Determine the ability of components and equipment to withstand random vibration of specified severity levels. GB/T 2423.14-1997 Environmental testing for electric and electronic products Part 2: Test method Test Fdc: Wideband random vibration - low reproducibility GB/T2423.14-1997 Standard download decompression password: www.bzxz.net

GB/T 2423.14—1997
This standard is equivalent to the International Electrotechnical Commission standard IEC68-2-37 "Environmental testing Part 2: Test method Test Fdc: Wide-band random vibration - low reproducibility" (1st edition in 1973) and Amendment No. 1 (August 1983). This standard replaces GB2423.14-82 "Basic environmental testing procedures for electrical and electronic products Test Fdc: Wide-band random vibration test method - low reproducibility". Chapters 1 and 2 of this standard are different from Chapters 1 and 2 of GB2423.14-82. GB2423.14-82 rewrites Chapters 1 and 2 of IEC68-2-37. This revision also adds the content of the International Electrotechnical Commission's Amendment No. 1 to IEC68-2-37 in August 1983.
This standard was first issued in 1982, revised for the first time in September 1997, and implemented on October 1, 1998. From the date of implementation of this standard, it will replace GB2423.14--82. This standard was proposed by the Ministry of Electronics Industry of the People's Republic of China. This standard is under the overall jurisdiction of the Standardization Institute of the Ministry of Electronics Industry. This standard is under the jurisdiction of the National Technical Committee for Environmental Technology Standardization of Electrical and Electronic Products. The drafting units of this standard are: the Standardization Institute of the Ministry of Electronics Industry, and the Fifth Institute of the Ministry of Electronics Industry. The main drafters of this standard are: Zhou Xincai, Wang Shurong, Zhang Youlan, Ji Chunyang, etc. 181
GB/T2423.14-1997
IEC Foreword
1. A formal resolution or agreement on a technical issue formulated by a technical committee of the International Electrotechnical Commission with the participation of all national committees that are particularly concerned about the issue. It reflects and expresses the international consensus on the issue as much as possible. 2. These resolutions or agreements are accepted by national committees in the form of recommended standards for international use. 3. In order to promote international unification, the International Electrotechnical Commission hopes that all member countries will adopt the contents of the International Electrotechnical Commission recommended standards as their national standards when formulating national standards, as long as the specific conditions of the country permit. Any differences between the International Electrotechnical Commission's recommended standards and national standards should be clearly pointed out in the national standards as much as possible. This standard was prepared by the 50A Subcommittee (Shock, Vibration and Other Dynamic Tests) of the 50th Technical Committee (Environmental Testing) of the International Electrotechnical Commission.
The first draft was discussed at the Stockholm Conference in 1968, and a new draft was discussed at the Tehran Conference in 1969. As a result of this conference, the final draft 50A (Central Office) No. 133 was submitted to the National Committees for voting according to the "six-month method" in February 1971. The following countries voted explicitly in favor of this standard: Australia
Austria
Belgium
Czechoslovakia
Hungary
Israel
Portugal
Turkey
National Standard of the People's Republic of China
Environmental testing for electric and electronic products
Part 2: Test methods
Test Fdc: Random vibration wide band - low reproducibilityEnvironmental testing for electric and electronic productsPart2:Test methods
Test Fdc: Random vibration wide band - low reproducibility band-Reproducibilitylow
1 Introduction
GB/T2423.14—1997
idt IEC 68-2-37: 1973
Replaces GB2423.14--82
The basic requirements for wide-band random vibration tests are given in GB/T2423.111997 (IEC68-2-34) Test Fd: General requirements for wide-band random vibration. In addition, three possible levels of reproducibility are specified, called high, medium and low reproducibility, and are represented by tests Fda, Fdb and Fdc respectively. Each of these test methods, together with its recommended verification method, constitutes a separate and complete standard. Therefore, all the information required by the specification writer is included in test Fd. The information required by the test engineer is included in test Fda, Fdb or Fdc respectively.
It is strongly recommended that users of this standard read this standard in conjunction with GB/T2423.11-1997 (IEC68-2-34). It must be noted that two particularly important terms in random vibration test issues are often mentioned throughout the standard text. In order to enable readers to better understand the content of this standard, the following definitions are given: Acceleration spectral density acceleration spectral density (ASD) Spectral density of acceleration variation, expressed as square of acceleration unit per unit frequency. Acceleration spectral density spectrum ASD spectrum The way in which the acceleration spectral density varies within the frequency range. 2 Purpose
To determine the ability of components and equipment to withstand random vibration of a specified severity level, this random vibration test is applicable to components and equipment that may be affected by random vibration conditions during use. The purpose of the test is to determine whether mechanical weaknesses and (or) specified performance have been degraded, and to use this information in conjunction with relevant specifications to determine whether the test sample is acceptable. When applying the environmental stress (conditional test) specified in this test, the test sample shall be subjected to a random vibration test of a given level within a wide frequency band. Because the test specimen and its fixture produce complex responses, this test requires special attention to the preparation, conduct and verification of the specified requirements.
3 Installation and control
3.1 Installation
The test specimen shall be installed on the test equipment in accordance with the requirements of GB/T2423.43--1995 (idt.IEC68-2-47) "Installation requirements and guidelines for components, equipment and other products in dynamic tests such as impact (Ea), collision (Eb), vibration (Fc and Fd) and steady-state acceleration (Ga)".
Approved by the State Administration of Technical Supervision on September 1, 1997 and implemented on October 1, 1998
3.2 Reference points and control points
GB/T2423.14-1997
The test requirements are verified by measurements made at all control points related to the reference points or, in some cases, the test specimen fixing points. When an assumed reference point is specified, only the control point needs to be measured. If many small test specimens are mounted on a fixture, then when the lowest resonant frequency of the load fixture exceeds the upper limit of the test frequency f2, the reference point and/or control point can be considered to be related to the fixture and not to the test specimen fixing point. 3.2.1 Fixing point
The fixing point is defined as the part of the test specimen that contacts the fixture or the vibration table. It is usually the place where the test specimen is normally tightened during use. If a part of the actual mounting structure is used as a fixture, then the fixing points of these mounting structures should be taken as the fixing points instead of the fixing points of the test specimen.
3.2.2 Control point
The control point is usually the fixing point. The control point should be as close to the fixing point as possible, and in any case its connection with the fixing point should be rigid.
If the test specimen has four or fewer fixing points, then each fixing point is used as a control point. If there are more than four fixing points, the relevant specification should specify four representative fixing points as control points. Note: For large and/or complex test samples, it is an important issue to specify control points in the relevant specifications. 3.2.3 Reference point
The reference point is a single point used to obtain the reference signal to verify the test requirements and represent the movement of the test sample. It can be a control point or an assumed point established by manually or automatically processing the signals of each control point. If an assumed point is used, the spectrum of the reference signal is specified as the arithmetic mean of the acceleration spectrum density values ​​of all control signals at each frequency. In this case, the total root mean square value of the reference signal is equal to the root mean square value of the root mean square value of the control point signal. The relevant specifications should state the reference point used, or explain how the reference point should be selected. For large and/or complex test samples, it is recommended to use assumed reference points.
4 Resonance check
If the relevant specification requires a resonance check, in the following sinusoidal test stage, the tolerance specified in GB/T2423.10-1995 (idtIEC68-2-6) Test Fc, Vibration (Sinusoidal) Test should be used. 4.1 Sine amplitude
Unless otherwise specified in the relevant specifications, the sine amplitude used for the resonance check shall be determined from Table 1 according to the acceleration spectral density level. This amplitude shall be applied to the reference point. If the random vibration condition test uses hypothetical points, then this sine amplitude shall be applied to the control point. Table 1
Acceleration spectral density level
(m/s)\/Hz
4.8--19.2
4.2 Resonance check method
(0.05--0.2)
Sine amplitude (peak value)
During the initial and final resonance checks, forward and reverse frequency sweeps shall be performed over the entire test frequency range. During the resonance check, the test sample shall be checked to determine the frequency of the following phenomena: a) malfunction and/or performance degradation of the test sample due to vibration; b) mechanical resonance of the test sample.
In order to study these effects more carefully and find the exact frequency, the frequency sweep may be interrupted. During the initial resonance check, all frequencies and amplitudes producing the above phenomena shall be recorded for comparison with the frequencies and amplitudes obtained in the final resonance check. The relevant specifications shall specify the measures to be taken when the resonant frequency changes. During the resonance check, the test sample shall be operated, if applicable. If the mechanical vibration characteristics of the test sample cannot be determined because it is in operation, an additional resonance check shall be carried out with the test sample in a non-operating state. Any arrangements made to detect internal effects of the test sample should not change the overall dynamic characteristics of the test sample too much. A recovery time must be specified after the conditioning test to allow the test sample to recover to the same conditions as at the beginning of the resonance check, such as temperature effects.
5 Vibration motion requirements
5.1 Basic motion
The basic motion of the fixed points of the test specimen shall be linear and its instantaneous acceleration values ​​shall have the random nature of a normal (Gaussian) distribution, and these points shall also have essentially the same motion. 5.2 Distribution
The distribution of instantaneous acceleration at the reference points shall normally be within the tolerance band shown in Figure 1. If assumed points are used, this distribution applies to the control points.
Note: For most random vibration tests, this distribution falls within the tolerance band and therefore only needs to be verified in exceptional cases. However, if possible, it is recommended to measure the acceleration waveform (e.g. visual inspection) to ensure that the peak value present is at least 2.5 times the root mean square value of the signal. 99.9
(X-3a)
(X+3g)
9——Total RMS acceleration
30 —2α —1#0
Figure 1 Tolerance band of instantaneous acceleration distribution
, 5.3 Spectrum of acceleration spectrum density and total RMS accelerationyo
The relevant specifications shall specify the level and frequency range of acceleration spectrum density. The spectrum of acceleration spectrum density is shown in Figure 2. With these values, the nominal value of total RMS acceleration can be determined at the same time. This value can also be obtained by looking up Table 3a and Table 3b. 185
GB/T2423.14——1997
Specified frequency range
N Nominal value of acceleration spectral density specified in I. Figure 2 Spectrum of acceleration spectral density
(Logarithmic scale)
The tolerance of the indicated value of acceleration spectral density and the tolerance of the true value of total root mean square acceleration read by the analysis equipment are shown in Table 2. It can be seen from this table that the tolerance of the true value of total root mean square acceleration is smaller than the tolerance of the indicated value of acceleration spectral density. In order to verify the motion requirements, it is only necessary to make acceleration measurements in the predetermined direction of the reference point. The verification of the tolerance of acceleration spectral density can be carried out by any method that meets the given tolerance. However, it is recommended to use the verification method specified in Appendix A of this standard.
Indicated value of acceleration spectral density
True value of total root mean square acceleration (f to f) ±2.0
Note: In special cases, it is specified to use a shaped spectrum. At this time, the specified method in Appendix A can still be used. 5.4 Total rms acceleration values ​​within the specified frequency range dB
The required total rms acceleration values ​​within the specified frequency range are given in Tables 3a and 3b. To verify these values, a low-pass filter is used with a cut-off frequency (3 dB) of f2. If the 3 dB bandwidth differs by more than 2% from the equivalent noise bandwidth obtained with a white noise input signal, this bandwidth shall be taken into account when using the rms values ​​calculated in this table. 5.5 Displacement limits
All shakers have displacement limits. In order to limit the peak displacement, a high-pass filter must be inserted in front of the power amplifier. Note: If the acceleration spectral density must be reduced in the low epilepsy range due to the displacement limit of the shaker, the reduced value must be stated and agreed upon by both the supplier and the buyer.
6 Initial testing
The test specimens shall be subjected to electrical and mechanical inspections in accordance with the relevant specifications. If the relevant specification requires a resonance check before and after the conditioning test, the entire procedure including the response check shall be completed on one axis and repeated on the other axes. The resonance check method is specified in 4.2. 7 Excitation before conditioning test
When a resonance check is performed using sinusoidal vibration, the time should be as short as possible and the amplitude applied is specified in 4.1. The complete test procedure including the resonance check and conditioning test shall be completed on one axis (and the test sample shall not be removed from the vibration table) and then repeated in sequence on the other axes. 186
GB/T2423.14—1997
Before conducting a formal (i.e. full-level) random vibration test, the test sample must first be subjected to a lower level of random excitation for pre-adjustment (i.e. equalization and preliminary analysis). The important issue is that the vibration level applied at this time should be kept to a minimum and the time should be kept to a minimum. Before the formal random vibration test is carried out, the pre-adjustment excitation time (i.e., the establishment time) allowed is: a) less than 25% of the specified level, no time limit; b) at 25% to 50% of the specified level, the time should not be more than 1.5 times the specified test time; c) at 50% to 100% of the specified level, the time should not be more than 10% of the specified test time. It must be noted that the above pre-adjustment excitation time should not be deducted from the specified test time. 8 Conditioning test
Unless otherwise specified in the relevant specifications, the test sample should be vibrated in three mutually perpendicular axes in turn, and the axis selection should be the easiest to expose the sample failure. The severity level is specified in the relevant specifications. Unless otherwise specified in the relevant specifications, in order to determine the function and mechanical effect, whenever applicable, during the conditioning test, the test equipment should be operated. For components, the relevant specifications should specify whether electrical and mechanical inspections are to be carried out during the conditioning test, and at which stage of the conditioning test these inspections are to be carried out.
The total root mean square acceleration within the specified frequency range shall be measured and controlled throughout the conditioning test. The values ​​are given in Tables 3a and 3b and the tolerances are as specified in 5.3.
To verify the velocity spectral density, samples of the instantaneous acceleration time history shall be taken during the conditioning test. The minimum duration of each sample shall be twice the maximum averaging time of the analysis equipment used. For tests lasting no more than 10 min, one sample is sufficient. For longer durations, samples shall be taken at the beginning and end of the conditioning test. If the settings of the vibration system are changed during the endurance conditioning test, additional samples shall be taken immediately after the change. For very long conditioning test durations, it is recommended that additional samples be taken during the conditioning test period.
The acceleration spectral density shall be verified both during and after the conditioning test. 9 Final testingWww.bzxZ.net
The test specimens shall be subjected to electrical and mechanical testing in accordance with the requirements of the relevant specifications. If a resonance check is required, a final resonance check shall be carried out as described in 4.2. Table 3a Total RMS acceleration values ​​
Total RMS acceleration for each frequency range for each acceleration spectral density (rectangular spectrum, unit; m/s\) Specified frequency range (~fz)
Specified
Acceleration
Spectral density
(m/s*)°/Hz
5~1505~20010~15Q10~20020~15Q20~20Q20~50020~2000|20~5 00050~50050~200050~5 000Total RMS acceleration
Specified
Acceleration
Spectral density
(m/s\)°/Hz
Specified
Acceleration
Spectral density
GB/T2423.14--1997
Table 3a (end)
Specified frequency range (f～f)
5~1505~20010~15010~20020~15020~20020~50020~2 000|20~500050~50050~2000/50~5000Total RMS acceleration
Total RMS acceleration value
Total RMS acceleration of hand-to-hand acceleration spectral density (rectangular spectrum, unit: g) Each frequency range for each
Specified frequency range (f～f)
5~1505-20010~15010-20020~15020~20020~50020~2 000|20~5 00050~50050~2 00050~5 000Total RMS acceleration
A1 Description
GB/T 2423.14—1997
Appendix A
(Standard Appendix)
Verification method
This verification method requires that the bandwidth of the analyzer used shall not be greater than one-third octave or 100 Hz (whichever is greater). The relevant specifications can specify the required system based on this requirement. The tolerances given for the acceleration spectral density values ​​are for the analyzer readings, not for the true values ​​of the acceleration spectral density. Because the accuracy of the analyzer spectrum depends on the bandwidth of the analyzer, this verification method refers to the requirements of the analyzer and does not cover all the peaks and valleys present in the response of the test sample. Due to this, the reproducibility from one laboratory to another is low. A2 Measurement of total deviation of equalizer
If a fixed filter equalizer is used, the filter bank should be checked according to the following procedure if necessary. The total deviation should be within ±2 dB or as specified in the relevant specifications.
The measurement of the equalization filter device should be carried out under the condition that all filters have the same level. The transfer function from the input to the output of the equalizer should be determined using a sinusoidal sweep signal from f, with a sweep rate not exceeding one octave per minute. The deviation (calculated in dB) within the range of f~f is the total deviation.
Note: In order to fully ensure that the filter device has good function in each test, the total deviation should be measured frequently. A3 Verification of acceleration spectral density
The bandwidth of the acceleration spectral density analyzer, whether it is a sweep or fixed filter, should not be greater than 100 Hz or one-third octave. The relevant specifications may specify a bandwidth that does not exceed these limits. If a sweep analyzer is used, the error caused by the selected sweep rate should be kept within the error range allowed when using a low sweep rate. If the sweep rate S value meets the following formula, the error is always small in any case. SAk
Where: S—-scan rate, Hz/s
B—analyzer bandwidth, Hz;
t—-averaging time, s;
Table———0.4, when true averaging time is used. Notes
1 If an RC circuit is used to calculate the average value, then t=2RC, =0.2.2 In addition to the true value deviation caused by the analysis method and the instrument, the readings obtained at each frequency are sometimes affected by time fluctuations. This is due to the randomness of random vibration. This fluctuation decreases as the averaging time increases. Without an averaging time of >30/B, this tolerance will not be met. The acceleration spectral density readings of the analyzer should be within ±3 dB at all points within the specified frequency range. A4 Verification of total root mean square acceleration
During the entire random vibration condition test, the total root mean square acceleration should be measured and controlled as specified in 5.3 and 5.4. This value should be within the tolerance of ±2 dB as the instrument error is reduced. 189
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