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GB/T 2423.5-1995 (GB/T2423.5-1995)

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GB/T 2423.5-1995English150 Add to Cart 0--10 minutes. Auto-delivery. Environmental testing for electric and electronic products - Part 2: Test methods - Test Ea and guidance: Shock GB/T 2423.5-1995 Obsolete GB/T 2423.5-1995


GB/T 2423.5-1995: PDF in English (GBT 2423.5-1995)
GB/T 2423.5-1995
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
GB/T 2423.5-1995 / IDT IEC 68-2-27:1987
Replacing GB 2423.5-81
GB 2424.3-81
Environmental Testing for Electric and Electronic
Products - Part 2: Test Methods - Test Ea and
Guidance: Shock
APPROVED ON: AUGUST 29, 1995
IMPLEMENTED ON: AUGUST 01, 1996
Approved by: State Bureau of Technical Supervision
Table of Contents
Foreword ... 3
IEC Foreword ... 4
1 Objective ... 5
2 General Description ... 5
3. Definitions ... 6
4. Description of Test Apparatus ... 7
5. Severities ... 8
6 Pre-Conditioning ... 9
7 Initial Inspection ... 9
8 Conditional Test ... 9
9 Recovery ... 10
10 Final Inspection ... 10
11 Information to be Given in the Relevant Specification ... 10
Appendix A (Normative) Guidance ... 14
Appendix B (Normative) Shock Response Spectrum and Other
Characteristics of Pulse Waveform ... 21
Appendix C (Normative) Comparison among Collision Tests ... 31
Foreword
This Standard equivalently adopts the International Electrotechnical Commission
standard 3rd edition (1987) of IEC 68-2-27 “Environmental Testing – Part 2: Test
Methods – Test Ea and Guidance: Shock”.
This Standard replaced GB 2423.5-81 “Electric and Electronic Products - Basic
Environmental Test Regulations for Electricians - Test Ea: The Impact Method” and GB
2424.3-81 “Electric and Electronic Products - Basic Environmental Test Regulations
for Electricians – Guidelines for Impact Tests”.
GB 2423.5-81 and GB 2424.3-81 were drafted by reference of the International
Electrotechnical Commission standard 2rd edition (1972) of IEC 68-2-27 “Basic
Environmental Test Regulations – Part 2: Test Methods – Test Ea and Guidance:
Shock”; divided one standard of the International Electrotechnical Commission into two
standards; its text became the shock test methods in GB 2423.5; while its appendix
became the shock test guidance in GB 2424.3. This revision incorporates the test
methods and guidance; like the 3rd edition of IEC 68-2-27, add Clause 3 Definitions.
Increase the appendix from 1 to 3; namely, Appendix A: Guidance; Appendix B: Shock
Response Spectrum and Other Characteristics of the Pulse Waveform; Appendix C:
Comparison of Shock Test Methods. Relax restrictions for tolerance requirements of
pulse waveforms.
This Standard was first-time published in 1981; first-time revised in August, 1995. It is
implemented since the August 01, 1996.
The original China’s national standards of GB 2423.5-81 and GB 2424.3-81 were
abolished at the same time since the date of implementation.
This Standard’s Appendixes A, B and C are standard ones.
This Standard was proposed by the Ministry of Electronics Industry of the People’s
Republic of China.
This Standard shall be under the jurisdiction of National Technical Committee on
Environmental Conditions of Electric and Electronic Products and Environmental Test
of Standardization of China.
Drafting organization of this Standard: No. 5 Institute of Ministry of Electronics Industry.
Chief drafting staffs of this Standard: Xu Yongmei, and Wang Shurong.
Environmental Testing for Electric and Electronic
Products - Part 2: Test Methods - Test Ea and
Guidance: Shock
1 Objective
To provide a standard procedure for determining the ability of a specimen to withstand
specified severities of bump.
2 General Description
This Standard was drafted according to the pulse waveforms; refer to Appendix A for
guidance on selecting and using these pulse waveforms. The characteristics of various
pulse waveforms shall be discussed in Appendix B. This Standard includes three pulse
waveforms, namely, semi-sine pulse, post-peak zigzag pulse and trapezoidal pulse.
The selection of pulse waveform depends on many factors, and the selection itself is
difficult, therefore, this Standard does not give priority sequence of the waveforms (see
Clause A3).
The purpose of the test is to reveal mechanical weakness and/or performance
degradation; use these materials, and combine with relevant regulations to determine
whether a specimen is acceptable or not. It may also be used, in some cases, to
determine the structural integrity of specimens or as a means of quality control (see
Clause A2).
This test is primarily intended for unpackaged specimens and for items in their
transport case when the latter may be considered as part of the specimen itself.
The bumps are not intended to reproduce those encountered in practice. Wherever
possible, the test severity applied to the specimen and shock pulse waveforms should
be such as to reproduce the effects of the actual transport or operational environment
to which the specimen will be subjected to or to satisfy the design requirements if the
object of the test is to assess structural integrity (see Clauses A2 and A4).
For the purpose of this test the specimen is always fastened to the fixture or the table
of the bump tester during conditioning.
In order to facilitate the use of this Standard, the text of this Standard also listed the
geographical latitude. For the purposes of this Standard, the value of gn, is rounded up
to the integer of 10 m/s2.
4. Description of Test Apparatus
4.1 Characteristic requirements
When the bump tester and/or fixture are loaded with the specimen, the shock pulse
applied at the check point shall be approximate to the one of the nominal curves about
acceleration versus time shown in virtual line.
4.1.1 Basic pulse shape
The true value of the pulse shall be within the tolerance limit in the relevant Figures
shown in solid line.
NOTE - Where it is not practicable to achieve a pulse waveform falling within the specified
tolerance. The relevant specification should state the alternative procedure to be applied (see
Clause A5).
All specified pulse waveforms are as follows, and their order of arrangement does not
indicate that the front pulse is prioritized.
Post-peak zigzag pulse: an asymmetrical triangle with a short fall time, as shown in
Figure1.
Half-sine pulse: half cycle of a sine wave, as shown in Figure 2.
Trapezoidal pulse: a symmetrical quadrilateral with short rise and fall time, as shown
in Figure 3.
4.1.2 Speed variation tolerance
For all pulse waveforms, the actual speed variation shall be within ±15% of its
corresponding nominal pulse value.
When the speed variation is determined by the integral of the actual pulse, it shall be
begun from pre-pulse 0.4D integral to post-pulse 0.1D, where D is the duration of the
nominal pulse.
NOTE: If the speed variation tolerance is not available due to lack of an accurate integration
device, the relevant specification should state the alternative procedure to be applied.
4.1.3 Transverse motion
The positive or negative peak acceleration at the check point, perpendicular to the
intended bump direction, shall not exceed 30% of the value of the peak acceleration
of the nominal pulse in the intended direction, when determined with a measuring
system in accordance with Sub-clause 4.2 (see Clause A5).
NOTE – If the transverse motion tolerance cannot be achieved, the relevant specification
should state the alternative procedure to be adopted (see Clause A5).
4.2 Measuring system
The frequency characteristics of the measuring system shall be such that it can be
determined that the true value of the actual pulse as measured in the intended direction
at the check point is within the tolerance range in the Figure prescribed by Sub-clause
4.1.1.
The frequency characteristics of the overall measuring system, which includes the
accelerometer, can have a significant effect on the measuring accuracy and shall be
within the tolerance limits shown in Figure 4 (see Clause A5).
4.3 Mounting
During the conditional test, the specimen shall be mounted to the fixture or the table of
the bump tester by its normal mounting means. Mounting method shall be as specified
in GB/T 2423.43-1995 Environmental Testing for Electric and Electronic Products -
Part 2: Test Methods - Mounting Requirements and Guidance of Components,
Equipment and Other Products for Shock (Ea), Collision (Eb), Vibration (Fc and Fd),
Stable Acceleration (Ga) and Similar Dynamic Tests.
5. Severities
The relevant specification shall give both the pulse waveform and the test severity level.
A pulse waveform given in 4.1.1 and a severity level specified in Table 1 shall be
selected.
Unless otherwise specified, a set of data on the same line in Table 1 shall be used.
The data of each line with * shall be preferred. The specified corresponding speed
variation is listed in Table 1 (see Clause A4).
NOTE: If the severity level in the Table 1 can’t simulate the effect of a known environment on
the sample, the relevant specification can use one of three standard pulse waveforms shown
in Figure 1, Figure 2 and Figure 3 (see Clause A4) to specify other suitable test severity level.
The relevant specifications state:
a) Whether the specimen is to be operated during the shock test and whether it is
to be monitored for its function; and/or
b) The specimen shall be able to subjected to the applied shock.
For both cases, the relevant specification shall give criteria for receipt or rejection.
9 Recovery
The relevant specification can propose recovery requirements.
10 Final Inspection
The specimen shall be submitted to the appearance, dimensional and functional
checks prescribed by the relevant specification.
The relevant specification shall give the criteria for receipt or rejection.
11 Information to be Given in the Relevant Specification
When relevant specification adopts this test, it shall give the following information:
a) Pulse waveforms (A3) (4.1.1);
b) Tolerance under special conditions (A5) (4.1.1);
c) Speed variation under special conditions (A6) (4.1.2);
d) Transvers motion under special conditions (4.1.3);
e) Mounting mode (4.3);
f) Severity level (A4) (Clause 5);
g) Pre-conditioning (Clause 6);
h) Initial inspection (Clause 7);
i) The direction and number of shocks only under special conditions (A7) (8.1);
j) Operating mode and functional monitoring (8.2);
Appendix A
(Normative)
Guidance
A1 Introduction
The test provides a method by which effects on a specimen comparable with those
likely to be experienced in practice in the environment to which the specimen will be
subjected during either transportation or operation can be reproduced in the test
laboratory. The basic intention of the test is not to simulate the real environment.
The parameters given are standardized and suitable tolerances are chosen in order to
obtain similar results when a test is carried out at different locations by different people.
The standardization of values also enables components to be grouped into categories
corresponding to their ability to withstand certain severities given in this Standard.
In order to facilitate the use of this Appendix the related clause numbers of the text are
referred to herein.
A2 Applicability range of shock test
Many specimens are susceptible to shock during use, loading/unloading,
transportation processes. The magnitude of these shock varies widely and has
complex properties. This Test provides a very convenient method for determining the
ability of a sample to withstand these non-repetitive shock conditions. For the repetitive
shock, it shall use GB/T 2423.6-1995 Environmental Testing for Electric and Electronic
Products - Part 2: Test Methods-Test Eb and Guidance: Bump (Appendix C).
The shock test is also applicable to structural integrity tests performed on the
component specimens for identification or quality management. In these cases, high
accelerations hocks are usually applied, the main purpose is to apply a known shock
to the internal structure of the specimen (especially for the specimens with cavities)
(Clause 2).
The specification writer intending to adopt this test should refer to Clause 11
“Information to be given in the relevant specification” in order to ensure that all such
information is so provided.
A3 Pulse waveform (Clause 2)
This Standard specifies three commonly used shock pulse waveforms. Any one of
them can be selected according to the purpose of the test (see also 4.1.1 and Table 1
of this Standard).
A5 Tolerance
The test method described in this standard is capable of a high degree of
reproducibility when the tolerance requirements relating to the pulse waveform,
velocity variation, and transverse motion are complied with.
However, there are certain exceptions to these tolerance requirements and these are
primarily applicable to specimens which provide a highly reactive load, that is with
mass and dynamic responses which would influence the characteristics of the bump
tester. In these cases, it is expected that the relevant specification will specify relaxed
tolerances or state that the values obtained will be recorded in the test report (see Sub-
clauses 4.1. 1, 4.1.2 and 4.1.3).
When testing highly reactive specimens it may be necessary to carry out preliminary
bump conditioning to check the characteristics of the loaded bump tester. With complex
specimens, where only one or a limited number is provided for test, the repeated
application of bumps prior to the definitive test, particularly for the lower number of
bumps, could result in an over-test and possibly unrepresentative cumulative damage.
In such instances it is recommended that, whenever possible, the preliminary checking
should be carried out using a representative specimen (such as rejected equipment),
or, when this is not available, it may be necessary to use model having the correct
mass and center of gravity position to carry out shock pre-conditioning. However, it
needs to be noted that the above model is unlikely to have the same dynamic response
as the real specimen.
For the frequency response of the entire measurement system including the
accelerometer, it is an important factor to reach the required pulse waveform and
severity level, which shall be within the tolerance range shown in Figure 4. If a low-
pass filter is used to reduce the high-frequency resonance effects inherent in the
accelerometer, then the amplitude-frequency characteristics and phase-frequency
characteristics of the measurement system must be considered to avoid the distortion
in the measurement system itself (see 4.2).
For the shock with pulse duration equal to or less than 0.5ms, the f3 and f4 shown in
Figure 4 may be too high; in this case, the relevant specification may be specified
otherwise (see 4.2).
A6 Speed variation (see 4.1.2)
For all pulse waveforms, it is necessary to determine the actual velocity variation. This
can be done in a number of ways., amongst which are:
- the shock pulses not involving rebound motion, which shall be determined by the
collision speed.
- the free-fall testers shall be determined by the height of falling and rebounding.
Appendix B
(Normative)
Shock Response Spectrum and Other Characteristics of Pulse
Waveform
Introduction
In order to utilize the improved technology in the shock test and to further develop the
impact tester, Test Ea requires one of three pulse waveforms with a specified severity
level to be applied to the fixed point of the specimen without limiting the used shock
tester. The selection of the pulse waveforms and severity levels shall be based on the
technical consideration applicable to the design and type of the specimen.
From the point of view for specifying the reproducibility of the test conditions and
reproducibility of influence on the actual shock environmental conditions, all methods
are feasible. In order to make the test both reproducible and practical, some basic
concepts must be considered when developing the test procedures and described as
follows:
B1 Concept of shock response spectrum
When developing the shock test procedures, the acceleration shock response
spectrum of various pulse waveforms has been considered; because under many
important practical situations, they provide useful magnitudes for potential damage to
the shock. However, it must be acknowledged that, from certain aspects, their
application has limitations.
The acceleration shock response spectrum can be considered to be the maximum
acceleration response as a function of the resonant frequency of the system for a given
undamped mass-elastic system under specified shock excitation. In most cases, the
maximum acceleration of the vibrations systems determines the maximum mechanical
stress of the joint and the maximum relative displacement of the elastic member.
Let the frame shown in Figure B1 withstand a shock excitation with a specified pulse
waveform, namely, the time period of the acceleration is d2Xf/dt2 = a(t). Since the mass,
m, determines the resonant frequencies (f1, f2, f3, etc.), the system response is an
oscillation with different acceleration time period.
Figure B2a is an example of pulse waveform with a peak acceleration of A and a
duration of D; its response acceleration d2X1/dt2 = a(t), etc. can refer to Figure B2b.
The shock response spectrum (see Figure B2c) is caused by an infinite number of
given in this Appendix has two coordinates, namely, amax/A as fD function, and amax as
f function shall be the special case of pulse duration and peak acceleration.
B2 Application of Level-I shock response spectrum in actual conditions
In components and equipment, their internal components typically form a more
complex system than an undamped system. For instance, the damped series multi-
degree-of-freedom system shown in Figure B3. In this case, when the external system
excites the oscillation due to the shock, the internal system may be damaged due to
the coupling resonance effect. Such effect can be illustrated by a series of effective
high-order shock spectra that give the mass-elastic separation system combined
resonant frequency.
If the resonant frequencies of the series system can be completely separated, then the
Level-I shock spectrum can give a reasonable magnitude of the potential damage
caused by comparing different pulse waveforms.
If the resonance is excited during the pulse period, then various masses in the system
shall reach the highest acceleration. In this case, the oscillation acceleration overlaps
with the pulse itself. Therefore, when suing a pulse with a short rise time, it is obvious
form Claus B3 that the damage is mostly likely to occur.
Generally, the damping can reduce the response of the mid-frequency-band during the
pulse duration and reduce the response of the mid-and-high-frequency-band after the
pulse. Meanwhile, damping can also reduce the amplitude of the oscillation and the
duration of oscillation; thus, attenuate the response of the internal system. So the
damage from the damping system may be lower than from the undamped system,
especially for the multi-degree-of-freedom system. Therefore, the shock response
spectrum of the undamped system represents the worst possible damage.
It can be seen from the above that the acceleration shock spectrum can’t fully explain
the damage capability of the shock. Nevertheless, this simplified method of expression
is sufficient to select a suitable shock pulse for the actual structure.
Before comparing the shock spectrum, the accurate shock test shall compare the long-
term response oscillation exhibited by the residual shock spectrum with the importance
of the short response oscillation exhibited by the initial response spectrum, and make
a judgment. Such judgment shall be based on a possible failure mode.
B3 Shock response spectrum of nominal pulse waveform
The acceleration shock response spectrum of the nominal pulse waveforms
recommended in this Standard can refer to Figures B4, B5 and B6.
Due to use of a dimensionless scale, for the same pulse waveform, regardless of its
pulse duration, it has the same form of shock spectrum. The normalized frequency
......
 
(Above excerpt was released on 2019-06-18, modified on 2021-06-07, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT2423.5-1995