CN206037972U - Fracture width change monitoring device based on string frequency of shaking - Google Patents
Fracture width change monitoring device based on string frequency of shaking Download PDFInfo
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Abstract
The utility model discloses a fracture width change monitoring device based on string frequency of shaking mainly comprises base support, string wire, transmission spring and induction coil, and the induction coil test crack string wire's of state vibration frequency is successively adopted in the transmission spring of the certain rigidity of its adoption and the connection combination that string wire necessarily constructed, through mechanics and materialogy principle calculation fracture width's change value to realize the dynamic monitoring of fracture width change. In view of the above, the inventor has still establish corresponding monitoring method. Use this monitoring method and device, combine the rigidity based on the spring that the inventor derived through mechanics of materials and dynamics of structure method, string wire's vibration physical characteristic's high accuracy fracture width to change solution formula, can realize fracture width's change discernment and monitoring, reduce people's intensity of labour and mechanics of materials 0, receive mechanics of materials 1 little, can extensively be applicable to discernment and monitoring that fracture width such as dam, mechanics of materials 2, mechanics of materials 3 change.
Description
Technical field
This utility model belongs to fracture width change identification and monitoring technical field, more particularly to a kind of based on string vibration frequency
Fracture width change monitoring device.
Background technology
In current civil engineering industry, the xoncrete structure such as building construction, railway, bridge, dam due to material, apply
Work, temperature, external load are equal to reason, and during operating in work progress or after building up, crack often occurs in body structure surface Jing.Have
A little cracks do not affect structure safety, only long-term to structure durability to have certain adverse effect；Some cracks but directly affect
Structure safety, is one of whether safe important symbol of structure.For this reason, it may be necessary to carry out in time to body structure surface crack progressing situation
Identification, monitoring, if fracture length and width sustainable development, be necessary to take reinforcing or other measures, to reduce because of structure
Damage or collapse the property loss for causing and personal safety threat.The identification of fracture length change easily and simply, can be adopted
With labelling, sign or direct repeatedly measurement fracture length data, the length change situation in crack is accurately determined by comparing；
Though some fracture length changes are not substantially, the minimum change of fracture width is unsatisfactory for using predictive of structural-load-carrying capacity and wants
Ask or dangerous.
However, as structural cracks width is less, (the minimum recognizable width 0.04mm in general crack, maximum crack width can
Up to 60mm), its fracture width change is also less, and the change of general structure fracture width increases with load or time change is linear
Or during non-linear acceleration cracking, that is, think that works occur than more serious disease or defect, it is unsuitable for continuing to carry making a reservation for
Function, or need to promptly reinforce disposal.Existing fracture width change identification common method has image amplifying method, pastes fragile material
Method, stickup strain gauge method etc..Wherein, image amplifying method is to adopt magnifying video image, judges fracture width according to benchmark scale,
Repeatedly observation fracture width simultaneously asks which poor, determines fracture width variable quantity, but edge of crack is obscured after image amplifies, reading have compared with
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 larger.Fragile material, such as paraffin paper, thin glass etc. are pasted in fracture faces, fracture width change increases to certain
After degree, fragile material can be torn or come off, and represent that fracture width has certain change, but it cannot be realized quantitatively, also with regard to nothing
Method accurately judges fracture width variable quantity.It is, in vertically across crack stickup foil gauge, to test strain variation feelings to paste strain gauge method
Condition, when fracture width is unchanged, foil gauge is produced without strain, and foil gauge represents that fracture width is also changed when changing generation,
With paste fragile material method it is similar, the method can only identify whether fracture width changes, but cannot fracture change width enter
Row is quantitative.
Utility model content
It is accurate, with low cost based on string vibration frequency that the technical problems to be solved in the utility model is to provide a kind of measurement
Fracture width change monitoring device, with the change realized dynamic, recognize fracture width exactly, is widely portable to dam, room
The identification of the fracture widths such as room building, bridge structure change and monitoring.
To solve above-mentioned technical problem, this utility model is employed the following technical solutions：
Based on the fracture width change monitoring device of string vibration frequency, mainly by base support, string wire, transmission spring and sensing
Coil is constituted；The string wire and transmission spring being connected with each other is installed between 2 base supports, one end of string wire penetrates and is fixed on which
In a base support top screw rod perforate in, the other end of string wire be connected with transmission spring one end, the transmission spring other end
It is connected with the screw rod on another base support top；Induction coil is arranged on string wire nearby and is connected with cymometer.
It is 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 in more than 1400MPa；The rigidity of transmission spring is more than 2000N/mm.
The problems such as existing fracture width change test accuracy deficiency, inventor establishes a kind of based on string vibration frequency
Fracture width variation monitoring method, the method carries out the connection group of certain construction using the transmission spring and string wire of certain rigidity
Close, the frequency of vibration of the string wire of crack priority state is tested using induction coil, crack is calculated by mechanics and materialogy principle
The changing value of width, so as to realize the dynamic monitoring of fracture width change.Accordingly, inventor has also designed and produced corresponding monitoring dress
Put.Using the monitoring method and device, with reference to the inventor Jing mechanics of materials and structural mechanics method derive based on the firm of spring
The high accuracy fracture width change solution formula of degree, the vibration physical characteristics of string wire, it is possible to achieve the change of fracture width is known
Other and monitoring, reduces the labor intensity and testing cost of people, is widely portable to the cracks such as dam, building construction, bridge structure
The identification of change width and monitoring.Compared with prior art, outstanding advantage of the present utility model 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, recognizes that by the frequency of vibration of string wire the derivation of string wire internal force, the Jing mechanics of materials and Structural Dynamicses determines fracture width
Variable quantity, physical quantity transmission are simple, clear and definite；
(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 is up to 0.001mm；
(4) the method relatively adopts strain actinobolia, not temperature influence, and data drift is little.
Description of the drawings
Fig. 1 is use state figure and its monitoring of this utility model based on the fracture width variation monitoring method of string vibration frequency
The structural representation (perpendicular to string wire and transmission spring) of device.
Fig. 2 is that mechanics principle of this utility model based on the fracture width variation monitoring method and device of string vibration frequency is illustrated
Figure.
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.
Specific embodiment
Fracture width change dynamic monitoring method and the ultimate principle of device of this utility model based on strain sensing
1. operating procedure
As depicted in figs. 1 and 2, in the body structure surface 1 of crack both sides, steel planting or welding 2 are distinguished in vertical fracture direction
Individual material, equivalently-sized base support；One end of string wire is penetrated in the screw rod perforate on one of 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 near string wire side and is connected with cymometer, and induction coil is used for exciting, and (excitation string wire shakes
It is dynamic) and pick-up (pickup of the faint electromotive force in induction coil obtains the frequency and frequency quantity of electromotive force), exciting and pick-up point
Shi Jinhang, first exciting, rear pick-up.Tightened on base support top using nut, 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 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, fiFor the string wire frequency of vibration that i ＆ lt reads, Δ L is fracture width variable quantity.
2. the derivation of equation
As shown in Fig. 2 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.In the presence of fracture width becomes the axial force F for causing, string wire is changed into ε, and the Zhongchang amount of spring is Δ t, by
This can obtain formula (1)
Δ tk=F, se ε=F
It is
Δ lk=se ε formulas (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 be fiWhen, the width in crack can be obtained
Degree variation delta L, is shown in formula (6)
3. application example
Using preceding method and device, wherein, the length of string wire, area of section, elasticity modulus of materials, mass density difference
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, measure 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 changes (mm) | / | 0.028 | 0.064 | 0.085 | 0.098 | 0.119 | 0.148 | 0.165 |
Claims (3)
1. a kind of 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；The string wire and transmission spring being connected with each other is installed between 2 base supports, one end of string wire is worn
Enter 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, is passed
The screw rod that the spring other end is passed with another base support top is connected；Induction coil be arranged on string wire nearby and with cymometer phase
Even.
2. the fracture width change monitoring device based on string vibration frequency according to claim 1, it is characterised in that：Described 2
It is the material of individual base support, equivalently-sized.
3. the fracture width change monitoring device based on string vibration frequency according to claim 1, it is characterised in that：The steel
The diameter of string is not more than 0.3mm, and string wire length is not less than 40mm, and not less than 190MPa, tensile strength exists elasticity modulus of materials
More than 1400MPa；The rigidity of the transmission spring is more than 2000N/mm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621056261.6U CN206037972U (en) | 2016-09-14 | 2016-09-14 | Fracture width change monitoring device based on string frequency of shaking |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621056261.6U CN206037972U (en) | 2016-09-14 | 2016-09-14 | Fracture width change monitoring device based on string frequency of shaking |
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| CN206037972U true CN206037972U (en) | 2017-03-22 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106289122A (en) * | 2016-09-14 | 2017-01-04 | 广西交通科学研究院 | Fracture width change monitoring device based on string vibration frequency |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106289122A (en) * | 2016-09-14 | 2017-01-04 | 广西交通科学研究院 | Fracture width change monitoring device based on string vibration frequency |
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