SU1366897A1 - Device for vibration tests - Google Patents

Abstract

The invention relates to a vibration measuring technique and can be used to determine the frequency characteristics of a test article. The aim of the invention is to improve the accuracy of determining the frequency characteristics of the product by compensating for dynamic amplitude distortion (AFC) and phase (AFF) frequency characteristics; The arising distortions of the frequency response and the frequency response are eliminated by solving in real time directly during the tests of the equation with the complex variable of the form W o (jw) W5.Xjuj-jVp d Wc (ju) / ЗИЯ-1 / 8v2 wa Uc (ja)) / Ju)% where W (, (jco) is the complex transfer function of the mechanical system (i.e., the transfer function obtained by the action of an external force of a constant frequency is the true transfer function of the system); W. (ju) is a dynamic complex transfer function mechanical system (i.e., obtained by the action of a variable frequency force), V is the velocity ki frequency v). with V const. The equation is solved for W (. (Ju)). 1 il. i SL

Description

00 od 9d (X SB

, rhythmic technique and can be used to determine the frequency characteristics of the test product.

The purpose of the invention is to increase the accuracy of measuring the frequency characteristics of the product by compensating for dynamic distortions of the amplitude and phase frequency characteristics.

The drawing shows a functional diagram of the proposed device.

The device contains a generator 1 with blocks of compression and frequency sweep, two heterodyne accompanying filters 2 and 3 connected to it by control inputs, connected by a control input recorder 4 and power amplifier 5 - vibrato r 6

two vibration transducers 7 and 8, the first 20 of the inverter 19, and its output through the latter of which is placed on the vibrator connected second multiply-6, and the second on the tested product 9, the first vibration transducer 7 through

36, fifth i-37, sixth 38, seventh 39 and eighth 40 telephones integrators are connected to the combined second one. The first matching amplifier 10 is connected to the information input of the filter 25 dd of the third 22 and seventh 23 shared 30

Step 2, the output of which is connected to the compression input of the generator 1. The second vibration converter 8 is connected via the second matching amplifier 11 to the information input of the filter 3. The phase detector 12 is connected to the unit outputs of filters 2 and 3. The device also contains an analog multiplier 13, differentiation unit 14, cosine function block 15 and sine function block 16, the combined inputs of which are connected to the output of the phase detector 12, and the outputs, respectively, with the first inputs of the first 13 and second 17. analog 40 output multiplier teley combined second inputs of which lervy through an inverter 18 connected to the data output of the second filter 3. Furthermore totelnyh entry blocks and a third quad Rhatore 41 (ditto). The second input of the first dividing unit 25 is combined with the input of the seventh integrator 39. A third adder 42, the inputs are connected respectively to the outputs of the second 34 and third 41 quadrants, and its output through the square-root extraction functional unit 43 is connected to the information input of the recorder 4 The information input of the second recorder 4 through the functional block 45 arctangent connected to the output of the seventh dividing unit 33.

The device works as follows.

The electrical signal from the output of the generator 1 after the amplifier 5 power output of the first 20, fourth 23 and nth 25 dividing blocks, and its

output through serially connected first block 28 multiplying by 8, first 29, second 30, third 31 and blue 32 integrators connected to the combined second input of the fourth 23 and the first input of the seventh 33 separating blocks, as well as to the input of the second quadrant 34. The second inverter 19 input connected to the output of the sixth dividing unit 26, the second input

which is combined with the input of the third integrator 31. The inputs of the second adder 35 are connected respectively to the outputs of the second 21 and third 22 dividing blocks and the output of the second inverter 19, a-its output through the serially connected second multiplier

36, fifth, i-37, sixth 38, seventh 39 and eighth 40 telephones integrators are connected to the combined second input 30

40

unit blocks and the input of the third quad 41 (as well). The second input of the fifth dividing unit 25 is combined with the input of the seventh integrator 39. A third adder 42, the inputs are connected respectively to the outputs of the second 34 and third 41 quadrants, and its output through the square-root extraction functional unit 43 is connected to the information input of the recorder 4. Information input of the second recorder 4 through the functional unit 45 arctangent connected to the output of the seventh dividing unit 33.

The device works as follows.

The electrical signal from the output of the generator 1 after amplifier 5 power

The device comprises a second inversion, which is converted by the vibrator 6 into a mecator 19.

The outputs of the analog multipliers 13 and 17 are connected respectively with the first inputs of the first 20 and second 21 dividing blocks, the second inputs of which, together with the first inputs of the third 22 and fourth 23 dividing blocks, are connected through the first quad 24 with the combined first inputs of the fifth 25 and sixth 26 dividing blocks connected in turn through the block 14 differentiated. with the output signal of the oscillator frequency sweep. The inputs of the first platform oscillations, the amplitude of which is stabilized by the compression circuit: vibration converter 7 — matching amplifier 10 — filter 2 50 input of the generator 1 compression unit 1. Filter 2 is tuned according to the signal. From generator 1 in order to select the main vibration frequency. Mounted on the tested product 9, the second vybro55 converter 8 generates an electrical signal proportional to the response of the product to the applied effect, which, after the matching amplifier 11, is applied to the information

the input of the second filter 3, rebuilt on the control input.

Dynamic complex transmitter function .WQ (you) of the subject

„

the resulting force of varying frequency at speed V, and the complex transfer function WCjcf) of the product is a true transfer function of the product that can be obtained by acting on a product of a constant frequency force or varying at a very low speed, are related by

W (ioJ) w (iu,). w vjiv; wuw; jVjj 2, 8 ayu

(

Replacing in (1) the functions Wa (jtJ) and W (jw) with their representations from the real and imaginary parts and equating the real and imaginary parts, respectively, to the left and right in (1), we obtain the original system of differential equations used by the device to eliminate distortion of the frequency response and phase response of the test product 9:

Sa (a)) cosiKu) S, (u)) 4V 9u) 1. „, (To)

 8 d

Sa (o)) s in tXw) S, (s) -Vjj

AF, (S) 2

 )

8 i 5v The electrical signal proportional to the amplitude of the response at the frequency U) (t) is removed from the information output of the filter 3, and the electrical signal proportional to the phase shift between the forced oscillations of the product 9 and the forcing vibrations of the vibrator 6 is removed from the output of the phase detector 12 connected by the signal inputs to the unit outputs of filters 2 and 3. The corresponding transformations of these signals by the first sine function block 16, inverter 18, analog multiplier 17, and first functions by the actual block 1 A cosine 5, an inverter 18, a second analog multiplier 13, outputs signals multiplier 13 and 17 respectively

,

-Sa (io) sin cfCto); and

-Sa (Lo) cos if (uj) j

the form

those. the left parts of equations (2) with the opposite sign.

Write the system (2) in the normal

/ Si (u)) 8 s. h 8.))

G, F

) W W

3UJ

Q

 -j- Sa (w) cosq (u)), u)

) - § s r h - -§1

  )

Y2

w

Yy

Q

-J Sa (cLi) sinc / (to).

LO

V

w

i

(3)

Integrators 29-32, which serve to reduce the order of the derivative of the first equation (3), and integrators 37-40, which serve to decrease the order of the derivative of the second equation (3), together with the separating elements 20-23 and 26 and 25, the inverter 19, adders 27 and 35 and blocks 28 and 36 multiplied by 8 are connected according to the solution of the system of equations (3). The necessary electrical signals proportional to the frequency sweep speed and the square of the sweep speed are obtained by differentiating in block 14 a voltage proportional to the frequency taken from the output of the oscillator frequency scanner 1, with further squaring by the square 24.

At the outputs of the integrators 32 and 40, respectively, electrical signals are obtained that are proportional to 5 (w) and SjCcj).

The quadratures 34 and 41, the adder 42 and the function block 43 for extracting the square root compute a function of the form

| W (ju3) l 5Ды) 2+ S (cJ) 2

those. the frequency response at frequency s, which is recorded by the recorder 4.

The dividing element 33 and the functional block 45 of the arctangent compute a function of the form

argW (ju)) arctg | - (,

those. the value of the phase response at the frequency u), which is recorded by the recorder 44.

Thus, the recorders 4 and 44 respectively fix the true, and

not distorted frequency response and phase response of the test product.

Claims (1)

Formula of gain A device for vibration tests, containing a generator with compression and frequency sweep blocks, two heterodyne accompanying filters connected to it by control inputs, a recorder connected by a control input, and a vibrator through a power amplifier, two vibrating transducers placed on the vibrator and the tested item, the first of which through the first matching amplifier is connected to the information I input of the first filter, the output of which is connected to the generator compression unit, the second vibration converter through the second A matching amplifier is connected to the information input of the second filter, connected by signal inputs to the unit outputs of the filters, a phase detector, an analog multiplier and a differentiation unit, characterized in that, in order to improve the accuracy of measuring the frequency characteristics, a cosine function block, a sine function block, and a second analog multiplier, two inverters, seven dividing units, three quadrants, three adders, two multipliers by 8, eight integrators, a functional unit of treating a square root, an arctangent function block and a second recorder connected to the generator to the generator, the phase detector is connected to the output via the cosine and sine function blocks respectively to the first inputs of the analog multipliers, the second inputs of which are connected through the first inverter to the information output of the second filter as well their outputs are with the first inputs of the first and second dividing blocks, respectively, the second inputs of which, together with the first inputs of the third and fourth dividing blocks, are connected via the first quad with the combined first inputs of the fifth and sixth dividing blocks, which in turn are connected via a differentiator to the output of the scanner generator frequency, the first adder is connected to the inputs respectively with the outputs of the first, fourth and nth: dividing blocks, and its output is connected in series with the first multiplication unit by 8, the first, second, third, fourth integrators are connected to the combined second input of the fourth, the first input of the seventh separating block and the input of the second quadr, and the second inverter is connected to the output of the sixth separating block the second input of which is combined with the input of the third integrator, the second with the mmator is connected with the inputs respectively with the outputs of the second and third separating units and the second inverter, and its output through edovatelno Multiplying unit connected to the second voltage 8, fifth, sixth, seventh, eighth integrator is connected to the combined second inputs of the third, seventh dividing elements and entry the third quad, the second input of the fifth separating unit is combined with the input of the seventh integrator, the third adder is connected by inputs with the outputs. the second and third quadrants, respectively, its output through the square-root extraction functional unit is connected to the input of the first recorder, and the input of the second recorder through the arctangent functional unit connected to the output of the seventh dividing unit.