SU1677533A1 - Method of measuring statodynamic parameters of articles under simultaneous action of vibration and temperature - Google Patents

Abstract

The invention relates to a measurement technique, mainly to radio wave methods for measuring the static-dynamic parameters of various products when tested on the simultaneous effects of vibration and temperature. The aim of the invention is to increase the accuracy. The measurements are carried out in the mode of dynamic frequency clamping, simultaneously with the determination of the resonant (P) frequencies for each K-th fixed level (V / excitation) are recorded at different (1 + 1) / temperature Y, where I 0.1,2,3 .., To 0,1,2,3 ... numbers Y, amplitude values of P and forced oscillations, and then align them to the initially controlled values of i-ro Y by changing the phase of the microwave signal and the spatial orientation of the antenna axis, set to fixed distance from the product, according to the result The alignments are judged on the vibration characteristics, as well as the relative magnitudes and directions of thermal deformations of the elements of the products. 2 Il. WITH S

Description

The invention relates to measurement methods for testing various products on the simultaneous effects of vibration and other operational factors and can be used for contactless radio frequency studies of the static-dynamic parameters of structural elements of products subjected to vibration and temperature.

The purpose of the invention is to increase the measurement accuracy.

Figure 1 shows the functional diagram of the device for carrying out the proposed measurement method; FIG. 2 is a diagram of an embodiment of a measurement method

Statodynamic parameters of a structural element of a cantilever-type product when combined with vibration and temperature.

In Figure 2, the following notation is accepted: a — normal conditions + vibration; b - the complex effect of vibration and temperature; And - the antenna; K - the element under study; O - base - vibrating table; Lou O) - amplitude value of the change in the phase of the reflected signal due to vibration; X (o) is the amplitude value of the vibration displacement; Dui is a component of the phase shift when the distance is changed due to thermal deformation, AHO is the linear deformation (deflection) of the surface of the product; I - Linear VI VJ ate with

J

the size of the antenna pattern in the measurement plane: L is the linear size of the product; Q is the vibration frequency, n is the normal to the element surface; O index refers to normal conditions; T index refers to complex test conditions.

The device consists of a C8H thermo-insulated measuring head of the autodyne 1, which is installed inside the camera of the thermal substation 2 on the coordinate device 3 with the following drive from the control unit 4 and the coordinate measurement 7, the processing and measurement path 5, and the product 7 Avtodin consists of a series-connected thermostatted oscillator 8, a directional coupler 9, the second output of which is connected to the input of an amplitude detector 10, a phase shifter 11 and a horn antenna. 12 with a radiotransparent heat shield 13. The processing and recording information path includes, in series, a following filter 14, connected by an input to an output of an amplitude detector 10 and an output to a control and coordinate measurement unit A, a recorder 15, t + 1 whose inputs are connected to m measuring outputs a control and measurement coordinate unit 4, and a master oscillator 16 connected by a second output to the second input of the following filter 14, as well as an adjustable source 17 of power connected by the first output to the input of the autogenerator 8, second - to a second input of the phase shifter 11.

The oscillation excitation system 6 of the product 7 includes a vibrostand 18 connected to the input of the power amplifier 19, the input of which is connected to the first output of the master oscillator 16, the second input of which is connected to the output of the vibro-measuring transducer 20 (VIP) installed on the vibrating table.

The device works as follows

The signal emitted by the autogenerator 8 in the form of a narrow beam with the help of a horn antenna 12 is directed to the product 7, the oscillations of which are excited by the vibrating stand 18 and maintained at a predetermined level using the feedback circuit from the output of the VIP 20 to the second input of the master oscillator 16. direct and phase-modulated reflected signals on the nonlinear conductivity of the oscillator 8 occurs tightening and synchronization of the radiation frequency of the autodyne 1.

The autogenerator 8 switches to the vibration element mode of the investigated product 7. Through the second output of the directional coupler 9 modulated in amplitude and frequency, the signal is fed to the input of the amplitude detector 10, the output of which separates the envelope of the carrier frequency

0 action of the excitation frequency. Due to the thermostatting of the autogenerator 8 and the thermal stabilization of the elements of the microwave path, as well as the use of the radio transparent heat shield 13 of the antenna 12, the influence

5 changes in the modes of the heat chamber 2 for the operation of autodyne 1 will be minimal. From the output of the amplitude detector 10, the signal is fed to the input of the path 5 processing and registration. Detuning main frequency

0 harmonics of the measured signal from the background of the side frequencies are performed by the following filter 14. The output voltage of the master oscillator 16 is used to excite the vibrating stand 18 via the amplifier 19, and to synchronize the excitation frequency to the fundamental harmonic frequency of the filter 14 via the second output, the output of which is fed to the first input of the recorder 15 level. The output of the recorder 15 synchronizes the speed of scanning the frequency of the generator 16.

When exposed to temperature, simultaneously with vibration, heat deformations can occur, which, with fixed test modes and antenna angular coordinates, will lead to changes in the direction of reception of signals of maximum levels coinciding with the direction of the normal K of the effective reflecting surface of the element being investigated. Instead of one-dimensional, spatial components of the vibration vector may arise, which, for a fixed direction of the antenna’s axis,

0 lead to a decrease in the signal level at the output of the detector 10, and, consequently, to the emergence of a methodological component of the error due to thermal deformations. Using the coordinate

5, the device 3 and the phase shifter 11 for each fixed K-th excitation level at different it-1 temperature levels align the current values with the initially monitored values of the i-ro level. The alignment is carried out by angular displacements of the measuring holoaki. -Cht 1 with antenna 12, and Tstkho changes g /. and the phase shift of the radiation signal, in a way.

so that the output of the detector 10 achieves the maximum values of the signals that are monitored, which are monitored by the level 15 recorder. When the levels of the recorded signals are changed relative to the initially set and monitored values, the control and measurement unit 4 generates an error signal, which triggers the next drive of the coordinate device 3 and moves the autodyne measuring head 1. When the error signal reaches zero, the actuator turns off and the angular measurements are taken coordinates. The error signal is the difference between the two monitored voltage levels of the signals from the output of the tracking filter 14, corresponding to the I and 1 + 1 values of the temperature levels. From the output of unit 4, measurements of the coordinates of the voltage of the signals of the angular coordinates are recorded by a multi-channel recorder 15. The dynamic parameters of the investigated product or its elements are determined for different i and k levels based on the recorded dependence of the maximum values of the vibration signal at the frequencies of resonant and forced oscillations on the angular coordinates of the antenna axis.

The magnitude of the equalization rate is chosen higher than the scanning frequency of the excitation frequency from the condition of providing the specified measurement error. If it is necessary to investigate several elements, the measuring head of autodyne 1 is moved with the help of the coordinate device 3 in the measurement plane at a fixed distance by the antenna 12 and the product 7. The voltage signals of the linear coordinates of the product elements from the output of the block 4 are fed to the input of the level recorder 15. Based on the measured values of the vibration signal levels and the corresponding coordinates, the magnitude and direction of thermal deformations are determined.

The strain levels are determined relative to the initially controlled position of the product element under normal conditions (i 0) and no vibration (K 0) or relative to the base of the shaker table by converting the angular coordinates of the axis of the antenna 12 to linear displacements (deformations) of each of the elements. At the same time, the amplitude values of the vibration displacements of the deformed elements of the products are determined at the frequencies of forced and resonant vibrations. Regulation within specified limits of the output voltage of source 17

0

five

by constant tsk, respectively, on 1-channel / channel, remote control of the operating modes of the oscillator 8, on the 2nd to the neutral of the phase shifter 11,

We use the notation of FIG. 2. assuming that the static odin measurement is carried out in the far zone of the autodin antenna. Due to the difference in the travels of the reflected signals 1 and 2 arriving at point C, a phase shift occurs;

.. (T);

L g - O with g - SteosQt - DG-UUU bU- Ш5д -1кз PD 7 L

where OO With the optical path of the beam 1; BC is the optical path of beam 2; w (t) is the frequency of the radiation signal: s is the speed of light;

 the angle between the normal and the n ° ipt.

It can be shown that in the dynamic frequency tightening mode (t) (i), the phase of the reflected signal, taking into account relations (1), will be equal;

 hwq + / 3 || ®sln (Qt + a)) (2)

0

five

0

ft J $ jjP a a - $$

71 (o) xOW. „2 (JDoLo

W-D-p-G;

35

, s (1) (3)

0) Q U) Q

"Where flv are, respectively, the parameters defining the levels of phase conversion n matching the autodyne path to the load (the test item);

po, (i) Q is the phase shift and the frequency of the radiation signal with a matched load;

(0) is the amplitude value of the phase shift due to the dynamic delay of frequency;

Dsho, (o) - respectively, the ranges of static and dynamic tightening of the frequency of the oscillator;

LO is the distance between the antenna and the product.

From relations (2) and (3), it follows that 5 the proposed measurement method has a higher sensitivity than the known one :;) conversion, since at (o) (o) 0 the relative phase coefficient due to dynamic pulling is 1 for all values / V (o) 0.

The assumption is that the ranges of dynamic and static frequency tightening satisfy: 1

AWi (0) AW0. m V t4) and also limited by the first harmonic of the frequency of the current envelope of the amplitude detector i (t), for the conversion coefficient of the static-dynamic parameters of the measurement method we have:

A M BoWoP; (5)

L / R Poexp (-2ooLo)

2c

Oh

()) 4 -М + тггСДУ

/ Ai

To

W

(6)

where roya is gdt- t- respectively power- to

ness and wavelength of radiation; Oo attenuation coefficient;

BO 1-у "а /" about 4тРУ respectively, the dielectric and magnetic permeability of air and material of the walls of the WAVE tract with a cross section a x b;

PO resistivity of the material of the walls at T 20 ° C

"TC is the temperature coefficient of resistance of the wall material;

T ° - ambient temperature, ° C;

B0 is a hardware parameter not dependent on W0 and P.

In accordance with relations (5) and (6), the magnitude of the error in measuring the vibration parameters during complex testing can be represented as

O + F2 P

Due to the use of thermal stabilization of the autogenerator and thermal insulation of the measuring head of the autodyne, the value of

OODo

the error component can be

U / q

do no worse. Taking into account the data from relation (7) for an A 5A radiation wave

8 mm we have

In accordance with the symbols of FIG. 2 and relation (1), the levels and directions of the relative thermal deformations of the surface of the structural element can be defined as DH 1

BUT

Yoah

where is the thermal strain strain,

E is the modulus of elasticity.

It is assumed that, when exposed to temperature, the arising on the unit surface of the material of the element of the stress

and as a first approximation, proprtsionalnye change in temperature L T, we have

And ATKAT,

where a ™ is the proportionality coefficient.

At D 1 and a fixed direction from the euthodin measuring system, the total phase shift of the reflected 0 signal in C due to vibration and temperature will be equal;

A (t) Ap (o) cosfit — Ary;

Arto) Px (o), 5d | M1 | Katkd-p (9)

From relations (8) and (9) it can be seen that with fixed coordinates of the antenna axis with a change in temperature, the signal level, 0, which characterizes the interaction between the radiation field and the product, can decrease.

When A y e (t) no matter what

.)), the amplitude value of the current of the detector 1 (0), Achievement of the initially set maximum level (0) is provided by the phase shifter 10 for compensating Auze’s phase shift and changing the direction of the antenna axis by

angle), so that the direction of the normal to the surface of the element under study when the temperature varies within

AT ТР + 1 - Тр coincided with the direction of the measurement axis, i.e. corresponded to the maximum direction of the radiation - reception of the antenna pattern,

Making the alignment 1 (0) to the initial value, in accordance with the ratio of (8) and (9), determine the magnitude and direction A / changeA o () and the angle of rotation of the antenna axis at T ° T ° ny relative to the values at T ° T ° i.

Since the determination is carried out

5 measurements 1 (0), the accuracy of measurements of the magnitude and direction of thermal deformations will be determined by the value of the methodical error of the relation (7), as well as the instrumental error of the block 4

0 coordinate measurements.

Thus, in comparison with the known, the proposed measurement method provides an increase in the accuracy of measurements of the static-dynamic parameters of the elements

5 products at complex tests; higher sensitivity of vibration characteristics measurements at resonant and forced oscillation frequencies; measurement of thermal deformations for the same point (microminiature element) of the product in real time vibration exposure.

Claims (1)

The invention of the method for measuring the static-dynamic parameters of products when subjected to vibration and temperature, is that the product is irradiated with an electromagnetic microwave wave and mechanical oscillations, sweep the microwave wave phase and record the amplitudes of the waves, scattered products, which determine the resonant frequencies that differ in that, in order to increase the measurement accuracy, sweep the frequency of the microwave wave, oscillations at resonant and non-resonant frequencies 0 excitations are determined by | 01 2 tem perature levels and K 0 1,2. product vibration levels, for which the amplitudes of the green waves at the 1st K m level are aligned with the amplitudes for each 1st temperature at each K th radiation level, respectively, at the 0th temperature and 0th level vibrations, respectively, by changing the phase and the direction of irradiation of the electromagnetic wave, judging by the results, the vibration characteristics, as well as the relative magnitudes and directions of thermal deformations of the elements of the product, are judged. FIG X xfa X (o) CoS $ t x &) ° X (o) tassd FIG. 2