SIST EN 60068-2-64:2008
Environmental testing -- Part 2-64: Tests - Test Fh: Vibration, broadband random and guidance
Environmental testing -- Part 2-64: Tests - Test Fh: Vibration, broadband random and guidance
This part of IEC 60068 demonstrates the adequacy of specimens to resist dynamic loads without unacceptable degradation of its functional and/or structural integrity when subjected to the specified random vibration test requirements. Broadband random vibration may be used to identify accumulated stress effects and the resulting mechanical weakness and degradation in the specified performance. This information, in conjunction with the relevant specification, may be used to assess the acceptability of specimens. This standard is applicable to specimens which may be subjected to vibration of a stochastic nature resulting from transportation or operational environments, for example in aircraft, space vehicles and land vehicles. It is primarily intended for unpackaged specimens, and for items in their transportation container when the latter may be considered as part of the specimen itself. 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. This standard may be used in conjunction with IEC 60068-2-47:2005, for testing packaged products. If the specimens are subjected to vibration of a combination of random and deterministic nature resulting from transportation or real life environments, for example in aircraft, space vehicles and for items in their transportation container, testing with pure random may not be sufficient. See IEC 60068-3-8:2003 for estimating the dynamic vibration environment of the specimen and based on that, selecting the appropriate test method. Although primarily intended for electrotechnical specimens, this standard is not restricted to them and may be used in other fields where desired (see Annex A).
Umgebungseinflüsse - Teil 2-64: Prüfverfahren - Prüfung Fh: Schwingen, Breitbandrauschen (digital geregelt) und Leitfaden
Essais d'environnement -- Partie 2-64: Essais - Essai Fh: Vibrations aléatoires à large bande et guide
La CEI 60068-2-64:2008 a pour objet de démontrer la capacité des spécimens à résister aux charges dynamiques sans dégradation inacceptable de leur intégrité de fonctionnement et/ou de structure, lorsqu'ils sont soumis à des exigences d'essais de vibrations aléatoires spécifiées. L'essai de vibration aléatoire à large bande peut être utilisé pour identifier les effets de contraintes accumulées ainsi que la faiblesse et la dégradation mécaniques résultantes de la performance spécifiée. Ces informations, conjointement avec la spécification particulière, peuvent être utilisées pour évaluer l'acceptabilité des spécimens. Cette norme est applicable à des spécimens qui peuvent être soumis à des vibrations de nature stochastique dues au transport ou à l'environnement rencontré en service, par exemple, à bord d'avions et de véhicules spatiaux ou à bord de véhicules terrestres. Elle est destinée en premier lieu à des spécimens non emballés et à des objets dans leur emballage de transport lorsque celui-ci peut être considéré comme faisant partie du spécimen lui-même. Cependant, si l'article est emballé alors l'article lui-même est désigné comme produit et l'article ainsi que son emballage sont désignés comme spécimen d'essai. Cette norme peut être utilisée conjointement avec la CEI 60068 2 47:2005, pour l'essai des produits emballés. Si les spécimens sont soumis à des vibrations d'une combinaison de nature aléatoire et déterministe résultant du transport ou des environnements de la vie réelle, par exemple à bord d'avions, de véhicules spatiaux et pour des éléments dans leur emballage de transport, les essais purement aléatoires peuvent ne pas être suffisants. Voir la CEI 60068-3-8:2003 pour l'estimation de l'environnement de vibrations dynamiques du spécimen et sur cette base, pour la sélection de la méthode d'essai appropriée. Les modifications principales par rapport à l'édition précédente concernent le retrait de la Méthode 1 et de la Méthode 2, remplacées par une méthode unique, et remplacement de l'Annexe A par des spectres d'essais préconisés et le retrait de l'Annexe C. Aussi inclus dans cette révision, l'essai des spécimens avec emballages mous. A le statut de publication fondamentale de sécurité, conformément au Guide CEI 104.
Okoljski preskusi - 2-64. del: Preskusi - Preskus Fh: Vibracije, naključne širokopasovne, in vodilo (IEC 60068-2-64:2008)
Ta del standarda IEC 60068 izkazuje primernost primerkov glede odpornosti proti dinamičnim obremenitvam brez nesprejemljivega poslabšanja funkcionalne in/ali strukturne celovitosti, kadar so izpostavljeni podanim naključnim zahtevam preskušanja vibracij. Naključne širokopasovne vibracije se lahko uporabijo za določanje nakopičenih učinkov obremenitve ter posledične mehanske šibkosti in poslabšanja podanih lastnosti. Te informacije se lahko skupaj z ustrezno specifikacijo uporabijo za vrednotenje sprejemljivosti primerkov. Ta standard se uporablja za primerke, ki so lahko izpostavljeni stohastičnim vibracijam zaradi transportnih ali obratovalnih okolij, na primer v letalih, vesoljskih plovilih in kopenskih vozilih. Prvotno je namenjen nezapakiranim primerkom in predmetom v njihovem transportnem vsebniku, pri čemer se slednji lahko obravnava kot del samega primerka. Kadar pa je predmet zapakiran, se sam predmet obravnava kot izdelek, izdelek in njegova embalaža pa se obravnavata kot preskušanec. Ta standard se lahko uporablja v povezavi s standardom IEC 60068-2-47:2005 za preskušanje zapakiranih izdelkov. Če so primerki izpostavljeni kombinaciji naključnih in določenih vibracij zaradi transportnih ali dejanskih življenjskih okolij (na primer v letalih, vesoljskih plovilih in za predmete v njihovem transportnem vsebniku), preskušanje zgolj z naključnimi morda ne bo zadostovalo. Glej standard IEC 60068-3-8:2003 za ocenjevanje okolja dinamičnih vibracij vzorca in (na podlagi tega) za izbiro ustrezne preskusne metode. Čeprav je prvotno namenjen elektrotehničnim primerkom, ta standard ni omejen nanje in se lahko poljubno uporablja na drugih področjih (glej dodatek A).
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.QDNOMXþQHUmgebungseinflüsse - Teil 2-64: Prüfverfahren - Prüfung Fh: Schwingen, Breitbandrauschen (digital geregelt) und LeitfadenEssais d'environnement -- Partie 2-64: Essais - Essai Fh: Vibrations aléatoires à large bande et guideEnvironmental testing -- Part 2-64: Tests - Test Fh: Vibration, broadband random and guidance19.040Preskušanje v zvezi z okoljemEnvironmental testingICS:Ta slovenski standard je istoveten z:EN 60068-2-64:2008SIST EN 60068-2-64:2008en01-november-2008SIST EN 60068-2-64:2008SLOVENSKI
STANDARDSIST EN 60068-2-64:20011DGRPHãþD
SIST EN 60068-2-64:2008
EUROPEAN STANDARD EN 60068-2-6 NORME EUROPÉENNE
EUROPÄISCHE NORM February 2008
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2008 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60068-2-6:2008 E
ICS 19.040 Supersedes EN 60068-2-6:1995
English version
Environmental testing -
Part 2-6: Tests -
Test Fc: Vibration (sinusoidal) (IEC 60068-2-6:2007)
Essais d'environnement -
Partie 2-6: Essais -
Essai Fc: Vibrations (sinusoïdales) (CEI 60068-2-6:2007)
Umgebungseinflüsse -
Teil 2-6: Prüfverfahren -
Prüfung Fc: Schwingen (sinusförmig)
(IEC 60068-2-6:2007)
This European Standard was approved by CENELEC on 2008-02-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
SIST EN 60068-2-64:2008
EN 60068-2-6:2008
- 2 -
Foreword The text of document 104/439/FDIS, future edition 7 of IEC 60068-2-6, prepared by IEC TC 104, Environmental conditions, classification and methods of test, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60068-2-6 on 2008-02-01. This European Standard supersedes EN 60068-2-6:1995. The major changes with regard to EN 60068-2-6:1995 concern: – the agreed wording from IEC technical committee 104 meeting held in Stockholm:2000 on the testing of soft packages; – reference to the latest version of EN 60068-2-47: Mounting; – simplification of the layout of the standard by replacing some tables with text; – addition of the test report requirements (see Clause 13). The following dates were fixed: – latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2008-11-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2011-02-01 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 60068-2-6:2007 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following note has to be added for the standard indicated: IEC 60068-2-64 NOTE
Harmonized as EN 60068-2-64:1994 (not modified). __________
SIST EN 60068-2-64:2008
- 3 - EN 60068-2-6:2008
Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
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.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60068-1
- 1) Environmental testing - Part 1: General and guidance EN 60068-1 1994 2)
IEC 60068-2-47 - 1) Environmental testing -
Part 2-47: Tests - Mounting of specimens for vibration, impact and similar dynamic tests EN 60068-2-47 2005 2)
IEC 60721-3 Series Classification of environmental conditions - Part 3: Classification of groups of environmental parameters and their severities EN 60721-3 Series
ISO 2041 - 1) Vibration and shock - Vocabulary - -
ISO/IEC 17025 2005 General requirements for the competence of testing and calibration laboratories EN ISO/IEC 17025 2005
1) Undated reference.
2) Valid edition at date of issue.
SIST EN 60068-2-64:2008
SIST EN 60068-2-64:2008
IEC 60068-2-64Edition 2.0 2008-04INTERNATIONAL STANDARD NORME INTERNATIONALEEnvironmental testing –
Part 2-64: Tests – Test Fh: Vibration, broadband random and guidance
Essais d’environnement –
Partie 2-64: Essais – Essai Fh: Vibrations aléatoires à large bande et guide
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE WICS 19.040 PRICE CODECODE PRIXISBN 2-8318-9745-9
SIST EN 60068-2-64:2008
– 2 – 60068-2-64 © IEC:2008 CONTENTS FOREWORD.4 INTRODUCTION.6
1 Scope.7 2 Normative references.7 3 Terms and definitions.8 4 Requirements for test apparatus.12 4.1 General.12 4.2 Basic motion.12 4.3 Cross-axis motion.13 4.4 Mounting.13 4.5 Measuring systems.13 4.6 Vibration tolerances.14 4.7 Control strategy.17 4.8 Vibration response investigation.17 5 Severities.18 5.1 Test frequency range.18 5.2 RMS value of acceleration.18 5.3 Shape of acceleration spectral density curve.18 5.4 Test duration.19 6 Preconditioning.19 7 Initial measurements and functional performance test.19 8 Testing.19 8.1 General.19 8.2 Initial vibration response investigation.20 8.3 Low-level excitation for equalization prior to testing.20 8.4 Random testing.21 8.5 Final vibration response investigation.21 9 Recovery.21 10 Final measurements and functional performance.21 11 Information to be given in the relevant specification.22 12 Information to be given in the test report.22
Annex A (informative)
Standardized test spectra.24 Annex B (informative)
Guidance.30
Bibliography.34
Figure 1 – Tolerance bands for acceleration spectral density;
initial and final slope (see B.2.3).14 Figure 2 – Time history of stochastically excitation; probability density function with Gaussian (normal) distribution (Example with crest factor = 3, see also 3.14 and
4.6.2).15 Figure 3 – Statistical accuracy of acceleration spectral density versus degrees of freedom for different confidence levels (see also
4.6.3).16 SIST EN 60068-2-64:2008
60068-2-64 © IEC:2008 – 3 –
Table A.1 – Categories for spectrum: transportation.24 Table A.2 – Break points for spectrum: transportation.25 Table A.3 – Categories for spectrum: stationary installation.25 Table A.4 – Break points for spectrum: stationary installation.26 Table A.5 – Categories for spectrum: equipment in wheeled vehicles.27 Table A.6 – Break points for spectrum: equipment in wheeled vehicles.28 Table A.7 – Categories for spectrum: equipment in airplanes and helicopters.29 Table A.8 – Break points for spectrum: equipment in airplanes and helicopters.29
SIST EN 60068-2-64:2008
– 4 – 60068-2-64 © IEC:2008 INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
ENVIRONMENTAL TESTING –
Part 2-64: Tests – Test Fh: Vibration,
broadband random and guidance
FOREWORD 1)
The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 60068-2-64 has been prepared by IEC technical committee 104: Environmental conditions, classification and methods of test. This second edition cancels and replaces the first edition, published in 1993, and constitutes a technical revision. The major changes with regard to the previous edition concern the removal of Method 1 and Method 2, replaced by a single method, and replacement of Annex A with suggested test spectra and removal of Annex C.
Also included in this revision is the testing of soft packed specimens. SIST EN 60068-2-64:2008
60068-2-64 © IEC:2008 – 5 – The text of this standard is based on the following documents: FDIS Report on voting 104/456/FDIS 104/459/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. It has the status of a basic safety publication in accordance with IEC Guide 104. A list of all the parts in the IEC 60068 series, under the general title Environmental testing, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be
• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended.
SIST EN 60068-2-64:2008
– 6 – 60068-2-64 © IEC:2008 INTRODUCTION This part of IEC 60068 deals with broadband random vibration testing intended for general application to components, equipment and other products, hereinafter referred to as ”specimens”, that may be subjected to vibrations of a stochastic nature. The methods and techniques in this standard are based on digital control of random vibration. It permits the introduction of variations to suit individual cases if these are prescribed by the relevant specification. Compared with most other tests, test Fh is not based on deterministic but on statistical techniques. Broad-band random vibration testing is therefore described in terms of probability and statistical averages. It is emphasized that random testing always demands a certain degree of engineering judgement, and both supplier and purchaser should be fully aware of this fact. The writer of the relevant specification is expected to select the testing procedure and the values of severity appropriate to the specimen and its use. The test method is based primarily on the use of an electrodynamic or a servo-hydraulic vibration generator with an associated computer based control system used as a vibration testing system. Annexes A and B are informative annexes giving examples of test spectra for different environmental conditions, a list of details to be considered for inclusion in specifications and guidance. SIST EN 60068-2-64:2008
60068-2-64 © IEC:2008 – 7 – ENVIRONMENTAL TESTING –
Part 2-64: Tests-Test Fh: Vibration,
broadband random and guidance
1 Scope This part of IEC 60068 demonstrates the adequacy of specimens to resist dynamic loads without unacceptable degradation of its functional and/or structural integrity when subjected to the specified random vibration test requirements. Broadband random vibration may be used to identify accumulated stress effects and the resulting mechanical weakness and degradation in the specified performance. This information, in conjunction with the relevant specification, may be used to assess the acceptability of specimens. This standard is applicable to specimens which may be subjected to vibration of a stochastic nature resulting from transportation or operational environments, for example in aircraft, space vehicles and land vehicles. It is primarily intended for unpackaged specimens, and for items in their transportation container when the latter may be considered as part of the specimen itself. 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. This standard may be used in conjunction with IEC 60068-2-47:2005, for testing packaged products. If the specimens are subjected to vibration of a combination of random and deterministic nature resulting from transportation or real life environments, for example in aircraft, space vehicles and for items in their transportation container, testing with pure random may not be sufficient. See IEC 60068-3-8:2003 for estimating the dynamic vibration environment of the specimen and based on that, selecting the appropriate test method. Although primarily intended for electrotechnical specimens, this standard is not restricted to them and may be used in other fields where desired (see Annex A). 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. IEC 60050-300: International Electrotechnical Vocabulary – Electrical and electronic measurements and measuring instruments – Part 311: General terms relating to measurements – Part 312: General terms relating to electrical measurements – Part 313: Types of electrical measuring instruments – Part 314: Specific terms according to the type of instrument
IEC 60068-1: Environmental testing – Part 1: General and guidance IEC 60068-2-6: Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal) IEC 60068-2-47:2005, Environmental testing – Part 2-47: Tests – Mounting of specimens for vibration, impact and similar dynamic tests SIST EN 60068-2-64:2008
– 8 – 60068-2-64 © IEC:2008 IEC 60068-3-8:2003, Environmental testing – Part 3-8: Supporting documentation and guidance – Selecting amongst vibration tests
IEC 60068-5-2: Environmental testing – Part 5-2: Guide to drafting of test methods – Terms and definitions IEC 60721-3 (all parts), Classification of environmental conditions – Part 3: Classification of groups of environmental parameters and their severities IEC Guide 104, The preparation of safety publications and the use of basic safety publications and group safety publications
ISO 2041: Vibration and shock – Vocabulary 3 Terms and definitions For the purposes of this document, the following terms and definitions apply.
NOTE The terms used are generally defined in IEC 60050-300, IEC 60068-1, IEC 60068-2-6, and IEC 60068-5-2 and ISO 2041. If a definition from one of those sources is included here, the derivation is indicated and departures from the definitions in those sources are also indicated. 3.1
cross-axis motion motion not in the direction of the stimulus; generally specified in the two axes orthogonal to the direction of the stimulus NOTE The cross-axis motion should be measured close to the fixing points. 3.2
actual motion motion represented by the wideband signal returned from the reference point transducer 3.3
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 If a part of the real mounting structure is used as the fixture, the fixing points are taken as those of the mounting structure and not of the specimen. 3.4
control methods 3.4.1 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 3.4.2 multipoint control
control method using the signals from each of the transducers at the checkpoints NOTE The signals are either continuously averaged arithmetically or processed by using comparison techniques, depending upon the relevant specification. See also 3.13. 3.5
gn standard acceleration due to the earth's gravity, which itself varies with altitude and geographical latitude SIST EN 60068-2-64:2008
60068-2-64 © IEC:2008 – 9 – NOTE For the purposes of this standard, the value of gn is rounded up to the nearest whole number, that is
10 m/s2. 3.6
measuring points specific points at which data are gathered for conducting the test NOTE These points are of three types, as defined in 3.7 to 3.9. 3.7
checkpoint 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 checkpoints 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 checkpoint. For packaged products, where a fixing point may be interpreted as the packaging surface in contact with the vibration table, one checkpoint 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 checkpoints. NOTE 3 In special cases, for example for large or complex specimens, the checkpoints will be prescribed by 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 with a number of fixing points, a single checkpoint (that is 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 procedure is only valid when the lowest resonance frequency of the loaded fixture is well above the upper frequency of the test.
3.8
reference point (single-point control) point, chosen from amongst the checkpoints, whose signal is used to control the test, such that the requirements of this standard are satisfied 3.9
fictitious reference point (multipoint control) point, derived from multiple checkpoints either manually or automatically, the result of which is used to control the test so that the requirements of this standard are satisfied 3.10
response points specific points on the specimen from which data is gathered for the purpose of the vibration response investigation NOTE These points are not the same as checkpoints or reference points. 3.11
preferred testing axes three orthogonal axes that correspond to the most vulnerable axes of the specimen 3.12
sampling frequency number of discrete magnitude values taken per second to record or represent a time-history in a digital form 3.13
multipoint control strategies method for calculating the reference control signal when using multipoint control NOTE Different frequency domain control strategies are discussed to in 4.7.1. SIST EN 60068-2-64:2008
– 10 – 60068-2-64 © IEC:2008 3.14
averaging process of determining the control acceleration spectral density formed from the arithmetic average of the acceleration spectral densities at each frequency line of more than one checkpoint
3.15
extremal (maximum or minimum) process of determining the control acceleration spectral density formed from the maximum or minimum acceleration spectral density at each frequency line of more than one checkpoint
3.16
crest factor
ratio of the peak value to the r.m.s. value of the time history
[ISO 2041] 3.17
–3 dB bandwidth frequency bandwidth between two points in a frequency response function which are at 0,707 of the maximum response when associated with a single resonance peak 3.18
acceleration spectral density ASD mean-square value of that part of an acceleration signal passed by a narrow-band filter of a centre frequency, per unit bandwidth, in the limit as the bandwidth approaches zero and the averaging time approaches infinity
3.19
control acceleration spectral density acceleration spectral density measured at the reference point or the fictitious reference point 3.20
control system loop sum of the following actions: – digitizing the analogue waveform of the signal derived from the reference point or fictitious reference point; – performing the necessary processing; – producing an updated analogue drive waveform to the vibration system power amplifier (see Clause B.1.) 3.21
drive signal clipping (see also Figure 1) limitation of the maximum crest factor of the drive signal effective frequency range
3.22
effective frequency range (see also Figure 1) frequency range between 0,5 times f1 and 2,0 times f2 NOTE Due to initial and final slope, the effective frequency range is higher than the test frequency range between f1 and f2. 3.23
error acceleration spectral density difference between the specified acceleration spectral density and the control acceleration spectral density SIST EN 60068-2-64:2008
60068-2-64 © IEC:2008 – 11 – 3.24
equalization
minimization of the error acceleration spectral density 3.25
final slope (see also Figure 1) part of the specified acceleration spectral density above f2 3.26
frequency resolution Be width of the frequency intervals in the acceleration spectral density in Hertz NOTE It is equal to the reciprocal of the record block length (T) in digital analysis; the number of frequency lines is equal to the number of intervals in a given frequency range 3.27
indicated acceleration spectral density estimate of the true acceleration spectral density read from the analyser presentation distorted by the instrument error and the random error 3.28
initial slope (see also Figure 1) part of the specified acceleration spectral density below f1 3.29
instrument error error associated with each analogue item of the input to the control system and control system analogue items 3.30
random error error changing from one estimate to another of the acceleration spectral density because of the limitation of averaging time and filter bandwidth in practice 3.31
record collection of equally spaced data points in the time domain that are used in the calculation of the Fast Fourier Transform 3.32
reproducibility
closeness of the agreement between the results of measurements of the same value of the same quantity, where the individual measurements are made – by different methods, – with different measuring instruments, – by different observers, – in different laboratories, – after intervals of time which are long compared with the duration of a single measurement, – under different customary conditions of use of the instruments employed NOTE The term “reproducible” also applies to the case where only certain of the preceding conditions are taken into account. [IEC 60050-300, modified] SIST EN 60068-2-64:2008
– 12 – 60068-2-64 © IEC:2008 3.33
root-mean-square value (see also Figure 2) root-mean-square value (r.m.s. value) of a single-valued function over an interval between two frequencies is the square root of the average of the squared values of all functions over the total frequency interval f1 and f2 3.34
standard deviation, σ (see also Figure 2) in vibration theory, the mean value of vibration is equal to zero; therefore for a random time history, the standard deviation is equal to the r.m.s. value 3.35
statistical accuracy ratio of true accelerat
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