CN106289122A - Fracture width change monitoring device based on string vibration frequency - Google Patents
Fracture width change monitoring device based on string vibration frequency Download PDFInfo
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- CN106289122A CN106289122A CN201610824037.5A CN201610824037A CN106289122A CN 106289122 A CN106289122 A CN 106289122A CN 201610824037 A CN201610824037 A CN 201610824037A CN 106289122 A CN106289122 A CN 106289122A
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- fracture width
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- string wire
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B17/00—Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
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- General Physics & Mathematics (AREA)
- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
Abstract
The invention discloses a kind of fracture width change monitoring device based on string vibration frequency, mainly it is made up of base support, string wire, transmission spring and induction coil, the connection combination that the transmission spring of its certain rigidity of employing and string wire necessarily construct, use the frequency of vibration of the induction coil test crack successively string wire of state, calculated the changing value of fracture width by mechanics and materialogy principle, thus realize the dynamic monitoring of fracture width change.Accordingly, inventor has also set up corresponding monitoring method.Use this monitoring method and device, rigidity based on spring, the high accuracy fracture width of the vibration physical characteristic of string wire derived through the mechanics of materials and Structural Dynamics method in conjunction with inventor change solution formula, change identification and the monitoring of fracture width can be realized, reduce labor intensity and the testing cost of people, temperature influence is little, is widely portable to identification and the monitoring of the fracture width changes such as dam, building construction, bridge structure.
Description
Technical field
The invention belongs to fracture width change identify and monitoring technical field, particularly relate to a kind of based on string vibration frequency split
Seam change width monitoring device.
Background technology
In current civil engineering industry, the xoncrete structure such as building construction, railway, bridge, dam due to material, execute
Work, temperature, external load are equal to reason, and in work progress or after building up during operation, crack often occurs in body structure surface.Have
A little cracks do not affect structural safety, only the durability that structure is long-term are had certain adverse effect；Some crack but directly affects
Structural safety, is one of structural safety whether important symbol.For this reason, it may be necessary to body structure surface crack progressing situation is carried out in time
Identification, monitoring, if fracture length and width sustainable development, then be necessary to take to reinforce or other measures, to reduce because of structure
Damage or collapse the property loss caused and personal safety threat.The identification of fracture length change easily and simply, can be adopted
By labelling, sign or direct repetitive measurement fracture length data, through comparing the length situation of change that can accurately determine crack；
Though the change of some fracture length is inconspicuous, but the minimum change of fracture width is unsatisfactory for using predictive of structural-load-carrying capacity and wants
Ask or dangerous.
But, owing to structural cracks width is less, (general crack minimum can recognize that width 0.04mm, and maximum crack width can
Reach 60mm), the change of its fracture width is the least, and the change of general structure fracture width increases with load or the time changes linearly
Or during non-linear acceleration cracking, i.e. think that ratio more serious disease or defect occurs in works, it is unsuitable for continuing carrying and makes a reservation for
Function, or need to promptly reinforce disposal.The change of existing fracture width identifies that common method has image amplifying method, pastes fragile material
Method, stickup strain gauge method etc..Wherein, image amplifying method is to use magnifying video image, judges fracture width according to benchmark scale,
Repeatedly observing fracture width and ask it poor, determining fracture width variable quantity, but after image amplifies, edge of crack obscures, reading has relatively
Big error, and repeatedly observation is difficult to ensure that the same position that can be directed at crack, the crack width tried to achieve after causing repeatedly observation
Degree variation error is bigger.Pasting fragile material in fracture faces, such as paraffin paper, thin glass etc., fracture width change increases to certain
After degree, fragile material can be torn or come off, and represents that fracture width has certain change, but it cannot realize quantitatively, also with regard to nothing
Method accurately judges fracture width variable quantity.Pasting strain gauge method is vertically to paste foil gauge across crack, testing strain variation feelings
Condition, when fracture width is unchanged, foil gauge produces without strain, and foil gauge changes and represents that fracture width also changes when producing,
Similar with pasting fragile material method, this method can only identify whether fracture width changes, but cannot fracture change width enter
Row is quantitatively.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of measures crack based on string vibration frequency accurate, with low cost
Change width monitoring device, to realize identifying dynamically, exactly the change of fracture width, is widely portable to dam, house is built
Build, the identification of the fracture width such as bridge structure change and monitoring.
For solve above-mentioned technical problem, the present invention by the following technical solutions:
Fracture width change monitoring device based on string vibration frequency, mainly by base support, string wire, transmission spring and sensing
Coil forms；Installing interconnective string wire and transmission spring between 2 base supports, one end of string wire penetrates and is fixed on it
In a base support top screw rod perforate in, the other end of string wire with transmission spring one end is connected, transmission the spring other end
It is connected with the screw rod on another base support top；Induction coil is arranged near string wire and is connected with cymometer.
The material of 2 base supports, equivalently-sized.
The diameter of string wire is not more than 0.3mm, and string wire length is not less than 40mm, elasticity modulus of materials not less than 190MPa,
Tensile strength is at more than 1400MPa；The rigidity of transmission spring is more than 2000N/mm.
For problems such as existing fracture width change test accuracy are not enough, inventor establishes a kind of based on string vibration frequency
Fracture width variation monitoring method, this method uses transmission spring and the connection group that necessarily constructs of string wire of certain rigidity
Close, use the frequency of vibration of the induction coil test crack successively string wire of state, calculate crack by mechanics and materialogy principle
The changing value of width, thus realize the dynamic monitoring of fracture width change.Accordingly, inventor has also designed and produced corresponding monitoring dress
Put.Use this monitoring method and device, in conjunction with inventor through the mechanics of materials and structural mechanics method derive based on spring firm
Degree, string wire vibration physical characteristic high accuracy fracture width change solution formula, it is possible to achieve fracture width change knowledge
And monitoring, do not reduce labor intensity and the testing cost of people, be widely portable to the cracks such as dam, building construction, bridge structure
The identification of change width and monitoring.Compared with prior art, the outstanding advantage of the present invention is:
(1) know-why is different from additive method, is converted into spring internal force by the change of fracture width, is transferred to steel
String, by the frequency of vibration identification string wire internal force of string wire, determines fracture width through the derivation of the mechanics of materials and Structural Dynamics
Variable quantity, physical quantity transmission is simple, clearly；
(2) test device instrument is simple, with low cost, it is easy to repair and replacement；
(3) fracture width change accuracy of identification is high, for the change accuracy of identification of fracture width up to 0.001mm；
(4) the method relatively uses strain actinobolia, not temperature influence, and data drift is little.
Accompanying drawing explanation
Fig. 1 is use state diagram and the monitoring device thereof of present invention fracture width based on string vibration frequency variation monitoring method
Structural representation (be perpendicular to string wire and transmission spring).
Fig. 2 is the mechanics principle schematic diagram of present invention fracture width based on string vibration frequency variation monitoring method and device.
In figure: 1 body structure surface, 2 cracks, 3 base supports, 4 string wires, 5 induction coils, 6 transmission springs, 7 nuts and screw rod.
Detailed description of the invention
Present invention fracture width based on strain sensing change dynamic monitoring method and the ultimate principle of device
1. operating procedure
As depicted in figs. 1 and 2, at the body structure surface 1 of both sides, crack, vertical fracture direction steel planting respectively or welding 2
Individual material, equivalently-sized base support；One end of string wire is penetrated in the screw rod perforate on one of them base support top, steel
The other end of string is connected with transmission spring one end, and the transmission spring other end is connected with the screw rod on another base support top；?
Works surface is installed induction coil and is connected with cymometer near string wire side, and for exciting, (excitation string wire shakes induction coil
Dynamic) and pick-up (pickup of the faint electromotive force in induction coil obtains frequency and the frequency quantity of electromotive force), exciting and pick-up divide
Shi Jinhang, first exciting, rear pick-up.Use nut to tighten on base support top, make transmission spring, string wire and base support abundant
Stress；The practical frequency f of string wire is read in variable interval or timingi；By formulaCalculating acquisition is split
The changing value of seam width；Wherein, string wire length, area of section, elastic modelling quantity and mass density be respectively l, s, e,Transmission bullet
The rigidity of spring is k, f0String wire vibration after representing transmission spring, string wire and the abundant stress of base support, before fracture width change
Original frequency reading, fiThe string wire frequency of vibration read for i & lt, Δ L is fracture width variable quantity.
2. the derivation of equation
As in figure 2 it is shown, the length of string wire, area of section, elastic modelling quantity and mass density be respectively l, s, e,Transmission bullet
The rigidity of spring is k.Under fracture width becomes the effect of the axial force F caused, string wire becomes ε, and the Zhongchang amount of spring is Δ t, by
This can obtain formula (1)
Δ tk=F, se ε=F
It is i.e.
Δ lk=se ε formula (1)
Fracture width total variation is L, L=l ε+Δ t, and under axial force F effect, total Zhongchang amount L is formula (2)
Again because string wire is flexible cable, then there is formula (3)
F=4ml2f2Formula (3)
Then there is formula (4)
After formula (4) brings formula (2) into, abbreviation obtains formula (5)
When string wire original frequency is f0, fracture width change after i & lt read string wire frequency is fiTime, the width in crack can be obtained
Degree variable quantity △ L, is shown in formula (6)
3. application example
Application preceding method and device, wherein, the length of string wire, area of section, elasticity modulus of materials, mass density are respectively
For l=60mm, s=1.131mm, e=210GPa,The tensile strength of string wire is 3000MPa, transmits spring
Rigidity be k=20N/mm.For the indoor static test of certain beam, record the change of span centre beam bottom horizontal fracture width and be shown in Table 1.
Table 1 surveys string vibration frequency and fracture width result of variations
| Class of loading | Original frequency | 1st grade | 2nd grade | 3rd level | 4th grade | 5th grade | 6th grade | 7th grade |
| String wire frequency (Hz) | 1000 | 1003.1 | 1007.2 | 1009.5 | 1011 | 1013.3 | 1016.6 | 1018.5 |
| Fracture width change (mm) | / | 0.028 | 0.064 | 0.085 | 0.098 | 0.119 | 0.148 | 0.165 |
Claims (3)
1. a fracture width change monitoring device based on string vibration frequency, it is characterised in that main by base support, string wire, biography
Pass spring and induction coil composition；Installing interconnective string wire and transmission spring between 2 base supports, one end of string wire is worn
Entering and be fixed therein in the screw rod perforate on a base support top, the other end of string wire is connected with transmission spring one end, biography
Pass the spring other end to be connected with the screw rod on another base support top；Induction coil be arranged near string wire and with cymometer phase
Even.
Fracture width change monitoring device based on string vibration frequency the most according to claim 1, it is characterised in that: described 2
The material of individual base support, equivalently-sized.
Fracture width change monitoring device based on string vibration frequency the most according to claim 1, it is characterised in that: described steel
The diameter of string is not more than 0.3mm, and string wire length is not less than 40mm, and elasticity modulus of materials is not less than 190MPa, and tensile strength exists
More than 1400MPa；The rigidity of described transmission spring is more than 2000N/mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610824037.5A CN106289122A (en) | 2016-09-14 | 2016-09-14 | Fracture width change monitoring device based on string vibration frequency |
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| CN201610824037.5A CN106289122A (en) | 2016-09-14 | 2016-09-14 | Fracture width change monitoring device based on string vibration frequency |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2510852Y (en) * | 2001-11-16 | 2002-09-11 | 长沙金码高科技实业有限公司 | Surface-sticked intelligent digital vibration wire strain gauge |
| CN2751282Y (en) * | 2004-12-01 | 2006-01-11 | 周国玉 | Steel plate strain meter |
| CN101776431A (en) * | 2010-03-24 | 2010-07-14 | 北京科技大学 | Surface pasting type vibration wire type reinforcing steel strain gauge |
| CN202709986U (en) * | 2012-04-18 | 2013-01-30 | 苏州筑邦测控科技有限公司 | Restorable vibrating wire type surface strainmeter |
| CN203629533U (en) * | 2013-11-15 | 2014-06-04 | 哈尔滨工业大学深圳研究生院 | Device for adjusting initial installation value of vibratory string type strain gauge |
| CN206037972U (en) * | 2016-09-14 | 2017-03-22 | 广西交通科学研究院 | Fracture width change monitoring device based on string frequency of shaking |
-
2016
- 2016-09-14 CN CN201610824037.5A patent/CN106289122A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2510852Y (en) * | 2001-11-16 | 2002-09-11 | 长沙金码高科技实业有限公司 | Surface-sticked intelligent digital vibration wire strain gauge |
| CN2751282Y (en) * | 2004-12-01 | 2006-01-11 | 周国玉 | Steel plate strain meter |
| CN101776431A (en) * | 2010-03-24 | 2010-07-14 | 北京科技大学 | Surface pasting type vibration wire type reinforcing steel strain gauge |
| CN202709986U (en) * | 2012-04-18 | 2013-01-30 | 苏州筑邦测控科技有限公司 | Restorable vibrating wire type surface strainmeter |
| CN203629533U (en) * | 2013-11-15 | 2014-06-04 | 哈尔滨工业大学深圳研究生院 | Device for adjusting initial installation value of vibratory string type strain gauge |
| CN206037972U (en) * | 2016-09-14 | 2017-03-22 | 广西交通科学研究院 | Fracture width change monitoring device based on string frequency of shaking |
Non-Patent Citations (3)
| Title |
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| 刘文峰: "《检测技术及仪器在桥梁健康监测系统中的应用》", 31 July 2013, 天津大学出版社 * |
| 孙汝建，关秉洪，何宁: "《国外岩土工程监测仪器》", 31 December 2006 * |
| 彭春雷，杨晓东，马栋: "《锚固与注浆设备手册》", 31 October 2013, 中国电力出版社 * |
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Application publication date: 20170104 |