Fatigue evaluation method and fatigue evaluation system for crane structure

Abstract

To provide a fatigue evaluation method and fatigue evaluation system for a crane structure capable of reliably evaluating fatigue on a structure based on crane loading and reducing an amount of data to be accumulated.SOLUTION: A method for evaluating fatigue on a structure of a crane Cr on the basis of accumulation of fatigue damage degrees includes steps of: acquiring strain data D1 indicating a change in a strain amount of a structure for each time through actual measurement using a strain gauge 2 installed on the crane Cr; specifying the strain data related to the loading among the strain data D1 as partial data D2 using a computing device 3 on the basis of a start time t0 and an end time t1 of loading whenever the crane Cr performs the loading; and calculating the fatigue damage degree of the loading from the partial data D2 to accumulate the fatigue damage degree for each loading and delete the partial data D2 specified among the strain data D1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and a system for fatigue evaluation of a crane structure. More specifically, the present invention relates to a method and a system for fatigue evaluation of a crane structure that can faithfully evaluate the fatigue of the structure based on the cargo handling in the crane and can reduce the amount of data to be accumulated.

Background Art

[0002] A crane has a number of structures such as a boom, a girder, and a leg tie beam. Fatigue accumulates in these structures each time the crane performs cargo handling. Therefore, in order to accurately determine the continuous use, renewal (repair), and disposal of the crane, it is required to evaluate the fatigue of the crane structure. As evaluation indices, the accumulation of fatigue damage degree (fatigue damage level), the number of stress amplitudes until fatigue damage calculated based on the accumulation, and the remaining life period (number of years or days) are used.

[0003] In the evaluation of fatigue in a crane structure, numerical analysis or actual machine measurement is generally used. In numerical analysis, since the structural calculation of the crane structure is performed, detailed design drawings of the structure are essential. When accurate design drawings or the like cannot be obtained, the structural calculation cannot be performed, and thus there is a problem that fatigue cannot be faithfully evaluated. On the other hand, in actual machine measurement, strain data of the structure is acquired using a strain measuring device such as a strain gauge (fatigue sensor). Therefore, actual machine measurement has higher versatility than numerical analysis and can evaluate the fatigue of the structure more faithfully. However, in actual machine measurement, there is a problem that the amount of strain data increases with time. In particular, in a crane having a plurality of structures, it is necessary to evaluate the fatigue of each structure, and in a container terminal where a plurality of cranes are operated, it is necessary to evaluate the fatigue of each crane. Therefore, the amount of data required for fatigue evaluation becomes enormous, and the processing load required for analyzing the enormous amount of data also increases.

[0004] Although not a crane, an apparatus and method for evaluating the remaining life of a composite material used in a wind power generation system or the like by actual machine measurement have been proposed (see Patent Document 1). In the invention described in Patent Document 1, regarding the problem that the amount of data in the actual machine measurement described above becomes enormous, a method is used in which processing is performed at regular intervals and the cumulative damage degree at regular intervals is stored (see paragraph 0016 of Patent Document 1). In this method, it is not necessary to store all the time history data, and only the cumulative damage degree at regular intervals needs to be stored, suppressing an increase in the amount of data.

[0005] In a crane, the loading situation changes each time a load is handled, and the weight of the load and its moving distance are different. Therefore, the degree of fatigue accumulated in the structure is different each time a load is handled. Also, the crane is managed based on a schedule (for example, the number of load handling operations per day) based on load handling. Therefore, in order to more faithfully evaluate the fatigue of the crane structure, it is desirable to use load handling as a reference. However, the period required for one load handling operation is different for each load to be handled. Therefore, even if the invention described in Patent Document 1 above is applied to a crane, with the actual machine measurement method based on a fixed period, it is not possible to evaluate the fatigue of the structure based on load handling. Therefore, further development is required to faithfully evaluate the fatigue of the structure based on load handling in a crane and reduce the amount of data accumulated.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a method and a system for evaluating the fatigue of a crane structure that can faithfully evaluate the fatigue of the structure based on load handling in a crane and can reduce the amount of data accumulated.

Means for Solving the Problems

[0008] The fatigue evaluation method of the crane structure according to the first invention of the present invention for achieving the above object is a fatigue evaluation method of the crane structure for evaluating the fatigue of the crane structure based on the accumulation of fatigue damage degrees. In this method, by actual machine measurement using a strain measuring device installed on the crane, strain data indicating the change in the amount of strain of the structure at each time is obtained. Each time the crane performs a cargo handling operation, based on the start time and end time of the cargo handling operation, an arithmetic unit specifies, as partial data, the strain data related to the cargo handling operation from the strain data, calculates the fatigue damage degree in the cargo handling operation from the partial data, accumulates the fatigue damage degree for each cargo handling operation, and deletes the partial data from the strain data.

[0009] The fatigue evaluation method of the crane structure according to the second invention of the present invention is a fatigue evaluation method of the crane structure for evaluating the fatigue of the crane structure based on the accumulation of fatigue damage degrees. In a period in which the cargo handling operation by the crane is repeated a large number of times, a creation step of calculating the fatigue damage degree for each cargo handling operation by actual machine measurement using a strain measuring device installed on the crane and creating a database, and a prediction step of predicting the fatigue damage degree for each cargo handling operation using the created database after the creation step is completed. In the creation step, by actual machine measurement using the strain measuring device, strain data indicating the change in the amount of strain of the structure at each time is obtained. Each time the crane performs the cargo handling operation, based on the start time and end time of the cargo handling operation, an arithmetic unit specifies, as partial data, the strain data related to the cargo handling operation from the strain data, calculates the fatigue damage degree in the cargo handling operation from the partial data, creates a database in which the fatigue damage degree for each cargo handling operation is classified according to the cargo handling situation. In the prediction step, each time the crane performs the cargo handling operation, an arithmetic unit predicts the fatigue damage degree in the cargo handling operation based on the cargo handling situation and the database in the cargo handling operation, and accumulates the fatigue damage degree for each cargo handling operation.

[0010] The fatigue evaluation system for the crane structure of the third invention of the present invention is a fatigue evaluation system for the crane structure that evaluates the fatigue of the crane structure based on the accumulation of fatigue damage degrees. In this system, a strain measuring device is installed on the crane to obtain strain data indicating changes in the amount of strain of the structure at each time by actual measurement, and an arithmetic unit that calculates the fatigue damage degree by processing the strain data is provided. The arithmetic unit, each time the crane performs a handling operation, performs data processing to specify, as partial data, the strain data related to that handling operation from among the strain data based on the start time and end time of that handling operation, data processing to calculate the fatigue damage degree in that handling operation from the partial data, and data processing to accumulate the fatigue damage degree for each handling operation and delete the partial data from the specified strain data. It is characterized by having such a configuration.

[0011] The fatigue evaluation system for the crane structure of the fourth invention of the present invention is a fatigue evaluation system for the crane structure that evaluates the fatigue of the crane structure based on the accumulation of fatigue damage degrees. In this system, a storage unit in which a database is stored and an arithmetic unit that predicts the fatigue damage degree based on the database are provided. The database accumulates the fatigue damage degree for each handling operation performed by the crane with respect to the handling situation, and the fatigue damage degree is calculated from partial data which is the strain data related to the handling operation specified from among the strain data obtained by actual measurement using a strain measuring device. The arithmetic unit, each time the crane performs the handling operation, predicts the fatigue damage degree in that handling operation based on the handling situation in that handling operation and the database, and executes data processing to accumulate the fatigue damage degree for each handling operation. It is characterized by having such a configuration.

Effect of the Invention

[0012] According to the first and third inventions of the present invention, since the fatigue damage degree is calculated based on the cargo handling, its accumulation faithfully represents the degree of fatigue accumulated in the structure each time the crane performs cargo handling. Also, each time the fatigue damage degree is accumulated, the strain data (partial data) applied to that cargo handling is deleted from the strain data. Therefore, it is advantageous for reducing the data volume of the accumulated strain data.

[0013] According to the second and fourth inventions of the present invention, since the fatigue damage degree is predicted using the cargo handling situation of the cargo handling performed by the crane and the database, it is not necessary to acquire strain data by actual machine measurement after the database is created. Therefore, it is more advantageous for reducing the data volume in the evaluation of fatigue. Also, although the strain measuring device needs to be replaced regularly, according to the second and fourth inventions, the labor required for the regular replacement of the strain measuring device can be saved.

[0014] In addition, since the database faithfully represents the relationship between the fatigue damage degree for each cargo handling obtained by actual machine measurement and the cargo handling situation, the fatigue damage degree predicted using the database can be regarded as the fatigue damage degree obtained by actual machine measurement. That is, the second and fourth inventions can significantly reduce the accumulated data volume without significantly reducing the evaluation accuracy of fatigue.

Brief Description of the Drawings

[0015]

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Mode for Carrying Out the Invention

[0016] Hereinafter, a method for evaluating fatigue of a crane structure and a fatigue evaluation system of the present invention will be described based on the embodiments shown in the drawings.

[0017] A method for evaluating fatigue of a crane structure is implemented using the fatigue evaluation system 1 illustrated in FIG. 1. The fatigue evaluation system 1 and the evaluation method are used to automatically evaluate the fatigue of the structure (for example, boom, gantry, leg tie beam, A-frame, fore stay, etc.) of the crane Cr that handles containers as cargo at a container terminal.

[0018] The outline of this fatigue evaluation method will be described. This fatigue evaluation method is a method for evaluating the fatigue of a structure each time the crane Cr performs a loading and unloading operation by actual measurement with the strain measuring device 2. In this method, first, strain data D1 is acquired by actual measurement with the strain measuring device 2. Next, the strain data applied to the loading and unloading operation of interest is specified as partial data D2, which will be described later, from the strain data D1 by the arithmetic unit 3. Next, the fatigue damage degree during the loading and unloading operation is calculated from the specified partial data D2. Then, the cumulative fatigue damage degree for each loading and unloading operation is calculated, and the partial data D2 is deleted from the strain data D1.

[0019] Generally, for the evaluation of the fatigue of a structure, as evaluation indices, the cumulative fatigue damage degree, the number of stress amplitudes until the structure reaches fatigue damage, and the remaining life period (number of years, number of days) are used. Each time the crane Cr performs a loading and unloading operation, the loading and unloading conditions such as the weight of the load to be loaded and unloaded and its moving distance are different. Also, the crane Cr is operated and managed based on the loading and unloading operation. Therefore, it is best for the evaluation index to be based on the loading and unloading operation. In this embodiment, as the evaluation indices, the cumulative fatigue damage degree for each loading and unloading operation, the number of loading and unloading operations (hereinafter referred to as the remaining number of loading and unloading operations) that can be performed until the structure reaches fatigue damage, and the remaining life period are used. Any one of the cumulative fatigue damage degree, the remaining number of loading and unloading operations, and the remaining life period can be arbitrarily selected as the evaluation index. Note that the remaining number of loading and unloading operations and the remaining life period are indices calculated based on the cumulative fatigue damage degree, as will be described later.

[0020] The handling operations performed by the crane Cr can adopt either a one-cycle handling operation or a half-cycle handling operation. One cycle means the period from when the crane Cr grabs the load to be handled until it grabs a new load to be handled. A half cycle means the period from when the crane Cr grabs the load to be handled until it releases the load, and the period from when the crane Cr releases the load to be handled until it grabs a new load to be handled. Two half-cycle handling operations in succession correspond to one one-cycle handling operation. In the fatigue evaluation of the structure, either the one-cycle handling operation or the half-cycle handling operation can be arbitrarily selected as the reference handling operation. Note that one cycle does not strictly mean the period from when the load handling tool of the crane Cr grabs the load to be handled until the load handling tool grabs a new load to be handled. One cycle means approximately the period from when the load handling tool can be considered to have grabbed the load to be handled until the load handling tool can be considered to have grabbed a new load to be handled. Similarly, a half cycle also means approximately the period between when the load handling tool can be considered to have grabbed the load to be handled and when the load handling tool can be considered to have released the load to be handled. In this embodiment, a one-cycle handling operation is adopted.

[0021] The crane Cr having the structure to be evaluated by the fatigue evaluation system 1 can use various known cranes such as gantry cranes, container cranes such as transfer cranes, jib cranes, and unloaders. However, since the handling cycle cannot be specified for a continuous unloader, the unloader is a non-continuous unloader such as a bucket unloader. The crane Cr has a structure (boom, girder, leg tie beam, leg, A-frame, fore stay), mechanical parts (load handling tool, trolley, traveling device, etc.), and electrical parts (control device PC, etc.).

[0022] The crane Cr may be a manned crane that an operator directly boards and operates, a remotely operated crane that an operator remotely operates from a remote location, or an automatically operated crane whose operation is automated by a computer. For the crane, acquisition values obtained by various sensors, operation signals transmitted from an operation device, etc. are input to a control device PC, and control signals are transmitted from the control device PC to various mechanical and electrical components, thereby controlling the cargo handling operation. The cargo handling operation of the crane Cr is, for example, the traveling of the crane Cr by a traveling device, the lateral movement of a trolley, the lifting and lowering of a spreader, the connection between the spreader and a load, etc.

[0023] The control device PC is composed of a computer, various data are input and stored therein, and data processing is performed using these data. The control device PC can use various known computers, for example, a programmable logic controller (PLC).

[0024] The fatigue evaluation system 1 illustrated in FIG. 2 includes a strain measuring device 2 and an arithmetic unit 3. The strain measuring device 2 and the arithmetic unit 3 are directly connected to be communicable, and the data acquired by the strain measuring device 2 is analyzed and arranged by the arithmetic unit 3 to create strain data D1, which is stored in the auxiliary storage unit of the arithmetic unit 3. Note that the strain measuring device 2 may directly create the strain data D1 and transmit the created strain data D1 to the arithmetic unit 3. The strain measuring device 2 is installed on the crane Cr having the structure to be evaluated. The arithmetic unit 3 may be installed on the crane Cr having the structure to be evaluated, or may be installed in a management building of a container terminal or the like. The fatigue evaluation system 1 can also evaluate each structure of a plurality of cranes Cr. When evaluating each structure of a plurality of cranes Cr, the fatigue evaluation system 1 includes a plurality of strain measuring devices 2 and one arithmetic unit 3, and the fatigue of each structure of a plurality of cranes Cr is evaluated by one arithmetic unit 3.

[0025] The strain measuring device 2 can use various known measuring devices having a strain gauge (fatigue sensor) or a digital image correlation method (DIC) analyzer. The strain measuring device 2 in the illustrated example has a plurality of strain gauges 4 and one measuring instrument 5. One strain gauge 4 may be installed for one structure, or a plurality of strain gauges 4 may be installed for one structure. Therefore, the number of strain gauges 4 may be equal to or greater than the number of structures to be evaluated by one crane Cr.

[0026] The strain gauge 4 is directly attached to a desired location of the structure. The desired location may be a location where the degree of fatigue accumulated in the structure is representative, or may be a location where the degree of fatigue accumulated in the structure is the greatest. The strain gauge 4 changes its electrical resistance value due to expansion and contraction according to the amount of strain of the attached structure. The measuring instrument 5 reads and converts this changed electrical resistance value to measure the amount of strain.

[0027] The measuring instrument 5 is electrically connected to a plurality of strain gauges 4. The measuring instrument 5 outputs a specified voltage to each strain gauge 4 at a predetermined period (sampling period), measures the voltage difference accompanying the change in the electrical resistance value of each strain gauge 4 to calculate the amount of strain, and associates and outputs each calculated amount of strain with the measurement time. The predetermined period can be arbitrarily set, but in the case of the structure of the crane Cr, for example, a range exceeding 0.001 s and less than 0.1 s is desirable, and 0.01 s is more desirable. If it is 0.001 s or less, the amount of data becomes enormous and it takes a great deal of time for data processing. Also, if it is 0.1 s or more, the measurement frequency decreases and the data becomes rough, resulting in poor accuracy. The strain data D1 stored in the auxiliary storage unit of the arithmetic unit 3 shows the change in the amount of strain of the structure over time with the amounts of strain output from the measuring instrument 5 arranged in time series. Details of this strain data D1 will be described later.

[0028] The measuring instrument 5 is electrically connected to the control device PC. The measuring instrument 5 receives the electrical signal S1 transmitted from the control device PC. In addition to the strain amount described above, the measuring instrument 5 outputs the received electrical signal S1 or data indicating the electrical signal S1. The electrical signal S1 is generated by the control device PC at each of the start time t0 and the end time t1 of the handling operation and transmitted to the measuring instrument 5. In one cycle of the handling operation, the start time t0 is the time when the spreader can be regarded as having grasped the load to be handled, and the end time t1 is the time when the spreader can be regarded as having grasped a new load to be handled. Also, in a half-cycle handling operation, the start time t0 is either the time when the spreader can be regarded as having grasped the load to be handled or the time when the spreader can be regarded as having released the load to be handled, and the end time t1 is the other time.

[0029] In one cycle of the handling operation, the start time t0 and the end time t1 are, for example, when the spreader is the spreader, when the spreader lands on the load to be handled, when the twist lock is locked, or when the load grasped by the spreader is cut off from the ground. Also, when the spreader is a bucket, it is either when the open bucket lands, when the bucket closes and grasps the load, or when the bucket is cut off from the ground. Each time can be specified by the operation signal of the twist lock mounted on the spreader, the ON / OFF signal of the landing sensor, the values measured by the accelerometer and load cell, the tension of the wire rope measured by the tension sensor, etc. The electrical signal S1 can use a voltage signal or a current signal. In the illustrated example, a 5V voltage signal is used. When the spreader is a spreader, for example, from the time when the twist lock is locked until the lock is released (unlocked), a 5V voltage signal flows from the control device PC to the measuring instrument 5, and from the time when the twist lock is released until it is locked again, the voltage signal becomes 0V. Therefore, in one cycle of the handling operation, the start time t0 is the time when the twist lock is locked, and the end time t1 is the time when the twist lock is locked again after the lock of the twist lock is released.

[0030] To the strain data D1, a start time t0 and an end time t1 based on the electrical signal S1 are added. In the present embodiment, the arithmetic unit 3 executes data processing to add the start time t0 and the end time t1 to the strain data D1 based on the electrical signal S1. When the strain data D1 is directly created by the strain measuring device 2, this data processing may be executed by the measuring instrument 5 of the strain measuring device 2. This data processing may be a process of superimposing the electrical signal S1 on the strain data D1, or a process of digitizing and adding the start time t0 and the end time t1 specified from the electrical signal S1. Details of the start time t0 and the end time t1 added to the strain data D1 will be described later.

[0031] The arithmetic unit 3 is composed of a computer, in which various data are input and stored, and data processing is performed using these data. The arithmetic unit 3 can use various known computers. The arithmetic unit 3 has an arithmetic processing unit (CPU), a main storage unit (memory), an auxiliary storage unit (for example, HDD), an input unit (keyboard), and an output unit (display). In the auxiliary storage unit, the strain data D1 for each structure acquired using the strain measuring device 2 is stored. When each structure of a plurality of cranes Cr is to be evaluated, the auxiliary storage unit stores the strain data D1 for each structure of each crane Cr. The number of strain data D1 stored is, for example, the same as the number of strain gauges 4 installed.

[0032] The strain data D1 illustrated in FIG. 3 shows the change in the strain amount of the structure at each time, with the horizontal axis representing time and the vertical axis representing the strain amount. In the illustrated example, the solid line and the dashed-dotted line indicate the strain data D1, and among them, the solid line indicates the partial data D2. The dashed line indicates the electrical signal S1. The strain data D1 is not limited to a graph, and may be tabular data in which the strain amounts at each time are arranged in time series.

[0033] The strain data D1 has the fluctuations of the electrical signal S1 transmitted from the control device PC added thereto. That is, the strain data D1 has the start time t0 and the end time t1 of one cycle of the cargo handling operation based on the electrical signal S1 added thereto. In addition to the start time t0 and the end time t1, a half-cycle time t2 is added as the time when the spreader releases the cargo to be handled. The half-cycle time t2 indicates, for example, the time when the lock of the twist lock is released.

[0034] The partial data D2 is the data related to the cargo handling operation within the strain data D1. "Related to the cargo handling operation" means the part that overlaps with the period during which the cargo handling operation of interest is performed within the strain data D1. Therefore, the partial data D2 shows the change in the amount of strain at each moment from the start time t0 to the end time t1 of one cycle of the cargo handling operation. In the partial data D2 in the illustrated example, the representative value of the amount of strain at each moment from the start time t0 to the half-cycle time t2 when the spreader is holding the cargo is larger than the representative value of the amount of strain at each moment from the half-cycle time t2 to the end time t1 when the spreader is not holding the cargo.

[0035] Next, the procedure of the embodiment of the method for evaluating the fatigue of the crane structure of the first invention will be described. This fatigue evaluation method is implemented using the above-described fatigue evaluation system 1, and is a method of calculating the degree of fatigue damage in the cargo handling operation by actual measurement of the strain measuring device 2 each time the crane Cr performs a cargo handling operation.

[0036] In the procedure illustrated in FIG. 4, first, strain data D1 is acquired by actual measurement of the strain measuring device 2 (S110). Next, the arithmetic unit 3 identifies the strain data related to the cargo handling operation from the strain data D1 as partial data D2, and calculates the degree of fatigue damage in one cargo handling operation from the identified partial data D2 (S120, S130). Finally, the cumulative degree of fatigue damage for each cargo handling operation is calculated, and the identified partial data D2 is deleted from the strain data D1 (S140, S150). The details of each step (S110 to S150) will be described below.

[0037] In step (S110), the strain amount of the structure to be evaluated is measured at a predetermined period by actual measurement using the strain measuring device 2, and strain data D1 is acquired. Actual measurement means actually measuring the strain amount of the structure to be evaluated, which is different from numerical analysis and prediction. Strain data D1 has data added at each predetermined period. Therefore, by executing step (S150) described later, unnecessary data in the strain data D1 is appropriately deleted, and an increase in its data volume is suppressed. This step (S110) is sequentially executed while the crane Cr is operating. The state where the crane Cr is operating includes not only the state where the crane Cr is performing a cargo handling operation but also the state where the crane Cr is traveling and the state where it is waiting for a scheduled cargo handling operation at a predetermined position. Therefore, the strain data D1 acquired in this step (S110) also includes data while the crane Cr is not performing a cargo handling operation.

[0038] In step (S120), based on the start time t0 and the end time t1 of the cargo handling operation, data processing is executed by the arithmetic unit 3 to identify partial data D2 related to the cargo handling operation from the strain data D1. In step (S120), when the crane Cr performs the nth cargo handling operation, the partial data D2 related to the nth cargo handling operation is identified. At this time, step (S120) is executed after the (n + 1)th cargo handling operation starts, that is, after the nth cargo handling operation ends. The execution of step (S120) can be at any time after the nth cargo handling operation ends, but the shorter the time from the end of the nth cargo handling operation to the execution of step (S120), the more advantageous it is for reducing the data volume. Therefore, it is desirable that step (S120) be executed at the timing when the nth cargo handling operation ends.

[0039] Specifically, in step (S120), based on the start time t0 and end time t1 of the handling operation added to the strain data D1, the arithmetic unit 3 executes data processing to specify, as partial data D2, the change in the amount of strain for each time point from the start time t0 to the end time t1. The start time t0 and end time t1 of the handling operation added to the strain data D1 are determined based on the electrical signal S1 transmitted from the control device PC to the measuring device 5, as illustrated in FIG. 3 described above.

[0040] In step (S130), based on the partial data D2, the arithmetic unit 3 executes data processing to calculate the degree of fatigue damage for one handling operation. In this data processing, first, using various known cycle counting methods such as the rainflow method, the stress frequency distribution for one handling operation is calculated from the partial data D2. Next, using a known linear cumulative damage rule (Miner's rule, modified Miner's rule) or non-linear cumulative damage rule, the degree of fatigue damage for one handling operation is calculated from the stress frequency distribution.

[0041] In step (S140), the arithmetic unit 3 executes data processing to accumulate the degree of fatigue damage for each handling operation performed by the crane Cr. For example, the accumulation of the degree of fatigue damage at the time when the nth handling operation is completed means the sum of the degrees of fatigue damage from the first to the nth calculated in step (S130) described above.

[0042] In step (S150), the arithmetic unit 3 executes data processing to delete the partial data D2 from the strain data D1. For example, when the degree of fatigue damage up to the nth handling operation is accumulated, the partial data D2 for the nth handling operation is the data to be deleted. That is, when the degree of fatigue damage up to the nth is accumulated, each partial data D2 from the first to the nth is deleted from the strain data D1 stored in the auxiliary storage unit of the arithmetic unit 3. In this step (S150), after deleting the partial data D2 to be deleted, if the data before that partial data D2 remains, that data can also be deleted. Such data includes data in a state where the crane Cr is traveling or waiting for a handling operation scheduled at a predetermined position.

[0043] The cumulative fatigue damage degree is output to the output unit (for example, monitor) of the arithmetic unit 3. When the cumulative fatigue damage degree for each handling operation reaches "1", it can be considered that the structure to be evaluated has a high possibility of suffering fatigue damage. Therefore, by using the cumulative fatigue damage degree for each handling operation as an evaluation index and outputting the evaluation index to the output unit, the fatigue of the structure can be faithfully evaluated.

[0044] In addition to the cumulative fatigue damage degree, the evaluation index can use the number of handling operations that can be performed until the structure reaches fatigue damage (hereinafter referred to as the remaining handling operation times), the period until fatigue damage (hereinafter referred to as the remaining life period), etc. The remaining handling operation times are calculated based on the value obtained by subtracting the cumulative fatigue damage degree from "1". This value indicates the remaining fatigue damage degree until the structure reaches fatigue damage. By dividing this remaining fatigue damage degree by the representative value of the fatigue damage degree for each handling operation, the remaining handling operation times are calculated. The remaining life period is the period required until the cumulative fatigue damage degree reaches "1", and days, months, or years are used for that period. The remaining life period is calculated by linearly approximating the transition of the cumulative fatigue damage degree over a predetermined period and determining the period until the straight line obtained by the approximation reaches "1". Also, the remaining life period is calculated by dividing the remaining handling operation times by the representative number of handling operations per day, per month, or per year for the crane Cr. Thus, by calculating the cumulative fatigue damage degree for each handling operation, it becomes possible to use the remaining handling operation times, the remaining life period, etc. as indices. The evaluation index may use any of the cumulative fatigue damage degree, the remaining handling operation times, and the remaining life period. However, in the case of the cumulative fatigue damage degree, it is difficult to grasp the specific progress until the structure reaches fatigue damage, so the remaining handling operation times and the remaining life period are more preferable.

[0045] In the fatigue evaluation method, it is sufficient to be able to output an evaluation index, but it is also possible to output an evaluation result by comparing the evaluation index with a preset threshold value. By outputting the evaluation result using the evaluation index by the arithmetic unit 3, it greatly contributes to the determination of continuous use, update (repair), disposal, etc. of the crane. For example, when using the cumulative fatigue damage degree for each handling operation as the evaluation index, a value within the range of 0.8 or more and less than 1.0 is used as the threshold value. When using the remaining number of handling operations as the evaluation index, a value within the range of more than 0 times and 400,000 times or less is used as the threshold value. When using the remaining life period as the evaluation index, a value within the range of more than 0 years and 4 years or less is used as the threshold value.

[0046] As described above, according to the present embodiment, the fatigue damage degree calculated from the partial data D2 related to the handling operation in the strain data D1 is calculated based on the handling operation performed by the crane Cr. Therefore, the cumulative value faithfully represents the degree of fatigue accumulated in the structure each time the crane Cr performs a handling operation. And by using the cumulative fatigue damage degree for each handling operation as an evaluation index, the fatigue of the structure can be faithfully evaluated based on the handling operation in the crane Cr. Further, each time the cumulative fatigue damage degree is calculated, the partial data D2 related to the handling operation is deleted. Therefore, it is advantageous for reducing the data amount of the strain data D1 stored in the auxiliary storage unit of the arithmetic unit 3.

[0047] In particular, the present embodiment is suitable for a crane Cr having a plurality of structures to be evaluated, and is particularly suitable for a container terminal where a plurality of cranes Cr are operated. The larger the number of structures and the larger the number of cranes Cr, the larger the number of strain data D1 accumulated, and the data amount thereof also becomes enormous. Therefore, it is better that the data amount of one strain data D1 is as small as possible. Therefore, in the crane Cr, it is best to adopt a configuration in which the fatigue of the structure is evaluated for each handling operation based on the handling operation, and thereby the partial data D2 can be accurately deleted from the strain data D1 for each handling operation.

[0048] In addition, in this embodiment, since the fatigue of the structure can be evaluated by actual measurement with the strain gauge 2, it is more versatile as it does not require an accurate drawing of the crane Cr having the structure to be evaluated. Therefore, it becomes possible to more faithfully evaluate the fatigue of the structures of various cranes Cr including those for which accurate drawings cannot be prepared. At a container terminal, even among cranes Cr performing the same cargo handling operation, multiple types of models may be adopted. Even in such a case, according to this embodiment, the fatigue of each structure of each crane Cr can be faithfully evaluated.

[0049] Next, Modification Example 1 of the embodiment will be described. In this Modification Example 1, the start time t0 and the end time t1 of the cargo handling are specified by the arithmetic unit 3 based on the history of the cargo handling performed by the crane Cr.

[0050] The fatigue evaluation system 1A of Modification Example 1 illustrated in FIG. 5 is different from the embodiment illustrated in FIG. 1 in that the strain gauge 2 and the control device PC are not electrically connected, and the time of the strain data D1a is synchronized with the time of the history data D3. The white arrows in the figure indicate the synchronization of the time between the strain data D1a and the history data D3. Also, the fatigue evaluation system 1A is different in that the start time t0 and the end time t1 of the cargo handling are specified by the arithmetic unit 3 based on the history data D3.

[0051] The fatigue evaluation system 1A includes a measurement arithmetic unit 6 interposed between the measuring instrument 5 and the arithmetic unit 3. The measurement arithmetic unit 6 is installed on the crane Cr having the structure to be evaluated. The measurement arithmetic unit 6 can use various known computers. The measurement arithmetic unit 6 analyzes and arranges the data transmitted from the measuring instrument 5 to create strain data D1, synchronizes the time of the created strain data D1 with the time of the history data D3, and transmits the strain data D1a with synchronized time to the arithmetic unit 3. This strain data D1a is stored in the auxiliary storage unit of the arithmetic unit 3.

[0052] When there are a plurality of structures to be evaluated, such as the crane Cr, it is preferable to provide a measurement arithmetic unit 6 that creates a plurality of strain data D1 and D1a from the data acquired by the strain measuring device 2. By providing the measurement arithmetic unit 6, the data processing in the arithmetic unit 3 (the data processing for creating the strain data D1 and D1a) is distributed to the measurement arithmetic unit 6, which is advantageous for reducing the arithmetic load of the arithmetic unit 3. Therefore, it is also preferable to provide the measurement arithmetic unit 6 between the strain measuring device 2 and the arithmetic unit 3 in the embodiment illustrated in FIG. 1 described above.

[0053] The control arithmetic unit PC2 is installed in the crane Cr having the structure to be evaluated. The control arithmetic unit PC2 can use various known computers. It should be noted that the history data D3 can also be transmitted from the control arithmetic unit PC2 to another computer, and the history data D3 can be transmitted from that other computer to the arithmetic unit 3.

[0054] The strain data D1a and the history data D3 are synchronized with each other using an NTP (Network Time Protocol) server. That is, the respective times of the measurement arithmetic unit 6 having the strain data D1a and the control arithmetic unit PC2 having the history data D3 are synchronized using the NTP server, so that the respective times of the strain data D1a and the history data D3 are synchronized. Also, the strain data D1a and the history data D3 can be created by a single arithmetic unit that integrates the respective functions of the measurement arithmetic unit 6 and the control arithmetic unit PC2. The respective times of the strain data D1a and the history data D3 created by a single arithmetic unit are synchronized.

[0055] The history data D3 illustrated in FIG. 6 is created by the control arithmetic unit PC2 that receives various signals output from the control device PC, and is transmitted from the control arithmetic unit PC2 to the arithmetic unit 3 and stored. The history data D3 represents the history of the handling operation of the crane Cr by the control device PC. Specifically, in the history data D3, the times for various handling operations in the left column of the table are accumulated. It is not necessary for the history data D3 to accumulate the history of all the handling operations of the crane Cr, and it is sufficient that the handling operations that can be regarded as being performed between the start time t0 and the end time t1 of the handling and the times thereof are accumulated. In the illustrated example, the operation of locking (ON) the twist lock of the spreader can be regarded as a handling operation performed at the start time t0, and the operation of unlocking (OFF) the twist lock can be regarded as a handling operation performed at the end time t1.

[0056] The procedure of the fatigue evaluation method of Modification 1 is the same as the procedure illustrated in FIG. 4 described above, but the content of step (S120) is slightly different. In step (S120) of Modification 1, based on the history data D3, the arithmetic unit 3 specifies the start time t0 and the end time t1 from the strain data D1a, and data processing is executed to specify the strain data D1a from the start time t0 to the end time t1 as partial data D2 applied to the handling. In the history data D3, the handling operations performed at the start time t0 and the end time t1 of the handling and the times thereof are accumulated. The specified times of the start time t0 and the end time t1 are based on the handling operations performed at the start time t0 and the end time t1 of the handling accumulated in the history data D3 and the times thereof.

[0057] As described above, according to Modification 1, based on the history data D3, the start time t0 and the end time t1 of the handling can be specified. The specification of the start time t0 and the end time t1 of the handling may use either the method using the electric signal S1 in the above-described embodiment or the method using the history data D3 in Modification 1, and can be appropriately selected.

[0058] Next, another embodiment of the fatigue evaluation method and fatigue evaluation system for the crane structure will be described. In this embodiment, when evaluating the fatigue of the structure of a single crane Cr, it is evaluated by actual machine measurement in the same manner as the embodiment illustrated in FIG. 1 described above, and a database D4 is automatically created in the process of the evaluation by actual machine measurement. After the creation of the database D4, it is automatically evaluated using the database D4 without using actual machine measurement.

[0059] The fatigue evaluation system 1B illustrated in FIG. 7 has a configuration including a strain gauge 2 and is performing the creation process S210 illustrated in FIG. 11 described later. The fatigue evaluation system 1C illustrated in FIG. 8 has a configuration without a strain gauge 2 and is performing the prediction process S230 illustrated in FIG. 11 described later.

[0060] The fatigue evaluation system 1B illustrated in FIG. 7 is different in that, in addition to the same configuration as the embodiment illustrated in FIG. 1 described above, the handling data D5 transmitted from the management server PC3 and the created database D4 are stored in the auxiliary storage unit of the arithmetic unit 3. The fatigue evaluation system 1C illustrated in FIG. 8 has a configuration in which the strain gauge 2 is removed from the configuration of the fatigue evaluation system 1B. That is, in the fatigue evaluation system 1C, the strain gauge 2 has been removed from the crane Cr having the structure to be evaluated. Although the control device PC is not illustrated in FIG. 8, the control device PC remains installed in the crane Cr and controls the handling operation of the crane Cr.

[0061] The management server PC3 can use various known computers. The management server PC3 is installed in the management building of the container terminal. The management server PC3 manages the goods in the container terminal. Management data is pre-stored in the management server PC3. The management data accumulates the weight of each piece of goods and its destination, etc. The management server PC3 issues commands to each crane Cr in the container terminal using this management data.

[0062] The handling data D5 illustrated in FIG. 9 is created by the management server PC3, transmitted from the management server PC3 to the arithmetic unit 3, and stored in the auxiliary storage unit of the arithmetic unit 3. The handling data D5 indicates the situation of the handling that the crane Cr is scheduled to perform or the situation of the handling that the crane Cr has performed. The handling situation is, for example, the weight of the load to be handled and the lateral travel distance (the travel distance of the trolley) of the load. The handling data D5 can use a part of the management data used by the management server PC3. Also, the handling data D5 can be created using the control arithmetic unit PC2 illustrated in FIG. 5 described above.

[0063] Specifically, for the number of handling operations (1, 2, ···, n) based on one cycle of handling in the leftmost column of the illustrated table, the handling data D5 accumulates the weight of the load to be handled, the position where the load is grasped, and the position where the load is released. For example, the situation of the first handling operation performed by the crane Cr is that the weight is 5 to 10 t and the lateral travel distance is a - e - a. The lateral travel distance a - e - a means that the trolley travels laterally from the span (a) to the outreach (e) and then returns to the span (a). In the case of a half-cycle handling operation, since two consecutive half-cycle handling operations are equivalent to one cycle of handling operation, the number of handling operations in the illustrated table becomes twice. Therefore, the situation of the first handling operation in the illustrated table indicates the situation of the first and second handling operations of the half-cycle handling operation when based on the half-cycle handling operation. The situation of the first handling operation of the half-cycle handling operation is that the weight is 5 to 10 t and the lateral travel distance is a - e because the spreader is grasping the load. The situation of the second handling operation of the half-cycle handling operation is that the weight is 0 to 5 t and the lateral travel distance is e - a because the spreader has released the load.

[0064] The handling data D5 only needs to be able to distinguish situations where it is not necessary to precisely classify the handling status and where the handling status can be regarded as generally the same, that is, situations where the degree of fatigue accumulated in the structure due to handling can be regarded as being of the same level. In the illustrated example, the weight of the cargo is divided into six sections at 5t intervals, with a minimum of 0t and a maximum of 30t. The position where the cargo is grasped and released is divided into two types (a, b), where one position is the span (between the legs of the crane Cr) or the back reach. The other position is where the outreach of the crane Cr is equally divided into eight parts, and each of the equally divided sections is assigned numbers c to j in sequence in the direction in which the outreach extends. When the position where the cargo is grasped is the span (a) or the back reach (b), the handling status from the container terminal to the ship is shown. When the position where the cargo is grasped is the outreach (c to j), the handling status from the ship to the container terminal is shown.

[0065] For the handling data D5, precise numerical values such as the weight [t] of the cargo and the traversing distance [m] can also be used as the handling status. However, while it becomes possible to more faithfully represent the relationship between the handling status and the degree of fatigue damage by precisely classifying the handling status, the amount of data of the handling data D5 will become extremely large. Therefore, in the handling data D5, it is advantageous for reducing the amount of data by roughly classifying the handling status based on the degree of fatigue accumulated.

[0066] The classification of the handling status can be set by grasping the general degree of fatigue accumulated in the structure for each handling operation using the data accumulated by the operator who operates and manages the container terminal or the manufacturer and seller of the crane Cr. The data accumulated by these operators includes measured values during the actual operation of the container terminal, results of multiple experiments and tests in research and development, and laboratory data such as computer simulation results. Therefore, the handling data D5 is appropriately set based on the knowledge obtained from those data accumulated by the operators.

[0067] When the handling data D5 indicates the handling situation in the transfer crane, for the position where the load is grasped and the position where the load is released, the row number which is the classification in the width direction of the storage lane existing in the container terminal, the travel line on which the transport vehicle installed adjacent to the width direction of the storage lane travels, etc. are used.

[0068] The database D4 illustrated in FIG. 10 is created by the arithmetic unit 3 and stored in the auxiliary storage unit of the arithmetic unit 3. The database D4 is created for each structure to be evaluated, similar to the strain data D1 and D1a. Therefore, when evaluating the fatigue of a plurality of structures, the number of databases D4 created is the same as the number of structures to be evaluated. In the database D4, the fatigue damage degree for each handling in the structure to be evaluated is classified according to the handling situation. Note that this fatigue damage degree is obtained in the creation process S210 described later, and specifically, it is obtained using the same method as the embodiment illustrated in FIG. 1 and the modification example 1 illustrated in FIG. 5 described above in the creation process S210.

[0069] Specifically, in the database D4, the uppermost row of the illustrated table is the classification of the weight [t] of the load to be handled (0 - 5, 5 - 10, ···, 25 - 30), and the leftmost column of the table is the classification of the lateral travel distance of the load to be handled (a - c - a, a - c - b, ···, b - j - b, c - a - c, ···, j - b - j). In the database D4, the fatigue damage degrees corresponding to each classification are accumulated. The accumulated fatigue damage degree is obtained by implementing the creation process S210 described later using the fatigue evaluation system 1B. In the process of creating the database D5, when a plurality of fatigue damage degrees are calculated for the same handling situation (a situation where the weight is the same and the lateral travel distance is the same), representative values (average value, mode value, median value) of the fatigue damage degrees of the same handling situation are adopted in the database D5. Also, when it can be considered that the degree of fatigue accumulated in the structure is the same, the classifications of the lateral travel distances may be integrated. For example, when it can be considered that the degree of fatigue accumulated in the structure is the same, the lateral travel distance a - c - a and the lateral travel distance c - a - c are integrated.

[0070] Next, the procedure of another embodiment of the fatigue evaluation method for the crane structure will be described. This fatigue evaluation method is implemented using the fatigue evaluation systems 1B and 1C described above. In the creation step S210 using the fatigue evaluation system 1B, each time the crane Cr performs a cargo handling operation, the fatigue damage degree in that cargo handling operation is calculated by actual measurement with the strain gauge 2, and the database D4 is automatically created. In the prediction step S230 using the fatigue evaluation system 1C, each time the crane Cr performs a cargo handling operation, the fatigue damage degree is automatically predicted based on the database D4.

[0071] In the procedure illustrated in FIG. 11, first, the creation step S210 of calculating the fatigue damage degree for each cargo handling operation by actual measurement using the strain gauge 2 and creating the database D4 is performed. Next, after the creation step S210 is completed and after the strain gauge 2 is removed from the crane Cr (S220), the prediction step S230 of predicting the fatigue damage degree for each cargo handling operation using the created database D4 is performed.

[0072] In the creation step S210 illustrated in FIG. 12, after each step S110 to S150 is performed in the same manner as the procedure illustrated in FIG. 4 described above, the database D4 is created (S240). In the prediction step S230 illustrated in FIG. 13, each time the crane Cr performs a cargo handling operation, the fatigue damage degree is predicted based on the cargo handling data D5 and the database D5 (S250), and the fatigue damage degree for each cargo handling operation is accumulated (S140). The details of each step (S210 to S250) will be described below.

[0073] The creation process S210 is carried out during a period in which the handling operations by the crane Cr are repeated many times. This period can be arbitrarily set based on a certain pre-set period, for example, about one week, but it is desirable to set it to a period that can generally cover all the handling operation situations of the crane Cr. Generally covering all the handling operation situations means covering more than 70% of all possible handling operation situations shown in the handling operation data D5. That is, it means that the number of blank cells in the database D4 is less than 30% of the total number of cells. The number of handling operations per day is different between the cranes Cr at the container terminals of the major ports (such as Tokyo, Yokohama, Nagoya, etc.) in Japan and the cranes Cr at other container terminals. Therefore, the period until all the handling operation situations are generally covered is about 2 weeks to 1 month for the cranes Cr at the container terminals of the major ports, and about 1 month to 2 months for the cranes Cr at other container terminals. This period may be configured to end when the arithmetic unit 3 performs data processing to determine whether the number of blank cells existing in the database D4 is less than 30% of the total number of cells and it is determined that it is less than 30%.

[0074] In step (S240), based on the handling operation data D5, data processing is executed by the arithmetic unit 3 to create a database D4 in which the fatigue damage degree for each handling operation is classified according to the handling operation situation. Immediately after the creation process S210 is carried out, in the database D4, all cells except the uppermost row and the leftmost column of the table illustrated in FIG. 10 described above are blank. Then, each time the creation process S210 is repeated, the fatigue damage degree is described in the blank cells and the data is filled up.

[0075] The database D4 created in the creation process S210 does not need to be recreated unless there are changes regarding the degree of fatigue accumulated in the structures for each handling operation such as the specifications and operating environment of the crane Cr. That is, once the database D4 is created, it can be used as it is any number of times with the same crane Cr. Therefore, if the database D4 has been created, the creation process S210 can be omitted. Also, the created database D4 can be used as it is with other cranes Cr that can be regarded as having generally the same specifications and operating environment. Thus, it is possible to share the same database D4 among cranes Cr with the same specifications and operating environment. The same specifications of the crane Cr mean, for example, that the crane type (such as gantry crane or transfer crane) is the same and the model is the same. Also, the same operating environment of the crane Cr means that the container terminal (port) where the crane Cr is operated is the same. Note that the specifications and operating environment do not need to be exactly the same, and it is sufficient as long as those skilled in the art can regard them as generally the same within a certain range.

[0076] When a predetermined period has elapsed and the creation of the database D4 is completed, if there are blanks in the database D4, it is advisable to interpolate those blanks. When the total weight (the sum of the weights of the trolley, the spreader, and the load to be handled) is different at the same transverse distance, let the larger total weight be X and the smaller total weight be Y. Then, the fatigue damage degree of the side with the larger total weight is approximately equal to the fatigue damage degree of the side with the smaller total weight multiplied by the cube of the total weight ratio ((X / Y) 3 ). Also, when the transverse distance is different at the same total weight, let the larger transverse distance be X and the smaller transverse distance be Y. Then, the fatigue damage degree of the side with the larger transverse distance is approximately equal to the fatigue damage degree of the side with the smaller transverse distance multiplied by the ratio of the transverse distances (X / Y).

[0077] Step (S220) is performed after the database D4 is created in the creation step S210. In step (S220), the strain gauge 2 is removed from the crane Cr. In the modification example 1 illustrated in FIG. 5 described above, in addition to the strain gauge 2, the measurement arithmetic unit 6 is also removed from the crane Cr. Step (S220) may be performed in accordance with the maintenance inspection work of the crane Cr that is periodically performed. The removal of the strain gauge 2 is not essential, and after the completion of the creation step S210, it is also possible to only stop the operation of the strain gauge 2 so as not to perform actual machine measurement. In this case, step (S220) can be omitted.

[0078] The prediction step S230 is performed each time the crane Cr performs a cargo handling operation. Each time the crane Cr performs a cargo handling operation, the cargo handling data D5 including the situation of the cargo handling operation is transmitted from the management server PC3 to the arithmetic unit 3 and stored in the auxiliary storage unit.

[0079] In step (S250), based on the cargo handling situation for each cargo handling operation and the database D4, data processing for predicting the fatigue damage degree during cargo handling is executed by the arithmetic unit 3. In this data processing, a method of comparing the situation of the cargo handling operation to be predicted with the database D4, or a method using a prediction model constructed by machine learning using the database D4 as learning data (teacher data) can be used.

[0080] In the method of comparing data, the cell indicated by the situation of the cargo handling operation to be predicted is selected from the table of the database D4, and the fatigue damage degree of the selected cell is predicted as the fatigue damage degree during the cargo handling operation to be predicted. This method is suitable when the cargo handling situation is roughly classified in the cargo handling data D5.

[0081] The prediction model is a type of computer program that predicts the degree of fatigue damage during cargo handling. The prediction model is constructed by supervised machine learning, with the cargo handling situation (weight, lateral distance) in database D4 as the explanatory variable and the degree of fatigue damage as the target variable. As the machine learning, various known machine learnings such as random forest and deep neural network (DNN) can be used. In the method using the prediction model, the degree of fatigue damage in the cargo handling to be predicted is predicted by processing data with the arithmetic unit 3 using the cargo handling situation to be predicted and the prediction model. This method is suitable when the cargo handling situation is precisely quantified.

[0082] When evaluating the fatigue of the structure of one crane Cr, in the creation process S210, the cumulative fatigue damage degree for each cargo handling obtained in the process of the creation process S210 is used as an evaluation index. And in the prediction process S230, the cumulative fatigue damage degree for each cargo handling obtained in each of the creation process S210 and the prediction process S230 is used as an evaluation index.

[0083] As described above, according to this embodiment, after the database D4 is created, since the degree of fatigue damage is predicted using the cargo handling situation and the database D4, it is not necessary to acquire the strain data D1 by actual measurement. Therefore, in the prediction process S230, the amount of data accumulated in the fatigue evaluation is significantly reduced. In addition, although the strain measuring device 2 needs to be periodically replaced according to the service life, according to this embodiment, after the database D4 is created, the strain measuring device 2 is removed from the crane Cr. Therefore, the labor required for the periodic replacement of the strain measuring device 2 can be saved.

[0084] In addition, in the database D4, the relationship between the fatigue damage degree for each handling operation obtained by actual machine measurement and the handling operation status is faithfully represented. Therefore, the fatigue damage degree predicted using the database D4 can be regarded as the fatigue damage degree calculated by actual machine measurement. Although the evaluation accuracy of fatigue in this embodiment is lower than that in the embodiment illustrated in FIG. 1 and the first modification illustrated in FIG. 5 described above, the decrease is slight. Therefore, this embodiment is more suitable for evaluating fatigue over a long period because it can significantly reduce the amount of data to be accumulated without significantly degrading the evaluation accuracy of fatigue.

[0085] In the crane Cr, the handling operation status is different each time a handling operation is performed, and the degree of fatigue accumulated in the structure is also different. Therefore, by using the database D4 in which the fatigue damage degree for each handling operation is accumulated with respect to the handling operation status, the fatigue damage degree considering the stress on different structures for each handling operation can be accurately predicted. In this way, the creation of the database D4 based on the handling operation is advantageous for faithfully evaluating the fatigue of the structure.

[0086] During the actual handling operation by the crane Cr, it is possible to obtain strain data D1 by the strain measuring device 2 and manually compare the strain data D1 with the history data D3 and the handling operation data D5 to create data equivalent to the database D4. However, creating human data requires a great deal of effort. On the other hand, in the creation step S210 of this embodiment, based on the start time t0 and the end time t1 of the handling operation, the arithmetic unit 3 calculates the fatigue damage degree for each handling operation, and automatically creates a database D4 in which the fatigue damage degree for each handling operation is accumulated with respect to the handling operation status. The start time t0 and the end time t1 of the handling operation can be specified by the arithmetic unit 3 through time synchronization using the electrical signal S1 and the history data D3. In this way, the creation step S210 can automatically create the database D4 by the arithmetic unit 3 without human intervention. Thereby, the effort required to create the database D4 can be significantly reduced. For example, data that would take about one month to create manually can be created in real time in the creation step S210, although it also depends on the processing speed of the arithmetic unit 3.

[0087] Instead of performing actual cargo handling by crane Cr, the database D4 can also be created by performing the creation process S210 in a simulated cargo handling that mimics the actual cargo handling situation. In simulated cargo handling, since the cargo handling situation can be arbitrarily selected, all the situations of cargo handling by crane Cr can be pseudo-replicated. Therefore, by using simulated cargo handling, a database D4 without excess or deficiency can be created in a shorter time than using actual cargo handling. However, it should be noted that crane Cr cannot perform actual cargo handling while creating the database D4 using simulated cargo handling.

[0088] Next, a second modification of the embodiment will be described. In this second modification, the fatigue of the structures of a group of cranes Cr consisting of a plurality of cranes Cr with the same specifications and operating environments is evaluated.

[0089] Each of the cranes Cr in the crane group can be regarded as having the same specifications and operating environments, that is, if the cargo handling situation is the same, the degree of fatigue accumulated in the structure can be regarded as generally the same. Therefore, each of the cranes Cr in the crane group can share the same database D4. For example, the crane group is a gantry crane of the same model operating in the same container terminal (port).

[0090] The fatigue evaluation system 1D illustrated in FIG. 14 is different from the embodiment illustrated in FIG. 8 described above in that the auxiliary storage unit of the arithmetic device 3 stores the cargo handling data D5a, ···, D5n for each crane Cr. In the procedure of the fatigue evaluation method using this fatigue evaluation system 1D, the prediction process S230 is performed while sharing the same database D4 for each of the cranes Cr in the crane group. The database D4 is created by performing the creation process S210 illustrated in FIG. 12 described above using only one crane Cr selected from the crane group. Note that the database D4 is created for each structure.

[0091] When evaluating the fatigue of the structures of a group of cranes, for the crane Cr that performs the creation process S210 among the group of cranes, the cumulative fatigue damage degree for each handling operation obtained in each of the creation process S210 and the prediction process S230 is used as an evaluation index. For the crane Cr that only performs the prediction process S230 among the group of cranes, the cumulative fatigue damage degree for each handling operation predicted in the prediction process S230 is used as an evaluation index.

[0092] As described above, according to this modification example 2, when evaluating the fatigue of the structures of a plurality of cranes Cr, by using the same database D4, it becomes more advantageous for reducing the amount of data. Thereby, the amount of data when evaluating the fatigue of each structure in a situation where a large number of cranes Cr such as a container terminal are in operation can be significantly reduced.

[0093] When evaluating the fatigue of each structure of a large number of cranes Cr, a plurality of arithmetic units 3 can be used. By using a plurality of arithmetic units 3, the arithmetic load can be dispersed. When using a plurality of arithmetic units 3 or sharing the same database D4 among a large number of cranes Cr, the database D4 may be stored in the auxiliary storage unit of the management server PC3. Also, it may be stored in a data server different from the management server PC3, for example, a cloud server. Therefore, the storage unit for storing the database D4 is not limited to the auxiliary storage unit of the arithmetic unit 3, and may be the management server PC3 or a data server.

[0094] The actual machine measurement by the strain gauge 2 can be carried out while the crane Cr is not operating, and the fatigue accumulated in the structure during that period can also be considered in the evaluation. For example, when the non-operating crane Cr is waiting and the structure shakes due to the influence of a storm or earthquake, fatigue accumulates in the structure of the crane Cr due to the shaking. Therefore, based on the strain data obtained by performing the actual machine measurement by the strain gauge 2 while the crane Cr is not operating, the fatigue damage degree while the crane Cr is not operating can be calculated. The strain data obtained while the crane Cr is not operating may be deleted after calculating the fatigue damage degree during that period.

[0095] In addition, devices such as a wind gauge or a seismograph that measure phenomena that cause the structure to shake, or a device that measures the vibration of the boom, are added to the crane Cr, and data in which the fatigue damage degrees for the values measured by these devices are accumulated is created. Based on this data, the fatigue damage degree while the crane Cr is not operating can also be predicted. For example, when the fatigue damage degree for the wind speed per unit time is accumulated as the data, the fatigue damage degree based on the transition of the wind speed while the non-operating crane Cr is waiting can be predicted.

[0096] In this way, in addition to the fatigue damage degree for each handling operation, by adding and accumulating the fatigue damage degree while the crane Cr is not operating, the fatigue actually accumulated in the structure can be evaluated more faithfully. Note that the power consumed by the strain gauge 2 and the arithmetic unit 6 for measurement while the crane Cr is not operating is very small.

[0097] In the above-described embodiments and modifications, a one-cycle cargo handling operation performed by the crane Cr is adopted, but a half-cycle cargo handling operation can also be adopted. In the half-cycle cargo handling operation, it is possible to clearly distinguish between the state where the spreader holds the cargo to be handled and the state where it does not. Therefore, the fatigue damage degree for each half-cycle cargo handling operation more faithfully represents the fatigue actually accumulated in the structure. Also, when adopting a half-cycle cargo handling operation, the fatigue damage degree in the state where the spreader does not hold the cargo to be handled can be regarded as generally the same even if the traversing distance is different for the same weight. Therefore, when adopting a half-cycle cargo handling operation, the fatigue damage degree when the spreader does not hold the cargo to be handled can be set to a constant value, and only the state where the spreader holds the cargo to be handled can be the target of actual measurement or prediction.

[0098] Even when the trolley traverses in the state where the spreader does not hold the cargo (the state of no load), fatigue accumulates in the structure. Therefore, the traversing of the trolley in the state of no load, which is not included in the one-cycle cargo handling operation or the half-cycle cargo handling operation, may also be regarded as a cargo handling operation and the fatigue damage degree may be calculated and predicted. The traversing of the trolley regarded as a cargo handling operation is, for example, the traversing of the trolley during the maintenance inspection work of the crane Cr or the traversing of the trolley between the continuous cargo handling from the container terminal to the ship and the cargo handling from the ship to the container terminal.

[0099] When swing occurs in the boom during the traveling operation of the operating crane Cr, fatigue accumulates in the structure of the crane Cr due to the swing of the boom. The actual measurement by the strain gauge 2 is sequentially performed during the operation of the crane Cr. Therefore, similar to the cargo handling operation, based on the start time and end time of the traveling operation of the crane Cr, the strain data related to the traveling operation can be specified as partial data from the strain data D1, and the fatigue damage degree in the traveling operation can be calculated from the partial data. Also, using the traveling speed and traveling distance as the situation of the traveling operation, a database in which the fatigue damage degree in the traveling operation accumulates for that situation can be created, and the fatigue damage degree in the traveling operation can be predicted using the situation of the traveling operation and the database. The partial data related to the traveling operation may be deleted after calculating the fatigue damage degree in the traveling operation.

[0100] As described above, the embodiments of the present invention have been explained. However, the method and system for fatigue evaluation of the crane structure of the present invention are not limited to specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

Explanation of Signs

[0101] 1, 1A, 1B, 1C, 1D Fatigue evaluation system 2 Strain measuring device 3 Arithmetic unit 4 Strain gauge 5 Measuring instrument 6 Measuring arithmetic unit D1, D1a Strain data D2 Partial data D3 History data D4 Database D5, D5a~D5n Cargo handling data Cr Crane PC Control device PC2 Arithmetic unit for control PC3 Management server

Claims

1. In a method for evaluating fatigue of a crane structure based on the accumulation of fatigue damage, strain data indicating changes in the amount of strain of the structure at each time is obtained by actual machine measurement using a strain measuring device installed on the crane, each time the crane performs a handling operation, based on the start time and end time of the handling operation, an arithmetic unit identifies strain data related to the handling operation as partial data from the strain data, calculates the fatigue damage degree in the handling operation from the partial data, accumulates the fatigue damage degree for each handling operation, and deletes the partial data from the strain data. A method for evaluating fatigue of a crane structure.

2. In a method for evaluating fatigue of a crane structure based on the accumulation of fatigue damage, a creation step of calculating the fatigue damage degree for each handling operation by actual machine measurement using a strain measuring device installed on the crane and creating a database during a period in which the handling operation by the crane is repeated a number of times, and a prediction step of predicting the fatigue damage degree for each handling operation using the created database after the creation step is completed. The method has, in the creation step, strain data indicating changes in the amount of strain of the structure at each time is obtained by actual machine measurement using the strain measuring device, each time the crane performs the handling operation, based on the start time and end time of the handling operation, an arithmetic unit identifies strain data related to the handling operation as partial data from the strain data, calculates the fatigue damage degree in the handling operation from the partial data, and creates the database in which the fatigue damage degree for each handling operation is classified according to the handling situation, in the prediction step, each time the crane performs the handling operation, the arithmetic unit predicts the fatigue damage degree in the handling operation based on the handling situation and the database in the handling operation, and accumulates the fatigue damage degree for each handling operation. A method for evaluating fatigue of a crane structure.

3. Synchronize the respective times of the strain data and the history data indicating the history of the cargo handling operation of the crane, The method for evaluating fatigue of a crane structure according to claim 1 or 2, wherein the calculation device specifies the start time and the end time based on the history data.

4. Electrically connect the strain measuring device and a control device that controls the cargo handling operation of the crane, The strain measuring device receives the electrical signals transmitted from the control device at the respective times of the start time and the end time, and based on the received electrical signals, the strain measuring device adds the start time and the end time to the strain data. The method for evaluating fatigue of a crane structure according to claim 1 or 2.

5. When evaluating the fatigue of the structure of one crane, perform the creation process and the prediction process with that crane, remove the strain measuring device from the crane between the creation process and the prediction process, and accumulate the fatigue damage degrees for each cargo handling obtained in each of the creation process and the prediction process. The method for evaluating fatigue of a crane structure according to claim 2.

6. When evaluating the fatigue of the structures of a group of cranes consisting of a plurality of cranes having the same specifications and operating environments, Perform the creation process with one crane selected from the group of cranes, In each of the group of cranes, perform the prediction process using the same database created in the creation process. The method for evaluating fatigue of a crane structure according to claim 2.

7. In the cargo handling situation, the weight of the cargo to be handled and the traverse distance are used. The method for evaluating fatigue of a crane structure according to any one of claims 2, 5, and 6.

8. In a fatigue evaluation system for a crane structure that evaluates the fatigue of a crane structure based on the accumulation of fatigue damage degrees, A strain measuring device installed on the crane to obtain strain data indicating changes in the amount of strain of the structure at each time by actual measurement, and an arithmetic unit that calculates the fatigue damage degree by processing the strain data. The arithmetic unit executes data processing for specifying, as partial data, strain data related to the handling operation from the strain data based on the start time and end time of the handling operation each time the crane performs a handling operation, data processing for calculating the fatigue damage degree in the handling operation from the partial data, and data processing for accumulating the fatigue damage degree for each handling operation and deleting the partial data from the specified strain data. A fatigue evaluation system for a crane structure.

9. The time of the strain data is synchronized with the time of history data indicating the history of the handling operation of the crane. The arithmetic unit is configured to execute data processing for specifying the start time and the end time based on the history data. The fatigue evaluation system for a crane structure according to claim 8.

10. The strain measuring device is electrically connected to a control device that controls the handling operation of the crane, and receives an electrical signal transmitted from the control device at each of the start time and the end time. In the strain data obtained by the strain measuring device, the start time and the end time based on the received electrical signal are added. The fatigue evaluation system for a crane structure according to claim 8.

11. In a fatigue evaluation system for a crane structure that evaluates the fatigue of the crane structure based on the accumulation of fatigue damage degree. A storage unit in which a database is stored, and an arithmetic unit that predicts the fatigue damage degree based on the database. The database accumulates the fatigue damage degree for each handling operation performed by the crane with respect to the handling situation, and the fatigue damage degree is calculated from partial data which is the strain data applied to the handling operation identified from the strain data obtained by actual measurement using a strain measuring device. The arithmetic unit is configured to predict the fatigue damage degree in each handling operation based on the handling situation in that handling operation and the database every time the crane performs the handling operation, and execute data processing for accumulating the fatigue damage degree for each handling operation. A fatigue evaluation system for a crane structure.

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