CN202216831U - Device for testing tangential dynamic property of joint surface - Google Patents

Abstract

The utility model discloses a device for testing the tangential dynamic property of a joint surface, belonging to the field of mechanical design and manufacture. A hammer is connected with a test system through a signal wire, and a joint surface specimen consists of a left specimen, a right specimen, an upper metal sheet and a lower metal sheet. A rod specimen is connected to the upper metal sheet and the lower metal sheet through two strain bolts, and the contact parts of the metal rod specimen and the metal sheets form two pairs of tangential joint surfaces. The strain bolts are connected to a dynamic strain gauge through an electric bridge; the dynamic strain gauge is connected with the test system and is additionally connected to a PC (Personal Computer). Two ends of the left specimen and the right specimen are symmetrically provided with acceleration transducers connected with the test system; processed data are transmitted to the PC by the test system; the frequency response function of a tested specimen is acquired by the PC according to acceleration and a force signal; and the tangential dynamic property parameter of the joint surface arranged between the left specimen and the right specimen is recognized according to the frequency response function. By using the device, the problem that the dynamic property at the joint surface is difficult to test is solved, and the tangential dynamic property of the joint surface is separated from the dynamic property of a test device/system.

Description

A kind of test faying face tangential dynamic perfromance device

Technical field

The utility model is a kind of device of testing faying face tangential dynamic perfromance, belongs to Machine Design and manufacturing field.

Background technology

Physical construction be by many parts by the integral body that certain functional requirement combines, the surface that mutually combines between the parts is called " faying face ".The existence of faying face makes physical construction become no longer continuous, causes the complicacy of mechanical oscillatory structure.Faying face can not only storage power, also can consumed energy, promptly show contact stiffness and contact damping.Contact stiffness and contact damping are very big to the influence of structure dynamic property, and the mechanism of action is very complicated.The factor that influences the faying face dynamic perfromance is a lot, and very complicated, and these factors mainly contain:

(1) size of the specific pressure on the faying face;

(2) homogeneity of pressure distribution;

(3) material of faying face;

(4) area of faying face;

(5) job operation of faying face (common method: car, mill, dig, grind, scrape etc.);

(6) dynamic loading character of faying face (tangential force, moment of torsion, moment of flexure) and size;

(7) error in geometrical form of surface in contact and nao-and micro relief;

(8) lubricating oil property between faying face etc.

Because influence factor is numerous, the influence degree of each factor and rule can't directly be confirmed with the method that theory is resolved again, can only be the numerical value that them are confirmed in the basis with the experiment therefore.

In order systematically to study and verify the relation between faying face tangential dynamic perfromance and its basic influence factor; And grasp faying face dynamic basis characterisitic parameter; Need the apparatus and method of the complete test faying face tangential dynamic perfromance of a cover, and also do not have the device of relevant test faying face tangential dynamic perfromance at present.

The utility model content

The purpose of the utility model is that design one cover is through power hammer exciting; The use test system obtains acceleration signal; And carry out model analysis; Obtain the apparatus and method of the test faying face tangential dynamic perfromance of unit area faying face dynamic perfromance; Utilize this device can obtain the dynamic characteristic parameter (tangential rigidity and damping) of faying face tangential under the various combination conditions (being various basic influence factor), obtain integrally-built inherent characteristic (Mode Shape, natural frequency, damping ratio, frequency response function etc.), utilize frequency response function to pick out the equivalent power mathematic(al) parameter of faying face.

To achieve these goals, the utility model has been taked following technical scheme:

A kind of test faying face tangential dynamic perfromance device and method comprises power hammer, left test specimen 2, right test specimen 5, sheet metal 4, acceleration transducer 1, dynamic strain indicator, strain bolt 3, electric bridge, test macro and PC; It is characterized in that: left test specimen 2, right test specimen 5 axis are placed on the same straight line relatively; Sheet metal 4 is positioned over the front of left test specimen 2, right test specimen 5 contact positions; Sheet metal 4 is positioned over the back of left test specimen 2, right test specimen 5 contact positions; Left side test specimen 2, right test specimen 5 radially respectively have a bolt hole near the contact position, the left bolt hole of sheet metal 4 aligns with the bolt hole of left test specimen 2, and the right bolt hole of sheet metal 4 aligns with the bolt hole of right test specimen 5; Two strain bolts 3 are left test specimen 2, right test specimen 5, sheet metal 4 bolts, and left test specimen 2, right test specimen 5 form two pairs of tangential faying faces with sheet metal 4 contacts site; Strain bolt 3 is that resistance strain plate is embedded the bolt in the high-strength bolt screw rod; The outer extension lead of the foil gauge of strain bolt 3 is connected with electric bridge; Electric bridge is connected with the input interface of dynamic strain indicator through output plug; Change the resistance change of foil gauge into the magnitude of voltage variation; The output terminal of dynamic strain indicator is connected to the signal sampling channel of test macro, and test macro is connected with PC through netting twine, and dynamic strain indicator links to each other with PC; Power hammer, left test specimen 2, right test specimen 5 linearly dispose; Acceleration transducer 1 is placed on the end of left test specimen 2, right test specimen 5; The force signal acquisition channel of power hammer test macro connects; Test specimen 2 ends, a power hammer vertical drive left side obtain acceleration signal and exciting force signal, send each signal to test macro through signal wire, are sent to PC through after the processing of test macro.

Said left test specimen 2 is a rectangular parallelepiped.

Acceleration transducer 1 is fixed on the right ends of test specimen through magnetic sheet.

The material of said left test specimen 2, right test specimen 5, sheet metal 4 adopts Q235-Q235 or HT250-HT250 or QT600-QT600.

The surfaceness of said left test specimen 2, right test specimen 5, sheet metal 4 is finish-milling-finish-milling or mill-mill.

Said left test specimen 2, right test specimen 5,4 of sheet metals add machinery oil No. 30.

It is the modal forces hammer of PCB-086C03 that said power hammer adopts model; It is the acceleration transducer of PCB-333B30 that said acceleration transducer adopts model; Dynamic strain indicator adopts the BZ2668 dynamic strain indicator.

The utility model can be obtained following beneficial effect:

(Fig. 1) can find out from experimental provision, and the characterisitic parameter that tests out only is the faying face part characteristic between left and right test specimen and the sheet metal, reduced the number of the physical quantity of measuring, and employing is the direct method of measurement;

For the ease of each the basic influence factor that influences the faying face dynamic perfromance is studied, this experimental provision guarantees that test specimen is easy to change, be easy to the location;

Owing to only be the tangential dynamic perfromance of faying face between left and right test specimen of test and the sheet metal, from the dynamic perfromance of experimental provision system, be easier to separate so can guarantee the faying face dynamic perfromance.

Description of drawings

Fig. 1 is the structural drawing of the utility model test faying face tangential dynamic perfromance.

Fig. 2 be embodiment illustrated in fig. 2 in the front view of left test specimen.(left and right test specimen is identical)

Fig. 3 be embodiment illustrated in fig. 2 in before the front view of sheet metal.(forward and backward sheet metal is identical)

Among the figure: 1, acceleration transducer, 2, left test specimen, 3, the strain bolt, 4, sheet metal, 5, right test specimen.

Embodiment

Below in conjunction with principle of work and structure accompanying drawing the further detailed description of face dynamic perfromance device do is closed in the test tangential.

Shown in Fig. 1-4; Left side test specimen 2, right test specimen 5 and former and later two sheet metals 4 are through strain bolt 3 bolts; The pretightning force of strain bolt 3 changes the variation of the built-in foil gauge resistance value of bolt into, and strain bolt 3 is connected to electric bridge through outer extension lead, and electric bridge is connected with dynamic strain indicator through transmission line; Change the resistance change of foil gauge into the magnitude of voltage variation, the output terminal of dynamic strain indicator is connected to the signal sampling channel of test macro through output signal line.Left side test specimen 2, right test specimen 5 and sheet metal 4 should guarantee the right alignment of left and right test specimen and sheet metal bolt hole with plane contact, guarantee that simultaneously the left test specimen 2 and the end face of right test specimen 5 do not come in contact.After installing, test specimen freely is suspended on the double ladder with lifting rope.

Acceleration transducer 1 is adsorbed on the end of left and right test specimen respectively with magnetic sheet, the power hammer is done vertical drive in the end of left test specimen 2.To test macro, data are delivered to PC through output after the processing of test macro to the output signal of power hammer pumping signal, acceleration transducer through signal wire transmits.

During use, measure the size of strain bolt 3 pretightning forces on the faying face through dynamic strain indicator.When firmly hammer encourages left test specimen 2 ends, should exert all one's strength and hammer the vertical drive end surface into shape, the force transducer in hammering into shape through power obtains the size of exciting force, obtains the acceleration signal of test block through the acceleration transducer 1 of test piece end absorption.After obtaining the response under the different excitation signal, utilization frequency response function identification method can obtain the faying face dynamic characteristic parameter.The big I of pretightning force of strain bolt 3 repeatedly changes the face pressure value of faying face on the adjustment test specimen faying face, promptly presses through different facial and studies the influence that faying face tangential rigidity is pressed by face.

Utilize this device can do following several types of experiments:

(1) at (area, roughness, processing mode, the material of faying face, the medium between the faying face that is faying face etc. certain situation under) under certain combination condition; The face that changes faying face is pressed (promptly through changing the face pressure that bolt pretightening changes faying face); The amplitude of the exciting force of power hammer keeps stable, probes into the influence of the change of faying face face pressure to faying face tangential rigidity.

(2) (being under the constant situation such as medium etc. between the area, roughness, processing mode, faying face of faying face) under certain combination condition; Keep the face of faying face to press constant (promptly the strain bolt on the faying face being applied constant pretightning force); The amplitude of the exciting force of change power hammer is probed into the influence of different exciting forces to faying face tangential rigidity.

(3) keep the face of faying face to press constant (promptly the strain bolt on the faying face being applied constant pretightning force); Change the combination condition and (for example change the roughness of faying face; And material of the area of faying face, processing mode, faying face, the medium between the faying face etc. are constant); The amplitude of exciting force of confining force hammer is constant, probes into the influence of different combination conditions to faying face tangential rigidity.

During experiment, left test specimen 2, right test specimen 5 and sheet metal 4 can be changed dissimilar, can be like different materials such as Q235-Q235, HT250-HT250, QT600-QT600, can be finish-milling-finish-milling, mill-different surface roughness such as mill.Can also between left test specimen 2, right test specimen 5 and sheet metal 4, add medium, like No. 30 machinery oil.

Dynamic characteristic parameter to the faying face tangential is discerned.Tangential faying face part in the test specimen is reduced to one group of spring, damping system respectively, totally four groups of springs, damping system.Test specimen and faying face are partly carried out Dynamic Modeling, because parameter recognition is only used axial first natural frequency of test specimen and damping ratio in the utility model, under this natural frequency, test specimen is done axial symmetrical tension and compression vibration, and intermediate point is a node.Therefore; According to this symmetry characteristic; Only whole test specimen left-half is carried out Dynamic Modeling; Modeling process: left test specimen 2 is reduced to homogeneous elastic rod a, and right test specimen 5 is reduced to homogeneous elastic rod b, and the length L of elastic rod, cross-sectional area A, elastic modulus E, linear mass μ conform to rod member; Front and back thin slice and strain bolt are reduced to the lumped mass piece, and lumped mass piece quality m is this two parts quality sum; Two groups of parallel connection springs, damping systems before and after the left half are reduced to one group of spring, damping system, spring constant K, ratio of damping C be about two groups of spring constants, ratio of damping sum; The test specimen intermediate node partly is reduced to solid to be connected.

So, the identification of bolted joint dynamic characteristic parameter is converted into to spring rate K the identification of ratio of damping C.Identifying is following:

For even strut and tie a, the axial free movement Newton's equation of bar b is respectively:

$\mathrm{EA}\frac{{\∂}^{2}U(x,t)}{{\∂x}^2}=\mathrm{\μ}\frac{{\∂}^{2}U(x,t)}{{\∂t}^2}---\left(1\right)$

Wherein (x, t) for bar a goes up coordinate x position at t vibration displacement constantly, μ is the rod member linear mass to U.EA is the tension and compression rigidity of rod member, and wherein E is an elastic modulus, and A is the rod member cross-sectional area.

We with bar vibration displacement U (x, t) carry out displacement and separate with the variable of time quantum:

U(x，t)＝U(x)e ^λt (2)

Equation (2) substitution equation (1) is obtained:

$\frac{d^{2}U\left(x\right)}{{\mathrm{dx}}^2}-{\mathrm{\β}}^{2}U\left(x\right)=0---\left(3\right)$

Wherein: ${\mathrm{\β}}^2=\frac{{\mathrm{\μ\; \λ}}^2}{\mathrm{EA}}---\left(4\right)$

Equation (3) is asked its general solution.Obtain about a according to the border coordination condition free, middle bolt of test specimen two ends in the test then ₁, a ₂Matrix equation, that is:

A _a＝0 (5)

Wherein:

a＝[a ₁，a ₂] ^T

For unknown number is the matrix equation (5) of a, and equation has the condition of separating to be: A=0, so obtain about the secular equation of λ following:

mβλ ²cosh(βL)-βcλcosh(βL)-βK?cosh(βL)

-β ²EA?sinh(βL)＝0 (6)

Wherein know by formula (4): ${\mathrm{\β}}^2=\frac{{\mathrm{\μ\; \λ}}^2}{\mathrm{EA}}$

For eigenvalue, we know that its value is under the free state:

$\mathrm{\λ}=-{\mathrm{\ξ\ω}}_n\±j\sqrt{1-{\mathrm{\ξ}}^2}{\mathrm{\ω}}_n---\left(7\right)$

Natural frequency ω in the formula (7) _nWith damping ratio ξ, the test specimen axial vibration experiment of introducing through preceding text obtains, so formula (6) only contains unknown number K, C.Formula (6) is carried out the arrangement of real part and imaginary part, and make real part, imaginary part be respectively zero, the final system of equations that obtains about K, C according to the condition that equality is set up.Utilize software for calculation that system of equations is resolved and find the solution, finally obtain the exact solution of unknown number K, C, be i.e. rigidity, the damping value of this tangential bolt faying face.

Claims (7)

1. a test faying face tangential dynamic perfromance device comprises power hammer, left test specimen (2), right test specimen (5), sheet metal (4), acceleration transducer (1), dynamic strain indicator, strain bolt (3), electric bridge, test macro and PC; It is characterized in that: left test specimen (2), right test specimen (5) axis are placed on the same straight line relatively; A sheet metal (4) is positioned over the front of left test specimen (2), right test specimen (5) contact position; A sheet metal (4) is positioned over the back of left test specimen (2), right test specimen (5) contact position; Left side test specimen (2), right test specimen (5) radially respectively have a bolt hole near the contact position; The left bolt hole of sheet metal (4) aligns with the bolt hole of left test specimen (2), and the right bolt hole of sheet metal (4) aligns with the bolt hole of right test specimen (5); Two strain bolts (3) are with left test specimen (2), right test specimen (5), sheet metal (4) bolt, and left test specimen (2), right test specimen (5) form two pairs of tangential faying faces with sheet metal (4) contact site; Strain bolt (3) is that resistance strain plate is embedded the bolt in the high-strength bolt screw rod; The outer extension lead of the foil gauge of strain bolt (3) is connected with electric bridge; Electric bridge is connected with the input interface of dynamic strain indicator through output plug; Change the resistance change of foil gauge into the magnitude of voltage variation; The output terminal of dynamic strain indicator is connected to the signal sampling channel of test macro, and test macro is connected with PC through netting twine, and dynamic strain indicator links to each other with PC; Power hammer, left test specimen (2), right test specimen (5) linearly dispose; Acceleration transducer (1) is placed on the end of left test specimen (2), right test specimen (5); The force signal acquisition channel of power hammer test macro connects; Test specimen (2) end, a power hammer vertical drive left side obtains acceleration signal and exciting force signal, sends each signal to test macro through signal wire, is sent to PC through after the processing of test macro.

2. a kind of test faying face according to claim 1 tangential dynamic perfromance device, it is characterized in that: said left test specimen (2) is a rectangular parallelepiped.

3. a kind of test faying face according to claim 1 and 2 tangential dynamic perfromance device, it is characterized in that: acceleration transducer (1) is fixed on the right ends of test specimen through magnetic sheet.

4. a kind of test faying face according to claim 1 and 2 tangential dynamic perfromance device is characterized in that: the material of said left test specimen (2), right test specimen (5), sheet metal (4) adopts Q235-Q235 or HT250-HT250 or QT600-QT600.

5. a kind of test faying face according to claim 1 and 2 tangential dynamic perfromance device and method, it is characterized in that: the surfaceness of said left test specimen (2), right test specimen (5), sheet metal (4) is finish-milling-finish-milling or mill-mill.

6. a kind of test faying face according to claim 1 and 2 tangential dynamic perfromance device is characterized in that: add machinery oil No. 30 between said left test specimen (2), right test specimen (5), sheet metal (4).

7. a kind of test faying face according to claim 1 and 2 tangential dynamic perfromance device is characterized in that: it is the modal forces hammer of PCB-086C03 that said power hammer adopts model; It is the acceleration transducer of PCB-333B30 that said acceleration transducer adopts model; Dynamic strain indicator adopts the BZ2668 dynamic strain indicator.

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