Device and method for evaluating life state of frame structure of mobile body

Abstract

In order to accurately estimate, by means of a small number of sensors, the overall life state of a frame structure of a mobile body including a position which is not measured by said sensors, this device for estimating the life state comprises: a detection unit that detects the acceleration or the stress at a measurement point in the frame structure of the mobile body which is traveling on a track; an extraction unit that calculates the degrees of contribution of natural modes with respect to vibrations of the frame structure on the basis of the detected stress or acceleration, and extracts a natural mode having a large contribution degree as an important natural mode; an estimation unit that estimates the overall stress of the frame structure, on the basis of the detected stress or acceleration and the important natural mode; and an evaluation unit that evaluates the overall life state of the frame structure from the estimated overall stress of the frame structure.

Description

Title of Invention: DEVICE AND METHOD FOR EVALUATING LIFE STATE OF FRAME STRUCTURE OF MOBILE BODY Technical Field

[0001] The present invention relates to a device and method for evaluating the life state of the frame structure of a mobile unit. Background Art

[0002] The frame structure of a mobile unit traveling on a track supports the load of passengers, luggage, and other cargo, but cracks or breaks in the frame structure could lead to serious accidents during travel.

[0003] Taking a railway vehicle as an example of a mobile unit, the bogie frame that supports the load of the car body with passengers inside thereof corresponds to the frame structure described above, but damage to this bogie frame during travel may lead to accidents such as derailment. Therefore, in order to prevent damage to the bogie frame, there is a need for a life state evaluation device that can monitor a strength load state of the entire bogie frame in the actual operating environment and determine its actual life.

[0004] For example. Patent Literature 1 describes a technology relating to a conventional life state evaluation device and life state evaluation method. Specifically, a first frequency characteristic of acceleration per unit load at an acceleration detection point on the car body when a load is applied to a load point on the bogie, and a second frequency characteristic of stress per unit load at an inspection point on the bogie when a load is applied to the load point are stored. Then, based on a third frequency characteristic of the magnitude of acceleration detected at the acceleration detection point while the vehicle is traveling and the first frequency characteristic, the load applied to the bogie during travel is calculated. Also, based on the load applied to the bogie during travel and the second frequency characteristic, the stress during vehicle travel at the inspection point is calculated. In addition, there is a description of a device and method for determining the life on the basis of the analysis results of the stress during travel over time. Citation List Patent Literature

[0005] Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2018-155517 Summary of Invention Technical Problem

[0006] In the method described in the above Patent Literature 1, it is necessary to determine an inspection position in advance and measure the stress with a sensor such as a strain gauge. Therefore, in order to increase the number of inspection positions, it is necessary to increase the number of sensors, and there may be issues such as limitations on positions where the life state can actually be evaluated due to the temporary installation costs and layout constraints.

[0007] Accordingly, the purpose of the present invention is to provide a device that can accurately estimate the life state of the entire frame structure of a mobile unit, including positions not measured by the sensors, with a small number of the sensors,. Solution to Problem

[0008] In order to solve the above problems, typical one of a life state evaluation device of the present invention includes: a detection unit that detects stress or acceleration at a measurement point in a frame structure of a mobile unit traveling on a track; an extraction unit that calculates a degree of contribution of each eigenmode to vibration of the frame structure on the basis of the detected stress or acceleration, and extracts the eigenmode having a high degree of contribution as a dominant eigenmode; an estimation unit that estimates the overall stress of the frame structure on the basis of the detected stress or acceleration and the dominant eigenmode; and an evaluation unit that evaluates an overall life state of the frame structure from the estimated overall stress of the frame structure. Advantageous Effects of Invention

[0009] The present invention makes it possible to estimate the stress of the entire frame structure of a mobile unit and evaluate its life state with a minimum number of sensors. Cumulative fatigue can be ascertained from the estimated stress, and efficient inspection and maintenance can be performed by ascertaining the appropriate timing for inspection and maintenance depending on the location and degree of damage. Brief Description of Drawings

[0010] [FIG. 1] FIG. 1 illustrates an example of the overall configuration of a railway vehicle including a life state evaluation device according to a first embodiment of the present invention. [FIG. 2] FIG. 2 illustrates an example of the configuration of the life state evaluation device according to the first embodiment and an example of a processing flow using that configuration . [FIG. 3] FIG. 3 is a schematic diagram of the behavior of two eigenmodes of a bogie frame. [FIG. 4] FIG. 4 is a flowchart illustrating an example of a processing procedure executed by a dominant eigenmode extraction unit. [FIG. 5] FIG. 5 is a bar graph illustrating the contribution degree of each eigenmode at the center of the cross beam of the bogie frame, as an example of contribution calculation results . [FIG. 6] FIG. 6 is a flowchart illustrating an example of a processing procedure executed by a modal coordinate calculation unit. [FIG. 7] FIG. 7 is a flowchart illustrating an example of a processing procedure executed by a stress estimation unit. [FIG. 8] FIG. 8 illustrates an example of application to life estimation of a rear frame of a dump truck as a construction machine. [FIG. 9] FIG. 9 illustrates an example of application to life estimation of an elevator car frame. [FIG. 10] FIG. 10 illustrates the overall configuration of a railway vehicle including a life state evaluation device according to a second embodiment of the present invention. [FIG. 11] FIG. 11 illustrates an example of the configuration of the life state evaluation device according to the second embodiment and an example of a processing flow using that configuration. Description of Embodiments

[0011] Hereinafter, a life state evaluation device according to the present invention will be described in a first embodiment and a second embodiment, which are Description of Embodiments, with reference to the drawings. Here, the first and second embodiments relate to a device and method whereby it is possible to accurately estimate the life of the entire frame structure of a mobile unit. In addition, a railway vehicle will be used as an example of a mobile unit. First Embodiment

[0012] FIG. 1 illustrates an example of the overall configuration of a railway vehicle including a life state evaluation device according to a first embodiment of the present invention. A railway vehicle traveling on a track 2 includes a car body 1 and a bogie 16, and the car body 1 is mounted on the bogie 16 via an air spring 8.

[0013] The bogie 16 includes a bogie frame 11, the air spring 8, a yaw damper 4, a wheelset 13, an axle spring device 14, an axle box 12 that serves as a bearing housing for the wheelset 13, and an axle box support rubber 15.

[0014] The wheelset 13 is held rotatably with respect to the axle boxes 12, which are installed in the sleeper direction (Y direction illustrated in FIG. 1). Between the axle box 12 and the bogie frame 11, the axle spring device 14 is elastically supported in the vertical direction, and the axle box support rubber 15 is elastically supported in the horizontal direction.

[0015] In addition, the air spring 8 is disposed between the car body 1 and the bogie frame 11, and the car body 1 is elastically supported on the bogie frame 11 by the air spring 8.

[0016] A data detection unit 10 for measuring the stress or acceleration of the bogie frame 11 is installed on the bogie 16. The data detection unit 10 does not specify the measurement means as long as it is capable of measuring stress or acceleration. For example, a strain gauge can be used for measuring stress, and an acceleration sensor can be used for measuring acceleration.

[0017] In addition, the data detection unit 10 can be installed so as to detect stress or acceleration at at least one point on the end of the side beam or the center of the cross beam of the bogie frame 11, thereby improving the accuracy of estimating the life state. This principle will be explained in the processing flow of a dominant eigenmode extraction unit 400 described later.

[0018] A data processing device 40 is mounted on the car body 1 and evaluates the life state from the stress or acceleration measured by the data detection unit 10.

[0019] In addition, a result display unit 60 is mounted on the car body 1 and notifies the driver of the car body 1, a ground operation manager, a maintenance worker, or the like of the life state evaluation results output by the data processing device 40.

[0020] Next, a specific processing flow for evaluating a life state using the life state evaluation device according to the first embodiment of the present invention will be described with reference to FIGS. 2 to 7. FIG. 2 illustrates an example of the configuration of the life state evaluation device according to the first embodiment and an example of a processing flow using that configuration.

[0021] In the first embodiment, as illustrated in FIG. 2, strain gauges 10a, 10b, and 10c, which are provided at both ends of a side beam 70 and at the center of a cross beam 71 of the bogie frame 11, are used as the data detection unit 10. Below, an example will be described in which the stresses detected by these gauges at three points on the bogie frame are used. Note that the processing mode in which the data detection unit 10 detects acceleration will be described later.

[0022] First, the strain gauges 10a, 10b and 10c measure the stress of the bogie frame 11 during travel at measurement points A, B and C, respectively, and the data detection unit 10 detects the stress as stress data at the respective measurement points A, B and C. Next, the stress data measured at the three measurement points (measurement points A to C) and detected by the data detection unit 10 is input to the data processing device 40.

[0023] As illustrated in FIG. 2, the data processing device 40 includes a data pre-processing unit 100, an eigenvalue analysis unit 200, a vehicle movement analysis unit 300, the dominant eigenmode extraction unit 400, a modal coordinate calculation unit 500, a stress estimation unit 600, a damage calculation unit 700, and a threshold determination unit 800 .

[0024] The stress data input from the data detection unit 10 to the data processing device 40 is filtered in the data pre-processing unit 100 using well-known filtering technology. Here, pre-processing such as removing frequency band components that do not contribute to stress is performed by filtering. The stress data processed by the data pre-processing unit 100 is input to the modal coordinate calculation unit 500.

[0025] Next, the eigenvalue analysis unit 200 calculates an eigenvalue and an eigenvector for each eigenmode of the bogie frame 11. Here, the eigenmode indicates the deformation shape of how a structure vibrates at an eigenvalue .

[0026] FIG. 3 is a schematic diagram of the behavior of two eigenmodes of the bogie frame 11. Mode A illustrated in (A) is a mode in which the ends of side beams 70a and 70b of the bogie frame are significantly deformed in the vertical direction (Z direction illustrated in FIG. 3). Mode B illustrated in (B) is a mode in which the central portions of cross beams 71a and 71b of the bogie frame are significantly deformed in the vertical direction (Z direction illustrated in FIG. 3).

[0027] Note that in general, regarding the eigenmodes of the bogie frame, there are about a dozen to several dozen eigenmodes in the frequency band that affects stress. To evaluate these eigenmodes, for example, eigenvalue analysis using a finite element method (FEM) model is used. Alternatively, evaluation may be performed using methods such as hammering tests.

[0028] The eigenvalue and eigenvector for each eigenmode, calculated by the eigenvalue analysis unit 200, are input to the dominant eigenmode extraction unit 400.

[0029] The vehicle movement analysis unit 300 uses travel conditions, such as traveling speed, and route conditions, such as track irregularities, as input to analyze vehicle movement, calculates the bogie frame stress at the position where the stress during actual traveling is to be estimated, and outputs the bogie frame stress as stress analysis data.

[0030] Here, for the analysis of vehicle movement, the method is not specified, as long as it is possible to calculate the stress at the estimation position using travel conditions, such as traveling speed, and route conditions, such as track irregularities, as input, and general FEM analysis or multibody dynamics analysis can be used.

[0031] The stress analysis data calculated by the vehicle movement analysis unit 300 is input to the dominant eigenmode extraction unit 400.

[0032] Next, the processing procedure in the dominant eigenmode extraction unit 400 will be described. FIG. 4 is a flowchart illustrating an example of the processing procedure executed by the dominant eigenmode extraction unit 400. In the following, each step of the flowchart is described as "S" in accordance with the figure. In addition, the entity that executes each step is the dominant eigenmode extraction unit 400, but the description of that entity will be omitted below.

[0033] In S401, the eigenvalue and eigenvector for each eigenmode, calculated by the eigenvalue analysis unit 200, and the stress analysis data calculated by the vehicle movement analysis unit 300 are acquired.

[0034] In S402, the contribution degree of each eigenmode to the stress is calculated from the stress analysis data at the estimation position. As mentioned above, in the case of a bogie frame, there are several dozen eigenmodes, but the magnitude of the contribution to the stress is different for each eigenmode, so this contribution degree is calculated.

[0035] A method for calculating the contribution degree of each eigenmode to the stress will be described below. Stress {o} generated by track vibration during travel is expressed by Equation (1). {o} =[cpo] {O ...(1)

[0036] where [<po] is an "eigenstress vector matrix" formed by arranging eigenvectors (poi, ..., (pan related to stress in each eigenmode, and n is the total number of eigenmodes. Furthermore, {O = {^i, ..., ^n} is the "modal coordinate" that represents the weight of the eigenmode, that is, how much of each eigenmode component is included.

[0037] From Equation (1), the stress generated by the r-th eigenmode can be expressed as the product of the r-th eigenvector cpar and the modal coordinate £r, which represents the weight of the r-th eigenmode.

[0038] From the above, a contribution degree p of the r-th eigenmode to the stress can be calculated by Equation (2). P = (Par ' r / S ((pc • ^ ) ...(2)

[0039] Here, Equation (2) expresses the contribution degree p of the rth eigenmode as the ratio of the stress due to the rth eigenmode, which can be calculated from the product of the eigenvector and modal coordinate of the rth eigenmode, to the sum of the stresses which can be calculated from the product of the eigenvectors and modal coordinates of all eigenmodes .

[0040] FIG. 5 is a bar graph (horizontal axis: eigenmode order, vertical axis: contribution degree) illustrating the contribution degree of each eigenmode at the center of the cross beam of the bogie frame, as an example of the contribution calculation results. FIG. 5 shows that the contribution degrees of the three eigenmodes of the 10th, 11th, and 21st orders are large.

[0041] Note that since the magnitude of the contribution of each eigenmode differs depending on the structure, a similar calculation is performed for each bogie frame to be estimated, and the contribution degree is calculated for each. In addition, calculation methods other than the above Equation (2) may be used as long as it is possible to calculate the contribution degree of each eigenmode to the stress .

[0042] Next, in S403, eigenmodes with large contribution degrees are extracted as "dominant eigenmodes" from the contribution calculation results acquired in S402.

[0043] In S404 , an eigenstress vector matrix[<p'o] is created by arranging the eigenvectors tpoi, ..., (pom of the dominant eigenmodes from all eigenmodes. Here, m is the number of dominant eigenmodes, and its relation to the number n of all eigenmodes is: number m of dominant eigenmodes <number n of all eigenmodes.

[0044] In the example illustrated in FIG. 5, m = 3, and the eigenstress vector matrix for only the dominant eigenmodes is formed by arranging the 10th, 11th, and 21st eigenvectors cpoio, (poii, and (pO2i.

[0045] In S405, the eigenstress vector matrix [<p' oA] at the stress measurement position for only the dominant eigenmodes is output to the modal coordinate calculation unit 500, and the eigenstress vector matrix [cp' ob] at the stress estimation position for only the dominant eigenmodes is output to the stress estimation unit 600.

[0046] Next, the processing flow of the modal coordinate calculation unit 500 will be described. FIG. 6 is a flowchart illustrating an example of the processing procedure executed by the modal coordinate calculation unit 500. In addition, the entity that executes each step is the modal coordinate calculation unit 500, but the description of that entity will be omitted below.

[0047] In S501, the measured stress data output by the data pre-processing unit 100 and the eigenstress vector matrix[tp'OA] at the stress measurement position for only the dominant eigenmodes output by the dominant eigenmode extraction unit 400 are acquired.

[0048] In S502, a transposed matrix [cp ' oA] T of the eigenstress vector matrix for the dominant eigenmodes is generated.

[0049] In step S503, modal coordinates are calculated from the measured stress data and the transposed matrix of the eigenstress vector matrix. A method for calculating modal coordinates will be described below. Multiplying the left side of Equation (1) by the transposed matrix of the eigenstress vector matrix gives Equation (3) . U' } = [cp %a] t {o' } ...(3)

[0050] where H’} is the modal coordinate of the dominant eigenmode and {o'} is the measured stress data. From Equation (3), the modal coordinate is calculated using the measured stress data and the eigenstress vector matrix for the dominant eigenmode. To calculate Equation (3), the number of stress measurement points required is equal to the number m of eigenmodes that make up the eigenstress vector matrix [cp ' oA] .

[0051] Therefore, by selecting only the modes with large contribution degrees in advance in the dominant eigenmode extraction unit 400, it is possible to reduce the number of measurement points required to calculate the modal coordinates. This makes it possible to reduce the number of sensors required to estimate stress.

[0052] Note that, among the eigenmodes of the bogie frame 11, there are modes in which the ends of the side beams 70a and 70b and the central portions of the cross beams 71a and 71b are significantly deformed, as illustrated in FIG. 3. Therefore, sensors for detecting the stresses at the ends of the side beams or the central portions of the cross beams are installed.

[0053] Thus, by placing the sensor at a position where the deformation of the eigenmode is larger, a signal-to-noise ratio, which is the ratio of the detection signal from the sensor to noise, can be increased. This allows for reduced noise effects and improved stress estimation accuracy.

[0054] In S504, the modal coordinates of the dominant eigenmodes calculated in S503 are output to the stress estimation unit 600.

[0055] Next, the processing flow of the stress estimation unit 600 will be described. FIG. 7 is a flowchart illustrating an example of the processing procedure executed by the stress estimation unit 600. In addition, the entity that executes each step is the stress estimation unit 600, but the description of that entity will be omitted below.

[0056] In S601, the modal coordinates of the dominant eigenmodes output by the modal coordinate calculation unit 500 and the eigenstress vector matrix [cp'oB] at the stress estimation position for only the dominant eigenmodes output by the dominant eigenmode extraction unit 400 are acquired.

[0057] In S602, the stress at the stress estimation position is calculated and estimated from Equation (1) using the modal coordinates of the dominant eigenmodes and the eigenstress vector matrix at the stress estimation position for only the dominant eigenmodes. In addition, by performing a similar processing on the entire bogie frame, the stress of the entire bogie frame can be estimated.

[0058] In S603, the stress waveform estimated in S602 is output to the damage calculation unit 700.

[0059] Then the damage calculation unit 700 evaluates the fatigue state on the basis of the stress waveform output by the stress estimation unit 600 and the S (Stress) - N (Number) curve to fatigue failure of a member. For example, the fatigue state is evaluated using the cumulative damage rule .

[0060] In the cumulative damage rule, for the case where stress varies randomly over time, loads with stress amplitudes oi, ..., op are assumed to act ni times, ..., np times. Here, the number of repetitions to fatigue failure of the material for the loads oi, ..., op, read from the S-N curve to fatigue failure of the member, and is defined as Ni times, ..., Np times. In this case, the cumulative damage degree D is expressed by Equation (4). D = m / Ni + ... + np / Np = Sm / Ni ...(4)

[0061] In general, if the cumulative damage degree D is greater than 1, is determined that fatigue failure will occur, and if it is less than 1, it is determined that fatigue failure will not occur. The cumulative damage degree D calculated by the damage calculation unit 700 is output to the threshold determination unit 800.

[0062] The threshold determination unit 800 compares the cumulative damage degree D calculated by the damage calculation unit 700 with a preset threshold value for the cumulative damage degree D. Here, the threshold value is obtained by dividing a reference value of 1 by an arbitrary safety factor.

[0063] If the comparison result indicates that the cumulative damage degree D is equal to or lower than the threshold value, the threshold determination unit 800 determines that fatigue failure will not occur. Meanwhile, if the cumulative damage degree D exceeds the threshold value, the threshold determination unit 800 determines that there is a high possibility that fatigue failure will occur, and outputs, to the result display unit 60, an alarm signal indicating the position of the bogie frame 11 that has exceeded the threshold value.

[0064] Upon receiving the alarm signal from the threshold determination unit 800, the result display unit 60 notifies the driver on the car, a ground operation manager, a maintenance worker, or the like of the alarm signal by using well-known communication technology.

[0065] The driver on the car, a ground operation manager, a maintenance worker, or the like can identify the inspection location and degree of damage of the bogie frame 11 on the basis of this alarm signal. Then efficient inspection and maintenance can be achieved by conducting inspections and performing maintenance, such as repairs or replacements of the bogie frame 11 at appropriate times, in accordance with the degree of damage.

[0066] As described above, by using dominant eigenmodes, the number of sensors can be reduced to be the same as the number of dominant eigenmodes. Therefore, it is possible to estimate the stress of the entire bogie frame with a minimum number of sensors and evaluate its life state. In addition, cumulative fatigue can be ascertained from the estimated stress, and efficient inspection and maintenance can be performed by ascertaining the appropriate timing for inspection and maintenance in accordance with the location and degree of damage.

[0067] Note that in the first embodiment, the case where stresses at three points on the bogie frame 11 detected using the strain gauges 10a, 10b, and 10c as the data detection unit 10 is exemplified, but the number of measurement points is not limited to the above and may be provided in accordance with the number of dominant eigenmodes .

[0068] Next, a case where acceleration is detected by the data detection unit 10 will be described. As the data detection unit 10, an acceleration sensor, for example, may be used as means by which modal coordinates can be calculated from the measured data, instead of the above-mentioned strain gauges. That is, by using the acceleration of the bogie frame 11 detected by the acceleration sensor, it is possible to evaluate the life state of the bogie frame in a processing mode similar to that described above.

[0069] When using the acceleration of the bogie frame 11, in Equation (3), an eigenvector matrix related to acceleration is used instead of the eigenstress vector matrix, and measured acceleration data {a'} can be used instead of the measured stress data {o'}.

[0070] When detecting acceleration in this way, an acceleration sensor is used, thereby eliminating the need to remove paint from the mounting location, as is necessary when using strain gauges. This facilitates measurement and reduces man-hours for sensor installation and maintenance costs .

[0071] Furthermore, the present invention can be applied not only to the bogie frames of railway vehicles, but also to mobile units with similar frame structures. For example, the present invention is also applicable to mobile units that travel on tracks of, such as construction machinery, elevators, and automobiles. That is, even in the frame structures of these mobile units, the stress of the entire frame structure caused by track vibration can be estimated in a similar manner by using dominant eigenmodes and sensor measurement data acquired at some measurement positions that deform significantly in the eigenmodes of the frame structure. This makes it possible to estimate the life of the entire frame structure with fewer sensors and provide similar effects.

[0072] For example, in the case of construction machinery, the life of the frame structure that supports the load of a loading unit can be estimated. FIG. 8 illustrates an example of application to life estimation of the rear frame of a dump truck as a construction machine.

[0073] A dump truck 50 that travels on a track 56 includes a front frame 51 on which an operator rides, tires 52 that serve as the traveling wheels, a vessel 53 on which the cargo is placed, and a rear frame 54 that supports the load of the vessel 53 and the like.

[0074] As for the stress induced in the rear frame 54 by track excitation, the stress or acceleration acquired at some measurement points on the rear frame 54 and the dominant eigenmodes of the rear frame 54 can be used to estimate the life of the entire rear frame by performing a processing mode similar to that described earlier with reference to FIGS. 2 to 7.

[0075] Here, in the case of the rear frame 54, in general, there are a vertically bending mode in which longitudinal central portions 55b and 55b' of the rear frame are significantly deformed in the vertical direction (Z direction illustrated in FIG. 8), and a torsional mode in which longitudinal ends 55a, 55a', 55c, and 55c' are significantly deformed in the vertical direction. Therefore, the sensor is preferably arranged so as to detect the stress or acceleration at at least one of these six ZX -I yx. -I— Cl Cl —X Cl C yx I C C Vx C Cl Vx I C Cl yx ys yJ Cl Cl yx f nJ U I 11 L O J J Cl f J J Cl f -J J U j xj .J U ? J J f Cl 11 LA xj •

[0076] In addition, for example, in the case of elevators, the life of the frame structure that supports the weight of passengers can be estimated. FIG. 9 illustrates an example of application to life estimation of an elevator car frame.

[0077] An elevator 80 that moves vertically on a track 85 includes a car 81 where passengers board, a car frame 82 that supports the car 81, an anti-vibration rubber 83 for reducing the transmission of vibration from the car frame 82 to the car 81, and a roller guide 84 that serves as a guide wheel.

[0078] The car frame 82 includes an upper frame 86, two vertical frames 87, a lower frame 88, and a floor frame 89. As for the stress induced in the car frame 82 by track excitation, the stress or acceleration acquired at some measurement points on the car frame 82 and the dominant eigenmodes of the car frame 82 can be used to estimate the life of the entire car frame by performing a processing mode similar to that described earlier with reference to FIGS. 2 to 7 .

[0079] Here, in the case of the car frame 82, in general, there are a bending deformation mode in which central portions 90b and 90b' of the vertical frames 87 are significantly deformed in the front-to-back direction (X direction illustrated in FIG. 9), and a torsional mode in which ends 90a, 90a', 90c, and 90c' of the floor frame 89 are significantly deformed in the vertical direction (Z direction illustrated in FIG. 9). Therefore, the sensor is preferably arranged so as to detect the stress or acceleration at at least one of these six points 90a, 90a', 90b, 90b', 90c, and 90c'. Second Embodiment

[0080] A life state evaluation device according to a second embodiment of the present invention will be described with reference to FIGS. 10 and 11. Note that the same configurations and processing as those described in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted. Only the differences from the first embodiment will be described below. In the second embodiment, as in the first embodiment, a railway vehicle will be used as an example of a mobile unit.

[0081] FIG. 10 illustrates an example of the overall configuration of a railway vehicle including the life state evaluation device according to the second embodiment. In the second embodiment, instead of the data detection unit 10 provided on the bogie frame 11, a data detection unit 30 is provided on the axle box 12. The data detection unit 30 detects the acceleration of the axle box 12 using an acceleration sensor. In the case of the second embodiment, measurement data of an existing acceleration sensor provided for the purpose of detecting damage to the bearings of the axle box 12, or the like, can be used. Therefore, there is an advantage in that the introduction cost of sensors for life state evaluation can be reduced.

[0082] FIG. 11 illustrates an example of the configuration of the life state evaluation device according to the second embodiment and a processing flow using that configuration. The configuration differs from that of the first embodiment in that a second vehicle movement analysis unit 900 for acquiring stress data from acceleration data is added, but the remaining configuration is similar.

[0083] The operation based on the processing flow illustrated in FIG. 11 will be described below. As the data detection unit 30, acceleration sensors 30a and 30b provided in the axle box 12 measure the acceleration at axle box measurement points D and E, and output the acceleration as acceleration data to the second vehicle movement analysis unit 900 added to a data processing device 40'.

[0084] The second vehicle movement analysis unit 900 calculates displacement by integrating twice over time the acceleration data acquired from the data detection unit 30. Using the calculated displacement as an analysis input, an analysis of the vehicle movement is performed to acquire analysis data of stress at representative locations (three analysis points A, B, and C illustrated in FIG. 11) such as at the end of the side beam or the center of the cross beam of the bogie frame 11. Here, by limiting the analysis target to the representative locations in advance, it is possible to reduce analysis costs.

[0085] In the subsequent configuration of the data processing device 40', the processing mode from the data pre-processing unit 100 to the threshold determination unit 800 and the processing mode of the result display unit 60 are similar to those described in the first embodiment.

[0086] As described above, in the life state evaluation device according to the second embodiment, the data detection unit 30 provided in the axle box 12 makes it possible to estimate the stress of the entire bogie frame and evaluate the life state.

[0087] Furthermore, as in the first embodiment, the second embodiment is also applicable not only to the bogie frames of railway vehicles, but also to mobile units such as construction machinery, elevators, and automobiles with similar frame structures.

[0088] For example, in the case of the construction machine illustrated in FIG. 8, instead of placing the sensor on the rear frame 54, an acceleration sensor can be provided on the tires 52 that is in contact with the track 56, to acquire the acceleration of the tires 52 and similar effects can be achieved by performing processing similar to the processing mode illustrated in FIG. 11 .

[0089] Furthermore, in the case of the elevator illustrated in FIG. 9, instead of placing the sensor on the car frame 82, an acceleration sensor can be provided on the roller guide 84 that is in contact with the track 85 to acquire the acceleration of the roller guide 84, and similar effects can be achieved by performing processing mode similar to the processing mode illustrated in FIG. 11.

[0090] The present invention is not limited to the above described first and second embodiments, and various modifications are possible without departing from the scope of the present invention. List of Reference Signs

[0091] 1 car body 2 track 4 yaw damper 8 air spring 10, 30 data detection unit 11 bogie frame 12 axle box 13 wheelset 14 axle spring device 15 axle box support rubber 16 bogie 40, 40' data processing device 50 dump truck 51 front frame 52 tire 53 vessel 54 rear frame 55 central portion and other portions in direction of rear frame 60 result display unit 70 side beam of bogie frame 71 cross beam of bogie frame 80 elevator 81 car 82 car frame 83 anti-vibration rubber 84 roller guide 85 track 86 upper frame 87 vertical frame 88 lower frame 89 floor frame 90 central portion of vertical frame and frame 100 data pre-processing unit 200 eigenvalue analysis unit longitudinal end of floor vehicle movement analysis unit dominant eigenmode extraction unit modal coordinate calculation unit stress estimation unit damage calculation unit threshold determination unit second vehicle movement analysis unit

Claims

1. A life state evaluation device comprising:a detection unit that detects stress or acceleration at a measurement point in a frame structure of a mobile unit traveling on a track;an extraction unit that calculates a degree of contribution of each eigenmode to vibration of the frame structure on the basis of the detected stress or acceleration, and extracts the eigenmode having a high degree of contribution as a dominant eigenmode;an estimation unit that estimates the overall stress of the frame structure on the basis of the detected stress or acceleration and the dominant eigenmode; andan evaluation unit that evaluates an overall life state of the frame structure from the estimated overall stress of the frame structure.

2. The life state evaluation device according to claim 1, whereinthe frame structure of the mobile unit is a bogie frame of a railway vehicle, andthe detection unit detects the stress or the acceleration at at least one point on either an end of a side beam of the bogie frame or a center of a cross beam of the bogie frame.

3. The life state evaluation device according to claim 2, whereintheextraction unitcalculates the contributiondegrees of a plurality of the eigenmodes based on the stress or acceleration of the bogie frame acquired from an analysis of vehicle movement of the railway vehicle, and extracts the dominant eigenmode based on the contribution degrees.

4. The life state evaluation device according to claim 3, whereinthe extraction unit calculates the contribution degree of each of the plurality of eigenmodes based on a ratio of a product of an eigenvector and a modal coordinate for each eigenmode to a sum of the products of the eigenvectors and the modal coordinates for the eigenmodes, the eigenvector being related to stress or acceleration, the modal coordinate representing a weight of each eigenmode.

5. The life state evaluation device according to claim 1, whereinthe frame structure of the mobile unit is a bogie frame of a railway vehicle, the detection unit detects an acceleration of an axle box that is connected to the bogie frame via an axle spring device, andthe extraction unit acquires the stress from ananalysis of vehicle movement of the railway vehicle on thebasis of the acceleration of the axle box, and calculates the contribution degree based on the acquired stress.

6. The life state evaluation device according to any one of claims 2 to 5, whereinthe evaluation unit evaluates the life state by determining whether or not a cumulative damage degree of the bogie frame calculated based on the stress or the acceleration exceeds a predetermined threshold value, and outputs an alarm signal when the cumulative damage degree exceeds the threshold value.

7. A life state evaluation method comprising:detecting stress or acceleration at a measurement point in a frame structure of a mobile unit traveling on a track;calculating a degree of contribution of each eigenmode to vibration of the frame structure with respect to the detected stress or acceleration;extracting the eigenmode having a high degree of contribution as a dominant eigenmode;estimating the overall stress of the frame structure on the basis of the detected stress or acceleration and the dominant eigenmode; andevaluating an overall life state of the frame structure from the estimated overall stress of the frame

8. The life state evaluation method according to claim 7, whereinthe frame structure of the mobile unit is a bogie frame of a railway vehicle, andthe stress or the acceleration at at least one point on either an end of a side beam of the bogie frame or a center of a cross beam of the bogie frame is detected as the measurement point.

9. The life state evaluation method according to claim 7, whereinthe frame structure of the mobile unit is a bogie frame of a railway vehicle,an acceleration of an axle box connected to the bogie frame via an axle spring device is detected,the stress is acquired from an analysis of vehicle movement of the railway vehicle on the basis of the acceleration of the axle box, andthe contribution degree is calculated based on the acquired stress .

10. The life state evaluation method according to claim 8 or 9, further comprising:calculating a cumulative damage degree of the bogie frame based on the stress or the acceleration;evaluating the life state by determining whether or not the cumulative damage degree exceeds a predetermined threshold value; andoutputting an alarm signal when the cumulative damage degree exceeds the threshold value.

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