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GB/T 2423.56-2018 (GB/T2423.56-2018)

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GB/T 2423.56-2018
Environmental testing--Part 2. Test methods--Test Fh. Vibration, broadband random and guidance
ICS 19.020
K04
National Standards of People's Republic of China
Replaces GB/T 2423.56-2006
2018-12-28 release
2019-07-01 Implementation
State Administration of Market Supervision
Published by China National Standardization Administration
Contents
Foreword I
Introduction III
1 range 1
2 Normative references 1
3 Terms and definitions 2
4 Test requirements 6
4.1 General requirements 6
4.2 Basic movements 6
4.3 Lateral motion 6
4.4 Installation 6
4.5 Measurement system 6
4.6 Vibration tolerance 7
4.7 Control 9
4.8 Vibration response check 10
5 Severity Level 10
5.1 Test frequency range 10
5.2 Root mean square value of acceleration 10
5.3 Spectral Patterns of Acceleration Spectral Density 10
5.4 Test duration 11
6 Pretreatment 11
7 Initial test and function test 11
8 Test 11
8.1 General requirements 11
8.2 Initial vibration response check 11
8.3 Low magnitude incentive equilibrium before the test 12
8.4 Randomized trials 12
8.5 Final Vibration Response Check 12
9 Recovery 13
10 Final test and function test 13
11 Information to be given in the relevant specifications 13
12 Information to be given in the test report 14
Appendix A (informative) Standard test spectrum 15
Appendix B (informative) Guideline 21
References 24
Foreword
GB/T 2423 "Environmental Test Part 2" is divided into several parts according to the test method.
This part is the 56th part of GB/T 2423.
This section is drafted in accordance with the rules given in GB/T 1.1-2009.
This section replaces GB/T 2423.56-2006 "Environmental Tests for Electrical and Electronic Products-Part 2. Test Methods Test Fh. Broadband
Random Vibration (Digital Control) and Guidelines. Compared with GB/T 2423.56-2006, in addition to editorial changes, the main technical changes are as follows.
--- Removed the bandwidth symbol "Br" (see 3.1 of the.2006 version);
--- Added "lateral motion", "actual motion", "fixed point", "control method", "single point control", "measurement point", "sampling frequency", and "multipoint control"
Terms and definitions for "control strategy", "peak factor", and "test frequency range" (see 3.1, 3.2, 3.3, 3.4, 3.4.1, 3.6, 3.12, 3.13,
3.16, 3.37);
--- Modified "multi-point average control" to "multi-point control" and the definition of terms (see 3.4.2, 3.20 of the.2006 version);
--- Added the acceleration spectrum density symbol "ASD" (see 3.18);
--- The definition of the term "controlling the acceleration spectral density" has added "or virtual reference points" (see 3.19, 3.5 of the.2006 version);
--- Modified the terminology of "Clip of the drive signal", "Effective frequency range", "Indication of acceleration spectral density", "Root mean square value" and "Standard deviation"
Meaning (see 3.21, 3.22, 3.27, 3.33, 3.34, 3.10, 3.11, 3.17, 3.28, 3.29 of the.2006 edition);
--- Increased the frequency resolution symbol "Be" (see 3.26);
--- Added the statistical DOF symbol "DOF" (see 3.36, 3.31 of the.2006 version);
--- Modify the term "random wave" in the definition of "true acceleration spectral density" to "random signal" (see 3.38,.2006 version
3.33);
--- Deleted the definitions of the terms "deviation", "damping ratio", "distortion", "frequency sweep cycle" and "window function" (see 3.3, 3.8,
3.9, 3.32, 3.34);
--- Amended the relevant content of "General requirements" (see 4.1, 4.1 of the.2006 version);
--- Amended the relevant content in the "Basic Movement" and added notes (see 4.2, 4.3.1 of the.2006 version);
--- Increased the "measurement system" (see 4.5);
--- Increased "control" (see 4.7);
--- Related relevant content in "Vibration Response Check" (see 4.8, 4.2 of.2006 edition);
--- Added the rule "Test samples should be installed in accordance with the requirements of IEC 60068-2-47. In all cases, in IEC 60068-2-47
To select a curve, first square it and then multiply it by the acceleration spectral density (ASD) or directly by the sine amplitude. "(See 4.4,.2006 edition
4.4);
--- Added the stipulation that "the probability density function for calculating the reference point at the beginning, middle and end of the test should last 2 minutes each. Related regulations
Fan should specify the tolerance of the normal distribution "and" Figure 2 "(see 4.6.2, 4.3.3 of the.2006 edition);
--- Added the title "ASD and rms values" (see 4.6.1, 4.3.4 of the.2006 version);
--- Added the rule "If the relevant regulations provide that the confidence level is to be met in the test, Figure 3 should be used to calculate the accuracy of the statistical results
Sex "(see 4.6.3, 4.3.5 of the.2006 edition);
--- Modified the method and formula for selecting the frequency resolution Be and related content (see 4.6.4, 4.3.6 of the.2006 version);
--- Modified "Acceleration Spectrum Density" to "Acceleration Root Mean Square" (see 5.2, 5.3 of the.2006 edition);
--- Modified the "initial test" to "initial test and function test" (see Chapter 7, Chapter 7 of the.2006 edition);
--- Modified "Vibration response" to "Initial vibration response" and related content (see 8.2,.2006 version 8.2);
--- Modified the "random vibration test" to "random test" and related content (see 8.4,.2006 version 8.4);
--- Modified the "test duration" (see 5.4, 5.5 of the.2006 version);
--- Modified the "intermediate detection" to "intermediate detection and function detection" and related content (see 8.4.2, 8.5 of the.2006 version);
--- Modified the "final test" to "final test and function test" and related content (see Chapter 10, Chapter 10 of the.2006 edition
chapter);
--- Added "Information to be given in the test report" (see Chapter 12);
--- Removed the normative appendix "Vibration Response Check" (see Appendix A of the.2006 edition);
--- Informative appendix "Standard Test Spectrum" (see Appendix A).
This section uses the translation method equivalent to IEC 60068-2-64..2008 "Environmental Tests Part 2-64. Test Test Fh. Broadband
Random Vibrations and Guidelines.
The Chinese documents that have a consistent correspondence with the international documents referenced normatively in this section are as follows.
--- GB/T 2298-2010 Vocabulary for mechanical vibration, shock and condition monitoring (ISO 2041..2009, IDT);
--- GB/T 2421.1-2008 Overview and guidelines for environmental testing of electric and electronic products (IEC 60068-1. 1988, IDT);
--- GB/T 2422-2012 Environmental Test Test Method Compilation Guide Terms and Definitions (IEC 60068-5-2..1990,
IDT);
--- GB/T 2423.10-2008 Environmental testing for electric and electronic products Part 2. Test methods Test Fc. Vibration (sine)
(IEC 60068-2-6..1995, IDT);
--- GB/T 16499-2017 Number of electrical and electronic safety publications and basic safety publications and multi-professional shared safety publications
Application guidelines (IEC Guide104..2010, NEQ).
The following editorial changes have been made in this section.
--- Modified the standard name.
This section is proposed and managed by the National Technical Committee for Environmental Conditions and Environmental Testing of Electrical and Electronic Products (SAC/TC8).
This section was drafted. Guangzhou University, the Fifth Institute of Electronics of the Ministry of Industry and Information Technology, Beijing University of Aeronautics and Astronautics, Shanghai Quality Supervision
Inspection Technology Research Institute, Suzhou Sutest Test Instrument Co., Ltd., Beijing Zhongyuan Environmental Test Electromechanical Equipment Technology Co., Ltd., China Aviation Comprehensive
Institute of Technology.
The main drafters of this section. Xu Zhonggen, Ji Chunyang, Li Chuanri, Lu Zhaoming, Xu Liyi, Zhang Yue, Xu Ming, and Liu Qihua.
The previous versions of the standards replaced by this section are.
--- GB/T 2423.56-2006.
introduction
The broadband random vibration test of this part of GB/T 2423 is applicable to components, equipment and other products that will be subjected to random vibration during their lifetime.
The product is called "test sample" in the following text. This test method is based on digitally controlled random vibration test technology. Relevant specifications such as
As required, this section allows appropriate adjustments to the test method to apply to test samples of other types of products.
Compared with most other experiments, the test Fh is not based on deterministic techniques but based on statistical techniques. Broadband Random Vibration
Tests are described in terms of probability and statistical averages.
It should be noted that random vibration tests always require a certain degree of engineering judgment, and both the supply and demand sides must fully realize this fact. Have
The author of the relevant specification needs to choose the test method and the severity level suitable for the test sample and its application.
This test method is mainly based on the use of an electric or a servo-hydraulic shaker with a computer-aided control system.
Appendices A and B are informative appendixes that give examples of test spectra for tests under different conditions, detailed rules to be considered when preparing specifications,
Guidelines.
Environmental tests. Part 2. Test methods
Test Fh. Broadband Random Vibration and Guidelines
1 Scope
This part of GB/T 2423 provides the standard test method for random vibration to determine whether the sample is subjected to the specified random vibration test.
The ability to resist dynamic loads without unacceptable functional degradation and/or compliance with the overall structure.
Broadband random vibration can be used to identify cumulative effects of stress and degradation of specific functions. Combining this information with relevant specifications, you can
Used to assess whether the sample is acceptable.
This section applies to samples that may be subjected to random vibrations in the transport or work environment, such as in aircraft, spacecraft and land vehicles
It is mainly used for samples without packaging, and samples whose packaging is part of the sample itself during transportation. However, for already
For packaged samples, the samples together with their packaging are regarded as samples. For the test of packed samples, this section can be compared with GB/T 2423.43-
Commonly used in.2008.
If the sample is subjected to random and deterministic mixed vibration during transportation or actual life cycle environment, such as in aircraft, spacecraft and container transportation
In losing, it is not enough to test the sample with purely random conditions. Refer to GB/T 2424.26-2008 to estimate the sample dynamic vibration ring
Environment, and select the appropriate test method based on this.
This section mainly applies to electrical and electronic products, but also applies to products in other fields (see Appendix A).
2 Normative references
The following documents are essential for the application of this document. For dated references, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
GB/T 2423.43-2008 Environmental test for electric and electronic products Part 2. Test methods Vibration, shock and similar dynamics
Installation of test samples (IEC 60068-2-47..2005, IDT)
GB/T 2424.26-2008 Environmental testing for electric and electronic products. Part 3. Supporting documents and guidelines for vibration test selection
(IEC 60068-3-8..2003, IDT)
IEC 60050-300 International Electrotechnical Terminology (IEV) Electronic measurement and electronic measuring instruments-Part 311. General principles of measurement
Part 312. General principles of electronic measurement. Part 313. Classification of electronic measuring instruments. Part 314. Technical terms related to the type of instrument.
IEC 60068-1 Environmental Testing Part 1. Overview and Guidelines (Environmental testing-Part 1. General and guidance)
IEC 60068-2-6 Environmental Tests Part 2-6. Test Methods Test Fc. Vibration (Sine) (Environmental testing-Part 2-6. Tests-TestFc. Vibration (sinusoidal)]
IEC 60068-5-2 Environmental Tests Part 5-2. Guidelines for the Preparation of Test Methods Terms and Definition
IEC 60721-3 (all parts) Classification of environmental conditions Part 3. Classification of environmental parameter groups and their severity
Preparation of IEC Guide104 safety publications and application guidelines for basic safety publications and multi-professional shared safety publications
ISO 2041 Vibration and Shock-Vocabulary
3 terms and definitions
The following terms and definitions apply to this document.
Note. The terms used are generally defined in IEC 60050-300, IEC 60068-1, IEC 60068-2-6, IEC 60068-5-2 and ISO 2041. If this
Including the definition of one of these sources will indicate the derivation process and point out deviations from the definitions in these sources.
3.1
Cross-axismotion
The movement along the non-excitation direction is generally performed along two axes orthogonal to the excitation direction.
Note. The lateral movement needs to be measured near the fixed point.
3.2
Actualmotion
The movement represented by the wideband signal returned by the reference point sensor.
3.3
Fixingpoint
The part of the test sample that is in contact with the fixture or shaker is usually the place where the test sample is fixed in use.
Note. If a part of the actual mounting structure is used as a fixture, the fixed point refers to the fixed point of the mounting structure and not the fixed point of the test sample.
3.4
Controlmethods
3.4.1
Single point control
A control method implemented by using a signal from a sensor at a reference point to keep the signal at a prescribed vibration level.
3.4.2
Multipoint control
The method is controlled by sensor signals from various inspection points.
Note. Whether the signal is processed by continuous arithmetic averaging or comparison technology is determined according to relevant specifications. See 3.13.
3.5
gn
The standard acceleration due to the gravity of the earth varies with altitude and geographic latitude.
Note. For ease of use, gn is rounded to 10m/s2 in this section.
3.6
Measuring points
Certain points of data collected during the experiment.
Note. These points are divided into three categories, see 3.7 ~ 3.9 for specific definitions.
3.7
Check-point
The point on the fixture, vibration table or test sample, as close as possible to the fixed point of the test sample, and in any case
Fixed point rigid connection.
Note 1. The use of multiple checkpoints is a measure to ensure that the test requirements are met.
Note 2. If there are less than or equal to four fixed points, all are used as checkpoints. For packaged products, the fixed point at this time is the packing table that the shaker contacts.
On the other hand, if there is no resonance effect of the shaking table or mounting structure in the frequency range of the test, a checkpoint can be used. Otherwise need to use multiple points
Control, but also refer to Note 3. If there are more than four fixed points, the relevant specifications need to specify 4 representative fixed points for inspection.
Note 3. In special cases, such as for large or complex test samples, if the inspection point is not required to be close to the fixed point, it shall be specified in the relevant specifications.
Note 4. When a large number of small test samples are installed on a fixture, or when a small test sample has many fixed points, a single checkpoint (i.e.
(Reference point) to derive the control signal. This signal reflects the characteristics of the fixture, not the fixed point of the test sample. This only works if the fixture is fitted with a test sample
It is only feasible if the lowest resonance frequency after the load is much higher than the upper limit of the test frequency.
3.8
Reference point (single-point control)
The signal selected from the check points is used for test control to meet the requirements of this section.
3.9
Fictitiousreferencepoint (multipointcontrol)
Points derived from multiple inspection points, either manually or automatically, are used for test control to meet the requirements of this section.
3.10
Responsepoints
Points located at specific locations on the test sample. Data are obtained from these points for vibration response analysis.
Note. These points are different from checkpoints or datum points.
3.11
Priority test axes preferredtestingaxes
According to the actual situation, the three orthogonal axes corresponding to the weakest test samples are selected.
3.12
Sampling frequency
The number of discrete amplitudes collected per second for digitally recording or representing a time course.
3.13
Multipointcontrolstrategies
The method of calculating the reference control signal when using multi-point control.
Note. For discussion of control methods in different frequency regions, see 4.7.1.
3.14
Average averaging
The process of determining the control of the acceleration spectral density formed by arithmetically averaging the acceleration spectral densities on the spectral lines corresponding to multiple checkpoints.
3.15
Extreme (maximum or minimum) extremal (maximum or minimum)
Determine the control acceleration spectral density formed by the maximum or minimum value of the acceleration spectral density on the corresponding spectral lines of multiple checkpoints
process.
3.16
Crestfactor
The ratio of the peak value to the root mean square value of the time history.
[ISO 2041]
3.17
-3dB bandwidth-3dBbandwidth
The frequency width between two points corresponding to 0.707 times the maximum response of a single resonance peak in the frequency response function.
3.18
Acceleration spectral density acceleration spectrum density; ASD
When the bandwidth approaches zero and the averaging time approaches infinity, the addition of the central frequency narrowband filter on each unit bandwidth
Mean squared speed signal.
3.19
Control acceleration spectral density
Acceleration spectral density measured at a fiducial or virtual fiducial.
3.20
Control system loop
This includes the following operations.
--- Digitization of analog random signals on reference points or virtual reference points;
--- Perform necessary data processing;
--- Generate an updated analog drive signal for the vibration system power amplifier (see B.1).
3.21
Clipping of drive signals
The limit of the maximum drive signal is expressed by a crest factor (see Figure 1).
3.22
Effective frequency range
Frequency range from 0.5 times f1 to 2.0 times f2 (see Figure 1).
Note. Because of the initial slope and falling slope, the effective frequency range is greater than the test frequency range between f1 and f2.
3.23
Acceleration spectrum density erroraccelerationspectraldensity
The difference between the specified acceleration spectral density value and the control-implemented acceleration spectral density value.
3.24
Equalization
The process of minimizing the acceleration spectral density error.
3.25
Final slope
The part of the acceleration spectral density greater than f2 (see Figure 1).
3.26
Frequency resolution
Be
The width of the frequency interval in the acceleration spectral density, in hertz.
Note. In order to calculate the specified acceleration spectral density in digital analysis, the sampling record is divided into several parts, and the reciprocal of the sampling length (T) of each part is
Resolution. In the frequency range, the number of frequency lines is equal to the number of frequency intervals.
3.27
Acceleration spectrum density indicated acceleration spectral density
The true acceleration spectral density read from the analyzer is affected by instrument error, random error, and system deviation.
3.28
Initial slope
The portion of the acceleration spectral density that is less than f1 (see Figure 1).
3.29
Instrument error
Errors caused by each analog link of the control system and its inputs.
3.30
Random error
Due to the limitation of different actual averaging time and filter bandwidth, the acceleration spectral density estimation error.
3.31
Record
A collection of equally spaced data points in the time domain for fast Fourier transform calculations.
3.32
Reproducibility
The degree of consistency between the results of the same parameter and value measurement under the following different conditions.
--- Different test methods;
--- different measuring instruments;
--- different observers;
--- different laboratories;
--- After a longer time interval relative to the duration of a single measurement;
--- Different instrument usage habits.
Note. The term "reproducibility" can also be applied when some of the above conditions are met.
[IEC 60050-300, amendment]
3.33
Root-mean-squarevalue
The root mean square values of all frequencies of the single-valued function in the interval f1 and f2 are the average of the squared average of the function values in the interval
Square root value (see Figure 2).
3.34
Standard deviation
According to the vibration theory, when the average value of the vibration amplitude is equal to 0, for a random time history, the standard deviation of the vibration is equal to the root mean square value (see
figure 2).
3.35
Statistical accuracy
The ratio of the true value of acceleration spectral density to the displayed value of acceleration spectral density.
3.36
Statistical degrees of freedom
DOF
When using the time averaging method to estimate the acceleration spectral density of random data, the statistical degree of freedom depends on the frequency resolution and the effective average time.
(See Figure 3).
3.37
Test frequency range
In the frequency range between f1 and f2 (see Figure 1), the relevant specifications need to specify that the ASD is a flat spectrum or other spectral shape.
3.38
True acceleration spectral density true acceleration spectral density
Acceleration spectral density of a random signal acting on a test sample.
4 Test requirements
4.1 General requirements
When testing, the entire vibration system including power amplifiers, vibration generators, test fixtures, test samples, and control systems should be full.
Meet the necessary performance requirements.
The standard test method generally consists of the following test sequences, which are applied to the mutually perpendicular axial directions in the test sample.
1) Check the initial vibration response with a low magnitude sine or random excitation (see 8.2);
2) Mechanical load or stress test with random excitation;
3) The final response check is compared with the results of the initial response check.
Mechanical failure (see 8.2 and 8.5).
When the dynamic response is known and irrelevant, or when sufficient data can be collected in the case of full-scale tests, the relevant regulations provide that
No vibration response check is required before and after the test.
4.2 Basic movement
Relevant specifications shall specify the basic movement of the fixed points of the test sample. These fixed points should have approximately the same operation in phase and amplitude.
It should move linearly with respect to the direction of excitation. If it is difficult to achieve exactly the same motion at each point, multi-point control should be used.
Note. For large structures and high frequency ranges, such as 20Hz ~.2000Hz, the dynamic characteristics of test samples may require multi-point control.
4.3 Lateral motion
If required by the relevant specifications, the lateral motion shall be checked by applying sinusoidal or random vibrations as specified in the relevant specifications before the test, or
During the test, additional monitoring channels of two orthogonal axes were used to check the lateral movement.
When the acceleration spectral density of each frequency point of the checkpoint is measured on two axes that are perpendicular to each other, it should not exceed 500Hz.
The specified value should not exceed -3dB of the specified value when it is below 500Hz. Root mean square value of total acceleration of any axis perpendicular to the specified axis
It should not exceed 50% of the root mean square value of the specified axis. For example, in the case of small test samples, the relevant specifications can limit the acceleration of lateral movement
Degree of spectral density to ensure that it does not exceed -3dB of basic motion.
At some frequencies or for test samples with large sizes or high centroids, achieving these values may be difficult. Again, in this case
It is also difficult to achieve these values when the relevant regulations specify a strict level with a large dynamic range. In this case, the relevant specifications
Provision should be made for one of the following.
a) Any lateral movement exceeding the above-mentioned values shall be recorded in the test report;
b) Transverse movements known not to cause damage to the test specimen need not be monitored.
4.4 Installation
The test samples shall be installed in accordance with the requirements of IEC 60068-2-47. In all cases, first select the curve when selecting the curve in IEC 60068-2-47
Multiply the square by the acceleration spectral density (ASD) or directly by the sine amplitude.
4.5 Measurement system
The characteristics of the measurement system shall be such that the actual value of the measured vibration from a given axial point in the reference point is within the tolerance required by the test.
The entire measurement system includes sensors, signal conditioners, data collectors and data processors, and its frequency response has a significant effect on measurement accuracy.
influences. The frequency range of the measurement system should extend from 0.5 times the lowest frequency (f1) of the test to 2.0 times the highest frequency (f2) (see Figure 1).
The frequency response of the measurement system in this frequency range should be flat and within ± 5%. Any further deviations outside this range should be
Recorded in the report.
Figure 1 Tolerance range, initial slope and final slope of acceleration spectral density (see B.2.3)
4.6 Vibration tolerance
4.6.1 ASD and rms values
The indicated values of the specified acceleration spectral density including the instrument error and random error at the reference point in the specified direction are shown in f1 and f2 in Figure 1.
Within ± 3dB tolerance range.
Within f1 and f2, the calculated root mean square value of acceleration must not deviate from the root mean square value of the specified acceleration spectral density by 10%
the above. This value applies to datum points and virtual datum points.
At some frequencies or for test samples with large sizes or high centroids, it may be difficult to achieve these values. In these cases, relevant
The specification should specify a wider tolerance.
The initial and final slopes should be no less than 6dB/oct and no more than -24dB/oct, respectively (see also B.2.3).
4.6.2 Distribution
As shown in Figure 2, the instantaneous acceleration value of the reference point should be approximately normal (Gaussian) distribution. If there is an explicit requirement,
Verification shall be performed (see B.2.2).
The clipping value of the drive signal should be at least 2.5 (see 3.16). Detect the crest factor of the acceleration waveform at the reference point to ensure that the signal contains the
Set a peak value of at least 3 times the rms value, unless otherwise specified by the relevant specifications.
If virtual reference point control is used, the required crest factor is applicable to all checkpoints that form acceleration spectral density control.
The probability density functions used to calculate the reference points at the beginning, middle, and end of the test should each last 2 min. Relevant specifications should provide for normal analysis
The tolerance of the cloth (see Figure 2).
Figure 2 Time history of random excitation;
Gaussian (normal) distribution probability density function
(Crest factor = 3 as an example, see 3.14 and 4.6.2)
4.6.3 Statistical accuracy
Statistical accuracy is determined by statistical degrees of freedom Nd and confidence values (see Figure 3). The statistical degrees of freedom are given by.
Nd = 2Be × Ta (1)
Where.
Be --- frequency resolution;
Ta --- effective average time;
Nd --- Unless otherwise specified in the relevant specifications, Nd should not be less than 120DOF statistical degrees of freedom. If the relevant regulations stipulate that
To meet the conf......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.