CN100578172C - Construction film structure pre-tension measurement method and apparatus thereof - Google Patents

Abstract

The invention provides a building membrane structure pretension force measuring method and a measuring device thereof. The method comprises the steps of launching a particle bead to a tensioned membrane with a fixed boundary to vibrate the membrane which rebounds the bead; measuring the incident speed v0, the return speed vt, the membrane middle point maximum displacement (amplitude) Tmax and the bead mass m0 of the bead in the tensioned membrane with the same fixed boundary; changing the latitude and longitudinal directions, measuring Tmax, v0 and vt; according to the formula: pi<2>habTmax<2>[((sigma0x/a<2>)+(sigma0y/b<2>))+(pi<2>/32)((Ex/a<4>)+(Ey/b4))Tmax<2>]=4m0(v0<2>-vt<2>), measuring two groups of Tmax, v0 and vt, to calculate the membrane tension force sigma0x and sigmax0y. The method is based on the membrane large deflection theory, to approach actuality theoretically and obtain high theory accuracy, having wide application for different membranes. The method can measure two orthogonal pretension forces of membranes and the tension force of a membrane under different loads. The invention can be quickly applied in actual projects. The measuring device has simple structure, low cost and simple application.

Description

Construction film structure pre-tension measurement method and device thereof

Technical field

The invention belongs to engineering survey and monitoring technical field, be specifically related to a kind of construction film structure pre-tension measurement method, and the measurement mechanism of realizing the method.

Background technology

The rigidity of building membrane structure realizes by applying pretension for the film material.The pretension of film material is big more, and the rigidity of membrane structure is just big more, and its ability of bearing external load is just corresponding strong more.Yet the pretension of film material is big more, and just high more to the requirement of the anchoring condition of construction tension device and boundary member, its margin of safety is also just low more.But the pretension of film material is too small, and rigidity is just too small outside its plane, descends in plane external load effects such as wind, rain and snow, and distortion can be very big, also may make roof ponding, accumulated snow when influencing appearance and modeling and influences the safety of structure, causes engineering accident.Therefore, the measurement of film material pretension becomes a key factor that influences membrane structure design, construction and the completion back acceptance of work in the membrane structure, also is the characteristics that membrane structure is different from the other types structure.

Hence one can see that, and the tension force of research membrane structure has practical significance: 1. measure the pretension of film, controlling diaphragm tension force is consistent with design load, guarantees construction quality; 2. by measuring the tension value of film under different load actions effectively, take effective measures controlling diaphragm tension force, can prevent that the film fold is lax or be torn, prevent or reduce engineering accident.

Measure at present both at home and abroad the method for building membrane structure film material tension force, mainly contain: Strain Method, frequency method, displacement method and " intending the rope method " etc. are several.Below the principle of main several method is wherein briefly introduced:

(1) laser spectrum method of testing (Strain Method)

The film material is the glass fibre of two-way braiding or the polymer matrix composites that dacron strengthens, be the orthotropic material, the material principal direction of stress is the direction of fiber, the tensile property of film material on machine direction depends mainly on the performance of fiber, and depends mainly on base material in the tensile property perpendicular to the direction of fiber.Because film material main performance is embodied in tensile property, ratio is very big mutually and the tensile property of base material is with fiber, and the film material is two-way simultaneously all fiber, so the mechanical property of two principal directions of stress all depends mainly on the performance of fiber.

Laser Raman spectroscopy was mainly used in the unrelieved stress of measuring compound substance and substrate interface originally, and from above analysis, this method is the test that can be used for film material pretension.After the film material was subjected to pulling force, any two atoms left the equilibrium position and in new position balance take place in the contact bed, and interatomic acting force changes thereupon.Interatomic acting force is determining the spacing of atom, and interatomic spacing is relevant with the atomic vibration frequency.Along with the increase that adds tension, atomic distance increases, and the atomic vibration frequency descends; Otherwise under compressive stress, atomic distance reduces, and the atomic vibration frequency increases.This vibration frequency change can be measured out with laser Raman spectroscopy, just can measure interatomic distortion come accordingly.

This method of testing is exactly to utilize the laser Raman spectroscopy technical calibration to go out relation between suffered strain of fiber and the Raman spectrum frequency shifting, measure the Raman spectrum frequency shifting of film material interlayer adjacent fiber then with laser Raman spectrometer, thereby converse the strain of fiber, according to the elastic modulus of fiber, obtain the stress of film material fiber.

For this reason, this method will be measured the raman frequency displacement diagram of fiber when not being subjected to load that stretches earlier, then fiber is added a series of loads, all answers corresponding certain strain value under each load.Simultaneously, measure its raman frequency displacement diagram along fibre length.According to external result of study, fiber is under different strain regimes, raman frequency spectrum peak and the strained linear dependence (as shown in Figure 1) that is are composed in the laser raman under differently strained so calibration experiment will be measured fiber, provide the straight line that concerns of raman frequency peak and strain at last.

The main starting point of the method is in the pars fibrosa of film material, and that building film material is actually fiber basic unit and coating is synthetic, coating is very big to the material character of film material and the influence of mechanical characteristic, this method has been ignored the influence of coating, obviously degree of accuracy is discounted, and the used instrument of the method is relatively more expensive, and it also be very difficult promoting on a large scale in actual engineering.

(2) frequency test method

When the vibration problem of research film material, get film material surface lateral load q=0, x, y when being elasticity principal direction, desirable N _Xy=0, have pretension N _x, N _yNon-vanishing.Then the differential equation of curved surface of film material is:

${\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="C2008102329520014H1.png"\; state="\{\{state\}\}">D</figure-callout>}}_1\frac{{\&PartialD;}^{4}W}{{\&PartialD;}_{x^4}}+{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="C2008102329520014H1.png"\; state="\{\{state\}\}">D</figure-callout>}}_2\frac{{\&PartialD;}^{4}W}{{\&PartialD;}_{{\mathrm{<figure-callout\; id="4"\; label="y"\; filenames="C2008102329520014H1.png,C2008102329520014H2.png"\; state="\{\{state\}\}">y</figure-callout>}}^4}}+{2D}_3\frac{{\&PartialD;}^{4}W}{{\&PartialD;}_{x^2}{\&PartialD;}_{y^2}}-{\mathrm{\&rho;h\&omega;}}^{2}W=N_x\frac{{\&PartialD;}^{2}W}{{\&PartialD;}_{x^2}}+N_y\frac{{\&PartialD;}^{2}W}{{\&PartialD;}_{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C2008102329520014H1.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}}$

ω is a circular frequency in the formula, D ₁, D ₂, D ₃Be the stiffness coefficient of film material, W is the amount of deflection of film, and ρ is the density of film, and h is the thickness of film.

As shown in Figure 2, length and width are respectively the rectangular membrane material of a, b simply supported on four sides, also are the parts of integral membrane structure.The trigonometric series if vibration shape W attaches most importance to; $W=\underset{m=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{A}_{\mathrm{mn}}\sin \frac{\mathrm{m\&pi;x}}{a}\sin \frac{\mathrm{n\&pi;x}}{b},$ Bring differential equation of curved surface into.Because each point all satisfies equation on the face, and A _Mn≠ 0, can get separating of natural frequency ω.When the film material does not have pretension, i.e. N _x=N _y=0 o'clock, natural frequency separate for:

${\mathrm{\&omega;}}_{\mathrm{mn}}=\frac{\mathrm{\&pi;}}{{\mathrm{<figure-callout\; id="2"\; label="a"\; filenames="C2008102329520014H1.png"\; state="\{\{state\}\}">a</figure-callout>}}^2\sqrt{\mathrm{\&rho;h}}}\sqrt{D_1{\mathrm{<figure-callout\; id="4"\; label="m"\; filenames="C2008102329520014H1.png,C2008102329520014H2.png"\; state="\{\{state\}\}">m</figure-callout>}}^4+{2D}_3{m}^2{n}^2{\left(\frac{a}{b}\right)}^2+D_2{n}^4{\left(\frac{a}{b}\right)}^4}.$

If there is pretension in the film material, the natural frequency of film material is also relevant with the value of pretension.The film material is the orthotropic material, and its derivation complexity is not derived here.Suppose it is isotropic material, then the formula for natural frequency of film material under no pretension state.

Under the tension-free state:

${\mathrm{\&omega;}}_{\mathrm{mn}}={\mathrm{\&pi;}}^2(\frac{m^2}{a^2}+\frac{n^2}{b^2})\sqrt{\frac{D}{\mathrm{\&rho;h}}},$

When there being pretension N _x, N _yThe time: ω ' _Mn=k ω _Mn, k is a correction factor

$k={[1+\frac{1}{{\mathrm{\&pi;}}^{2}D}\frac{N_x{\left(\frac{m}{a}\right)}^2+N_y{\left(\frac{n}{b}\right)}^2}{{[{\left(\frac{m}{a}\right)}^2+{\left(\frac{n}{b}\right)}^2]}^2}]}^{\frac{1}{2}}$

As seen frequency and N _x, N _ySubstantial connection is arranged.

The N of certain point on the actual measurement membrane structure _x, N _yThe time, can adopt purpose-made device, isolate the rectangular area that x, y are respectively a, b in film material part, make regional boundary condition aid the border areas between being, measure the frequencies omega of the local rectangular membrane material in this zone ₁, reverses its direction makes y, x be respectively a, b then, measuring frequency again is ω ₂ω ₁, ω ₂All with this local N _x, N _yRelation is arranged, can set up two equations, the N that solves _x, N _yIt promptly is pretension in the part.

The bendind rigidity item that contains film in the formula of the used fundamental frequency of this method is actually according to the theory of plate and is calculating film, but film is a flexible structure, does not consider its bendind rigidity, so there is defective in theory in this method.If revised in theory, as long as can test out the fundamental frequency of more accurate film material by better method, this method should be feasible.

(3) displacement method

Membrane structure is wider in the application of Japan, aspect the research of film tonometry some achievements is being arranged also.The film tension measuring device of Kajima Corporation's exploitation is made up of an acrylic acid container, a vacuum pump and the measuring box with the digital Presentation Function of calculating.A non-contact displacement transducer and a barometer are installed in the container.Container is the box of bottom surface opening, and flat shape is the Long Circle of 200mm * 500mm, and two ends are that diameter is the semi arch of 200mm.When measuring: at first, container bottoms is adjacent on film material surface, form the space of a sealing, the gas of container be reduced to a specific level by the vacuum pump that is connected with it, the face that this moment, container bottoms enclosed under even suction function to the container sunken inside.And then, measure the maximum depression displacement of film material with non-contact displacement transducer.At last, the film tension force and depression displacement calculus of relation membrane tension force by demarcating in advance.Therefore, this is a kind of device that displacement method is measured film tension force of using under constant load action.Container is the Long Circle of band fillet, so just can measure the film tension force of film material in warp-wise and broadwise respectively.Container length to film tension force more much smaller to the influence of displacement than short, can ignore approx.So the film tension force of container short can be obtained according to displacement.The material of film material, coating, thickness, all influential to the displacement of film material through tieing up between parameters such as two-way Young modulus and film material surface and container bottoms friction factor.For different film materials, these factors are different.Therefore, must carry out rating test respectively to different film materials.

Obtain the film tension force of various film materials and the correlation formula between the depression displacement by rating test, just can use this device in the actual membrane structure, to measure the film tension force of corresponding membrane material.

This method is exactly the restriction of the applicable scope film assortment class that is subjected to having demarcated.Use this method, also all must demarcate displacement and stress relation curve earlier to the warp-wise and the broadwise of variety classes, different-thickness and same kind film material, workload is huge.Therefore, the precision of this method is also very limited.

(4) intend the rope method

Domestic at present also seldom to the research of membrane structure tonometry aspect, Deng Changgen, Zhang Qilin, Sun Zhanjin are doing some research work aspect the film material tonometry, and are obtaining some achievements.

In " theory and the experimental study of the test of building film material pretension value " literary composition that Sun Zhanjin writes film material tonometric " intending the rope method " has been proposed.Its basic ideas are: for the regional area of a membrane structure, as the length ratio b/a of the length on the long limit of this rectangular area size and minor face enough greatly the time, can think that this zone stress performance and one-way slabs under the evenly load q effect outside the plane is similar.Like this, outside the plane under the evenly load effect, the plane outer displacement of one-way slabs central point and the stress of short depend mainly on the character of plate short and span and with long to parameters relationship less, find as calculated when b/a 〉=5, do not consider to grow to the error that influence caused can be enough little.Such conclusion has been arranged, research to one-way slabs size film piece just can be converted into the research of module length to the film bar of center unit width so, and the film bar mechanical property of this unit width and having and the same area of film bar, the mechanical property unanimity of the rope that elastic modulus is the same with film material short elastic modulus again, like this, solving film material pretension measurement problem also just can discuss by theory revised of relevant single rope.By a series of theoretical derivation, drawn about intending the rope method and measured the theoretical formula of film material tension force:

$\frac{H-H_0}{E^{\&prime;}}=\frac{{8\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="C2008102329520014H1.png"\; state="\{\{state\}\}">f</figure-callout>}}^2}{{3l}^2}-\frac{{32\mathrm{<figure-callout\; id="4"\; label="f"\; filenames="C2008102329520014H1.png,C2008102329520014H2.png"\; state="\{\{state\}\}">f</figure-callout>}}^4}{{5\mathrm{<figure-callout\; id="4"\; label="l"\; filenames="C2008102329520014H1.png,C2008102329520014H2.png"\; state="\{\{state\}\}">l</figure-callout>}}^4},$ Wherein $H=\frac{{\mathrm{<figure-callout\; id="2"\; label="ql"\; filenames="C2008102329520014H1.png"\; state="\{\{state\}\}">ql</figure-callout>}}^2}{8f}$

In the formula: H---the tension force of film unit length; H ₀---the pretension of film unit length; E '---be equivalent elastic modulus; F---be the displacement of diaphragm area central point; L---the span of diaphragm area minor face

In the actual measurement process, as long as under same condition, apply more approaching two-stage load q at the measuring point place ₁, q ₂, survey the central point displacement f under the load ₁, f ₂, calculate corresponding H then ₁, H ₂Two groups of data (q ₁, f ₁, H ₁) and (q ₂, f ₂, H ₂) the substitution theoretical formula can try to achieve pretension H ₀

The method essence is similar to displacement method, just carries out the calculating of film in theory approx with the theory of rope.The method also has an advantage to be: having introduced does not have the equivalent elastic modulus of practical significance E ', and can not spend the actual elastic modulus of being concerned about the film material, thereby eliminated elastic modulus E inaccurate influence is provided, reduce the error that this factor caused, on certain degree, improved the precision of measuring.But the method is in the measurement of reality, and its boundary condition is difficult to satisfy, and the measuring process more complicated, and the device of measurement carries also inconvenient.

Summary of the invention

At the prior art above shortcomings, the purpose of this invention is to provide a kind of convenient and swift, construction film structure pre-tension measurement method that precision is high.

Another object of the present invention provides a kind of simple in structure, and measuring method is simple, applied widely; And, the measurement mechanism of the construction film structure pre-tension of reliable measuring data.

The object of the present invention is achieved like this: construction film structure pre-tension measurement method, it is characterized in that, and comprise the steps:

A) with the stretch-draw face of a particle bead incident one fixed boundary, make face produce vibration, bead is rebounded simultaneously;

B) the incidence rate v of bead in the stretch-draw face of the same fixed boundary of measurement ₀, return speed v _t, face mid point peak swing T _Max, and the quality m of bead ₀The duplicate measurements of transposing direction of warp and weft goes out T _Max, v ₀, v _t

C) according to formula:

${\mathrm{\&pi;}}^2{\mathrm{habT}}_{\max }^2[(\frac{{\mathrm{\&sigma;}}_{0x}}{a^2}+\frac{{\mathrm{\&sigma;}}_{0y}}{b^2})+\frac{{\mathrm{\&pi;}}^2}{32}(\frac{E_x}{a^4}+\frac{E_y}{b^4})\&CenterDot;T_{\max }^2]={4m}_0(v_0^2-v_t^2)$

And step B) two groups of T that record _Max, v ₀, v _tValue is found the solution and is obtained face tension force σ _0xAnd σ _0y

In the formula: h is a film material thickness, a be the rectangular membrane material along x to length, b be the rectangular membrane material along y to length, T _MaxBe face maximum central amplitude, σ _0xFor x to first tension, σ _0yFor y to first tension, E _xFor x to elastic modulus, E _yFor y to elastic modulus; The unit of each amount adopts International System of Units.

The construction film structure pre-tension measurement mechanism is characterized in that, is made up of measuring box and control enclosure; Be electrically connected between measuring box and the control enclosure; Wherein,

Measuring box is made up of transparent box body, bead transmitting and receiving device, bead parameter measuring apparatus, vacuum pump and displacement transducer; Box opening is downward, and edge of opening is provided with groove shape sucker; The bead transmitting and receiving device is located at directly over the box body, and the bead parameter measuring apparatus is located at the below of bead transmitting and receiving device; The bead parameter measuring apparatus is by displacement sensor amplitude T _Max, and measurement result is transferred to control enclosure by data line;

Control enclosure is made up of shell, control circuit board, display panel and power supply; Comprise power switch on the control enclosure front, the switch of bleeding, detect knob, working indicator lamps and display screen; Its back side is provided with the interface of power supply, connecting line.

The computation model of construction film structure pre-tension measurement method of the present invention is to be based upon on the basis of actual engineering: its basic thought is exactly the stretch-draw face of regarding bead incident one fixed boundary of particle as with one, make face produce vibration, bead is rebounded simultaneously.Can be in this process by the incidence rate v of bead ₀, return speed v _t, face mid point peak swing T _Max, and the quality m of bead ₀, derive face tension force σ _0xAnd σ _0yThe thought of theoretical derivation is to utilize the energy of film dissipation of vibrations to equate to obtain v with the loss of bead kinetic energy ₀, v _t, T _Max, m and pretension σ _0xAnd σ _0yRelational expression.Face is regarded the orthotropic film as in the derivation, and bead will be regarded particle as, but will consider its quality.To carry out according to accurate large deflection during the vibration of derivation face.

Compared to existing technology, the present invention has following advantage:

1. construction film structure pre-tension measurement method of the present invention is based on the film theory of large-deflection plate, method than before, and its more approaching in theory reality, theoretical precision is higher;

2. the method is applicable to various film materials, can measure the pretension of film material quadrature both direction, and the tension force of energy measurement film under different load actions, can be applied in the actual engineering very soon;

3. this apparatus structure is simple, cost is lower, uses very convenient;

4. this measurement mechanism is simple to operation, and can read measurement data immediately;

5. this measurement mechanism measuring accuracy height, and when measuring, do not destroy the film material, do not influence the normal use of membrane structure after the measurement;

6. this measurement mechanism volume is little, is easy to carry, and is economical and practical, can both measure under any external environment.

Description of drawings

Fig. 1 is the linear relation figure of raman frequency peak value and tensile strain;

Fig. 2 is the rectangular membrane material synoptic diagram of simply supported on four sides;

Fig. 3 is that the present invention measures construction film structure pre-tension device synoptic diagram;

Fig. 4 is the method for testing schematic diagram of construction film structure pre-tension measurement method of the present invention;

Fig. 5 is building film face mid point peak swing T _MaxSynoptic diagram.

Embodiment

Referring to Fig. 4, a kind of construction film structure pre-tension measurement method, the present invention is the method for launching, and comprises the steps:

A) with the stretch-draw face of particle bead incident one fixed boundary (a*b), make face produce vibration, bead is rebounded simultaneously;

B) the incidence rate v of bead in the stretch-draw face of the same fixed boundary of measurement ₀, return speed v _t, face mid point peak swing T _Max, and the quality m of bead ₀The duplicate measurements of transposing direction of warp and weft goes out T _Max, v ₀, v _t

C) according to formula:

${\mathrm{\&pi;}}^2{\mathrm{habT}}_{\max }^2[(\frac{{\mathrm{\&sigma;}}_{0x}}{a^2}+\frac{{\mathrm{\&sigma;}}_{0y}}{b^2})+\frac{{\mathrm{\&pi;}}^2}{32}(\frac{E_x}{a^4}+\frac{E_y}{b^4})\&CenterDot;T_{\max }^2]={4m}_0(v_0^2-v_t^2)$

And step B) two groups of T that record _Max, v ₀, v _tValue is found the solution and is obtained face tension force σ _0xAnd σ _0y

In the formula: h is a film material thickness, a be the rectangular membrane material along x to length, b be the rectangular membrane material along y to length, T _MaxBe face maximum central amplitude, σ _0xFor x to first tension, σ _0yFor y to first tension, E _xFor x to elastic modulus, E _yFor y to elastic modulus; The unit of each amount adopts International System of Units.

The present invention proposes to measure " launching method " of film material pretension by to the theoretical research of film material mechanical characteristic, and the correctness of proof theory is by experiment made the surveying instrument that can be applied to engineering reality at last again.This method can directly apply in the engineering reality of film structure pre-tension measurement, is a kind of simple and effective measuring method.Have method novelty, convenient and swift and advantage of high precision, range of application is wider in actual engineering.

Rationale of the present invention is:

(1) theoretical model of applied film theory of large-deflection plate construction film structure pre-tension and incident bead parameter;

(2) according to the material behavior of film material, set up the finite element model of analogue membrane material characteristic, carry out a large amount of numerical analysis and calculate, the correctness of proof theory from the numerical analysis;

(3) research that experimentizes, the correctness of proof theory and numerical evaluation (by having the correctness of the film experimental verification theory under different pretension levels, different film material specification, the different impact load level).

The tonometric theoretical model computation model of jacking membrane structure is to be based upon on the basis of actual engineering: its basic thought is exactly the stretch-draw face of regarding bead incident one fixed boundary of particle as with one, makes face produce vibration, and bead is rebounded simultaneously.Can be in this process by the incidence rate v of bead ₀, return speed v _t, face mid point peak swing T _Max, and the quality m of bead ₀, derive face tension force σ _0xAnd σ _0yThe thought of theoretical derivation is to utilize the energy of film dissipation of vibrations to equate to obtain v with the loss of bead kinetic energy ₀, v _t, T _Max, m and pretension σ _0xAnd σ _0yRelational expression.Face is regarded the orthotropic film as in the derivation, and bead will be regarded particle as, but will consider its quality.To carry out according to accurate large deflection during the vibration of derivation face.Theoretical calculation model is illustrated in fig. 2 shown below:

Through derivation, and simplify, can obtain Practical Formula:

${\mathrm{\&pi;}}^2{\mathrm{habT}}_{\max }^2[(\frac{{\mathrm{\&sigma;}}_{0x}}{a^2}+\frac{{\mathrm{\&sigma;}}_{0y}}{b^2})+\frac{{\mathrm{\&pi;}}^2}{32}(\frac{E_x}{a^4}+\frac{E_y}{b^4})\&CenterDot;T_{\max }^2]={4m}_0(v_0^2-v_t^2)---\left(1\right)$

In the formula: h is a film material thickness, a be the rectangular membrane material along x to length, b be the rectangular membrane material along y to length, T _MaxBe face maximum central amplitude, σ _0xFor x to first tension, σ _0yFor y to first tension, E _xFor x to elastic modulus, E _yFor y to elastic modulus, m ₀Be bead quality, v ₀Be bead incidence rate, v _tSpeed when rebounding back incidence point for bead.The unit of each amount adopts International System of Units.

In the formula, T _Max, v ₀, v _tBe the amount that needs measurement, σ _0xAnd σ _0yBe amount to be asked, and other amounts are material parameter and physical dimension, are known quantities.But be noted that: σ is arranged in the formula _0xAnd σ _0yTwo amounts to be asked are so must measure the T of two groups of different values of same point _Max, v ₀, v _t, could solve σ according to (1) formula _0xAnd σ _0y

In practical project, can obtain two groups of T of different value by such mode _Max, v ₀, v _t:

Measuring box is made rectangle, so at first that the long limit of measuring box and the warp-wise of film material (be x to) is parallel, the broadwise of the minor face of measuring box and film material (be y to) is parallel, at this moment measures the first group of measurement parameter T of a bit _Max, v ₀, v _tIn same point that the long limit of measuring box and the broadwise of film material (be y to) is parallel then, the warp-wise of the minor face of measuring box and film material (be x to) is parallel, at this moment measures second group of measurement parameter T ' of this point _Max, v ' ₀, v ' t.So just can obtain two equations to these two groups of data difference substitution formula (1), these two equations of simultaneous solution just can solve one and point out σ _0xAnd σ _0ySo formula also can be write as:

$\left\{\begin{array}{c}{\mathrm{\&pi;}}^2\mathrm{hab}{T}_{\mathrm{mad}}^2[(\frac{{\mathrm{\&sigma;}}_{0x}}{a^2}+\frac{{\mathrm{\&sigma;}}_{0y}}{b^2})+\frac{{\mathrm{\&pi;}}^2}{32}(\frac{E_x}{a^4}+\frac{E_y}{b^4})\&CenterDot;T_{\max }^2]={4m}_0(v_0^2-v_t^2)\\ {\mathrm{\&pi;}}^2\mathrm{hab}{T}_{\max }^{\&prime;2}[(\frac{{\mathrm{\&sigma;}}_{0x}}{a^2}+\frac{{\mathrm{\&sigma;}}_{0y}}{b^2})+\frac{{\mathrm{\&pi;}}^2}{32}(\frac{E_x}{a^4}+\frac{E_y}{b^4})\&CenterDot;T_{\max }^{\&prime;2}]{4m}_0(v_0^{\&prime;2}-v_t^{\&prime;2})\end{array}\right.---\left(2\right)$

Compile computer program according to this formula, when recording T _Max, v ₀, v _tAnd T ' _Max, v ' ₀, v ' _tAfter, can directly read σ by Computer Control Technology _0xAnd σ _0y(N _0x=h σ _0x, N _0y=h σ _0y), this will be described in detail in will and realizing in Design of device.

Referring to Fig. 3, realize the device of above-mentioned construction film structure pre-tension measurement method, form by measuring box and control enclosure; Be electrically connected between measuring box and the control enclosure; Wherein,

Measuring box is made up of box body 1, bead transmitting and receiving device 2, bead parameter measuring apparatus 3, vacuum pump 4 and displacement transducer 5; Open Side Down for box body 1, and edge of opening is provided with groove shape sucker 6; Bead transmitting and receiving device 2 is located at directly over the box body 1, bead parameter measuring apparatus 3 be located at bead transmitting and receiving device 2 under; Displacement transducer 5 is measured the amplitude T of film _Max(referring to Fig. 5), and measurement result is transferred to control enclosure 7 by data line.In addition, box body 1 is made by transparent material, with convenient emission situation of observing inner bead; Certainly, be not limited to and make by transparent material.

Described bead transmitting and receiving device 2 is cylinder-like structures, and the inside is provided with the spring transmitter, and the transmitter front is provided with the unidirectional baffle plate with the transmitter interlock; The spring transmitter adopts existing known technology to get final product.When bead was launched, baffle plate was automatically opened and is allowed bead pass through, and closed automatically when the bead backboard that rebounds, and did not allow bead fall.Described bead parameter measuring apparatus 3 is laser velocimeters, be contained in the bead transmitting and receiving device under, its hole of testing the speed is with the transmitting aperture correspondence of bead transmitting and receiving device 2, when detector switch was opened, laser velocimeter was just opened and is measured.

Control enclosure 7 is made up of shell, control circuit board, display panel and power supply; Control enclosure comprises power switch on 7 fronts, bleed switch and detection knob 8, working indicator lamps 9 and display screen; Its back side is provided with the interface of power supply, connecting line.

Box body 1 adopts transparent organic glass to make, and the organic glass measuring box is mainly used in the closed region that forms face, meets with the simple boundary that guarantees actual face border and theoretical model.Groove shape sucker along measuring box end opening limit is housed on the organic glass measuring box, and measuring box relies on this sucker to hold face, makes it form the quadrilateral face of sealing, and this quadrilateral face can abstractly be the film of simply supported on four sides; Sucker is again to bleed and produce suction by vacuum pump.The bead transmitting and receiving device 2 that is contained in middle above the measuring box is used to transmit and receive bead, and bead parameter measuring apparatus 3 is used to measure parameter (speed v during incident of bead ₀, speed v when receiving _t).Impinge perpendicularly on face and then rebound in the process that is received by this device when bead installs emission thus, the bead parameter measuring apparatus 3 that are contained in below the bead transmitting and receiving device 2 can accurately be measured the bead parameter.The displacement transducer 5 that is contained on the measuring box is used for measuring face maximum central amplitude T _MaxThe signal wire that is electrically connected between measuring box and the control enclosure passes to control enclosure with the concrete data of the bead parameter that records., by display screen tension value is shown again bead parameter calculation film forming face tension force by the computer program in the control enclosure.Calculation procedure in the control enclosure is worked out according to the formula of theoretical derivation.Power switch on the control enclosure is used for Switching Power Supply; The switch of bleeding control is bled; Detector switch is used for the carrying out of control detection, by one-time detection once.Pilot lamp 9 on the control enclosure is used to refer to power supply, bleeds and detected state.All be provided with connecting line and electric source line interface on control enclosure and the detection box.The present invention measures measurement control, data processing and the Presentation Function of construction film structure pre-tension device and is finished by control enclosure 7.

Use this device, the concrete steps of measuring construction film structure pre-tension are as follows:

1) press the power switch knob, energized, power light lights simultaneously.

2) measuring box is buckled on the face that is subjected to tension force, allows the warp-wise or the broadwise of box limit parallel membrane material as far as possible.

3) press lower pumping switch knob, the pilot lamp of bleeding simultaneously lights.At this moment vacuum pump begins to bleed, and makes the sucker on measuring box end opening limit hold face; The square face of a closed region of interruption-forming under the measuring box like this.

4) when step 3) finish reach can Testing requirement after, measure pilot lamp and light, expression can have been measured, and at this moment will close the switch of bleeding.

5) click the measuring switch knob, the simultaneous displacement sensor is opened, and the bead parameter measuring apparatus is opened, and the bead emitter is launched bead and rebounded; Also at the same time, connecting line passes to control enclosure with the bead parameter that records and the maximum displacement of face mid point and is stored in the computer system.

6) turning off all switches except that power switch, is round dot with measuring box at former center of sentencing the rectangular membrane face, with measuring box revolve turn 90 degrees after, repeating step 3 again) to step 5).

7) press compute switch, this computer-chronograph begins to calculate σ _0xAnd σ _0y, and its value is presented on the display screen.

The tension value that needs to survey difference just repeats above step.And before each the measurement, to press empty switch with before data empty.Empty the bright explanation of pilot lamp and empty, can measure.Explanation has data not empty if do not work, and can not measure.

Claims (4)

1, construction film structure pre-tension measurement method is characterized in that, comprises the steps:

A) with the stretch-draw face of a particle bead incident one fixed boundary, make face produce vibration, bead is rebounded simultaneously;

B) the incidence rate v of bead in the stretch-draw face of the same fixed boundary of measurement ₀, return speed v _t, face mid point peak swing T _Max, and the quality m of bead ₀Transposing warp, the duplicate measurements of latitude direction go out T _Max, v ₀, v _t

C) according to formula:

${\mathrm{\&pi;}}^2\mathrm{hab}{T}_{\max }^2[(\frac{{\mathrm{\&sigma;}}_{0x}}{a^2}+\frac{{\mathrm{\&sigma;}}_{0y}}{b^2})+\frac{{\mathrm{\&pi;}}^2}{32}(\frac{E_x}{a^4}+\frac{E_y}{b^4})\&CenterDot;T_{\max }^2]=4m_0(v_0^2-v_t^2)$

And step B) two groups of T that record _Max, v ₀, v _tValue is found the solution and is obtained face tension force σ _0xAnd σ _0y

In the formula: h is a film material thickness, a be the rectangular membrane material along x to length, b be the rectangular membrane material along y to length, T _MaxBe face maximum central amplitude, σ _0xFor x to first tension, σ _0yFor y to first tension, E _xFor x to elastic modulus, E _yFor y to elastic modulus; The unit of each amount adopts International System of Units.

2, the construction film structure pre-tension measurement mechanism is characterized in that, is made up of measuring box and control enclosure; Be electrically connected between measuring box and the control enclosure; Wherein,

Measuring box is made up of box body (1), bead transmitting and receiving device (2), bead parameter measuring apparatus (3), vacuum pump (4) and displacement transducer (5); Open Side Down for box body (1), and edge of opening is provided with groove shape sucker (6); Bead transmitting and receiving device (2) is located at directly over the box body (1), and bead parameter measuring apparatus (3) is located at the below of bead transmitting and receiving device (2); Bead parameter measuring apparatus (3) is through the amplitude T of the tested face of displacement sensor _Max, and measurement result is transferred to control enclosure (7) by data line;

Control enclosure (7) is made up of shell, control circuit board, display panel and power supply; Control enclosure (7) is provided with power switch, the switch of bleeding, detect knob, working indicator lamps and display screen; Its back side is provided with the interface of power supply, connecting line.

3, construction film structure pre-tension measurement mechanism according to claim 2 is characterized in that, described bead transmitting and receiving device (2) comprises the spring transmitter, and with the unidirectional baffle plate of spring transmitter interlock.

4, construction film structure pre-tension measurement mechanism according to claim 2, it is characterized in that, described bead parameter measuring apparatus (3) is a laser velocimeter, is located at the below of bead transmitting and receiving device, its hole transmitting aperture correspondence with bead transmitting and receiving device (2) that tests the speed.

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