CN-122003586-A - Optical fiber measuring device for monitoring bolt axial force and optical fiber measuring system for monitoring bolt axial force

CN122003586ACN 122003586 ACN122003586 ACN 122003586ACN-122003586-A

Abstract

The optical fiber measuring device (100) for monitoring bolt axial force comprises an optical fiber (23) for measuring strain of a measured object, an optical fiber mounting fixture (25) having an optical fiber mounting nut (21S) on which the optical fiber (23) is mounted by changing the shape of the outer peripheral portion of the nut (21) related to at least one of a plurality of sets of bolts (20) and nuts (21), and an optical fiber strain distribution measuring unit (24) for measuring the circumferential strain distribution of the optical fiber mounting nut (21S) caused by the bolt axial force along the optical fiber (23) mounted on the outer peripheral surface of the optical fiber mounting nut (21S), wherein the circumferential strain and the circumferential strain distribution of the optical fiber mounting nut (21S) are measured in advance by the optical fiber strain distribution measuring unit (24), and the optical fiber (23) is mounted at a predetermined axial position corresponding to the previously measured circumferential strain value or circumferential strain distribution, and the bolt axial force is monitored.

Inventors

KISHITA KINZO
YAMAUCHI YOSHIAKI
Ma Ningxu

Assignees

光纳株式会社

Dates

Publication Date: 20260508
Application Date: 20231013

Claims (7)

1. An optical fiber measuring device for monitoring bolt axial force, which is characterized in that a fixed body is fixed by a fixed body composed of a plurality of groups of bolts and nuts, and the bolt axial force generated in the bolts is monitored by using optical fibers, The optical fiber measuring device for monitoring the axial force of the bolt comprises: An optical fiber for measuring strain of a measurement object; a fiber mounting fixture that changes a shape of a nut involved in at least one of the plurality of sets of bolts and nuts so that the optical fiber is mounted at an outer peripheral portion of the nut to have a fiber mounting nut to which the optical fiber is mounted, and An optical fiber strain distribution measuring section that measures a circumferential strain distribution of the optical fiber mounting nut caused by an axial force of the bolt along the optical fiber mounted on an outer peripheral surface of the optical fiber mounting nut, The circumferential strain and the circumferential strain distribution of the optical fiber mounting nut are measured in advance by the optical fiber strain distribution measuring unit, and the optical fiber is mounted at a predetermined axial position of the optical fiber mounting nut according to the value of the circumferential strain or the circumferential strain distribution measured in advance, so that the bolt axial force is monitored.
2. The optical fiber measuring device for monitoring bolt shaft force according to claim 1, wherein, And installing the optical fiber at a specified axial position of the optical fiber installation nut according to the circumferential strain distribution which is measured in advance, measuring the circumferential strain distribution by the optical fiber strain distribution measuring part, obtaining a position of positive and negative intersection of strain values of the circumferential strain distribution, and monitoring the bolt axial force based on the variation of the position of positive and negative intersection of the strain values.
3. The optical fiber measuring device for monitoring bolt shaft force according to claim 1 or 2, wherein, The optical fiber mounting nut has a cylindrical shape, and an axial predetermined position in which the optical fiber is mounted in the optical fiber mounting nut is set on a surface side of the optical fiber mounting nut where the object to be fixed is fixed in an axial upper and lower surface thereof.
4. The optical fiber measuring device for monitoring bolt shaft force according to claim 1 to 3, The optical fiber is disposed and attached to the fixing body so as to measure a bolt axial force generated in the bolts of the fixing body fixed by the plurality of sets of bolts and the optical fiber attachment nut at a time.
5. An optical fiber measuring system for monitoring bolt shaft force, which is characterized in that a fixed body is fixed by a fixed body composed of a plurality of groups of bolts and nuts, and the bolt shaft force generated in the bolts is monitored by using optical fibers, The optical fiber measuring system for monitoring the axial force of the bolt comprises: An optical fiber for measuring strain of a measurement object; a fiber mounting fixture that changes a shape of a nut involved in at least one of the plurality of sets of bolts and nuts so that the optical fiber is mounted at an outer peripheral portion of the nut, thereby having a fiber mounting nut to which the optical fiber is mounted; An optical fiber strain distribution measuring unit that measures an axial circumferential strain distribution of the optical fiber mounting nut due to an axial force of the bolt along the optical fiber mounted on an outer peripheral surface of the optical fiber mounting nut; An optical fiber bus arranged at an outer peripheral surface portion inside a cable for transmitting electric power, having two or more of the optical fibers inside, and A dual port module capable of being identified by an ID and storing physical quantities measured by a Rayleigh method and a Brillouin method using optical fibers provided in the optical fiber bus, The optical fibers of the optical fiber bus are led out to the outside and connected to two different parts of the dual-port module, the circumferential strain and the circumferential strain distribution of the optical fiber mounting nut are measured in advance by the optical fiber strain distribution measuring part, the measured data are stored in the dual-port module, And installing the optical fiber at a specified axial position of the optical fiber installation nut according to the value of the circumferential strain or the circumferential strain distribution stored in the dual-port module, so as to monitor the bolt shaft force.
6. The optical fiber measuring system for monitoring bolt shaft force according to claim 5, comprising: A bolt axial force monitoring structure module for fastening the fixed body by applying a bolt axial force by combining the optical fiber mounting nuts with all the bolts of the fixed body composed of a plurality of sets of bolts and nuts, respectively; A computer having a processor and a memory, for performing arithmetic processing on input data and outputting the processed data; A first database including a bolt tensioner capable of setting a bolt shaft force of the bolt shaft force monitoring structure module to a predetermined value when the initial setting of the fixed object is fixed, measuring, by the optical fiber strain distribution measuring unit, a circumferential strain at each position in an axial direction of each optical fiber mounting nut generated with respect to the bolt shaft force when the bolt shaft force is changed within a predetermined range by taking the bolt shaft force as a parameter, and storing the measured data as initial data, and A second database for measuring, for a plurality of fixed periods, circumferential strain values of the optical fiber mounting nut at each axial position after a fixed period has elapsed from an initial setting, the fixed period being a period set based on an existing maintenance standard and shorter than a period of periodic spot inspection specified by the maintenance standard, The optical fiber strain distribution measuring unit measures the circumferential strain generated in the nut at predetermined elapsed time intervals, stores the measured data in the optical fiber strain distribution measuring unit and the computer as measured data associated with the elapsed time, and compares the maximum axial force of each of the optical fiber attachment nuts obtained from the measured data stored in the computer with the maximum axial force of each of the optical fiber attachment nuts corresponding to the initial data stored in the first database or the maximum axial force of each of the optical fiber attachment nuts obtained from the maintenance data stored in the second database after the lapse of a fixed period, thereby monitoring the fixed body.
7. The optical fiber measuring system for monitoring bolt shaft force according to claim 5 or 6, wherein, The object to be fixed is a constituent member of a floating body type offshore wind farm installed at sea, and the optical fiber strain distribution measuring unit is installed at a remote location about 10km or more from the floating body type offshore wind farm.

Description

Optical fiber measuring device for monitoring bolt axial force and optical fiber measuring system for monitoring bolt axial force Technical Field The present disclosure relates to an optical fiber measuring device for monitoring bolt axial force and an optical fiber measuring system for monitoring bolt axial force. Background With the continuous accumulation of usage records of windmills used in wind power generation, problems occurring in long-term use are gradually combed. For example, during the operation of a windmill facility, the entire blade (wing) of the windmill may fall, break, etc., and 20% -30% of the blades may be damaged during 10 years. After analyzing the cause of the damage, it was found that bolts used for fixing the constituent elements of the wind turbine to each other, such as the joint between the blade and the nacelle (the attachment body for the blade) and the joint between the nacelle and the tower (the support body for the nacelle), are considerably loosened. In addition, in analyzing the cause of damage, attention has been paid particularly to the reduction of the axial force received by the bolt due to loosening of the bolt (for example, refer to non-patent documents 1 and 2). Therefore, it is necessary to measure the bolt shaft force or the like by spot inspection or inspection, confirm the installation state of the bolt at the joint portion, prevent such bolt loosening (shaft force decrease), breakage or the like from occurring, and enable early detection at the time of occurrence. In order to improve the occurrence of the loosening of the bolts, periodic spot inspection is required in addition to the initial spot inspection of the wind power plant. In view of this, in recent years, a regular inspection guide has been developed for a method of inspecting a wind power plant (see non-patent document 3). On the other hand, checking and confirming the presence or absence of loosening and breakage of such bolts requires a great deal of expense, which is a significant problem affecting the efficiency of wind power generation. The total number of bolts used in the joint portions of the windmill may be 50 or more per joint portion. Therefore, at the time of regular inspection, it is currently difficult to perform all-round inspection of the bolt mounting state of the joint portion such as the bolt shaft force. In particular, in offshore facilities, how to enter wind power generation facilities has become an urgent problem from the viewpoints of safety and economy. As a conventional bolt axial force measurement technique, there is a wireless method (for example, refer to non-patent document 4), but it is not applicable to a common nut, in which a nut having a special mechanism and a dynamically deformable shape is used. In addition, there is no method that can be applied to the entire wind turbine as a conventional method for managing the axial force torque of a bolt used in the wind turbine, and only a method that can be applied to individual inspection is known (see non-patent document 5). Prior art literature Non-patent literature Non-patent document 1, screw bolt damage investigation report of machine 1 and machine 3 of the kyoto tai drum wind power plant, 2014, 5 and 29 days. [ online ], [ order and 5-9-month 25-day check out ], internet ＜URL:https://www.meti.go.jp/shingikai/sankoshin/hoan_shohi/denryoku_anzen/newenergy_hatsuden_wg/pdf/003_01_01.pdf＞. Non-patent document 2, middle electric corporation, before wasaki wind power plant No. 3 blade mounting bolt break (final report), 2015, 7 months, 30 days. [ online ], [ order and 5-9-month 25-day check out ], internet ＜URL:https://www.meti.go.jp/shingikai/sankoshin/hoan_shohi/denryoku_anzen/newenergy_hatsuden_wg/pdf/007_04_00.pdf＞. Non-patent document 3 general society, the institute of electrical and electronics of japan, the institute of electrical and electronics of general society, code, manual for periodic point inspection of wind power generation equipment, JEAG5005-2017, pages 11, 15, 16, 20, 22, 24, 27, 31, 29 years, 4 months and 1 day (the first edition) Non-patent document 4 NRJ _lst product catalog, [ online ], [ order and 5, 9, 25 days check out ], internet ＜URL:https://www.nord-lock.com/globalassets/mediavalet/web-assets/downloads/brochure/00297_sb_lst_4-pager-jp-web.pdf＞. Non-patent document 5 catalog NejiLaw, online, order and 9 months 25 days check, internet < URL: https:// www.nejilaw.com/special_smart neji html >. Non-patent document 6 reports the Definition of IEA Wind 15 megawatt offshore reference windmill (Definition of THE IEA WIND-Megawatt Offshore REFERENCE WIND Turbine), IEA WIND TCP TASK, pages 25-28, month 3 of 2020. Patent literature Patent document 1 Japanese patent laid-open publication No. 2010-216877 Disclosure of Invention Technical problem to be solved by the invention As described above, conventionally, in wind power generation facilities, the number of bolts used per blade is 80 to 300, and theref