluation method capable of accurately evaluating the damage degree in real time.

In order to solve the above problems, damage evaluation apparatus of the present invention, the inspection is permanent to the object, and make and receive possible ultrasound probe the ultrasound transmitted from the ultrasound probe, test a signal acquisition unit that acquires an ultrasonic signal ultrasonic wave received reflected to the ultrasonic probe within the査object is represented, inspection based on ultrasonic signals obtained by the signal acquisition unit A damage evaluation unit for evaluating the degree of damage to the object is provided , and the damage evaluation unit is an ultrasonic signal acquired by an unused test body, and a differential signal between the ultrasonic signal acquired at a predetermined timing. Based on, to estimate the damage level of the inspection object, from the damage threshold for the unused inspection object, subtract a correction value according to the estimated damage level, the ultrasonic signal acquired at a predetermined timing, With the ultrasonic signal acquired after the predetermined timing Min signal, and, based on the damage threshold of the corrected, to assess the degree of damage of the test object.

The difference component deriving unit derives the envelope of the difference component signal, the derived follicle絡線derive the area by Ritsutsumi絡線to integrating, damage evaluation unit, based on the surface product Te, may be assessed the degree of damage of the inspection object.

The damage evaluation method of the present invention, transmits ultrasonic waves from an ultrasonic probe that is permanently relative to the examination object, reflected inside the inspection object is received by the ultrasonic probe ultrasonic Obtain an ultrasonic signal indicating a sound wave , based on the difference signal between the ultrasonic signal acquired by an unused test body and the ultrasonic signal acquired at a predetermined timing, the degree of damage to the inspection object From the damage threshold for the unused inspection object, subtract the correction value according to the estimated damage degree, the ultrasonic signal acquired at a predetermined timing, and the ultrasonic signal acquired after the predetermined timing The degree of damage to the inspection object is evaluated based on the difference signal from the difference and the corrected damage threshold.

  Further, the damage evaluation method of the present invention is to transmit an ultrasonic wave from an ultrasonic probe that is permanently installed to the inspection object, reflect the ultrasonic wave inside the inspection object, and receive the ultrasonic wave by the ultrasonic probe. An ultrasonic wave signal indicating an ultrasonic wave is acquired, and the degree of damage to the inspection target is evaluated based on the acquired ultrasonic wave signal.

  According to the present invention, it is possible to evaluate the degree of damage accurately in real time.

It is a figure explaining the structure of a damage evaluation apparatus. It is a figure explaining the process of a difference derivation | leading-out part. It is a figure which shows the relationship between the damage degree of an inspection target object, and an area. It is a flow chart explaining a flow of processing by a control part. It is a figure which shows comparison of the derivation | leading-out interval of a parameter value by a damage evaluation device and the damage evaluation device which measures a damage degree regularly. FIG. 8 is a diagram illustrating an arrangement of ultrasonic probes according to a modified example 1. It is a figure explaining the evaluation method of the damage degree of the inspection object in the modification 2. It is a figure explaining the damage threshold when the ultrasonic probe is made to be permanently installed in the inspection target already used.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention unless otherwise specified. In this specification and the drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to omit redundant description, and elements not directly related to the present invention are omitted. To do.

  FIG. 1 is a diagram illustrating a configuration of the damage evaluation device 100. As shown in FIG. 1, the damage evaluation device 100 includes an ultrasonic probe 110, a pulser receiver 112, a digitizer 114, a control device 116, and a warning device 118. The damage evaluation apparatus 100 is, for example, due to creep damage of the inspection object M exposed to a high temperature environment of 200 ° C. or higher (more specifically, 500 ° C. to 800 ° C.) such as boiler piping made of stainless steel or alloy steel. Assess the degree of damage.

  The ultrasonic probe 110 is a probe having resistance to a high temperature environment and capable of transmitting and receiving ultrasonic waves, and is fixed to the outer surface of the inspection object M by an adhesive or a fastening mechanism such as a band. Being permanently installed. The ultrasonic probe 110 emits ultrasonic waves toward the inside of the inspection target M, receives ultrasonic waves (reflected waves) reflected (or diffracted, scattered) inside the inspection target M, and generates electricity. Convert to signal (analog signal).

  Here, since the ultrasonic wave has a characteristic of being reflected at the boundary of substances having different densities, when creep damage occurs in the inspection object M, the amount of reflected ultrasonic wave increases at the location where the creep damage occurs. . Therefore, the damage evaluation apparatus 100 can grasp the degree of damage due to the creep damage of the inspection object M by receiving and analyzing the ultrasonic waves reflected inside the inspection object M.

  The pulsar receiver 112 supplies electric power to the ultrasonic probe 110 to emit ultrasonic waves. Further, the pulsar receiver 112 acquires an electric signal (analog signal) indicating (the amplitude of) the ultrasonic wave received by the ultrasonic probe 110.

  The digitizer 114 converts the electric signal acquired by the pulsar receiver 112 into an ultrasonic signal represented by a digital value and transmits the ultrasonic signal to the control device 116.

  The control device 116 is a computer including a control unit 120 and a storage unit 122. The control unit 120 is composed of a semiconductor integrated circuit including a CPU (central processing unit), reads a program for operating the CPU itself from the ROM, and cooperates with the RAM functioning as a work area and other electronic circuits. It manages and controls the entire damage evaluation apparatus 100.

  The storage unit 122 is a storage medium such as an HDD (Hard Disk Drive) or a flash memory, and stores an initial ultrasonic wave signal 140 described later in detail.

  In the present embodiment, the control unit 120 functions as the signal acquisition unit 130, the difference derivation unit 132, the damage evaluation unit 134, and the warning control unit 136.

  After the ultrasonic probe 110 is permanently installed on the unused inspection object M, the signal acquisition unit 130, when the inspection object M is unused (at a predetermined timing), the pulsar receiver 112 and the digitizer 114. The ultrasonic probe 110 transmits and receives ultrasonic waves to and from the inspection target M. Then, the signal acquisition unit 130 stores the ultrasonic signal based on the ultrasonic waves reflected inside the unused inspection object M as the initial ultrasonic signal 140 in the storage unit 122.

  After that, when the inspection target M is used (when the boiler or the like is operated), the signal acquisition unit 130 controls the pulsar receiver 112 and the digitizer 114 at each preset inspection interval (after a predetermined timing). Then, the ultrasonic probe 110 transmits and receives ultrasonic waves to the inspection object M. Then, the signal acquisition unit 130 acquires an ultrasonic signal based on the ultrasonic waves reflected inside the inspection object M as the evaluation ultrasonic signal 142 (see FIG. 2B).

  FIG. 2 is a diagram illustrating the processing of the difference deriving unit 132. In FIG. 2, the horizontal axis represents distance (distance from the outer surface), and the vertical axis represents signal amplitude (strength). Actually, various signals are acquired by time-division digital values, but since the propagation speed of ultrasonic waves is known, the time from the transmission of ultrasonic waves to the reception and the propagation speed. Based on and, it can be converted to the distance from the outer surface.

  Comparing FIG. 2A and FIG. 2B, since the unused inspection object M has no creep damage, there is almost no ultrasonic wave reflected inside, and it is shown in FIG. The amplitude of the initial ultrasonic signal 140 becomes smaller. On the other hand, the creep damage occurs in the inspection object M according to the environment (temperature, time, etc.) in which it is used, and therefore, the creep damage increases inside the inspection object M as the period of use increases. I will do it. Therefore, the longer the period of use is, the more the ultrasonic waves reflected inside increase, so that the amplitude of the evaluation ultrasonic signal 142 shown in FIG. 2B increases.

  When the evaluation ultrasonic signal 142 is acquired by the signal acquisition unit 130, the difference derivation unit 132, as illustrated in FIG. 2C, the acquired evaluation ultrasonic signal 142 and the initial value stored in the storage unit 122. The difference from the ultrasonic signal 140 is derived as a difference signal 144 (evaluation ultrasonic signal 142-initial ultrasonic signal 140).

  After that, the difference deriving unit 132 performs the Hilbert transform on the difference signal 144, thereby deriving the envelope curve of the difference signal 144 as the envelope signal 146 as shown in FIG. The initial ultrasonic wave signal 140, the evaluation ultrasonic wave signal 142, and the difference signal 144 swing to the plus side and the minus side with 0 as a reference, while the envelope signal 146 swings only to the plus side with 0 as a reference. In FIG. 2D, the evaluation range 148 of the envelope signal 146 is shown enlarged.

  Subsequently, the difference deriving unit 132 integrates the envelope signal 146 of the evaluation range 148 (between X1 and X2) to be evaluated in the inspection object M, so that the hatched portion in FIG. , The area of the evaluation range 148 is derived. The evaluation range 148 is preset to a range (distance) where creep damage is likely to occur in the inspection object M.

  FIG. 3 is a diagram showing the relationship between the damage degree and the area of the inspection object M. As described above, as the creep damage progresses on the inspection object M (the damage degree increases), the amplitude of the evaluation ultrasonic wave signal 142 increases, and therefore, the difference from the initial ultrasonic wave signal 140 varies. The amplitude of a certain difference signal 144 also increases, and the area of the evaluation range 148 also increases. Therefore, as shown in FIG. 3, as the degree of damage due to creep damage in the evaluation range 148 of the inspection object M increases, the area of the evaluation range 148 also increases.

  Therefore, the damage evaluation unit 134 evaluates the damage degree due to the creep damage of the evaluation range 148 in the inspection object M based on the area derived by the difference derivation unit 132. Specifically, the damage evaluation unit 134 compares the area derived by the difference derivation unit 132 with a preset damage threshold Th. The damage threshold Th is determined in advance by experiment and set to a value corresponding to the degree of damage at which the inspection object M may be broken due to creep damage or the inspection object M needs to be replaced. Has been done.

  When the area derived by the difference deriving unit 132 is equal to or larger than the damage threshold Th, the warning control unit 136 may cause the inspection target M to be broken due to creep damage via the warning device 118, or may be inspected. A warning indicating that the object M needs to be replaced is issued. The warning device 118 is a speaker or a display device, and gives a warning by voice or image.

  FIG. 4 is a flowchart illustrating the flow of processing by the control unit 120. The process (damage evaluation method) shown in FIG. 4 is executed at each inspection interval. As shown in FIG. 4, first, the signal acquisition unit 130 controls the pulsar receiver 112 and the digitizer 114 to cause the ultrasonic probe 110 to transmit and receive ultrasonic waves to and from the inspection object M, and the inspection object. An ultrasonic signal based on the ultrasonic waves reflected inside M is acquired (S100).

  Then, the signal acquisition unit 130 determines whether or not an ultrasonic signal for the unused inspection object M has been acquired (S102). It should be noted that whether or not the ultrasonic signal is for the unused inspection object M is determined by a user's instruction.

  As a result, when the ultrasonic signal for the unused inspection object M is acquired (YES in S102), the signal acquisition unit 130 stores the acquired ultrasonic signal in the storage unit 122 as the initial ultrasonic signal 140 (S104). ).

  On the other hand, when the ultrasonic signal for the unused inspection object M is not acquired (NO in S102), that is, when the ultrasonic signal for the inspection object M in use is acquired, the difference deriving unit 132 performs the above-mentioned operation. The difference between the evaluation ultrasonic signal 142 acquired in step S100 and the initial ultrasonic signal 140 stored in the storage unit 122 is derived as a difference signal 144 (S106).

  After that, the difference deriving unit 132 derives the envelope of the difference signal 144 by applying the Hilbert transform to the difference signal 144 derived in step S106 to obtain the envelope signal 146 (S108). Further, the difference deriving unit 132 derives the area of the evaluation range 148 by integrating the envelope signal 146 of the evaluation range 148 to be evaluated in the inspection target M (S110).

  Subsequently, the damage evaluation unit 134 determines whether the area derived in step S110 is equal to or larger than the damage threshold Th (S112). As a result, when the area is equal to or larger than the damage threshold Th (YES in S112), the warning control unit 136 issues a warning via the warning device 118 (S114), and ends the process. The warning may be given each time the processing is repeated, or the warning may be given once and then not given again. On the other hand, when the area is not equal to or larger than the damage threshold Th (NO in S112), the warning control unit 136 ends the process without giving a warning.

  As described above, in the damage evaluation apparatus 100, the ultrasonic probe 110 is permanently installed on the inspection object M, thereby deriving the parameter value (area) regarding the creep damage of the inspection object M in real time, and performing the inspection. The degree of damage due to creep damage of the object M can be evaluated in real time.

  FIG. 5 is a diagram showing a comparison of parameter value derivation intervals by the damage evaluation device 100 that continuously evaluates the damage level and the damage evaluation device 10 that regularly checks the damage level. As shown in FIG. 5, the damage evaluation device 100 can continuously derive a parameter value (area) and evaluate the damage degree in real time. On the other hand, in the damage evaluation device 10, the parameter value can be derived only periodically, for example, every year, so the parameter value becomes discrete.

  Therefore, the damage evaluation device 10 may not be able to give a warning at the timing when it should be warned, and if creep damage progresses between inspections, the inspection target M may be damaged. It can happen. On the other hand, in the damage evaluation device 100, the parameter value (area) can be continuously derived in real time to evaluate the damage degree. Therefore, a warning is given before the inspection object M is damaged. be able to. Further, the damage evaluation apparatus 100 can detect the creep damage of the inspection object M at an early stage.

  Further, in the damage evaluation device 10, when deriving (measuring) the parameter value, it is necessary to stop the device (for example, the boiler) connected to the inspection object M. On the other hand, in the damage evaluation device 100, it is not necessary to stop the device connected to the inspection target M, and the operation efficiency of the device connected to the inspection target M can be improved.

  Further, in the damage evaluation device 10, since the ultrasonic probe 110 is attached to the inspection object M at every inspection, there is a problem that the accuracy of deriving the parameter value is deteriorated due to an error in the attachment position. I will end up. On the other hand, in the damage evaluation apparatus 100, by permanently installing the ultrasonic probe 110 with respect to the inspection object M, an error in the mounting position does not occur, so that the parameter value (area) can be derived accurately. The degree of damage can be accurately evaluated.

  Further, compared with the method of estimating the damage degree of the inspection object by indirect parameter values such as temperature, strain, and stress, the damage evaluation apparatus 100 directly damages the inspection object M by creep damage by ultrasonic waves. Since the degree is derived as the area, it is possible to evaluate the damage degree (area) with high accuracy by reducing the estimation judgment as much as possible.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such embodiments. It is obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the claims, and it should be understood that these also belong to the technical scope of the present invention. To be done.

<Modification 1>
FIG. 6 is a diagram illustrating an arrangement of the ultrasonic probe 110 according to the modified example 1. In the damage evaluation apparatus 100 described above, the ultrasonic signal is acquired by using one ultrasonic probe 110, but the ultrasonic signal is acquired by using each of the plurality of ultrasonic probes 110. May be. For example, as shown in FIG. 6, when the inspection object M is curved, the ultrasonic probes are respectively displaced by 90 ° with respect to the outer surface of the inspection object M orthogonal to the fluid flow direction. The four children 110 may be permanently installed.

  This makes it possible to specify a position at which creep damage progresses rapidly especially when the condition under which damage occurs is different in the circumferential direction, such as when the inspection target M is curved, and the degree of damage at that position is specified. It is possible to give a warning according to (area).

  In addition, when using a plurality of ultrasonic probes 110, one pulser receiver 112 may be provided for one ultrasonic probe 110. Further, a multiplexer is provided between one pulsar receiver 112 and the plurality of ultrasonic probes 110, and an ultrasonic signal transmitted / received by one pulsar receiver 112 is branched to the plurality of ultrasonic probes 110. You may do it.

<Modification 2>
In the damage evaluation apparatus 100, the differential signal 144 between the evaluation ultrasonic signal 142 and the initial ultrasonic signal 140 is derived, the envelope of the differential signal 144 is derived to be the envelope signal 146, and based on the envelope signal 146. The parameter value (area) was derived. However, the method of evaluating the damage degree of the inspection object M is not limited to this.

  FIG. 7 illustrates a method of evaluating the degree of damage to the inspection target M in the second modification. For example, as shown in FIG. 7, the damage evaluation unit 134 derives a signal distribution in which the horizontal axis represents the amplitude and the vertical axis represents the frequency of the amplitude with respect to the initial ultrasonic signal 140 and the evaluated ultrasonic signal 142. The center of the signal distribution is 0.

  After that, the damage evaluation unit 134 applies the derived signal distribution to a normal distribution, derives the variance σ, and derives the parameter value S using the following formula 1 for the region on the plus side of the variance σ. In addition, the damage evaluation unit 134 similarly derives the parameter value S for the area on the negative side of the variance −σ.

…（数式１）
ここで、Ｖｐは振幅を示し、ＮｐはＶｐの信号の個数を示し、Ｖｔｈは分散σの振幅を示し、ΔＶは振幅の最小単位を示す。

… (Equation 1)
Here, Vp represents the amplitude, Np represents the number of signals of Vp, Vth represents the amplitude of variance σ, and ΔV represents the minimum unit of the amplitude.

  Then, the damage evaluation unit 134 adds the parameter value S on the plus side and the parameter value S on the minus side. Further, the damage evaluation unit 134 may cause the inspection object M to break due to creep damage when the total value of the derived parameter values S is equal to or larger than the damage threshold value corresponding to the damage degree determined in advance by experiment. There is, or it is determined that the inspection target M needs to be replaced. This makes it possible to evaluate the degree of damage due to creep damage of the inspection object M in real time.

<Modification 3>
In the damage evaluation device 100 described above, the ultrasonic probe 110 is permanently installed in the unused inspection object M, and the initial ultrasonic signal 140 is acquired by transmitting ultrasonic waves to the unused inspection object M, Based on the initial ultrasonic signal 140 and the evaluation ultrasonic signal 142, the degree of damage to the inspection object M is evaluated. However, the present invention is not limited to this, and the ultrasonic probe 110 may be permanently installed in the inspection target M that has already been used, and the degree of damage to the inspection target M thereafter may be evaluated.

  FIG. 8 is a diagram for explaining a damage threshold value when the ultrasonic probe 110 is permanently installed on the inspection object M which has already been used. When the ultrasonic probe 110 is permanently installed on the inspection object M that has already been used, the storage unit 122 of the control device 116 stores an unused test object that is made of the same material and shape as the inspection object M in advance. The initial ultrasonic signal 140 is stored.

  Then, when the ultrasonic signal (evaluation ultrasonic signal 142) is acquired for the first time after the ultrasonic probe 110 is permanently installed on the inspection object M, the difference derivation unit 132 is initially stored in the storage unit 122. A difference signal 144 between the ultrasonic signal 140 and the evaluation ultrasonic signal 142 is derived. Further, the difference deriving unit 132 derives the envelope of the difference signal 144 by applying the Hilbert transform to the difference signal 144 to obtain the envelope signal 146, and derives the area of the evaluation range 148 in the inspection object M. .

  Then, the damage evaluation unit 134 refers to the relationship between the area measured experimentally in advance and the damage degree of the inspection target M, estimates the current damage degree based on the derived area, and unused. The corrected damage threshold Th is derived by subtracting a correction value according to the estimated damage degree from the damage threshold Th for the inspection object M. Further, the signal acquisition unit 130 stores the ultrasonic signal (evaluation ultrasonic signal 142) acquired for the first time as the initial ultrasonic signal 140.

  This makes it possible to evaluate the degree of damage not only for the unused inspection object M but also for the inspection object M that has already been used.

<Modification 4>
In the damage evaluation apparatus 100, the ultrasonic probe 110 is fixed to the outer surface of the inspection object M by an adhesive, a fastening mechanism such as a band, or the like so as to be permanently installed. However, the present invention is not limited to this, and the ultrasonic probe 110 may be embedded in the outer surface of the inspection target M by, for example, the sol-gel method.

  INDUSTRIAL APPLICATION This invention can be utilized for the damage evaluation apparatus and damage evaluation method which evaluate the damage of an inspection target object using an ultrasonic wave.

100 Damage Evaluation Device 110 Ultrasonic Probe 130 Signal Acquisition Unit 132 Difference Derivation Unit 134 Damage Evaluation Unit M Inspection Object

Claims (3)

An ultrasonic probe that is permanently installed on the inspection object and is capable of transmitting and receiving ultrasonic waves,
A signal acquisition unit that acquires an ultrasonic signal that is transmitted from the ultrasonic probe and that is reflected inside the inspection object and indicates the ultrasonic wave received by the ultrasonic probe,
A damage evaluation unit that evaluates the damage degree of the inspection object based on the ultrasonic signal acquired by the signal acquisition unit,
Equipped with
The damage evaluation unit,
Based on the difference signal between the ultrasonic signal acquired in an unused test body and the ultrasonic signal acquired at a predetermined timing, the degree of damage to the inspection object is estimated, and the unused From the damage threshold for the inspection object, subtract the correction value according to the estimated damage degree,
Based on the differential signal between the ultrasonic signal acquired at the predetermined timing and the ultrasonic signal acquired after the predetermined timing, and the corrected damage threshold, the degree of damage to the inspection object damage evaluation apparatus characterized by evaluating the. The difference deriving unit,
Deriving the envelope of the differential signal, deriving the area of the envelope by integrating the derived envelope,
The damage evaluation unit,
Based on the area, damage evaluation apparatus according to claim 1, characterized in that to evaluate the degree of damage of the test object. Transmit ultrasonic waves from the ultrasonic probe that is permanently installed on the inspection object,
Obtaining an ultrasonic signal indicating the ultrasonic waves reflected inside the inspection object and received by the ultrasonic probe,
Based on the difference signal between the ultrasonic signal acquired in an unused test body and the ultrasonic signal acquired at a predetermined timing, the degree of damage to the inspection object is estimated, and the unused From the damage threshold for the inspection object, subtract the correction value according to the estimated damage degree,
Based on the differential signal between the ultrasonic signal acquired at the predetermined timing and the ultrasonic signal acquired after the predetermined timing, and the corrected damage threshold, the degree of damage to the inspection object damage evaluation method and evaluating the.

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