Method and apparatus for estimating delamination of FRP laminated piping members

Abstract

To provide a non-destructive inspection method capable of easily and inexpensively estimating the existence of a peeling defect of an FRP laminated piping member.SOLUTION: In a peeling estimation method of an FRP laminated piping member, a surface of the FRP laminated piping member P having a laminated structure including an FRP layer is struck by a striking hammer 13 using a measuring device provided with the striking hammer 13 and an acceleration sensor 17 attached to the striking hammer 13. The acceleration of the striking hammer 13 is measured with time by the acceleration sensor 17. On the basis of the measured acceleration of the striking hammer 13, the existence of a peeling defect of the FRP laminated piping member P is estimated.SELECTED DRAWING: Figure 1

Description

[Technical Field] 【0001】 The present invention relates to a method and apparatus for estimating the presence or absence of delamination defects in an FRP laminated piping member having a laminated structure including an FRP layer, based on impact with a striking hammer. [Background technology] 【0002】 FRP is an abbreviation for Fiber Reinforced Plastics, a material made by combining reinforcing fiber materials such as glass fibers and carbon fibers with synthetic resin materials such as unsaturated polyester resin, vinyl ester resin, and epoxy resin. Compared to synthetic resin materials, it has higher strength. For this reason, it is used in a variety of industrial products, such as piping components, interior and exterior components of automobiles and railway vehicles, agricultural materials, and residential equipment such as bathrooms. 【0003】 In industrial products, FRP (fiber-reinforced plastic) with a laminated structure, made by impregnating fibers with synthetic resin and laminating multiple layers, is frequently used. One defect that is prone to occur in FRP with such a laminated structure is delamination between layers. Furthermore, FRP is not only used as a standalone material, but also in piping components, for example, laminated piping components are often seen in which the base material of the pipe is covered with an FRP lining layer. In piping components with such a structure, delamination can also occur between the base material layer and the FRP lining layer. Thus, in piping components made from FRP with a laminated structure, or piping components in which a base material layer is covered with an FRP lining layer (hereinafter referred to as PFR laminated piping components), the above-mentioned delamination defects caused by the use of FRP can occur, leading to deterioration of strength, and therefore, there is a need for inspection methods for delamination defects caused by the use of FRP. 【0004】 Non-destructive testing methods for detecting delamination defects in FRP laminated piping components include ultrasonic testing and radiographic testing. These methods are used to determine the presence, location, and approximate size of delamination defects in FRP laminated piping components. However, in ultrasonic testing, if the surface of the FRP is not smooth, it is necessary to apply gel or other materials to prevent gaps from forming between the testing equipment and the FRP laminated piping component being tested, which requires time-consuming application and wiping. Furthermore, depending on the object being tested, such as when the entire piping system is being inspected, not only is the inspection time long, but the inspection costs are also high. In addition, radiographic testing has the problem of being difficult to perform for long periods due to the high cost of the testing equipment and the risk of radiation exposure. 【0005】 To solve the above-mentioned problems, a non-destructive testing method for FRP structures has been proposed, as described in Patent Document 1, which enables the quantitative and non-personal identification of defects in FRP structures. In the non-destructive testing method for FRP structures disclosed in Patent Document 1, an FRP sample is prepared in which areas without defects and areas with defects are known. When the surface of the FRP sample in the area without defects is vibrated with an impulse hammer, the frequency band in the frequency spectrum of the impact sound that shows a larger value than that of the area with defects is defined as F1. When the surface of the defective area of ​​the FRP sample in the area with defects is vibrated with an impulse hammer, the frequency band in the frequency spectrum of the impact sound that shows a larger value than that of the area without defects is defined as F2. When the surface of the FRP structure to be inspected is vibrated with an impulse hammer, the combined decibel value of the impact sound at F1 is defined as dB1, and the combined decibel value of the impact sound at F2 is defined as dB2. The index is Δ = dB2 - dB1. Furthermore, Patent Document 1 discloses a method of combining the above-mentioned non-destructive testing method with a non-destructive testing method for FRP structures in which the FRP surface is vibrated with an impulse hammer and the width of the time waveform of the excitation force is used as an indicator. [Prior art documents] [Patent Documents] 【0006】 [Patent Document 1] Japanese Patent Publication No. 2006-275742 [Overview of the project] [Problems that the invention aims to solve] 【0007】 In the non-destructive testing method for FRP structures disclosed in Patent Document 1 mentioned above, it is necessary to determine two characteristic frequency bands of the impact sound frequency spectrum in order to obtain an index: frequency band F1 in which a value greater than that of the defective area appears, and frequency band F2 in which a value greater than that of the non-defective area appears. However, in the method disclosed in Patent Document 1, the criteria for determining frequency bands F1 and F2 are not clear, and the spectral waveform of the impact sound frequency is not necessarily a simple shape. Therefore, depending on the spectral waveform of the impact sound frequency in response to excitation by an impulse hammer, it may not be possible to accurately identify these bands, or even to confirm the spectrum of the responding impact sound frequency itself, which may prevent an accurate diagnosis of delamination defects. 【0008】 Therefore, the object of the present invention is to provide a non-destructive testing method that can easily and inexpensively estimate the presence or absence of delamination defects in FRP laminated piping members in order to solve the problems of the prior art. [Means for solving the problem] 【0009】 In view of the above objectives, the present invention, in a first aspect, provides a method for estimating the presence or absence of delamination defects in an FRP laminated piping member having a laminated structure including an FRP layer, using a measuring device comprising a striking hammer and an acceleration sensor attached to the striking hammer, wherein the surface of the laminated piping member is struck with the striking hammer, and the acceleration of the striking hammer is measured over time with the acceleration sensor, From the measured acceleration of the striking hammer, at least one of the following is determined: the waveform of the change in striking force over time, which is the product of the mass of the striking hammer and the acceleration of the striking hammer; the mechanical impedance ZR during the rebound process when the striking hammer bounces back from the surface of the FRP laminated piping member in the opposite direction to when it struck the surface of the FRP laminated piping member; and an index I, which is the ratio of the impact velocity Va when the striking hammer strikes the surface of the FRP laminated piping member to the rebound velocity Vr when the striking hammer bounces back from the surface of the FRP laminated piping member. Based on the number of peaks in the waveform of the change in striking force over time from when it starts to increase until it falls below the initial value again, the determined mechanical impedance ZR, and at least one of the index I, the presence or absence of delamination defects in the FRP laminated piping member is estimated. The impact velocity Va is calculated by integrating the measured acceleration over time from 0 to the maximum value, and the rebound velocity Vr is calculated by integrating the measured acceleration over time from the maximum value to 0 again. The maximum value of the striking force generated when the striking hammer strikes the surface of the FRP laminated piping member is F max When this is the case, F is calculated from the mass of the striking hammer and the acceleration of the striking hammer measured by the acceleration sensor. max The mechanical impedance ZR is calculated, and the formula ZR = F max It is determined by / Vr, and the index I is determined as the ratio of the collision velocity Va to the rebound velocity Vr. This invention provides a method for estimating delamination of FRP laminated piping members. 【0010】 In the above method for estimating delamination of FRP laminated piping members, the presence or absence of delamination defects in the FRP laminated piping member is estimated by striking the surface of the FRP laminated piping member with a striking hammer equipped with an acceleration sensor. The striking of the surface of the FRP laminated piping member with a striking hammer is broadly divided into two processes: a penetration process in which the striking hammer collides with the surface of the FRP laminated piping member and the FRP laminated piping member deforms due to the force from the striking hammer, and a rebound process in which the deformation of the FRP laminated piping member reaches its maximum, and the striking hammer is pushed in the opposite direction to the striking direction and detached from the surface of the FRP laminated piping member due to the rebound force from the FRP laminated piping member as it recovers from deformation. The inventors have found that the presence or absence of delamination defects in the FRP laminated piping member affects the acceleration of the striking hammer during the recovery from deformation of the FRP laminated piping member after being struck with a striking hammer, i.e., during the rebound process. Utilizing this finding, the above method for estimating delamination of FRP laminated piping members estimates the presence or absence of delamination defects in the FRP laminated piping member based on the acceleration of the striking hammer. Here, the term "FRP laminated piping member" includes a piping member composed of an FRP laminate having a laminated structure in which multiple FRP layers are laminated, a composite piping member composed of a base material layer and a single layer of FRP lining covering it, and a composite piping member composed of a base material layer and an FRP lining layer made of an FRP laminate (i.e., FRP having a laminated structure) covering it. Furthermore, the delamination defect of the FRP laminated piping member includes delamination between layers in the FRP laminate and delamination between the base material layer and the FRP lining layer. 【0012】 In addition,The impact force from a striking hammer is calculated as the product of the mass of the striking hammer and the acceleration of the striking hammer. The inventors have found that when delamination defects exist in the FRP laminated piping member, multiple peaks appear in the time-dependent waveform of the impact force from the striking hammer from the start of the increase until it falls below the initial value again, and the number of peaks can be used as a basis for estimating the presence or absence of delamination defects in the FRP laminated piping member. Furthermore, the impact velocity Va is calculated by integrating the acceleration of the striking hammer from 0 to its maximum value during the penetration process, and the rebound velocity Vr is calculated by integrating the acceleration of the striking hammer from its maximum value to 0 during the rebound process, and the maximum impact force F generated when the striking hammer collides with the surface of the FRP laminated piping member is calculated. max The force m of the striking hammer and the maximum acceleration a max It is calculated as the product of the two. Equation ZR = F max If the value obtained by / Vr is taken as the mechanical impedance ZR during the rebound process, and the ratio of the impact velocity Va to the rebound velocity Vr is taken as index I, then both the mechanical impedance ZR and index I include the rebound velocity Vr, and if there is a delamination defect in the FRP laminated piping member, it should be reflected in the mechanical impedance ZR and index I. From this prediction, the inventors further found that the mechanical impedance ZR and index I during the rebound process can be used as estimation material for whether or not there is a delamination defect in the FRP laminated piping member. From these findings, the inventors found that the presence or absence of a delamination defect in the FRP laminated piping member can be estimated based on the number of peaks in the waveform of the change in impact force over time, and at least one of the mechanical impedance ZR and index I during the rebound process. In the above-mentioned method for estimating delamination of an FRP laminated piping member, the presence or absence of a delamination defect in the FRP piping member is estimated by striking the surface of the FRP laminated piping member with an impact hammer equipped with an acceleration sensor. 【0013】 As one embodiment, the index I is calculated by the formula I = Va / Vr. For the mechanical impedance ZR and the index I, threshold values are determined in advance. When the number of peaks in the waveform of the change over time of the impact force by the impact hammer is two or more, or when at least one of the measured mechanical impedance ZR and the index I is lower than the respective predetermined threshold values of the mechanical impedance ZR and the index I, it may be estimated that there is a peeling defect in the FRP laminated pipe member. 【0014】 In this case, when the number of peaks in the waveform of the change over time of the impact force by the impact hammer is two or more and both the measured mechanical impedance ZR and the index I are lower than the respective predetermined threshold values of the mechanical impedance ZR and the index I, it can be estimated that the probability of the presence of a peeling defect in the FRP laminated pipe member is higher. 【0015】 The method for estimating peeling of the FRP laminated pipe member includes cases where the FRP laminated pipe member includes an FRP laminate having a laminated structure and the peeling defect is an interlayer peeling in the FRP laminate, and cases where the FRP laminated pipe member includes a base material layer and an FRP liner layer covering the base material layer and the peeling defect is a peeling between the base material layer and the FRP liner layer. 【0016】 Further, as a second aspect, the present invention is a peeling estimation device for an FRP laminated pipe member that estimates a peeling defect of an FRP laminated pipe member having a laminated structure including an FRP layer, the device including an impact hammer for striking the surface of the FRP laminated pipe member, an acceleration sensor attached to the impact hammer, a measurement value storage unit for storing over time the acceleration of the impact hammer measured by the acceleration sensor, and a peeling estimation unit for estimating the presence or absence of a peeling defect of the FRP laminated pipe member based on the acceleration stored in the measurement value storage unit. The peeling estimation unit determines, from the acceleration stored in the measurement value storage unit, at least one of the following: the waveform of the change in impact force over time, which is the product of the mass of the impact hammer and the acceleration of the impact hammer; the mechanical impedance ZR during the rebound process in which the impact hammer rebounds from the surface of the FRP laminated piping member in the opposite direction to when it impacted the surface of the FRP laminated piping member; and an index I, which is the ratio of the impact velocity Va when the impact hammer impacts the surface of the FRP laminated piping member to the rebound velocity Vr when the impact hammer rebounds from the surface of the FRP laminated piping member. Based on the number of peaks in the time-dependent waveform of the impact force, the determined mechanical impedance ZR, and at least one of the index I, the presence or absence of delamination defects in the FRP laminated piping member is estimated, the impact velocity Va is calculated by integrating the acceleration stored in the measurement value storage unit over the time it takes to increase from 0 to the maximum value, the rebound velocity Vr is calculated by integrating the acceleration stored in the measurement value storage unit over the time it takes to decrease from the maximum value back to 0, and the maximum impact force generated when the impact hammer collides with the surface of the FRP laminated piping member is F max When this is done, F is calculated from the mass of the striking hammer and the acceleration of the striking hammer stored in the measurement value storage unit. max The mechanical impedance ZR is calculated, and the formula ZR = F max / VrThis invention provides a device for estimating delamination of FRP laminated piping members. 【0017】 In the above-described FRP laminated piping member delamination estimation device, similar to the above-described FRP laminated piping member delamination estimation method, the presence or absence of delamination defects in the FRP laminated piping member can be estimated based on the acceleration of the impact hammer when the surface of the FRP laminated piping member is struck. 【0019】 In one embodiment, the peeling estimation device for the FRP laminated piping member further includes a threshold storage unit that stores predetermined thresholds for the mechanical impedance ZR and the index I for each combination of pipe type and nominal diameter of the FRP laminated piping member. The peeling estimation unit calculates the index I using the formula I = Va / Vr, and estimates that a peeling defect exists in the FRP laminated piping member when the number of peaks in the time-dependent waveform of the impact force by the impact hammer is two or more, and at least one of the mechanical impedance ZR and the index I obtained by measurement is lower than the predetermined thresholds for the mechanical impedance ZR and the index I corresponding to the combination of pipe type and nominal diameter of the FRP laminated piping member to be measured. 【0020】 In this case, the delamination estimation unit may estimate that the probability of delamination defects existing in the FRP laminated piping member is higher when the number of peaks in the time-dependent waveform of the impact force by the impact hammer is two or more, and both the mechanical impedance ZR and the index I obtained by measurement are lower than predetermined thresholds for the mechanical impedance ZR and index I corresponding to the combination of pipe type and nominal diameter of the FRP laminated piping member being measured. 【0021】 The estimation of delamination defects in the above-mentioned FRP laminated piping member delamination estimation device includes cases where the FRP laminated piping member includes an FRP laminate having a laminated structure and the delamination defect is interlayer delamination within the FRP laminate, and also cases where the FRP laminated piping member includes a base material layer and an FRP liner layer covering the base material layer and the delamination defect is delamination between the base material layer and the FRP liner layer. [Effects of the Invention] 【0022】 According to the present invention, by simply striking the surface of an FRP laminated piping member with a striking hammer and measuring the acceleration of the striking hammer, it is possible to estimate the presence or absence of delamination defects in the FRP laminated piping member based on the measured acceleration of the striking hammer. Therefore, the presence or absence of delamination defects can be estimated by simple and inexpensive non-destructive testing. Furthermore, since the estimation criteria are clear, there are no cases where estimation is not possible, and automation is easy. In addition, since non-destructive testing can be performed only on the FRP laminated piping member to be diagnosed to determine the presence or absence of delamination defects, it is possible to reduce the cost of accurate diagnosis. [Brief explanation of the drawing] 【0023】 [Figure 1] This is an overall configuration diagram of the peeling estimation device for FRP laminated piping members according to the present invention. [Figure 2] Figure 1 is a functional block diagram of the peeling estimation device for FRP laminated piping members. [Figure 3] Figure 1 shows the acceleration waveform when an FRP laminated piping member is struck by the impact hammer of the peeling estimation device for FRP laminated piping members. [Figure 4] This graph shows the time-dependent waveform of the impact force obtained in an experiment where a sound FRP laminated straight pipe was struck with an impact hammer. [Figure 5] This graph shows the time-dependent waveform of the impact force obtained in an experiment in which a straight FRP laminated pipe with delamination defects, of the same pipe type (material composition and structure) as the one used in the experiment in Figure 4, was struck with an impact hammer. [Figure 6]This graph compares the mechanical impedance ZR of a defective FRP laminated straight pipe of the first pipe type and first nominal diameter with that of a sound pipe. [Figure 7] This graph compares the delamination index INDEX of defective and sound FRP laminated straight pipes of the first pipe type and first nominal diameter. [Figure 8] This graph compares the mechanical impedance ZR of a defective FRP laminated straight pipe of the first pipe type and second nominal diameter with that of a sound pipe. [Figure 9] This graph compares the delamination index INDEX of defective and sound FRP laminated straight pipes of the first pipe type and second nominal diameter. [Figure 10] This graph compares the mechanical impedance ZR of a defective FRP laminated straight pipe of the first pipe type and third nominal diameter with that of a sound pipe. [Figure 11] This graph compares the delamination index INDEX of defective and sound FRP laminated straight pipes of the third nominal diameter for the first pipe type. [Figure 12] This graph compares the mechanical impedance ZR of a defective FRP laminated straight pipe of the second pipe type and second nominal diameter with that of a sound pipe. [Figure 13] This graph compares the delamination index INDEX of defective and sound FRP laminated straight pipes of the second pipe type and second nominal diameter. [Modes for carrying out the invention] 【0024】 Hereinafter, embodiments of the delamination estimation method and delamination estimation apparatus for FRP laminated piping members according to the present invention will be described with reference to the drawings. 【0025】 First, with reference to Figures 1 and 2, the overall configuration of the FRP laminated piping member P delamination estimation device 11, which can implement the FRP laminated piping member P delamination estimation method according to the present invention, will be described. FRP is an abbreviation for Fiber Reinforced Plastics, meaning fiber-reinforced plastic. As FRP, for example, materials such as glass mat, roving cloth, or glass cloth impregnated with polyester resin can be used. Generally, there are two methods for manufacturing FRP: one in which synthetic resin is impregnated into fibers such as glass fibers or carbon fibers, and another in which shredded fibers and synthetic resin are uniformly mixed and molded. The FRP used in the FRP laminated piping member P that is the target of diagnosis by the FRP laminated piping member P delamination estimation method and delamination estimation device 11 according to the present invention includes FRP manufactured by either method, and the manufacturing method of the FRP used in the FRP laminated piping member P that is the target of diagnosis is not particularly limited. 【0026】 The peeling estimation device 11 for FRP laminated piping members P (hereinafter simply referred to as the "peeling estimation device") estimates whether or not peeling defects exist inside by striking the surface of FRP laminated piping members P such as pipes, fittings, elbows, crosses, sockets, unions, valves, and tanks that have a laminated structure including an FRP layer. The peeling estimation device 11 comprises a striking hammer 13 for striking the surface of the FRP laminated piping member P and a measurement and analysis device 15 for analyzing the measured values ​​of the acceleration of the striking hammer 13. Hereinafter, in this specification, the FRP laminated piping member P includes a piping member composed of an FRP laminate having a laminated structure in which multiple types of FRP are laminated, a composite piping member composed of a base material layer and a single layer of FRP lining layer covering it, and a composite piping member composed of a base material layer and an FRP lining layer made of an FRP laminate (i.e., FRP having a laminated structure) covering it. Furthermore, the delamination defects of the FRP laminated piping member P include delamination between layers in the FRP laminate and delamination between the base material layer and the FRP lining layer. The base material layer can be made of synthetic resins such as polyvinyl chloride (PVC), chlorinated polyvinyl chloride (PVC-C), polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF), or steel, cast iron, or non-ferrous metals. 【0027】 The striking hammer 13 includes a striking part 13a for striking the surface of the FRP laminated piping member P, a gripping part 13b connected to the striking part 13a for the operator to grip, and an acceleration sensor 17 attached to the side of the striking part 13a opposite to the striking surface. The operator can grip the gripping part 13b and strike the surface of the FRP laminated piping member P with the striking part 13a, and the acceleration of the striking part 13a during the striking can be measured. The acceleration sensor 17 is connected to a measurement and analysis device 15 via a cable 19 that runs through the gripping part 13b to the outside, and the measurement signal measured by the acceleration sensor 17 (i.e., the acceleration of the striking part 13a) can be transmitted to the measurement and analysis device 15. 【0028】 The striking part 13a has a certain mass m and can be any shape as long as it is capable of striking the surface of the FRP laminated piping member P. Furthermore, as the acceleration sensor 17, any suitable type of acceleration sensor can be used, such as a piezoelectric element type, a semiconductor gauge type, or a resistance wire strain type. 【0029】 As shown in detail in Figure 2, the measurement and analysis device 15 includes a measurement value storage unit 15a that stores the measurement signal (acceleration of the striking unit 13a) transmitted from the acceleration sensor 17 via the cable 19, a threshold storage unit 15b that stores predetermined threshold values ​​for the mechanical impedance ZR and the peeling index INDEX, respectively, which will be described later, a correction data storage unit 15c that stores data for performing temperature correction on the mechanical impedance ZR and the peeling index INDEX, a peeling estimation unit 15d that estimates the presence or absence of peeling defects in the FRP laminated piping member P based on the measured acceleration of the striking hammer 13 by the acceleration sensor 17, a display unit 15e for displaying the results estimated by the peeling estimation unit 15d, and a temperature measurement unit 15f for measuring the temperature of the measurement environment. 【0030】 When the striking hammer 13 strikes the surface of the FRP laminated piping member P, the surface of the FRP laminated piping member P undergoes elastic deformation or a small amount of plastic deformation in addition to the impact of the striking hammer 13, and at the same time, the striking hammer 13 receives a reaction force from the surface of the FRP laminated piping member P due to the deformation. As a result, after the striking part 13a of the striking hammer 13 collides with the surface of the FRP laminated piping member P at time t=T1, the striking part 13a is decelerated by the reaction force from the surface of the FRP laminated piping member P from the initial collision velocity Va at the moment of impact (hereinafter also simply referred to as "collision velocity") Va to become 0 at time t=T2, and is further accelerated by a(t) in the opposite direction to the velocity at the time of impact, so that the striking part 13a separates from the surface of the FRP laminated piping member P at time t=T3, and at that moment the acceleration a(t) becomes 0 and the rebound velocity becomes the maximum rebound velocity (hereinafter also simply referred to as "rebound velocity") Vr. Here, t represents time, and acceleration a(t) represents the acceleration of the striking hammer 13 at time t. Therefore, the collision velocity Va can be calculated by integrating acceleration a(t) from time t=T1 to time t=T2, and the rebound velocity Vr can be calculated by integrating acceleration a(t) from time t=T2 to time t=T3. Furthermore, the impact force F(t) generated on the surface of the piping member P by the impact of the striking hammer 13 can be obtained by the equation F(t)=m·a(t), where m is the mass of the striking hammer 13. 【0031】 Assuming that the deformation of the FRP laminated piping member P is mostly elastic, the repulsive force from the surface of the FRP laminated piping member P is maximum when the velocity V of the striking hammer 13 becomes 0, and the acceleration a(t) is maximum when the velocity V of the striking hammer 13 becomes 0. Therefore, the acceleration a(t) at time t is 0 at time t=T1 when the striking part 13a of the striking hammer 13 collides with the surface of the FRP laminated piping member P, and at time t=T3 when the striking part 13a of the striking hammer 13 leaves the surface of the FRP laminated piping member P, as shown in Figure 3, and the maximum value a is reached at time t=T2 when the velocity V of the striking hammer 13 becomes 0. max It becomes so. Also, the striking force F reaches its maximum value at time t=T2. max It becomes F max is equation Fmax =m·a max This is determined by [the following method]. In the following explanation, the period from time t=T1 to time t=T2 will be referred to as the penetration process, and the period from time t=T2 to time t=T3 will be referred to as the repulsion process. 【0032】 If delamination defects exist within the FRP laminated piping member P, the rebound force when the FRP laminated piping member P is struck will also decrease, and the maximum acceleration a max In other words, the maximum value of striking force F max Furthermore, it is thought that this affects the maximum rebound velocity Vr. From this, the inventors believe that during the recovery from deformation of the FRP laminated piping member P after being struck by the striking hammer 13, i.e., during the rebound process, the presence or absence of delamination defects in the FRP laminated piping member P affects the acceleration of the striking hammer 13 and the maximum striking force F max The mechanical impedance of the rebound process is ZR = F, which is the value obtained by dividing by the maximum rebound velocity Vr. max We found that the presence or absence of delamination defects in the FRP laminated piping member P can be estimated based on / Vr and the delamination index INDEX = Va / Vr, which is the ratio of the impact velocity Va to the rebound velocity Vr. Needless to say, the delamination index INDEX can also be expressed as Vr / Va. 【0033】 Furthermore, the mechanical impedance ZR during the rebound process depends on the collision velocity Va. max Since it is obtained by dividing by Vr, which depends on the impact velocity Va, it is a value that is not affected by the impact velocity, and the delamination index INDEX is also a value that is not affected by the impact velocity, as it is the ratio of the impact velocity Va to the rebound velocity Vr. Therefore, it is not affected by the force of the impact. Furthermore, the effect of the presence or absence of delamination defects in the FRP laminated piping member P appears in the rebound process, so the mechanical impedance ZA = F max The mechanical impedance of the repulsion process is ZR=F, not / Va. max / Vr is used as an indicator to estimate the presence or absence of delamination defects. 【0034】 Furthermore, the inventors have found that the mechanical impedance ZR and delamination index INDEX of the rebound process of the FRP laminated piping member P are temperature-dependent. Utilizing this finding, the temperature at the time of measurement for estimating the presence or absence of delamination defects is measured by the temperature measuring unit 15f, using the temperature at the time of measurement for determining the threshold described later as a reference. Based on the measured temperature, the mechanical impedance ZR and delamination index INDEX of the rebound process, obtained from the acceleration measurement values, are temperature-corrected, thereby enabling a more accurate estimation of the presence or absence of delamination defects in the FRP laminated piping member P. 【0035】 In addition, the inventors found that when the product of the mass of the striking hammer 13 and the acceleration of the striking hammer 13 is used as the impact force applied to the FRP laminated piping member P by the striking hammer 13, and comparing the case where the FRP laminated piping member P has delamination defects and the case where it does not, if the FRP laminated piping member P has delamination defects, two or more peaks are observed in the time-dependent waveform of the impact force, which is obtained from the acceleration of the striking hammer 13 measured by the acceleration sensor 17, and the presence or absence of delamination defects can be estimated based on the number of peaks in the time-dependent waveform of the impact force. Here, the number of peaks in the time-dependent waveform of the impact force is calculated as the number of peaks in the time-dependent waveform from when the impact force starts to increase after the striking hammer 13 strikes the FRP laminated piping member P until the impact force returns to its initial value (value before striking) (the number of peaks after the impact force becomes 0 or less is not included). 【0036】 Utilizing the above findings by the inventors, the delamination estimation unit 15d estimates the presence or absence of delamination defects in the FRP laminated piping member P based on the acceleration of the impact hammer 13 measured by the acceleration sensor 17. More specifically, it estimates the presence or absence of delamination defects in the FRP laminated piping member P based on the number of peaks in the time-dependent waveform of the impact force by the impact hammer 13 obtained from the acceleration measurement of the impact hammer 13 by the acceleration sensor 17, the mechanical impedance ZR of the rebound process obtained from the acceleration measurement of the impact hammer 13 by the acceleration sensor 17, and at least one of the delamination index INDEX. The procedure for estimating the presence or absence of delamination defects in the FRP piping member P based on the acceleration measurement of the impact hammer 13 by the acceleration sensor 17 using the delamination estimation device 11 shown in the figure will be described in detail below. 【0037】 First, for each combination of pipe type and nominal diameter of the FRP laminated piping member P, multiple FRP laminated piping members P are divided into sound products without delamination defects and products with delamination defects. For each, the mechanical impedance ZR and delamination index INDEX during the rebound process are calculated from the measured acceleration a(t) obtained by striking with a striking hammer 13. A threshold value for distinguishing between sound products and products with delamination defects in terms of mechanical impedance ZR and delamination index INDEX is predetermined for each combination of pipe type and nominal diameter of the FRP laminated piping member P and stored in the threshold value storage unit 15b. It is preferable to measure the acceleration a(t) of the striking hammer 13 for determining the threshold value under specific temperature conditions. When the pipe type is specified, the material (type), shape, and laminate structure of the FRP and base material used in the FRP laminated piping member are also specified. Furthermore, since the nominal diameter of the piping member is generally determined according to standards, when the nominal diameter is specified, the outer diameter and thickness (i.e., inner diameter) are specified based on the standards. Therefore, defining thresholds for sound products and delamination-defective products for mechanical impedance ZR and delamination index INDEX for each pipe type and nominal diameter of FRP laminated piping member P is equivalent to defining thresholds for sound products and delamination-defective products for mechanical impedance ZR and delamination index INDEX for each material (type), shape, laminate structure, outer diameter, and thickness (i.e., inner diameter) of the FRP and base material of the FRP laminated piping member P. 【0038】 Furthermore, for each pipe type and nominal diameter of the FRP laminated piping member P, it is preferable to measure the acceleration a(t) by striking with the impact hammer 13 while changing the temperature conditions, calculate the mechanical impedance ZR and peel index INDEX during the rebound process from the measured acceleration a(t), and pre-determine the correlation between temperature, mechanical impedance ZR, and peel index INDEX for each combination of pipe type and nominal diameter of the FRP laminated piping member P, and pre-store it in the correction data storage unit 15c. Alternatively, for each combination of pipe type and nominal diameter of the FRP laminated piping member P, an approximate function that approximates the correlation between temperature, mechanical impedance ZR, and peel index INDEX may be determined, and the determined approximate function may be stored in the correction data storage unit 15c. Alternatively, for each combination of pipe type and nominal diameter of the FRP laminated piping member P, a temperature correction coefficient for each temperature may be determined based on the temperature conditions at the time of measurement for determining the threshold, and the temperature correction coefficient may be stored in the correction data storage unit 15c. 【0039】 Next, the impact hammer 13 strikes the surface of the FRP laminated piping member P to be diagnosed, and the acceleration a(t) of the impact hammer 13, measured by the acceleration sensor 17, is measured over time and stored in the measurement value storage unit 15a. The maximum impact force F will be described later. max It is preferable to set upper and lower limits and use only the measured values ​​when the maximum impact force falls within that range. From the measured values ​​of acceleration a(t) over time, the maximum value of acceleration a max This also tells us the time T2 at which that value was observed. 【0040】 In the delamination estimation unit 15d, the time-dependent waveform of the impact force F applied to the FRP laminated piping member P by the impact hammer 13 is calculated using the formula F = m·a(t), that is, as the product of the measured acceleration a(t) of the impact hammer 13 and the mass m of the impact hammer 13, based on the known mass m of the impact hammer 13 and the time-dependent measured values ​​of acceleration a(t) stored in the measurement value storage unit 15a. Furthermore, based on the calculated time-dependent waveform of the impact force F, the delamination estimation unit 15d determines the number of peaks in the time-dependent waveform of the impact force F from the time the impact by the impact hammer 13 starts to increase until it returns to its initial value (i.e., becomes 0 or less), and uses this as the first estimation index. If there are two or more peaks in the time-dependent waveform of the impact force, it is estimated that there is a possibility of delamination defects in the FRP laminated piping member P. 【0041】 Furthermore, in the separation estimation unit 15d, the collision velocity Va is calculated by integrating the measured values ​​of acceleration a(t) over time from the measured value storage unit 15a until the acceleration a(t) increases from 0 to its maximum value (i.e., from time T1 to time T2), and the rebound velocity Vr is calculated by integrating the measured values ​​of acceleration a(t) over time until the acceleration a(t) decreases from its maximum value back to 0 (i.e., from time T2 to time T3). From the measured values ​​of acceleration a(t) over time stored in the measured value storage unit 15a, the maximum acceleration a max Since this is known, from the mass m of the striking hammer 13 which is known in advance and the measured value of the acceleration a(t) over time stored in the measurement value storage unit 15a, equation F max =m·a max The maximum value F of the impact force generated when the impact part 13a of the impact hammer 13 collides with the surface of the FRP laminated piping member P. max The following is calculated: The collision velocity Va, rebound velocity Vr, and the maximum value F of the impact force calculated in this way. max Therefore, the peeling estimation unit 15d is given by the formula ZR=F max Based on / Vr and the formula INDEX=Va / Vr, the mechanical impedance ZR and the separation index INDEX during the rebound process are determined. 【0042】 Furthermore, the delamination estimation unit 15d preferably measures the temperature at the time of measurement for estimating the presence or absence of delamination defects using the temperature measurement unit 15f, and after determining the mechanical impedance ZR and delamination index INDEX in the rebound process, it preferably corrects the mechanical impedance ZR and delamination index INDEX obtained as described above based on the temperature correction data stored in the correction data storage unit 15c, according to the temperature conditions at the time of measurement. The temperature correction may be performed using, for example, an approximate function of the mechanical impedance ZR and delamination index INDEX with respect to temperature stored in the correction data storage unit 15c, as described above, or a correction coefficient for the mechanical impedance ZR and delamination index INDEX at each temperature based on the temperature conditions at the time of measurement for determining the threshold may be stored in the correction data storage unit 15c, and the correction may be performed using the correction coefficient stored in the correction data storage unit 15c. The method of correction is not limited. By performing temperature correction in this way, it becomes possible to estimate the presence or absence of delamination defects more accurately. 【0043】 When temperature correction is performed, the delamination estimation unit 15d uses the values ​​of mechanical impedance ZR' and delamination index INDEX' obtained by temperature correction using the method described above, which are derived from the measured acceleration of the FRP laminated piping member P to be diagnosed by striking. When temperature correction is not performed, the unit uses the values ​​of mechanical impedance ZR and delamination index INDEX obtained from the measured acceleration of the FRP laminated piping member P to be diagnosed by striking. The unit compares these values ​​with the threshold values ​​corresponding to the pipe type and nominal diameter of the FRP laminated piping member P to be diagnosed, which are pre-stored in the threshold storage unit 15b. The delamination estimation unit 15d further uses at least one of the mechanical impedance ZR and delamination index INDEX values ​​of the FRP laminated piping member P to be diagnosed, or at least one of the temperature-corrected mechanical impedance ZR' and delamination index INDEX' values, as a second estimation index. If these values ​​fall below the thresholds for mechanical impedance ZR and delamination index INDEX pre-stored in the threshold memory unit 15b corresponding to the pipe type and nominal diameter of the FRP laminated piping member P to be diagnosed, the unit estimates that there is a possibility of delamination defects in the FRP laminated piping member P to be diagnosed. In particular, if both the mechanical impedance ZR and delamination index INDEX values ​​of the FRP laminated piping member P to be diagnosed, or both the temperature-corrected mechanical impedance ZR' and delamination index INDEX' values, fall below the thresholds for mechanical impedance ZR and delamination index INDEX pre-stored in the threshold memory unit 15b corresponding to the pipe type and nominal diameter of the FRP laminated piping member P to be diagnosed, the delamination estimation unit 15d estimates that there is a higher probability of delamination defects in the FRP laminated piping member P to be diagnosed. 【0044】 The delamination estimation unit 15d uses at least one of the following as estimation indicators: the number of peaks in the waveform of the change in impact force over time, the mechanical impedance ZR of the FRP laminated piping member P, and the value of the delamination index INDEX. If (1) the number of peaks in the waveform of the change in impact force over time is two or more, or (2) at least one of the mechanical impedance ZR and the value of the delamination index INDEX of the FRP laminated piping member P, or at least one of the temperature-corrected mechanical impedance ZR' and the value of the delamination index INDEX', falls below the threshold values ​​of the mechanical impedance ZR and delamination index INDEX stored in advance in the threshold storage unit 15b, the unit estimates that a delamination defect exists in the FRP laminated piping member P being diagnosed, i.e., that it is a product with a delamination defect, and displays the estimation result on the display unit 15e. On the other hand, if the number of peaks in the time-dependent waveform of the impact force is one, and if both the mechanical impedance ZR and the peel index INDEX of the FRP laminated piping member P, or both the temperature-corrected mechanical impedance ZR' and the peel index INDEX', are greater than or equal to the threshold values ​​for mechanical impedance ZR and peel index INDEX stored in advance in the threshold storage unit 15b corresponding to the pipe type and nominal diameter of the FRP laminated piping member P, respectively, the peel estimation unit 15d estimates that there are no peel defects in the FRP laminated piping member P to be diagnosed, i.e., that it is a sound product, and displays the estimation result on the display unit 15e. 【0045】 Furthermore, when the two requirements (1) and (2) above are met, the delamination estimation unit 15d may estimate that there is a higher probability that the FRP laminated piping member P to be diagnosed has a delamination defect, i.e., a higher probability that it is a defective product, and display this fact on the display unit 15e. In addition, if both the mechanical impedance ZR and the delamination index INDEX values ​​of the FRP laminated piping member P to be diagnosed, or both the temperature-corrected mechanical impedance ZR' and the delamination index INDEX' values, fall below the threshold values ​​for mechanical impedance ZR and delamination index INDEX that are pre-stored in the threshold storage unit 15b corresponding to the pipe type and nominal diameter of the FRP laminated piping member P to be diagnosed, the delamination estimation unit 15d may estimate that there is a higher probability that the FRP laminated piping member P to be diagnosed has a delamination defect, i.e., a higher probability that it is a defective product, and display this fact on the display unit 15e. 【0046】 In this way, by using the delamination estimation device 11, the delamination estimation method for FRP laminated piping member P according to the present invention can be implemented, and by measuring the acceleration of the impact hammer 13 when the FRP laminated piping member P to be diagnosed is struck, the presence or absence of delamination defects in the FRP laminated piping member P can be easily estimated. In particular, if (1) the number of peaks in the waveform of the change in impact force over time is two or more, and (2) one or both of the mechanical impedance ZR and delamination index INDEX values ​​of the FRP laminated piping member P, or one or both of the temperature-corrected mechanical impedance ZR' and delamination index INDEX' values ​​are below the threshold values ​​of mechanical impedance ZR and delamination index INDEX stored in advance in the threshold memory unit 15b, then it can be estimated that there is a higher possibility that delamination defects exist in the FRP laminated piping member P to be diagnosed. Of course, if both the mechanical impedance ZR and the delamination index INDEX of the FRP laminated piping member P, or both the temperature-corrected mechanical impedance ZR' and the delamination index INDEX', fall below the threshold values ​​for mechanical impedance ZR and delamination index INDEX pre-stored in the threshold memory unit 15b, it can be estimated that there is a higher probability that delamination defects exist in the FRP laminated piping member P being diagnosed. 【0047】 Therefore, by using the delamination estimation device 11, even when inspecting the entire piping system, it is possible to estimate the locations where delamination defects exist in a short time and at low cost. Furthermore, if a more accurate diagnosis is desired, conventional non-destructive testing methods such as ultrasonic testing and radiographic testing, or destructive testing, may be performed on the FRP laminated piping member P that has been estimated to have delamination defects. If conventional non-destructive testing is performed only on the FRP laminated piping member P that has been estimated to have delamination defects using the FRP laminated piping member P delamination estimation device 11 or the FRP laminated piping member P delamination estimation method according to the present invention, the inspection time can be significantly reduced and costs can be greatly lowered compared to performing conventional non-destructive testing on the entire piping system. In addition, by using the FRP laminated piping member P delamination estimation device 11 or the FRP laminated piping member P delamination estimation method according to the present invention, it is possible to narrow down the locations where there is a high probability of delamination defects in the FRP laminated piping member P, making it easier to apply radiographic testing. Furthermore, by performing destructive testing only on FRP laminated piping members P that are estimated to be defective due to delamination using the FRP laminated piping member P delamination estimation device 11 or the FRP laminated piping member P delamination estimation method according to the present invention, it becomes possible to reduce downtime by requiring only the minimum necessary parts replacement. [Examples] 【0048】 Figures 4 and 5 show the time-varying waveform of the impact force applied to the test specimens by the impact hammer 13 (i.e., the mass m of the impact hammer 13 and the measured acceleration a(t)), obtained from the experimental results of the measured acceleration a(t) of the impact hammer 13. The test specimens were FRP laminated piping members (manufactured by Asahi Organic Chemicals: AV-GU) of the same pipe type, which are straight pipes of rigid polyvinyl chloride with a nominal diameter of 300 mm according to the JIS K6741:2016 standard, reinforced by coating the outer surface with an FRP liner layer. The experiment involved striking multiple test specimens with the impact hammer 13 for both sound and delamination-defective specimens, and measuring the acceleration a(t) of the impact hammer 13. Figure 4 is a graph showing the results for sound test specimens, and Figure 5 is a graph showing the test results for delamination-defective specimens. 【0049】 As can be seen from Figure 4, in sound products, regarding the time-varying waveform of the impact force, fluctuations are observed due to the rebound force from the test specimen after it starts to increase and returns to its initial value, and multiple peaks are observed, but only one peak is observed from the time the impact force starts to increase until it returns to its initial value. On the other hand, as can be seen from Figure 5, in products with delamination defects, two or more peaks are observed in the time-varying waveform of the impact force from the time the impact force starts to increase until it returns to its initial value. Therefore, regarding the time-varying waveform of the impact force obtained from the acceleration a(t) of the impact hammer 13 measured when striking with the impact hammer 13, if only one peak is observed, it can be estimated that it is a sound product, while if two or more peaks are observed, it can be estimated that it is potentially a product with delamination defects. 【0050】 Figures 6 and 7 show graphs plotting the mechanical impedance ZR and delamination index INDEX during the rebound process. The experiment involved using FRP laminated piping members (manufactured by Asahi Organic Chemicals: AV-GU), which are straight pipes of rigid polyvinyl chloride with a nominal diameter of 25 mm, reinforced by coating the outer surface with an FRP liner layer, as test specimens. Multiple test specimens of both sound and delamination-defective products were struck with a striking hammer 13, and the acceleration a(t) of the striking hammer 13 was measured to determine the mechanical impedance ZR and delamination index INDEX. Figure 6 is a graph showing the test results for mechanical impedance ZR for test specimens with a nominal diameter of 25 mm, and Figure 7 is a graph showing the test results for delamination index INDEX for test specimens with a nominal diameter of 25 mm. In Figure 6, the mechanical impedance ZR obtained from sound test specimens is plotted as "○", and the mechanical impedance ZR obtained from delamination-defective test specimens is plotted as "×". Similarly, in Figure 7, the delamination index IDEX obtained from healthy specimens is plotted as "○", while the delamination index INDEX obtained from specimens with delamination defects is plotted as "×". 【0051】 Figures 8 and 9 show graphs plotting the mechanical impedance ZR and delamination index INDEX during the rebound process. These were obtained by striking multiple test specimens of both sound and delamination-defective rigid polyvinyl chloride straight pipes with a nominal diameter of 100 mm, reinforced by coating the outer surface with an FRP liner layer, as in the experiments related to Figures 6 and 7. The test specimens were FRP laminated piping members (manufactured by Asahi Organic Chemicals: AV-GU), the same type of pipe as in the experiments related to Figures 6 and 7. The test specimens were struck with a striking hammer 13, and the acceleration a(t) of the striking hammer 13 was measured to determine the mechanical impedance ZR and delamination index INDEX during the rebound process. Figure 8 is a graph showing the test results for mechanical impedance ZR for test specimens with a nominal diameter of 100 mm, and Figure 9 is a graph showing the test results for delamination index INDEX for test specimens with a nominal diameter of 100 mm. Furthermore, in Figure 8, the mechanical impedance ZR obtained from a sound specimen is plotted as "○", while the mechanical impedance ZR obtained from a delamination-defective specimen is plotted as "×". Similarly, in Figure 9, the delamination index IDEX obtained from a sound specimen is plotted as "○", while the delamination index INDEX obtained from a delamination-defective specimen is plotted as "×". 【0052】 Figures 10 and 11 show graphs plotting the mechanical impedance ZR and delamination index INDEX during the rebound process. These were obtained by using the same type of FRP laminated piping member (manufactured by Asahi Organic Chemicals: AV-GU) as the test specimens for the experiments in Figures 6 and 7, where a rigid polyvinyl chloride straight pipe with a nominal diameter of 300 mm was reinforced by coating the outer surface with an FRP liner layer according to the JIS K6741:2016 standard. Multiple test specimens of both sound and delamination-defective products were struck with a striking hammer 13, and the acceleration a(t) of the striking hammer 13 was measured to determine the mechanical impedance ZR and delamination index INDEX. Figure 10 is a graph showing the test results for mechanical impedance ZR for a test specimen with a nominal diameter of 300 mm, and Figure 11 is a graph showing the test results for delamination index INDEX for a test specimen with a nominal diameter of 300 mm. Furthermore, in Figure 6, the mechanical impedance ZR obtained from a sound specimen is plotted as "○", while the mechanical impedance ZR obtained from a delamination-defective specimen is plotted as "×". Similarly, in Figure 7, the delamination index IDEX obtained from a sound specimen is plotted as "○", while the delamination index INDEX obtained from a delamination-defective specimen is plotted as "×". 【0053】 Figures 6, 8, and 10 show that a threshold for the mechanical impedance ZR used to distinguish between sound products and products with delamination defects can be determined for each nominal diameter. Regardless of the nominal diameter, if the mechanical impedance ZR, calculated from the acceleration a(t) of the impact hammer 13 measured on the FRP laminated piping member under diagnosis, falls below the threshold, it is considered a product with delamination defects; if it is above the threshold, it is considered a sound product. This confirms that the presence or absence of delamination defects in the product under diagnosis can be estimated based on whether the mechanical impedance ZR is below the threshold. Furthermore, Figures 7, 9, and 11 show that a threshold for the delamination index INDEX used to distinguish between sound products and products with delamination defects can be determined for each nominal diameter. Regardless of the nominal diameter, if the delamination index INDEX, calculated from the acceleration a(t) of the impact hammer 13 measured on the FRP laminated piping member under diagnosis, falls below the threshold, it is considered a product with delamination defects; if it is above the threshold, it is considered a sound product. This confirms that the presence or absence of delamination defects can be estimated based on whether the delamination index INDEX is below the threshold. Naturally, using both mechanical impedance ZR and delamination index INDEX as estimation indicators, it can be estimated that if both mechanical impedance ZR and delamination index INDEX fall below predetermined thresholds for each, there is a higher probability that delamination defects exist in the object being diagnosed. Furthermore, from the experimental results shown in Figure 4 and Figures 10 and 11, it can be seen that if the number of peaks in the time-dependent waveform of the impact force is two or more, and both mechanical impedance ZR and delamination index INDEX fall below predetermined thresholds for each, there is an even higher probability that delamination defects exist in the object being diagnosed. 【0054】 Figures 12 and 13 show graphs plotting the mechanical impedance ZR and delamination index INDEX during the rebound process. The experiment involved using a rigid polyvinyl chloride straight pipe with a nominal diameter of 100 mm, manufactured according to the JIS K6741:2016 standard, as a test specimen. The test specimen was reinforced by covering the outer surface with an FRP liner layer made of a different material with reduced strength than that used in the experiments related to Figures 8 and 9. Multiple test specimens of both sound and delamination-defective products were struck with a striking hammer 13, and the acceleration a(t) of the striking hammer 13 was measured to determine the mechanical impedance ZR and delamination index INDEX. The obtained mechanical impedance ZR and delamination index INDEX are plotted in comparison between sound and delamination-defective products. Figure 12 shows the test results for mechanical impedance ZR for a test specimen with a nominal diameter of 100 mm, and Figure 13 shows the test results for delamination index INDEX for a test specimen with a nominal diameter of 100 mm. Furthermore, in Figure 12, the mechanical impedance ZR obtained from a sound specimen is plotted as "○", while the mechanical impedance ZR obtained from a delamination-defective specimen is plotted as "×". Similarly, in Figure 13, the delamination index IDEX obtained from a sound specimen is plotted as "○", while the delamination index INDEX obtained from a delamination-defective specimen is plotted as "×". 【0055】 Figures 8 and 9, and Figures 12 and 13 show that even with different pipe types, a threshold for mechanical impedance ZR can be determined to distinguish between sound products and products with delamination defects. Regardless of the pipe type, if at least one of the mechanical impedance ZR and delamination index INDEX, obtained from the acceleration a(t) of the impact hammer 13 measured on the FRP laminated piping member under diagnosis, falls below a predetermined threshold, it is considered a product with delamination defects; if it is above the threshold, it is considered a sound product. This confirms that, regardless of the pipe type, the presence or absence of delamination defects in the product under diagnosis can be estimated based on whether at least one of the mechanical impedance ZR and delamination index INDEX falls below the threshold. Similarly, if both mechanical impedance ZR and delamination index INDEX are used as estimation indices, and both fall below predetermined thresholds for each, it can be estimated that there is a higher probability of delamination defects in the product under diagnosis. 【0056】 Thus, according to the FRP laminated piping member P delamination estimation method and delamination estimation apparatus 11 of the present invention, the surface of the FRP laminated piping member P is struck with a striking hammer 13, the acceleration of the striking hammer 13 is measured, and the number of peaks in the time-dependent change waveform of the striking force obtained based on the measured acceleration of the striking hammer 13, and at least one of the mechanical impedance ZR and delamination index INDEX of the FRP laminated piping member P are used as estimation indicators, and if (1) the number of peaks in the time-dependent change waveform of the striking force is two or more, or (2) at least one of the mechanical impedance ZR and delamination index INDEX of the FRP laminated piping member P, or at least one of the temperature-corrected mechanical impedance ZR' and delamination index INDEX' values ​​falls below the threshold values ​​of mechanical impedance ZR and delamination index INDEX stored in advance in the threshold storage unit 15b, it can be estimated that the FRP laminated piping member P to be diagnosed is a product with delamination defects. If the number of peaks in the time-dependent waveform of the impact force is one, and if both the mechanical impedance ZR and the delamination index INDEX of the FRP laminated piping member P, or both the temperature-corrected mechanical impedance ZR' and delamination index INDEX', are greater than or equal to the threshold values ​​for mechanical impedance ZR and delamination index INDEX pre-stored in the threshold memory unit 15b corresponding to the pipe type and nominal diameter of the FRP laminated piping member P, then the piping member P to be diagnosed can be estimated to be a sound product without delamination defects. Therefore, the presence or absence of delamination defects can be estimated by simple and inexpensive non-destructive testing. Furthermore, since the estimation criteria are clear, there are no cases where estimation is not possible, and automation is easy. In addition, since non-destructive testing can be performed only on the FRP laminated piping member to be diagnosed to diagnose the presence or absence of delamination defects, it is possible to reduce the cost of accurate diagnosis. 【0057】 The peeling estimation method and peeling estimation apparatus for FRP laminated piping member P according to the present invention have been described above with reference to the illustrated embodiments, but the present invention is not limited to the illustrated embodiments. For example, in the peeling estimation apparatus 11 for FRP laminated piping member P of the illustrated embodiment, a display unit 15e is provided in the measurement and analysis device 15, and the estimation result regarding the presence or absence of peeling defects is displayed on the display unit 15e. However, it is also possible for the measurement and analysis device 15 to be equipped with an alarm unit, which emits an alarm sound when it is estimated that peeling defects exist. Furthermore, in the peeling estimation apparatus 11 for FRP laminated piping member P of the illustrated embodiment, the striking hammer 13 and the measurement and analysis device 15 are configured as separate units, but the measurement and analysis device 15 may be formed integrally with the striking hammer 13. [Explanation of symbols] 【0058】 11. Peeling Estimation Device 13. Striking Hammer 13a Hitting section 13b Grip part 15 Measurement and analysis equipment 15a Measurement value storage unit 15b Threshold memory unit 15d Estimated peeling area 15e Display section 17. Accelerometer

Claims

[Claim 1] A method for estimating the presence or absence of delamination defects in an FRP laminated piping member having a laminated structure including an FRP layer, using a measuring device comprising a striking hammer and an acceleration sensor attached to the striking hammer, The surface of the FRP laminated piping member is struck by the striking hammer, and the acceleration of the striking hammer is measured over time by the acceleration sensor. From the measured acceleration of the striking hammer, at least one of the following is determined: the time-dependent waveform of the striking force, which is the product of the mass of the striking hammer and the acceleration of the striking hammer; the mechanical impedance ZR during the rebound process when the striking hammer repels the surface of the FRP laminated piping member in the opposite direction to when it impacted the surface; and an index I, which is the ratio of the impact velocity Va when the striking hammer impacts the surface of the FRP laminated piping member to the rebound velocity Vr when the striking hammer repels the surface of the FRP laminated piping member. Based on the number of peaks in the time-dependent waveform of the striking force from the start of increase until it falls below the initial value again, the determined mechanical impedance ZR, and at least one of the index I, the presence or absence of delamination defects in the FRP laminated piping member is estimated. The collision velocity Va is calculated by integrating the measured acceleration over time from zero to its maximum value. The rebound velocity Vr is calculated by integrating the measured acceleration over time until it decreases from its maximum value back to zero. When the impact hammer collides with the surface of the FRP laminated piping member, the maximum impact force generated is defined as F max. F max is calculated from the mass of the impact hammer and the acceleration of the impact hammer measured by the acceleration sensor. A method for estimating delamination of an FRP laminated piping member, characterized in that the mechanical impedance ZR is determined by the formula ZR = F max / Vr, and the index I is determined as the ratio of the collision velocity Va to the rebound velocity Vr. [Claim 2] The index I is calculated using the formula I = Va / Vr. A threshold value is predetermined for the mechanical impedance ZR and the index I, respectively. A method for estimating delamination defects in an FRP laminated piping member according to claim 1, wherein when the number of peaks in the time-dependent waveform of the impact force by the impact hammer is two or more, or when at least one of the mechanical impedance ZR and the index I, as determined by measurement, falls below a predetermined threshold for each of the mechanical impedance ZR and the index I, it is estimated that delamination defects exist in the FRP laminated piping member. [Claim 3] The method for estimating delamination of an FRP laminated piping member according to claim 2, wherein the number of peaks in the time-dependent waveform of the impact force by the impact hammer is two or more, and when both the mechanical impedance ZR and the index I, as determined by measurement, are lower than predetermined thresholds for each of the mechanical impedance ZR and the index I, the probability of delamination defects existing in the FRP laminated piping member is estimated to be higher. [Claim 4] A method for estimating delamination of an FRP laminated piping member according to any one of claims 1 to 3, wherein the FRP laminated piping member includes an FRP laminate having a laminated structure, and the delamination defect is interlayer delamination within the FRP laminate. [Claim 5] A method for estimating delamination of an FRP laminated piping member according to any one of claims 1 to 3, wherein the FRP laminated piping member comprises a base material layer and an FRP liner layer covering the base material layer, and the delamination defect is delamination between the base material layer and the FRP liner layer. [Claim 6] A delamination estimation device for FRP laminated piping members having a laminated structure including an FRP layer, which estimates delamination defects in FRP laminated piping members, A striking hammer for striking the surface of FRP laminated piping members, An acceleration sensor attached to the striking hammer, A measurement value storage unit that stores the acceleration of the striking hammer measured by the acceleration sensor over time, A delamination estimation unit estimates whether or not there are delamination defects in the FRP laminated piping member based on the acceleration stored in the measurement value storage unit, Equipped with, The delamination estimation unit determines, from the acceleration stored in the measurement value storage unit, at least one of the following: the waveform of the change in impact force over time, which is the product of the mass of the impact hammer and the acceleration of the impact hammer; the mechanical impedance ZR during the rebound process when the impact hammer repels the surface of the FRP laminated piping member in the opposite direction to when it impacts the surface of the FRP laminated piping member; and an index I, which is the ratio of the impact velocity Va when the impact hammer impacts the surface of the FRP laminated piping member to the rebound velocity Vr when the impact hammer repels the surface of the FRP laminated piping member. Based on the number of peaks in the waveform of the change in impact force over time from when it starts to increase until it falls below the initial value again, the determined mechanical impedance ZR, and at least one of the index I, the presence or absence of delamination defects in the FRP laminated piping member is estimated. The collision velocity Va is calculated by integrating the acceleration stored in the measurement value storage unit over time until it increases from zero to its maximum value. The rebound velocity Vr is calculated by integrating the acceleration stored in the measurement value storage unit over time until it decreases from its maximum value back to zero. When the impact hammer collides with the surface of the FRP laminated piping member, the maximum impact force generated is defined as F max. F max is calculated from the mass of the impact hammer and the acceleration of the impact hammer stored in the measurement value storage unit. The delamination estimation device for FRP laminated piping members is characterized in that the mechanical impedance ZR is determined by the formula ZR = F max / Vr. [Claim 7] The system further includes a threshold memory unit that stores predetermined threshold values ​​for each combination of pipe type and nominal diameter of the FRP laminated piping member, for the mechanical impedance ZR and the index I. The peeling estimation unit calculates the index I using the formula I = Va / Vr, and estimates that a peeling defect exists in the FRP laminated piping member when there are two or more peaks in the waveform of the change in the impact force over time by the impact hammer, or when at least one of the mechanical impedance ZR and the index I obtained by measurement is lower than predetermined thresholds for the mechanical impedance ZR and the index I, respectively, corresponding to the combination of pipe type and nominal diameter of the FRP laminated piping member to be measured, according to claim 6. [Claim 8] The peeling estimation device for an FRP laminated piping member according to claim 7, wherein the peeling estimation unit estimates that there is a higher probability that peeling defects exist in the FRP laminated piping member when the number of peaks in the time-dependent waveform of the impact force by the impact hammer is two or more, and both the mechanical impedance ZR and the index I obtained by measurement are lower than predetermined thresholds for the mechanical impedance ZR and the index I corresponding to the combination of pipe type and nominal diameter of the FRP laminated piping member to be measured. [Claim 9] The peeling estimation device for an FRP laminated piping member according to any one of claims 6 to 8, wherein the FRP laminated piping member includes an FRP laminate having a laminated structure, and the peeling defect is interlayer delamination within the FRP laminate. [Claim 10] The peeling estimation device for an FRP laminated piping member according to any one of claims 6 to 8, wherein the FRP laminated piping member comprises a base material layer and an FRP liner layer covering the base material layer, and the peeling defect is the peeling of the base material layer and the FRP liner layer.

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