JP6754584B2 - Monitoring device and monitoring method - Google Patents

Description

The present invention relates to a monitoring device and a monitoring method for monitoring a sign of destruction due to peeling of a composite material component made of a fiber reinforced resin material.

In recent years, composite material parts are lightweight and have high strength, and are therefore used in structures such as aircraft, automobiles, railroad vehicles, ships, wind power generation blades, civil engineering, and construction.

However, since composite materials are often used in layers, their interlayer strength is lower than that of isotropic materials such as metals. Therefore, for example, delamination may occur when an excessive external load is applied, and this may be the starting point for fatal destruction. Therefore, it is necessary to pay attention to delamination when using the composite material. In particular, when used for a long period of time, the resin gradually deteriorates due to repeated loading, and the strength held by the composite material decreases, so that delamination is likely to occur.

Since such delamination leads to a significant decrease in the strength of the composite material component, it is desirable to detect it at an early stage, but it is difficult to visually confirm the delamination from the outside.

Therefore, conventionally, a non-destructive inspection device such as an ultrasonic flaw detector has been used to confirm the soundness of composite material parts by periodic inspection (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-98921

In the case of metal parts, the growth of cracks due to fatigue is slow, and it is not too late even after being found by regular periodic inspections. However, in the case of composite material parts, cracks due to delamination may grow at once, and it is possible that regular inspections will not be in time. Especially when composite material parts are used for moving objects, if the composite material parts are destroyed before the periodic inspection, it may lead to a serious accident. Therefore, it is necessary to monitor the signs of destruction due to peeling of the composite material parts. I have been asked.

The present invention has been made in view of this point, and provides a monitoring device and a monitoring method for monitoring the vibration of the precursor of the peeling in order to detect the sign of destruction due to the peeling of the composite material component at an early stage. The purpose.

In order to achieve the above object, the monitoring device according to one aspect of the present invention is a monitoring device that monitors signs of destruction caused by peeling of a composite material component made of a fiber reinforced resin material, and vibrates due to the peeling. It features a monitoring device equipped with vibration detecting means for detecting.

Further, in order to achieve the above object, the monitoring method according to one aspect of the present invention is a monitoring method for monitoring signs of destruction due to peeling of a composite material component made of a fiber-reinforced resin material by using a monitoring device. Therefore, the monitoring device for detecting the vibration due to the peeling is characterized by a monitoring method which is a monitoring device according to one aspect of the present invention.

Further, in order to achieve the above object, the monitoring method according to one aspect of the present invention is a monitoring method for monitoring a sign of destruction caused by peeling of a composite material part made of a fiber reinforced resin material, and is based on the peeling. It features a monitoring method that predicts the destruction when vibration is detected.

According to the monitoring device and the monitoring method according to one aspect of the present invention, a sign of destruction due to peeling of a composite material component can be detected at an early stage.

It is the schematic which shows the monitoring apparatus which concerns on one aspect of this invention. It is a graph which shows the frequency distribution in the longitudinal direction of a test piece 1. It is a graph which shows the frequency distribution in the width direction of a test piece 1. The frequency distribution in the thickness direction of the test piece 1 is a graph. It is a graph which shows the frequency distribution in the longitudinal direction of a test piece 2. It is a graph which shows the frequency distribution in the width direction of a test piece 2. FIG. 5 is a graph showing the frequency distribution of the test piece 2 in the thickness direction.

<< Overview >>
The monitoring device according to one aspect of the present invention is a monitoring device for monitoring a sign of destruction caused by peeling of a composite material component made of a fiber reinforced resin material, and includes a vibration detecting means for detecting vibration due to the peeling. There is.

The monitoring device according to one aspect of the present invention does not directly monitor the peeling of the composite material component, but monitors the sign that the composite material component peels off, and based on the monitoring result, originally visually observes from the outside. It is possible to monitor signs of destruction due to peeling of composite material parts that cannot be confirmed by.

Further, the vibration detecting means exhibits an acceleration sensor that detects vibration of the composite material component, a frequency conversion unit that converts a signal detected by the acceleration sensor into a frequency distribution, and vibration due to peeling from the frequency distribution. It is provided with a detection unit that detects a frequency domain.
As a result, it is possible to detect the peculiar vibration generated when the composite material part is peeled off, and the accuracy of monitoring is improved.

Further, the frequency conversion unit converts the signal into frequency and acceleration, and the detection unit detects that the acceleration in the specific frequency domain exceeds the threshold value, and if the acceleration exceeds the threshold value, an abnormality is generated. Equipped with an alarm means to notify.
As a result, it is possible to notify a person of a sign that peeling will occur, and for example, it is possible to prevent an accident when it is used for a moving body such as a railroad vehicle.

Further, the monitoring method according to one aspect of the present invention is a monitoring method for monitoring a sign of destruction caused by peeling of a composite material component made of a fiber reinforced resin material by using a monitoring device, and the vibration due to the peeling is observed. The monitoring device to detect is the monitoring device according to one aspect of the present invention.

The monitoring method according to one aspect of the present invention does not directly monitor the peeling of the composite material component, but monitors the sign that the composite material component peels off, so that it can be visually confirmed from the outside. Monitor the signs of failure due to peeling of composite parts that cannot.

<Embodiment>
(Overall configuration of monitoring device)
FIG. 1 is a schematic view showing a monitoring device according to an aspect of the present invention. Here, a case where a composite material component is applied to a leaf spring for a railroad vehicle bogie, which is an example of a moving body structure, will be described as an example. 1 is a leaf spring for a railroad vehicle bogie, 2 is an acceleration sensor, 3 is a frequency conversion device, 4 is a cable, 5 is an alarm device, 6 is a railroad vehicle, and 7 is a railroad vehicle bogie.

(Left springs for railroad bogies)
The leaf spring 1 for a railroad vehicle bogie is one aspect of a composite material component made of a fiber reinforced resin material. Examples of the fiber-reinforced resin material constituting the composite material component include a thermosetting resin such as epoxy resin and polyimide resin, a resin material such as a thermoplastic resin such as polyamide resin, polyethylene resin and polystyrene resin, and carbon. A fiber reinforced resin material (FRP (Fiber Reinforced plastic)) formed by compounding a reinforcing fiber material such as fiber, aramid fiber, and glass fiber can be used. Specific examples of the fiber reinforced plastic material (FRP) include carbon fiber reinforced plastic material (CFRP (Carbon Fiber Reinforced plastic)), glass fiber reinforced plastic material (GFRP (Glass Fiber Reinforced plastic)), and aramid fiber reinforced plastic material. (AFRP (Aramid Fiber Reinforced Plastic)), Boron fiber reinforced resin material (BFRP (Boron Fiber Reinforced Plastic)) and the like can be mentioned.

The leaf spring 1 for a railroad vehicle bogie has a bow-shaped shape, supports the railroad vehicle 6, and alleviates vibration from the railroad track. The leaf spring 1 for a railroad vehicle bogie includes, for example, a hybrid type including an upper surface member made of CFRP, a lower surface member made of CFRP, and a core member arranged between the upper surface member and the lower surface member and made of GFRP. Can be used.

(Accelerometer)
The acceleration sensor 2 is attached to the outer surface of the leaf spring 1 for the railroad vehicle bogie, and constantly detects vibration while the railroad vehicle 6 is traveling. The acceleration sensor 2 detects not only the vibration transmitted from the railroad track but also the vibration caused by the delamination of the leaf spring 1 for the railroad vehicle bogie.
As the accelerometer 2, for example, a highly sensitive piezo accelerometer is used. The piezo type accelerometer can measure accelerations in three directions, and can detect accelerations in the longitudinal direction, the width direction, and the thickness direction of the leaf spring 1 for a railroad vehicle carriage 1, respectively. The vibration in the thickness direction detects not only the vibration at the time of peeling but also the vibration normally acting on the composite material component. Therefore, it can be used to compare the normal vibration and the vibration at the time of peeling.
Since the direction of vibration differs depending on the mode of destruction, vibration in three directions of longitudinal direction, width direction, and thickness direction is detected. In the case of delamination of composite material parts, the vibration mainly in the fiber axis direction is large. Therefore, when the fiber axis direction coincides with the longitudinal direction of the composite material component, delamination can be detected by measuring the acceleration in the longitudinal direction of the composite material component.
The acceleration sensor 2 is preferably mounted at a location within 500 [mm] from the predicted peeling occurrence position of the leaf spring 1 for the railroad vehicle bogie from the viewpoint of peeling detection accuracy and the like. The predicted position of peeling can be grasped by conducting a test in advance.

(Frequency converter)
The frequency conversion device 3 is a device that converts a signal (acceleration) detected from the acceleration sensor 2 into a frequency distribution, and constantly converts the signal (acceleration) into a frequency distribution by FFT conversion. The frequency distribution is, for example, a distribution of frequency (horizontal axis) and acceleration (vertical axis), a distribution of frequency (horizontal axis) and amplitude (vertical axis), and the like.

(Detection unit)
The monitoring device according to one aspect of the present invention includes a detection unit that detects a frequency region peculiar to vibration. As the detection unit, an FTT analyzer or the like having the above-mentioned frequency conversion function and detection function can be used, or the program can be executed by a CPU or the like.
Further, as will be described in detail in FIG. 2 and the like described later, the detection unit detects that the threshold value of the acceleration (vertical axis) in the specific frequency region (horizontal axis) has been exceeded. By capturing this frequency region as a peeling phenomenon and providing it as a threshold value, it becomes possible to grasp a sign of peeling. The threshold value is set so that noise is not grasped as a sign of destruction due to peeling.

The frequency range peculiar to delamination of composite material parts differs depending on the weight and dimensions of the composite material parts, the load applied to the composite material parts, etc., including the reinforcing fiber material and resin material used for the composite material parts. Therefore, it is necessary to specify it according to its specifications. The unique frequency domain (horizontal axis) is in the range of 8 [kHz] or more and 20 [kHz] or less. The frequency domain is specified by a preliminary destruction experiment or the like. Further, the setting of the threshold value of the acceleration (vertical axis) is appropriately determined by a preliminary fracture experiment or simulation.

(Alarm device)
The alarm device 5 includes a loudspeaker or an alarm lamp. When the alarm device 5 detects that the detection unit exceeds the acceleration threshold value, it notifies the driver or conductor in the railway vehicle 6 of the abnormality. This makes it possible to prevent accidents.

(cable)
The cable 4 connects the acceleration sensor 2 and the frequency conversion device 3. Usually, the acceleration sensor 2 is on the outside of the railroad vehicle 6, and the frequency converter 3 is on the inside of the railroad car 6, so that the cable 4 is preferably waterproof. The cable 4 is formed with a hole (not shown) in a part of the railway vehicle 6, and is connected to the frequency conversion device 3 inside the railway vehicle 6 through the hole. This hole is sealed to prevent rainwater, wind, etc. from entering the railway vehicle 6.

(Railway bogie)
The railroad vehicle bogie 7 is an important device that affects the running performance and riding comfort, and as a basic function and performance, it smoothly supports the vehicle body carrying passengers, cargo, etc. from under the vehicle body and smoothly on the track. It has an important role to drive. The railroad vehicle bogie 7 is composed of an electric motor as a drive mechanism, a brake, wheels and axles, a pillow spring (air spring) for running stability, a shaft spring, and a bogie frame supporting these. The railroad vehicle bogie 7 is preferably a bolsterless bogie without a pillow beam (bolster) between the vehicle body and the bogie frame, particularly a shaft beam type bogie. The bogie type bogie receives the entire load of the vehicle in the order of the lateral beam of the vehicle body, the pillow beam, the pillow spring (air spring), the bogie frame, the axle spring, the axle box, the axle / wheel, and the rail.

(Monitoring method)
The monitoring method according to one aspect of the present invention uses the monitoring device according to one aspect of the present invention to monitor signs of destruction due to delamination of composite material parts. Specifically, an acceleration sensor 2 is attached to the outer surface of the leaf spring 1 for the railroad vehicle bogie, and vibration due to delamination of the leaf spring 1 for the railroad vehicle bogie is detected. The signal detected by the acceleration sensor 2 is converted into a frequency distribution by the frequency conversion device 3. When the detection unit detects that the acceleration threshold value has been exceeded in the peculiar frequency region caused by the peeling, the alarm device 5 notifies the driver or conductor in the railway vehicle 6 of the abnormality. This makes it possible to prevent accidents.

According to such a configuration, it is possible to capture the vibration of delamination of the leaf spring 1 for the railroad vehicle bogie and notify a person. When the leaf spring 1 for the railroad vehicle bogie undergoes delamination that is not fatal due to repeated fatigue, the alarm device 5 notifies the train.

The driver immediately stops the rolling stock 6 and returns to the depot, and inspects in detail the presence or absence of abnormalities in the leaf spring 1 for the rolling stock bogie by a non-destructive inspection device such as an ultrasonic flaw detector. The leaf spring 1 is replaced.
Further, in the case of the railway vehicle 6, a collision with an automobile at a railroad crossing or the like is considered. When it collides with a car, it receives a large vibration, but by analyzing the frequency distribution using the acceleration sensor 2, it is possible to grasp on the spot whether or not the leaf spring 1 for the railroad vehicle bogie is damaged (magnitude). It is possible to judge whether or not to move to the vehicle maintenance base.

(Fracture properties of composite materials)
There are various fracture modes in the fracture mode of the composite material component, such as tensile fracture in the fiber axis direction of the composite material, compressive fracture, and peel fracture between layers. Composite material parts have low interlayer strength, and preventing this peeling fracture is a major technical issue in applications such as railway trains and aircraft. The delamination vibration has a characteristic, and in the case of a vehicle application moving on the ground, it has a characteristic that the frequency is different from the normal vibration received from a railroad track, a road, or the like while traveling. By identifying the vibration of peeling and setting a threshold value classified in the direction of the vibration, it is possible to distinguish it from other vibrations, and it is possible to detect a sign of destruction.
The composite material parts gradually deteriorate due to the repeated load due to normal use, but by detecting this vibration, it is possible to predict the destruction due to peeling, and it is possible to prevent accidents by replacing the composite material parts.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

An example in which the frequency of the composite material component is measured experimentally is shown. Since it is not possible to detect signs of peeling in a running railroad vehicle for safety reasons, the frequency was measured with a testing machine.

[Example 1]
20 layers of carbon fiber prepregs (Toho Tenax prepreg (Q-C1118), thickness: 0.187 [mm]) are laminated so that the carbon fibers extend in the longitudinal direction (fiber orientation angle is 0 degrees). A test piece 1 (length: 300 [mm], width 12.7 [mm]) was prepared, and a part of the peeled surface was cracked in advance so that delamination was likely to occur. An acceleration sensor is attached to the outer surface (40 [mm] from the left end) of the test piece 1, and a bending tester is used to detect vibration under a three-point bending load (so-called GIIC load mode) and frequency. The frequency distribution was measured using a converter. The frequency distributions of the test piece 1 in the longitudinal direction, the width direction, and the thickness direction are shown in FIGS. 2 to 4. In the distribution, the frequency is on the horizontal axis and the acceleration is on the vertical axis.

Accelerometer: Small 3-axis ICP accelerometer (manufactured by Toyo Corporation, model number 356A03 139133)
Frequency converter (FFT analyzer): manufactured by Toyo Corporation, OR34J-4FFT analyzer Load mode: GIIC (bending test)
Test (displacement) speed: 0.1 [in / min]

FIG. 2 is a graph showing the frequency distribution of the test piece 1 in the longitudinal direction. The frequency distribution on the high frequency side (here, in the range of 11 k [Hz] or more and 17 k [Hz] or less, which corresponds to a peculiar frequency region) is caused by vibration due to delamination of the test piece 1. The frequency distribution on the low frequency side (here, in the range of 4 [Hz] or more and 7 k [Hz] or less) is the normal vibration (here, from the tester) in which a load is simply applied under the same test conditions as the test piece. It is considered to be transmitted vibration, and in actual use, it is considered to be vibration received from a railroad track or the like while a railroad vehicle is running). As described above, the vibration due to delamination of the test piece 1 is on the higher frequency side than the normal vibration and the acceleration is large, so that the vibration due to delamination can be clearly distinguished. Therefore, by detecting the acceleration on the high frequency side, it is possible to detect a sign of delamination.

Further, also in the graphs of FIGS. 3 and 4 showing the frequency distribution in the width direction and the thickness direction of the test piece 1, the vibration due to the delamination of the test piece 1 was detected on the higher frequency side than the normal vibration. However, the difference in frequency distribution between the high frequency side and the low frequency side is clearer in the graph of FIG. 2 showing the frequency distribution in the longitudinal direction of the test piece 1 than in the graphs of FIGS. 3 and 4. It is preferable to detect vibration in the longitudinal direction of the test piece 1, which has many 0 degree fiber orientations. That is, it is preferable to detect the vibration in the extending direction of the fiber having the largest orientation ratio among the fiber orientations.

[Example 2]
Test piece 2 (length: 300) formed by laminating 20 layers of carbon fiber prepreg (prepreg (Q-11112) manufactured by Toho Tenax Co., Ltd., thickness: 0.187 [mm]) so that the carbon fibers extend in the longitudinal direction. [Mm], width 12.7 [mm]) was prepared, and a part of the peeled surface was cracked in advance so that delamination was likely to occur. The frequency distributions in the longitudinal direction, the width direction, and the thickness direction of the test piece 2 were measured in the same manner as in Example 1 except that the test piece 2 was used. The results are shown in FIGS. 5 to 7. In the distribution, the frequency is on the horizontal axis and the acceleration is on the vertical axis.

FIG. 5 is a graph showing the frequency distribution of the test piece 2 in the longitudinal direction. The frequency distribution on the high frequency side (here, in the range of 8 k [Hz] or more and 18 k [Hz] or less, which corresponds to a peculiar frequency region) is caused by vibration due to delamination of the test piece 2. The frequency distribution on the low frequency side (here, the range is 4 k [Hz] or more and less than 7 k [Hz] or less) is set to normal vibration (for example, vibration received from a railroad track or the like while a railroad vehicle is running). to cause. As described above, the vibration due to delamination of the test piece 2 is on the higher frequency side than the normal vibration and the acceleration is large, so that the vibration due to delamination can be clearly distinguished. Therefore, by detecting the acceleration on the high frequency side, it is possible to detect a sign of delamination.

Further, also in the graphs of FIGS. 6 and 7 showing the frequency distribution in the width direction and the thickness direction of the test piece 2, the vibration due to the delamination of the test piece 2 is detected at a higher acceleration on the high frequency side than the normal vibration. It was. However, the difference in frequency distribution between the high frequency side and the low frequency side is clearer in the graph of FIG. 5 showing the frequency distribution in the longitudinal direction of the test piece 2 than in the graphs of FIGS. 6 and 7. It is preferable to detect the frequency distribution in the longitudinal direction of the test piece 2, which has many 0 degree fiber orientations.

In both Example 1 and Example 2, the normal vibration considered to be the vibration transmitted from the testing machine exists on the same low frequency side, and the specific frequency region considered to be the vibration due to delamination exists on the same high frequency side. .. In this way, it can be inferred that the vibration due to delamination occurs at a unique frequency.
Comparing Example 1 and Example 2, the vibration characteristics differed greatly depending on the test piece, and the test piece 1 using the high toughness resin had a smaller vibration (amplitude) than the test piece 2. Further, the test piece 1 using the high toughness resin had a smaller difference in waveform due to vibration on the high frequency side and the low frequency side than the test piece 2. When the specifications of the test pieces are different in this way, the frequency distribution is slightly different, but the peculiar frequency due to delamination is clearly present.
However, it can be inferred that the composite material component used in the actual machine also has a peculiar frequency region due to delamination as in the above embodiment. The peculiar frequency domain can be grasped by pre-testing with a scaled-down sample, and by using this result, highly accurate monitoring becomes possible.

<< Modification example >>
Although the above description is based on the embodiment, the present invention is not limited to the embodiment. For example, any of the modified examples and the embodiments described below may be appropriately combined, or a plurality of modified examples may be appropriately combined.

1. 1. Composite Material Parts In the embodiment, the leaf spring 1 for a railroad vehicle bogie has been described as a composite material part, but it is used for a structure used for a moving body such as an aircraft, an automobile, a railroad, and a ship, and a wind power generation blade. It can also be applied to structures, civil engineering, structures in the field of construction, etc.
Further, although the leaf spring 1 for a railroad vehicle carriage is composed of a glass fiber composite material and a carbon fiber composite material, it may be composed of either one of the composite materials, or another composite material such as an aramid fiber composite material. It may contain a composite material or may be composed of other composite materials. Even if the type of reinforcing fiber is changed, it can be inferred that a peculiar frequency region due to peeling exists. However, it is necessary to test the numerical values in the frequency domain.
Further, the composite material component of the embodiment is composed of a composite material in which prepregs are laminated. For example, the composite material is molded by an RTM (resin transfer molding) molding method or a hand lay-up molding method. The composite material component may be composed of a composite material or the like.
When the composite material component as described above is used, it can be monitored by grasping the position where peeling, which is a sign of fracture, occurs in advance by a test and arranging an acceleration sensor near the predicted peeling occurrence position.

2. 2. Alarm device Although an alarm device is provided in the embodiment, it is not essential, and it is possible to notify the driver or conductor in the railway vehicle of the abnormality by other means.

3. 3. Specimen The material, size, etc. of the test piece are not limited to the examples, and can be appropriately changed according to the use of the composite material component.

4. Peeling The peeling in the present embodiment includes the case where it occurs between the reinforcing fiber material and the resin material and the case where it occurs in the resin material existing between the reinforcing fiber materials. Further, when the composite materials are laminated, the peeling occurs between the composite materials and the peeling that occurs within each composite material (the peeling that occurs between the reinforcing fiber material and the resin material and the resin material existing between the reinforcing fiber materials). Is included.)

1 Leaf spring for railroad vehicle bogie 2 Accelerometer 3 Frequency converter

Claims (6)

It is a monitoring device that monitors signs of destruction caused by peeling of composite material parts made of fiber reinforced resin material.
A vibration detecting means for detecting the vibration due to the peeling is provided.
The vibration detecting means includes an acceleration sensor that detects the traveling vibration of the composite material component when the moving body using the composite material component as a structure is traveling .
The composite material component is a laminated composite material made of a fiber reinforced resin material.
The acceleration sensor is a monitoring device that detects vibration in the stretching direction of fibers having the highest orientation ratio in a plane orthogonal to the stacking direction of the composite material component. The vibration detecting means includes a frequency conversion unit that converts a signal detected by the acceleration sensor into a frequency distribution, and a detection unit that detects a specific frequency region indicating vibration due to the peeling from the frequency distribution.
The frequency conversion unit converts the signal into a distribution of frequency and acceleration, and then converts the signal into a distribution.
The monitoring device according to claim 1, wherein the detection unit detects that the acceleration in the specific frequency region exceeds a threshold value. The monitoring device according to claim 2, further comprising an alarm means for notifying an abnormality when the threshold value is exceeded. The monitoring device according to any one of claims 1 to 3, wherein the acceleration sensor is attached to a place within 500 [mm] from a position where peeling occurrence of the composite material component is predicted. It is a monitoring method that uses a monitoring device to monitor signs of destruction caused by peeling of composite material parts made of fiber reinforced resin material.
The monitoring method according to any one of claims 1 to 4 , wherein the monitoring device for detecting vibration due to peeling is the monitoring device according to any one of claims 1 to 4 . It is a monitoring method that monitors the signs of destruction caused by peeling of composite material parts that are laminated with composite materials made of fiber reinforced resin material.
When a moving body using the composite material component as a structure is running, the acceleration sensor detects vibration in the direction in which the fiber having the highest orientation ratio is in the plane orthogonal to the stacking direction of the composite material component. A monitoring method that predicts the destruction when it is determined that the vibration is due to the peeling.