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GB/T 2423 Environmental testing - Part 2: Test methods comprises of several parts according to test methods.
This is part 10 of GB/T 2423.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 2423.10-2008 Environmental testing for electric and electronic products - Part 2: Tests methods - Test Fc: Vibration (sinusoidal). The following technical changes have been made with respect to GB/T 2423.10-2008:
—— test content for packaged specimens is added;
—— the selection of severity parameters is specified in details (see Clause 5 of this standard and Clause 5 of Edition 2008);
—— specification and description of control strategy are added (see 4.2);
—— the requirements for test report are added (see Clause 13).
This part, by means of translation, is identical to IEC 60068-2-6: 2007 Environmental testing - Part 2-6: Tests - Test Fc: Vibration (sinusoidal).
The Chinese documents consistent and corresponding with the normative international documents in this part are as follows:
—— GB/T 2298-2010 Mechanical vibration, shock and condition monitoring - Vocabulary (ISO 2041: 2009, IDT);
—— GB/T 2421.1-2008 Environmental testing for electric and electronic products - General and guidance (IEC 60068-1: 1988, IDT);
—— GB/T 2423.43-2008 Environmental testing for electric and electronic products - Part 2: Test methods - Mounting of specimens for vibration, impact and similar dynamic tests (IEC 60068-2-47: 2005, IDT);
—— GB/T 4798 (all parts) Environmental conditions existing in the application of electric and electronic [IEC 60721-3 (all parts)], and see Annex NA for the degree of consistency between various parts of the two standards.
For the convenience of use, the following editorial changes are made in this part:
—— the standard name is modified.
This part was proposed by and is under the jurisdiction of SAC/TC 8 Technical Committee on Environmental Condition for Electric and Electronic Products and environment test of Standardization Administration of China.
The previous editions of this part are as follows:
—— GB/T 2423.10-1981, GB/T 2423.10-1995, and GB/T 2423.10-2008;
—— GB/T 2423.7-1981.
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Introduction
This part of GB/T 2423 gives a method of test applicable to components, equipment and other articles (hereinafter referred to as specimen) which, during transportation or in service, may be subjected to conditions involving vibration of a harmonic pattern, generated primarily by rotating, pulsating or oscillating forces, such as occur in ships, aircraft, land vehicles, rotocraft and space applications or are caused by machinery and seismic phenomena.
This standard consists basically of subjecting a specimen to sinusoidal vibration over a given frequency range or at discrete frequencies, for a given period of time. The specified vibration response investigation shall be adopted to determine the critical frequencies of the specimen.
The relevant specification shall indicate whether the specimen shall function during vibration or whether it suffices that it still works after having been submitted to vibration.
It is emphasized that vibration testing always demands a certain degree of engineering judgement, and both the supplier and purchaser should be fully aware of this fact. However, sinusoidal testing is deterministic and, therefore, relatively simple to perform. Thus it is readily applicable to both diagnostic and service life testing.
The main part of this standard deals primarily with the methods of controlling the test at specified points using either analogue or digital techniques, and gives, in detail, the testing procedure. The requirements for the vibration motion, choice of severities including frequency ranges, amplitudes and endurance times are also specified. The relevant specification writer is expected to choose the testing procedure and values appropriate to the specimen and its use
Certain terms have been defined to facilitate a proper understanding of the text. These definitions are given in Clause 3.
Annex A gives general guidance for the test and Annexes B and C provide guidance on the selection of severities for components and equipment.
Environmental testing - Part 2：Tests methods - Test Fc: Vibration (sinusoidal)
1 Scope
This part of GB/T 2423 gives a method of test which provides a standard procedure to determine the ability of components, equipment and other articles, hereinafter referred to as specimens, to withstand specified severities of sinusoidal vibration. If an item is to be tested in an unpackaged form, that is, without its packaging, it is referred to as a test specimen. However, if the item is packaged then the item itself is referred to as a product and the item and its packaging together are referred to as a test specimen.
The purpose of this test is to determine any mechanical weakness and/or degradation in the specified performance of specimens, and to use this information, in conjunction with the relevant specification, to decide upon the acceptability of the specimens. In some cases, the test method may also be used to demonstrate the mechanical robustness of specimens and/or to study their dynamic behavior. Categorization of components can also be made on the basis of a selection from within the severities quoted in the test.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 27025-2008 General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025: 2005, IDT)
IEC 60068-1 Environmental testing - Part 1: General and guidance
IEC 60068-2-47 Environmental testing - Part 2-47: Tests - Mounting of specimens for vibration, impact and similar dynamic tests
IEC 60721-3 (all parts) Classification of environmental conditions - Part 3: Classification of groups of environmental parameters and their severities
ISO 2041 Vibration and shock - Vocabulary
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
Note 1: The terms used are generally taken from ISO 2041 and IEC 60068-1. However, “sweep cycle” (3.4) and “signal tolerance” (3.5) have specific meanings in this standard.
Definitions in alphabetical order:
actual motion 3.7
basic motion 3.6
centered resonance frequencies 3.10
check point 3.2.1
critical frequencies 3.9
damping 3.8
fictitious reference point 3.2.3
Fixing point 3.1
gn 3.12
measuring point 3.2
multipoint control 3.3.2
reference point 3.2.2
restricted frequencies sweeping 3.11
signal tolerance 3.5
single point control 3.3.1
sweep cycle 3.4
Note 2: Terms described below are either not identical to, or not defined in ISO 2041 or in IEC 60068-1.
3.1
fixing point
part of the specimen in contact with the fixture or vibration table at a point where the specimen is normally fastened in service
Note 1: If a part of the real mounting structure is used as the fixture, the fixing points are those of the mounting structure and not of the specimen.
Note 2: Where the specimen consists of a packaged product, fixing point may be interpreted as the surface of the specimen which is in contact with the vibration table.
3.2
measuring point
specific points at which data are gathered conducting the test
Note 1: These are of two main types, the definitions of which are given below.
Note 2: Measurements may be made at points within the specimen in order to assess its behavior, but these are not considered as measuring points in the sense of this part. For further details, see A.2.1 of Annex A.
3.2.1
check point
point located on the fixture, on the vibration table or on the specimen as close as possible to one of its fixing points, and in any case rigidly connected to it
Note 1: A number of check points are used as a means of ensuring that the test requirements are satisfied.
Note 2: If four or fewer fixing points exist, each is used as a check point. For packaged products, where a fixing point may be interpreted as the packaging surface in contact with the vibration table, one check point may be used, provided that there are no effects due to resonances of the vibration table or the mounting structure in the frequency range specified for the test. If this is the case, multipoint control may be necessary, but see also Note 3. If more than four fixing points exist, four representative fixing points will be defined in the relevant specification to be used as check points.
Note 3: In special cases, for example for large or complex specimens, the check points will be prescribed in the relevant specification if not close to the fixing points.
Note 4: Where a large number of small specimens are mounted on one fixture, or in the case of a small specimen where there are several fixing points, a single check point (i.e. the reference point) may be selected for the derivation of the control signal. This signal is then related to the fixture rather than to the fixing points of the specimen(s). This is only valid when the lowest resonance frequency of the loaded fixture is well above the upper frequency of the test.
3.2.2
reference point
point, chosen from the check points, whose signal is used to control the test, so that the requirements of this standard are satisfied
3.2.3
fictitious reference point
point, chosen from multiple reference point synthesized manually or automatically, so that the requirements of this standard are satisfied
3.3
control point
3.3.1
single point control
control method using the signal from the transducer at the reference point in order to maintain this point at the specified vibration level (see 4.1.4.1)
3.3.2
multipoint control
control method achieved by using the signals from each of the transducers at the check points
Note: The signals are either continuously averaged arithmetically or processed by using comparison techniques, depending upon the relevant specification (see 4.1.4.1).
3.4
sweep cycle
traverse of the specified frequency range once in each direction, for example 10 Hz to 150 Hz to 10 Hz
Note: Manufacturers' handbooks for digital sine control systems often refer to a sweep cycle as f1 to f2, and not f1 to f2 to f1
3.5
signal tolerance
where,
NF—— the r.m.s value of the unfiltered signal;
F—— the r.m.s value of the filtered signal.
Note: This parameter applies to whichever signal, i.e. acceleration, velocity or displacement, is being used to control the test (see A.2.2).
3.6
basic motion
motion at the driving frequency of vibration at the reference point (see 4.1.1)
3.7
actual motion
motion represented by the wideband signal returned from the reference point transducer
3.8
damping
generic term ascribed to the numerous energy dissipation mechanisms in a system
Note: In practice, damping depends on many parameters, such as structural system, mode of vibration, strain, applied forces, velocity, materials, joint slippage, etc.
3.9
critical frequencies
frequencies at which
—— malfunctioning and/or deterioration of performance of the specimen are exhibited which are dependent on vibration, and/or
—— mechanical resonances and/or other response effects occur, for example, chatter
3.10
centered resonance frequencies
frequency automatically centered on the actual resonance frequency derived from the vibration response investigation
3.11
restricted frequencies sweeping
sweeping over a restricted frequency range between 0,8 and 1,2 times the critical frequency
3.12
gn
standard acceleration due to the earth's gravity, which itself varies with altitude and geographical latitude
Note: For the purposes of this standard, the value of gn is rounded up to the nearest whole number, that is, 10 m/s2.
4 Requirements for testing
4.1 Required characteristics
The required characteristics apply to the complete vibration system, which includes the power amplifier, vibrator, test fixture, specimen and control system when loaded for testing.
4.1.1 Basic motion
The basic motion shall be a sinusoidal function of time and such that the fixing points of the specimen move substantially in phase and in straight parallel lines, subject to the limitations of 4.1.2 and 4.1.3.
4.1.2 Spurious motion
4.1.2.1 Cross-axis motion
The maximum vibration amplitude at the check points in any axis perpendicular to the specified axis shall not exceed 50% of the specified amplitude up to 500 Hz or 100% for frequencies in excess of 500 Hz. The measurements need only cover the specified frequency range. In special cases, e.g. Small specimens, the amplitude of the permissible cross axis motion may be limited to 25%, if required by the relevant specification.
In some cases, for example for large size or high mass specimens or at some frequencies, it may be difficult to achieve the figures quoted above. In such cases, the relevant specification shall state which of the following requirements apply:
a) any cross-axis motion in excess of that stated above shall be noted and stated in the test report; or
b) cross-axis motion which is known to offer no hazard to the specimen need not be monitored.
4.1.2.2 Rotational motion
In the case of large size or high mass specimens, the occurrence of spurious rotational motion of the vibration table may be important. If so, the relevant specification shall prescribe a tolerable level. The achieved level shall be stated in the test report (see also A.2.4).
4.1.3 Signal tolerance
Acceleration signal tolerance measurements shall be performed if stated in the relevant specification They shall be carried out at the reference point and shall cover the frequencies up to 5 000 Hz or five times the driving frequency whichever is the lesser. However, this maximum analyzing frequency may be extended to the upper test frequency for the sweep, or beyond, if specified in the relevant specification. Unless otherwise stated in the relevant specification, the signal tolerance shall not exceed 5 % (see 3.5).
If stated in the relevant specification, the acceleration amplitude of the control signal at the fundamental driving frequency shall be restored to the specified value by use of a tracking filter (see A.4.4).
In the case of large or complex specimens, where the specified signal tolerance values cannot be satisfied at some parts of the frequency range, and it is impracticable to use a tracking filter, the acceleration amplitude need not be restored, but the signal tolerance shall be stated in the test report (see A.2.2).
Foreword i
Introduction iii
1 Scope
2 Normative references
3 Terms and definitions
4 Requirements for testing
4.1 Required characteristics
4.2 Control strategy
4.3 Mounting
5 Severities
5.1 Frequency range
5.2 Vibration amplitude
5.3 Duration of endurance test
6 Preconditioning
7 Initial measurements
8 Test
8.1 General
8.2 Vibration response inspection
8.3 Endurance test
9 Intermediate measurements
10 Recovery
11 Final measurements
12 Information to be given in the relevant specification
13 Information to be given in the test report
Annex A (Informative) Guide to test Fc
Annex B (Informative) Examples of severities primarily intended for components
Annex C (Informative) Examples of severities primarily intended for equipment
Annex NA The consistency degree of GB/T 4798 (all parts) and IEC 60721-3 (all parts)
Bibliography
