WO2014057987A1

WO2014057987A1 - Inspection method and inspection system for composite container

Info

Publication number: WO2014057987A1
Application number: PCT/JP2013/077511
Authority: WO
Inventors: 幸次郎中川; 順二岡崎
Original assignee: Ｊｘ日鉱日石エネルギー株式会社
Priority date: 2012-10-11
Filing date: 2013-10-09
Publication date: 2014-04-17
Also published as: JP6238901B2; JPWO2014057987A1

Abstract

An inspection method for a composite container is a method for inspecting a composite container provided with a liner that forms the container, and a reinforcing layer that is formed by winding a fiber around the liner, the method being provided with: a signal acquisition step for acquiring an acoustic emission signal from an acoustic emission sensor attached to the composite container; and a first determination step for determining, on the basis of the acoustic emission signal acquired in the signal acquisition step, whether or not a first condition showing a sign of a fatigue failure of the liner is satisfied, and the first condition being a condition set on the basis of acoustic emission energy.

Description

Inspection method and inspection system for composite container

The present invention relates to a composite container inspection method and inspection system.

Conventionally, it has been known to employ various inspection methods as a non-destructive inspection method for containers enclosing a fluid. For example, as a nondestructive inspection method for a steel container, a magnetic jet flaw test, a penetrating deep flaw test, an ultrasonic flaw detection test, a radiation transmission test, an overflow flaw test, and the like have been adopted. For example, Patent Document 1 describes that an ultrasonic flaw detection test is employed as a nondestructive inspection method for a steel container.

JP-A-10-38858

Here, since the steel container is heavy and expensive, a composite container in which fibers are wound around a liner is being used instead of the container having the structure. Such a composite container is advantageous in that although it has sufficient strength, it is easy to handle because of its light weight, and its price is low. However, since the structure of the composite container is different from that of a steel container, there is a problem that an appropriate inspection cannot be performed when the non-destructive inspection method generally used for steel containers is adopted. It was.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a composite container inspection method capable of appropriately inspecting a composite container.

An inspection method for a composite container according to an aspect of the present invention is a composite container inspection method including a liner that forms a container, and a reinforcing layer that is formed by winding a fiber around the liner, and is attached to the composite container. Based on a signal acquisition step of acquiring an acoustic emission signal from the acoustic emission sensor, and whether or not a first condition indicating a sign of fatigue failure of the liner is satisfied based on the acoustic emission signal acquired by the signal acquisition step. 1 determination step, and the first condition is a condition determined based on the energy of acoustic emission.

As a result of intensive studies, the present inventors have found that a predetermined relationship is established between the energy of acoustic emission and the progress of liner fatigue. Therefore, it is possible to set the first condition indicating a sign of fatigue fracture of the liner based on the measurement result of acoustic emission measured in advance. In the composite container inspection method according to an aspect of the present invention, in the first determination step, whether or not the first condition is satisfied based on an acoustic emission signal acquired from an acoustic emission sensor attached to the composite container. Judgment. This makes it possible to inspect signs of fatigue failure of the liner of the composite container related to the inspection target, and to appropriately inspect the composite container.

The composite container inspection method may further include a second determination step of determining whether or not a second condition indicating damage of the reinforcing layer is satisfied based on the acoustic emission signal acquired by the signal acquisition step. A relationship different from the degree of progress of fatigue of the liner is established between the damage of the reinforcing layer formed by winding the fiber around the liner and the acoustic emission. Therefore, by setting the second condition that is different from the first condition that indicates the signs of fatigue failure of the liner, the reinforcing layer can be inspected appropriately.

In the composite container inspection method, the acoustic emission sensor may be attached to the surface of the liner and the reinforcing layer. By attaching an acoustic emission sensor to the surface of the liner, it is possible to accurately determine the first condition indicating an indication of fatigue failure of the liner. On the other hand, by attaching an acoustic emission sensor to the surface of the reinforcing layer, it is possible to accurately determine the second condition indicating damage to the reinforcing layer. Thus, even when a liner and a reinforcing layer having different properties are present in one composite container, appropriate inspection can be performed for each location.

In the composite container inspection method, the acoustic emission sensor attached to the surface of the reinforcing layer may be disposed in the cylinder portion of the composite container. Of the reinforced layer, the cylinder part that causes the destruction in the circumferential direction is set to be more easily broken than the dome part that causes the destruction in the axial direction. Therefore, by attaching an acoustic emission sensor to the cylinder portion, it is possible to more accurately inspect the reinforcement layer for damage.

In the composite container inspection method, the acoustic emission sensor attached to the surface of the reinforcing layer may be disposed in the dome portion of the composite container. Since the liner of the composite container is exposed at the tip end side of the dome portion, an acoustic emission sensor is attached to the position. Therefore, the acoustic emission sensor attached to the surface of the reinforcing layer is also arranged in the dome portion, so that the attachment positions of both sensors are close and the sensor attachment work at the time of inspection is facilitated.

An inspection system for a composite container according to the present invention is an inspection system for a composite container comprising a liner forming the container and a reinforcing layer formed by winding fibers around the liner, and an acoustic emission sensor attached to the composite container; Based on the signal acquisition unit that acquires the acoustic emission signal from the acoustic emission sensor and the acoustic emission signal acquired by the signal acquisition unit, it is determined whether or not the first condition indicating the sign of fatigue fracture of the liner is satisfied A first condition is a condition determined based on the energy of acoustic emission.

According to this inspection system, it is possible to obtain the same operations and effects as the above-described composite container inspection method.

According to the present invention, the composite container can be inspected appropriately.

FIG. 1 is a diagram showing a configuration of an inspection system for carrying out a composite container inspection method according to an embodiment of the present invention. FIG. 2 is a conceptual diagram for explaining the contents of the cycle test of the composite container. FIG. 3 is a schematic graph showing the relationship between the number of cycles and the AE energy for the liner. FIG. 4 is a schematic graph showing the relationship between pressure and AE energy for the reinforcing layer. FIG. 5 is a flowchart showing an example of the composite container inspection method according to the embodiment of the present invention. FIG. 6 is a flowchart showing an example of the composite container inspection method according to the embodiment of the present invention. FIG. 7 is a flowchart showing an example of the composite container inspection method according to the embodiment of the present invention. FIG. 8 is a diagram showing the attachment position of the AE sensor for measuring the data shown in FIG. FIG. 9 is a graph plotting the relationship between the number of cycles and the AE accumulated energy based on the measurement results. FIG. 10 is a view showing a modified example of the composite container.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment.

As shown in FIG. 1, the composite container 1 includes a cylindrical liner 2 and a reinforcing layer 3 provided to cover the outer surface side of the liner 2. Both ends of the liner 2 are formed in a dome shape, and a base 4 is attached to the tip of the both ends. The material of the liner 2 is not particularly limited, but resin or metal is selected depending on the application. Examples of the resin-made liner 2 include those obtained by forming a thermoplastic base resin such as high-density polyethylene into a container shape by rotational molding or blow molding, and a metal base 4 attached thereto. Examples of the metal liner 2 include those that form the shape of the base 4 after forming a container shape by spinning or the like from a pipe shape or a plate shape made of aluminum alloy, steel, or the like. The reinforcing layer 3 is formed by winding a fiber in which a curable resin is pre-impregnated around a liner. Examples of the fiber include carbon fiber, glass fiber, aramid fiber, boron fiber, polyethylene fiber, steel fiber, Zylon fiber, and vinylon fiber. Particularly, high-strength, high elastic modulus and lightweight carbon fiber is used. Good.

The composite container 1 is provided with the cylindrical cylinder part 1a and the dome part 1b of both ends by the above structures. The entire region of the cylinder portion 1a and the substantially entire region of the dome portion 1b are covered with the reinforcing layer 3, and the surface of the liner 2 is exposed at the base 4 (and its peripheral region) at the tip of the dome portion 1b.

The use of the composite container 1 is not particularly limited. For example, the composite container 1 is a container for storing a fuel gas such as hydrogen or natural gas at a high pressure. The composite container 1 may be used as a stationary type or mounted on a moving body. For example, the composite container 1 has a total length of 0.5 to 10 m and a diameter of about 200 to 1000 mm, and can withstand a pressure of about 0 to 150 MPa when used. However, the composite container 1 is not limited to such a numerical range.

As shown in FIG. 1, an inspection system 100 for inspecting a composite container 1 controls an acoustic emission sensor (hereinafter referred to as “AE”) 5 attached to the composite container 1 and the entire system. A control unit 10, a display unit 11, and an input unit 12 are provided.

The AE sensor 5 is a sensor that detects an AE that occurs when a material is deformed or damage such as a microcrack is generated in the material, or an AE that is generated when a crack grows and the material is destroyed. . In the example shown in FIG. 1, the AE sensor 5A is attached to the surface of the liner 2 with respect to the portion where the liner 2 is exposed, the AE sensor 5B is attached to the surface of the reinforcing layer 3 in the dome portion 1b, and the cylinder portion 1a. An AE sensor 5C is attached to the surface of the reinforcing layer 3 in FIG. The AE sensor 5A attached to the surface of the liner 2 makes it easy to detect signs of fatigue failure of the liner 2. Moreover, it becomes easy to detect the damage of the reinforcement layer 3 by the

AE sensors

5B and 5C attached to the surface of the reinforcement layer 3. The number of AE sensors 5 is not particularly limited. Moreover, regarding the attachment position, you may attach to at least one location of the surface of the liner 2, the surface of the reinforcement layer 3 in the dome part 1b, and the surface of the reinforcement layer 3 in the cylinder part 1a. For example, the AE sensor 5 may not be provided only on the surface of the liner 2 and the dome portion 1b and may not be provided on the cylinder portion 1a, and the AE sensor 5 may be provided only on the surface of the liner 2 and the cylinder portion 1a and not provided on the dome portion 1b. Good. The AE sensor 5 is electrically connected to the control unit 10 and outputs the detected AE signal to the control unit 10.

The display unit 11 has a function of displaying information to an operator who performs inspection, and is configured by a display or the like. The display unit 11 displays information transmitted from the control unit 10. Note that information may be output by voice through a speaker or the like. The input unit 12 has a function of inputting necessary information by an operator's operation, and includes a mouse, a touch panel, a pen tablet, a keyboard, and the like. The input unit 12 transmits the input information to the control unit 10. The control part 10 is comprised by CPU, ROM, RAM, etc., for example. The control unit 10 includes a signal acquisition unit 13, a measurement unit 14, a determination unit 15, and a processing unit 16.

The signal acquisition unit 13 has a function of acquiring an AE signal output from the AE sensor 5. The measurement unit 14 has a function of measuring various values used for determination for inspection using the AE signal acquired by the signal acquisition unit 13. Note that when the noise is included in the AE signal due to the relationship between the inspection location and the like, the measurement unit 14 can measure the measurement value using the AE signal excluding the noise. The measurement unit 14 can measure AE caused by damage caused by fatigue of the liner 2 and can measure AE caused by damage of the reinforcing layer 3 (fiber damage, curable resin damage).

The determination unit 15 has a function of performing various determinations for inspection. The determination unit 15 determines whether or not the first condition indicating a sign of fatigue fracture of the liner 2 is satisfied based on the measurement value by the measurement unit 14, that is, based on the AE signal acquired by the signal acquisition unit 13. It has a function to do. For example, the determination unit 15 determines that the first condition is satisfied when the measurement value by the measurement unit 14 is equal to or greater than a preset threshold value. The threshold value set for the determination of the first condition is not particularly limited as long as it is a value indicating a sign of fatigue fracture of the liner 2 and how much the threshold value indicates the degree of progress of fatigue. . For example, a value indicating that it is immediately before fatigue failure may be set as a threshold value, and a value indicating that it is an intermediate period from the start of use to fatigue failure may be set as a threshold value. Further, the threshold value used for the determination of the first condition is set with respect to a value based on the energy of the AE detected by the AE sensor 5, and specifically, the accumulated energy of the AE (for example, from the start of measurement). (Accumulated energy), AE energy amount within a predetermined time, and AE hit rate. Note that the AE energy may be calculated from the waveform of the AE signal, but may be approximately calculated to facilitate the calculation. For example, the number of AEs is considered to be equivalent to the magnitude of the AE accumulated energy, and the count number of the AE number may be set as the AE accumulated energy (Note that the number of AEs may be simply counted, or a large AE. Are considered to have high energy and may be counted according to their size). Alternatively, the first condition may be that an AE signal having a sign of fatigue failure of the liner 2 or an AE signal having an AE frequency distribution is detected.

Regarding the fatigue failure of the liner 2, by performing a cycle test in which the composite container 1 is repeatedly used, the AE signal generated due to the fatigue of the liner 2 from the start of use until the liner 2 eventually undergoes fatigue failure. Can be detected. For example, as shown in FIG. 2, after the fluid is put into the composite container 1 and the internal pressure is raised, the fluid is taken out from the composite container 1 and the internal pressure is lowered as one cycle. AE sound is detected by the AE sensor 5. When such a cycle test is performed, as shown in FIG. 3, a substantially silent state continues from the initial stage of use to the middle period, and an AE signal indicating the occurrence of fatigue / cracking of the liner 2 of the composite container 1 at the number indicated by P1. Is detected. As the cycle continues further, an AE signal indicating an increase in fatigue crack growth is detected at the number of times indicated by P3. As the cycle continues further, the final fatigue failure of the liner 2 occurs (leak occurs) at the number of times indicated by P3, and the AE signal generated by the fatigue failure is detected. From such a test result, the progress of the fatigue of the liner 2 can be inspected by measuring the AE sound during the inspection of the composite container 1. For example, it can be determined that the fatigue of the liner 2 has progressed to some extent by performing an inspection based on the AE signal detected at P1 and P2. For example, L2 shown in FIG. 3 can be set as the threshold value. Alternatively, it is possible to determine that the liner 2 is in a state immediately before fatigue failure by performing an inspection based on the AE signal immediately before the detection of the AE signal at P3. For example, L1 shown in FIG. 3 can be set as the threshold value. As described above, the first condition used for the determination by the determination unit 15 is determined based on the data indicating the relationship between the use cycle of the composite container 1 and the AE caused by the fatigue of the liner 2 measured in advance. For example, the first condition may be that the accumulated energy of AE corresponding to P1 or P2 is set as a threshold, and the accumulated energy of AE measured by the measurement unit 14 is equal to or greater than the threshold. Alternatively, the first condition may be that the accumulated energy of AE immediately before reaching P3 is set as a threshold, and the accumulated energy of AE measured by the measurement unit 14 is equal to or greater than the threshold.

Further, the determination unit 15 determines whether or not the second condition indicating damage to the reinforcing layer 3 is satisfied based on the measurement value obtained by the measurement unit 14, that is, based on the AE signal acquired by the signal acquisition unit 13. It has a function to do. Since the AE signal generated by the damage of the reinforcing layer 3 has a different specification from the AE signal generated by the fatigue of the liner 2, the second condition can be set as a condition different from the first condition. . For example, the determination unit 15 determines that the second condition is satisfied when the measurement value by the measurement unit 14 is greater than or equal to a preset threshold value. Further, the threshold value used for the determination of the second condition may be set with respect to a value based on the energy of the AE detected by the AE sensor 5, and specifically, the accumulated energy of the AE (for example, measurement) Cumulative energy from the start), AE energy amount within a predetermined time, and AE hit rate. Alternatively, the second condition may be that an AE signal indicating damage to the reinforcing layer 3 is detected. Note that the AE signal due to damage to the reinforcing layer 3 clearly shows the damage to the reinforcing layer 3 than the AE signal due to fatigue of the liner 2, and it is easier to make a determination by analyzing the AE signal.

Regarding damage to the reinforcing layer 3, as shown in FIG. 4, when the pressure during normal use is PL1, if the pressure is further increased beyond the pressure PL1, damage to the fibers and the resin of the reinforcing layer 6 proceeds. The composite container 1 is destroyed at the pressure PL2. At this time, the AE sound based on the damage of the reinforcing layer 6 increases sequentially. Accordingly, during the inspection of the composite container 1, when an AE signal indicating damage is detected from the reinforcing layer 6 even though the composite container 1 is used at a normal operating pressure (for example, detected at the pressure PL3 at the stage before the breakdown occurs). It is possible to determine that the reinforced layer 6 is damaged. From the above, the second condition used for the determination by the determination unit 15 is determined based on the data indicating the relationship between the pressure of the composite container 1 and the AE signal generated by the damage of the reinforcing layer 6 measured in advance.

The processing unit 16 has a function of executing various control processes in the system. For example, the processing unit 16 executes an operation start / operation stop process for the composite container 1, a process for feeding back information to that effect when it is detected that there is a sign of fatigue failure of the liner 2, and the like.

Next, an example of an inspection method for the composite container 1 according to this embodiment will be described with reference to FIGS. The processing in FIGS. 5 to 7 is processing executed in the control unit 10. As an inspection method for the composite container 1, a constant monitoring method for constantly monitoring the composite container 1 in operation may be employed, or a periodic inspection method for performing regular inspection may be employed.

First, the inspection method shown in FIG. 5 will be described. FIG. 5 shows an example of processing when the composite container 1 in operation is constantly monitored. In the example of FIG. 5, as a first condition indicating signs of fatigue failure of the liner 2, the AE accumulated energy immediately before the final fatigue failure is set as a threshold, and the measured value of the AE accumulated energy is equal to or greater than the threshold. Was set as a condition. For example, in the example of FIG. 3, the AE accumulated energy in the vicinity of P3 where the final fatigue failure occurs can be set as the threshold value.

Before the process of FIG. 5 is started, preparation for the inspection of the composite container 1 is performed. The AE sensor 5 is attached to the composite container 1, and the composite container 1 is installed in the hydrogen station. Next, the processing unit 16 executes an operation start process for the composite container 1. The processing unit 16 starts operation of an apparatus or an apparatus for supplying and taking out fuel from the composite container 1 (step S10). As a result, a cycle in which fuel is supplied to the composite container 1 to increase the pressure and fuel is taken out from the composite container 1 to decrease the pressure is repeated. Next, the control unit 10 grasps noise specific to the hydrogen station that enters the AE sensor 5 when the composite container 1 is actually operated at the hydrogen station (step S11). As the inherent noise, for example, ambient noise caused by gas compressor, electromagnetic valve operation sound, vehicle traffic, and the like can be cited. The measurement unit 14 grasps the noise by analyzing the AE signal acquired by the signal acquisition unit 13.

Next, the signal acquisition unit 13 acquires the AE signal from the AE sensor 5, and the measurement unit 14 measures the AE accumulated energy based on the AE signal (step S12). At this time, the measurement unit 14 measures the AE accumulated energy by subtracting the AE energy due to the noise grasped in S11. Next, the determination unit 15 determines whether or not the reinforcing layer 3 is damaged by determining whether or not the second condition is satisfied based on the AE signal acquired in S12 (step S13). ). Specifically, when the AE accumulated energy indicating damage to the reinforcing layer 3 is set as the threshold, the determination unit 15 determines whether or not the AE accumulated energy measured in S12 is equal to or greater than the threshold. Thus, it is determined whether or not the reinforcing layer 3 is damaged. Alternatively, the determination unit 15 determines whether or not the enhancement layer 3 is damaged by determining whether or not an AE signal indicating damage to the enhancement layer 3 is detected as a result of the analysis of the AE signal by the measurement unit 14. Determine whether.

When it is determined in S13 that the reinforcing layer 3 is damaged, the processing unit 16 executes an operation stop process for stopping the operation of the composite container 1 (step S16). The processing unit 16 stops the operation of the apparatus and equipment for supplying and taking out fuel from the composite container 1. When the reinforcing layer 3 is damaged, the strength of the composite container 1 is affected, so that the use of the composite container 1 needs to be stopped immediately. Therefore, the operation stop process is performed immediately after the determination of S13.

When it is determined in S13 that the reinforcing layer 3 is not damaged, the determination unit 15 determines whether the first condition is satisfied based on the AE signal acquired in S12. It is determined whether or not fatigue failure is near (step S14). Specifically, the determination unit 15 determines whether or not the fatigue failure of the liner 2 is near by determining whether or not the AE accumulated energy measured in S12 is equal to or greater than a threshold value.

In S14, when it is determined that the fatigue failure of the liner 2 is not near, the process is repeated from S12. On the other hand, when it is determined in S14 that the liner 2 is close to fatigue failure, the process proceeds to S16, and the processing unit 16 executes the operation stop process of the composite container 1. Thus, the process shown in FIG. 5 is completed, and the composite container 1 related to the inspection object is removed from the hydrogen station.

Next, the inspection method shown in FIG. 6 will be described. FIG. 6 shows an example of processing when the composite container 1 in operation is constantly monitored. In the example of FIG. 6, as a first condition indicating a sign of fatigue failure of the liner 2, the AE accumulated energy in the intermediate period from the start of operation to the final fatigue failure is set as a threshold, and the AE accumulated energy is set. It was set on condition that the measured value of became more than the said threshold value. For example, in the example of FIG. 3, the AE accumulated energy in the vicinity of P1 where the AE signal due to the fatigue of the liner 2 is detected in the intermediate period can be set as the threshold value.

In FIG. 6, the same processing as in FIG. 5 is performed in S10, S11, S12, S13, and S16. When it is determined in S13 that the reinforcing layer 3 is not damaged, the determination unit 15 determines whether or not the first condition is satisfied based on the AE signal acquired in S12. It is determined whether there is a sign of destruction (step S17). Specifically, the determination unit 15 determines whether or not there is a sign of fatigue failure of the liner 2 by determining whether or not the AE accumulated energy measured in S12 is equal to or greater than a threshold value.

In S17, when it is determined that the fatigue fracture of the liner 2 is not near, the process is repeated from S12. On the other hand, when it is determined in S17 that there is a sign of fatigue fracture of the liner 2, the processing unit 16 executes a process of feeding back information to the operator that the liner 2 has a sign of fatigue fracture (step S18). . Here, since a state in which fatigue has not progressed to such an extent that the use of the composite container 1 is immediately stopped is detected, information feedback is performed instead of the operation stop processing of the composite container 1. For example, the processing unit 16 may feed back the number of cycles at the present time and the estimated value of the remaining usable cycles to the operator. Alternatively, when the cycle of use is earlier (slower) than expected, the processing unit 16 feeds back that fatigue failure will occur earlier (slower) than the life (for example, 15 years) set for the composite container 1. It's okay. At that time, the remaining remaining life as a guide may be fed back. The processing unit 16 feeds back information by outputting the information to the display unit 11.

Thus, the process shown in FIG. 6 is completed. When the process is terminated by the operation stop process of S16, the composite container 1 related to the inspection target is removed from the hydrogen station. When the process is terminated by the information feedback process in S18, the process may proceed to S12 in FIG. 5 and it may be determined that the fatigue failure of the liner 2 is close. Alternatively, by setting a threshold value higher than the threshold value set in S <b> 17 of FIG. 6, information feedback processing may be performed at a time when further fatigue has progressed.

Next, the inspection method shown in FIG. 7 will be described. FIG. 7 shows an example of processing when the composite container 1 is inspected during the periodic inspection of the hydrogen station.

Before the processing of FIG. 7 is started, preparation for the inspection of the composite container 1 is performed. The AE sensor 5 is attached to the composite container 1 already installed in the hydrogen station. Next, the processing unit 16 executes a process of increasing the pressure inside the container for the pressure resistance test in the composite container 1 (step S20). Next, the signal acquisition unit 13 acquires an AE signal from the AE sensor 5. The determination unit 15 determines whether the AE signal acquired in S21 is a signal related to sound or a signal related to silence (step S22). Note that the determination unit 15 determines that a sound that is extremely small and close to silence is also silent. When it determines with it being silence in S22, the determination part 15 determines with the composite container 1 which concerns on a test | inspection being a healthy state (step S28).

On the other hand, when it is determined that there is sound in S22, the determination unit 15 determines whether or not the sound is noise (step S23). If it is determined in S23 that the noise is noise, the composite container itself does not generate a sound of destruction, so the determination unit 15 determines that the composite container 1 related to the inspection is in a healthy state (step S28). .

On the other hand, if it is determined in S23 that it is not only noise, there is a possibility that destructive sound is generated, and soundness may be impaired, so that the processing unit 16 further proceeds with the inspection. Then, the boosting process is performed again (step S24). The measuring unit 14 measures the amount of AE energy at the time of boosting (step S26). The determination unit 15 determines whether or not the AE energy amount measured in S26 is greater than or equal to a preset threshold value (step S27). As the threshold value, a threshold value for determining fatigue of the liner 2 (for example, a threshold value set in the processing examples of FIGS. 5 and 6) may be set. Further, at the timing of S27, it may be determined whether or not the reinforcing layer 3 is damaged. In S27, when it is determined that the AE energy amount is less than the threshold, the determination unit 15 determines that the composite container 1 related to the inspection is in a healthy state (step S28). On the other hand, in S28, when it is determined that the AE energy amount is equal to or greater than the threshold, the determination unit 15 determines that the composite container 1 related to the inspection is not in a healthy state (step S29).

When it is determined in S28 that the composite container 1 is healthy and the processing shown in FIG. 7 is finished, the periodic inspection is finished and the use of the composite container 1 at the hydrogen station is continued. On the other hand, when it is determined in S28 that the composite container 1 is not healthy and the process shown in FIG. 7 is completed, the composite container 1 is removed from the hydrogen station (the state of unhealthy that requires immediate replacement). If). Alternatively, information such as the remaining life of the composite container 1 is fed back.

Next, with reference to FIG. 8 and FIG. 9, an example of a setting method for setting the first condition indicating the signs of fatigue fracture of the liner 2 using actual measurement data will be described. However, the setting method of the first condition is not limited to this.

First, as a composite container 1 used for measurement, a 300 L container having a length of 3800 mm and an outer diameter of 480 mm was used. The normal pressure of this composite container 1 was 82 MPa. A preamplifier built-in type AE sensor (V150-RIC) was attached to the composite container 1. As shown in FIG. 8 (a), the plurality of AE sensors 5 are attached to both ends of the composite container and the cylinder portion at predetermined intervals. In FIG. 8A, it is attached at a position indicated by A in a pattern as shown in FIG. 8B when viewed from the axial direction, and at a position indicated by B as shown in FIG. 8C when viewed from the axial direction. It was attached with a pattern like this. In addition, “AMSY-5M37” manufactured by Vallen was used as an AE measurement unit, and “VisualAE” manufactured by Vallen was used as measurement software. Further, as a method for installing the AE sensor 5 in the composite container 1, a silicon adhesive or the like was used, and silicon grease or the like was used as a contact medium.

A cycle test was performed using the equipment as described above, and the AE accumulated energy during the cycle was measured. In addition, the value which accumulated the number of AE in a cycle was made into AE accumulated energy. The measurement results are shown in FIG. Note that the number of cycles was 25,000 when the cycle test was stopped assuming that cracks grew due to fatigue of the liner 2 and eventually fatigue failure occurred. The “cycle count” on the horizontal axis in FIG. 9 is a numerical value made dimensionless by dividing the corresponding count by 25000 times. The “AE accumulated energy” on the vertical axis is a numerical value made dimensionless by dividing the measured value of the corresponding AE accumulated energy by the measured value at 25000 times.

As shown in FIG. 9, there are three steps from the start of operation of the composite container 1 to the final fatigue failure. In the first step, there is almost no sound. The first step continues from the start of use until the number of cycles is around 0.5. In the second step, an AE signal indicating a crack or the like due to fatigue of the composite container 1 is generated. In the second step, the AE accumulated energy increases rapidly at first, and then increases gradually. The second step continues from around the cycle number 0.5 to around 0.8. In the third step, the AE accumulated energy sequentially increases toward fatigue failure. The third step continues from the cycle number around 0.8 to the final fatigue failure.

Based on the measurement data indicating the relationship between the use cycle of the composite container and the AE signal generated by the fatigue of the liner 2, the first condition for determining the signs of fatigue failure of the liner 2 can be set. it can. For example, the allowable energy value L3 indicated by the dotted line in FIG. 9 can be set as a threshold for determining that the liner 2 is immediately before fatigue failure. When the composite container 1 is inspected, if the measured value of the AE accumulated energy is equal to or greater than the allowable energy value L3, the operation of the composite container 1 is stopped assuming that the first condition is satisfied.

Next, the operation and effect of the inspection method for the composite container 1 according to the present embodiment will be described.

First, it was possible to employ various inspection methods as non-destructive inspection means for conventional steel containers that do not have the reinforcing layer 3. For example, as a test method for a steel container, a magnetic jet flaw test, a penetrating deep flaw test, an ultrasonic flaw test, a radiation transmission test, an overflow flaw test, and the like have been adopted.

On the other hand, the composite container 1 in which the reinforcing layer 3 is formed by winding the fiber around the liner 2 cannot be inspected by the method described above. Since the steel container has a uniform tube thickness and a smooth surface, it can be satisfactorily inspected by the method described above. However, since the composite container 1 winds the fibers, the surface is not smooth and the layer structure in the thickness direction is not completely uniform depending on the location. Therefore, even if the method used in the steel container is employed in the composite container 1, the inspection cannot be performed satisfactorily. For example, since the reinforcing layer 3 does not have magnetism, it is impossible to employ a magnetic flaw detection test, and since the surface is not smooth, it is possible to employ a penetrating deep wound test in which a chemical is applied to the surface scratch. Furthermore, since the tube wall structure is not uniform, an ultrasonic flaw detection test in which ultrasonic waves are emitted from a sensor for observation cannot be employed, and other methods cannot be employed structurally.

Furthermore, since the steel container is a container that is resistant to fatigue failure, in the inspection, it is only necessary to determine whether the steel container is healthy or not, and the necessity of determining the degree of fatigue is low. On the other hand, the liner 2 of the composite container 1 has a configuration in which fatigue failure is likely to occur (particularly when an aluminum alloy is employed) compared to a steel container. In addition, the steel container is resistant to fatigue failure, and it is unlikely that the fatigue failure will occur before the predetermined specified life. However, in the case of the composite container 1, the period until the fatigue failure occurs depends on the operating environment and conditions. The life of the liner 2 itself may fluctuate due to the operating environment and conditions. Therefore, even if the specified life is determined for the composite container, the life can be influenced by changing the use environment and use conditions. As described above, a suitable inspection method has been demanded so that the composite container 1 which is greatly different from the steel container in terms of the situation and premise can be satisfactorily inspected.

Therefore, as a result of intensive studies, the present inventors have found that it is preferable to employ the AE method as a nondestructive inspection method for the composite container 1. Further, the present inventors have found that a predetermined relationship is established between the degree of progress of fatigue of the liner 2 of the composite container 1 and the energy of AE. Furthermore, it is possible to determine whether or not there is a sign of fatigue failure in the liner 2 of the composite container 1 related to the inspection by setting conditions based on the measurement result of AE measured in advance. I found.

Therefore, in the method for inspecting the composite container 1 according to this embodiment, based on the AE signal acquired from the AE sensor 5 attached to the composite container 1 in the step of determining the first condition such as S14, S17, and S27. Whether or not the first condition is satisfied is determined. Accordingly, it is possible to inspect signs of fatigue failure of the liner 2 of the composite container 1 to be inspected, and it is possible to inspect the composite container 1 appropriately.

Here, a relationship different from the progress of fatigue of the liner 2 is established between the damage of the reinforcing layer 3 formed by winding the fiber around the liner 2 and the AE. The liner 2 is likely to be damaged due to fatigue (compared to the reinforcing layer 3) by repeating the high-pressure and low-pressure cycles. On the other hand, since the fiber is strong against repeated cycles, the reinforcing layer 3 has a large number of cycles. Damage due to fatigue is less likely to occur. Next, the case where the pressure in the composite container 1 becomes higher than the pressure during normal use and the composite container 1 expands will be described. Since the liner 2 is made of a material that is easy to stretch, even if the composite container 1 expands, it does not immediately cause damage. On the other hand, the fiber of the reinforcing layer 3 can firmly support the composite container 1 so as not to be deformed even when subjected to a load, but after the composite container 1 has expanded, the fiber breaks, the resin cracks, etc. Are more likely to occur (compared to the liner 2). As described above, the liner 2 is more susceptible to fatigue than the reinforcement layer 3 with respect to fatigue due to repeated cycles, and the reinforcement layer 3 is more susceptible to damage than the liner 2 with respect to damage caused by increased pressure. As described above, the liner 2 and the reinforcing layer 3 have different structural properties, and thus have different damage modes. Therefore, the AE signal generated by the damage also has different properties.

The method for inspecting the composite container 1 according to the present embodiment further includes a step (S13, S27, etc.) of determining whether or not the second condition indicating damage to the reinforcing layer 3 is satisfied based on the acquired AE signal. I have. As described above, a relationship different from the degree of progress of fatigue of the liner 2 is established between the damage of the reinforcing layer 3 formed by winding the fiber around the liner 2 and AE. Therefore, by setting the second condition different from the first condition indicating the signs of fatigue failure of the liner 2, the reinforcing layer 3 can be appropriately inspected. Since the steel container has a simple structure in which the pipe wall is composed of only a single steel material, even if the conventional AE method for steel containers is diverted to the composite container 1, sufficient inspection cannot be performed. There was sex. On the other hand, in this embodiment, the composite container 1 can be more appropriately inspected by performing an inspection in consideration of the structure (including the liner 2 and the reinforcing layer 3) and the properties of the composite container 1.

In the inspection method of the composite container 1 according to this embodiment, the AE sensor 5 is attached to the surfaces of the liner 2 and the reinforcing layer 3. By attaching an AE sensor to the surface of the liner 2, it is possible to accurately determine the first condition that indicates a sign of fatigue failure of the liner 2. On the other hand, by attaching the AE sensor 5 to the surface of the reinforcing layer 3, the second condition indicating damage to the reinforcing layer 3 can be accurately determined. As described above, even when the liner 2 and the reinforcing layer 3 having different properties are present in one composite container 1, appropriate inspection can be performed for each portion. For example, it is difficult to determine where an AE is generated even if an AE is detected when only the AE signal from the same location is detected. 2 When the AE signal detected from the surface (the surface of the reinforcing layer 3) is small, while the AE signal detected from the surface of the reinforcing layer 3 (the surface of the liner 2) is large, the damage on the reinforcing layer 3 (the liner 2) is large. Can be judged.

In the inspection method of the composite container 1 according to the present embodiment, the AE sensor 5 attached to the surface of the reinforcing layer 3 is disposed in the cylinder portion 1a of the composite container 1. Of the reinforced layer 3, the cylinder portion 1 a that causes destruction in the circumferential direction is more likely to break than the dome portion 1 b that causes destruction in the axial direction. Therefore, by attaching the acoustic emission sensor 5 to the cylinder part 1a, it is possible to inspect the reinforcing layer 3 for damage more accurately.

In the inspection method of the composite container 1 according to the present embodiment, the AE sensor 5 attached to the surface of the reinforcing layer 3 is disposed on the dome portion 1b of the composite container 1. Since the liner 2 of the composite container 1 is exposed at the distal end side of the dome portion 1b, the AE sensor attached to the surface of the liner 2 is attached at this position. Therefore, by arranging the AE sensor attached to the surface of the reinforcing layer 3 in the dome portion 1b, the attachment positions of both sensors become close, and the sensor attachment work at the time of inspection becomes easy.

The present invention is not limited to the embodiment described above. For example, the structure of the inspection system used for the inspection method may not be related to the above-described embodiment, and the inspection flow is not limited to the above-described embodiment.

In the above-described embodiment, a composite container having a liner and a reinforcing layer is taken as an example of a composite container to be inspected. However, if the composite container is composed of a plurality of different properties and materials, the composite container described above is used. The inspection method of the present invention can be applied to any composite container without being limited to the container. That is, the composite container only needs to include at least a liner and a reinforcing layer formed by winding a fiber. For example, the composite container may have another layer outside the reinforcing layer. The liner may include a container body made of metal or resin, and may have layers of different materials on the outer peripheral side or inner peripheral side of the container main body. In the composite container shown in FIG. 1, the base 4 protrudes from the reinforcing layer 3. However, for example, as shown in FIG. 10, the base 4 may be embedded in the reinforcing layer 3. In addition, when attaching AE sensor 5A to the surface of liner 2 with respect to such a composite container 1, you may attach to the part exposed to the vicinity of the end surface of the nozzle | cap | die 4, and the reinforcement layer 3. FIG. The composite container may include members such as a valve and an extension pipe attached to the liner base. Therefore, “attaching the AE sensor to the composite container” includes attaching the AE sensor to such a member.

DESCRIPTION OF SYMBOLS 1 ... Composite container, 1a ... Cylinder part, 1b ... Dome part, 2 ... Liner, 3 ... Reinforcement layer, 4 ... Base, 5 ... Acoustic emission sensor, 10 ... Control part, 13 ... Signal acquisition part, 14 ... Measurement part, 15: determination unit, 16: processing unit, 100: inspection system.

Claims

A method for inspecting a composite container comprising a liner forming a container, and a reinforcing layer formed by winding fibers around the liner,
A signal acquisition step of acquiring an acoustic emission signal from an acoustic emission sensor attached to the composite container;
A first determination step of determining whether or not a first condition indicating a sign of fatigue fracture of the liner is satisfied based on the acoustic emission signal acquired by the signal acquisition step;
The method for inspecting a composite container, wherein the first condition is a condition determined based on an energy of acoustic emission.
2. The method according to claim 1, further comprising a second determination step of determining whether or not a second condition indicating damage of the reinforcing layer is satisfied based on the acoustic emission signal acquired by the signal acquisition step. Inspection method for composite containers.
The method for inspecting a composite container according to claim 1 or 2, wherein the acoustic emission sensor is attached to surfaces of the liner and the reinforcing layer.
The method for inspecting a composite container according to claim 3, wherein the acoustic emission sensor attached to the surface of the reinforcing layer is disposed in a cylinder portion of the composite container.
The method for inspecting a composite container according to claim 3, wherein the acoustic emission sensor attached to the surface of the reinforcing layer is disposed in a dome portion of the composite container.
A composite container inspection system comprising a liner forming a container, and a reinforcing layer formed by winding fibers around the liner,
An acoustic emission sensor attached to the composite container;
A signal acquisition unit for acquiring an acoustic emission signal from the acoustic emission sensor;
A determination unit that determines whether or not a first condition indicating a sign of fatigue fracture of the liner is satisfied based on the acoustic emission signal acquired by the signal acquisition unit;
The said 1st condition is a test | inspection system of a composite container which is a condition defined based on the energy of acoustic emission.