Environmental testing - Part 2-85: Tests - Test Fj: Vibration - Long time history replication

IEC 60068-2-85:2019 demonstrates the adequacy of specimens to resist dynamic loads without unacceptable degradation of its functional and/or structural integrity when subjected to the specified vibration test requirements as defined by a time history (long time history replication). These can either be recorded in measurement exercises or generated artificially. In both cases, this method allows for generating a test tailored to very specific applications.

Essais d'environnement - Partie 2-85 : Essais - Essai Fj: Vibrations - Reproduction dans le temps par accélérogrammes

L'IEC 60068-2-85:2019 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 aux exigences d'essais de vibrations spécifiées, définies par un accélérogramme (reproduction des vibrations dans le temps). Ces vibrations peuvent être enregistrées lors de sessions de mesure ou être générées artificiellement. Dans les deux cas, cette méthode permet de réaliser un essai adapté à des applications bien spécifiques.

General Information

Status
Published
Publication Date
19-Jun-2019
Current Stage
PPUB - Publication issued
Completion Date
20-Jun-2019
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IEC 60068-2-85
Edition 1.0 2019-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-85: Tests – Test Fj: Vibration – Long time history replication
Essais d'environnement –
Partie 2-85: Essais – Essai Fj: Vibrations – Reproduction dans le temps par
accélérogrammes
IEC 60068-2-85:2019-06(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60068-2-85
Edition 1.0 2019-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-85: Tests – Test Fj: Vibration – Long time history replication
Essais d'environnement –
Partie 2-85: Essais – Essai Fj: Vibrations – Reproduction dans le temps par
accélérogrammes
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040 ISBN 978-2-8322-7079-0

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 60068-2-85:2019 © IEC 2019
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 7

4 Requirements for test apparatus ...................................................................................... 9

4.1 General ................................................................................................................... 9

4.2 Basic motion ........................................................................................................... 9

4.3 Cross-axis motion ................................................................................................... 9

4.4 Mounting ............................................................................................................... 10

4.5 Measuring systems ............................................................................................... 10

5 Severities ...................................................................................................................... 10

6 Preconditioning .............................................................................................................. 10

7 Initial measurements and functional performance test.................................................... 10

8 Testing .......................................................................................................................... 10

8.1 General ................................................................................................................. 10

8.2 Initial vibration response investigation .................................................................. 11

8.3 Low-level excitation for equalization prior to testing .............................................. 12

8.4 Testing with specimen functioning ......................................................................... 12

8.5 Final vibration response investigation ................................................................... 12

9 Recovery ....................................................................................................................... 12

10 Final measurements and functional performance ........................................................... 13

11 Information to be given in the relevant specification ....................................................... 13

12 Information to be given in the test report........................................................................ 13

Annex A (informative) Guidance ........................................................................................... 15

A.1 General ................................................................................................................. 15

A.2 Requirements for testing ....................................................................................... 15

A.2.1 Single-point control ........................................................................................ 15

A.2.2 Controlled input testing .................................................................................. 16

A.2.3 Controlled response testing ........................................................................... 16

A.2.4 Verification parameters .................................................................................. 16

A.3 Testing procedures ............................................................................................... 18

A.4 Equipment normally used with vibration isolators .................................................. 18

A.4.1 Transmissibility factors for isolators ............................................................... 18

A.4.2 Temperature effect ........................................................................................ 18

A.5 Test severities ...................................................................................................... 18

A.6 Equipment performance ........................................................................................ 18

A.7 Initial and final measurements .............................................................................. 19

A.8 Frequency range ................................................................................................... 19

Bibliography .......................................................................................................................... 21

---------------------- Page: 4 ----------------------
IEC 60068-2-85:2019 © IEC 2019 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL TESTING –
Part 2-85: Tests – Test Fj: Vibration –
Long time history replication
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

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rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 60068-2-85 has been prepared by IEC technical committee 104:

Environmental conditions, classification and methods of test.
The text of this International Standard is based on the following documents:
FDIS Report on voting
104/833/FDIS 104/840/RVD

Full information on the voting for the approval of this International Standard can be found in the

report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 60068 series, published under the general title Environmental testing,

can be found on the IEC website.
---------------------- Page: 5 ----------------------
– 4 – IEC 60068-2-85:2019 © IEC 2019

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 6 ----------------------
IEC 60068-2-85:2019 © IEC 2019 – 5 –
INTRODUCTION

This first edition of IEC 60068-2-85 was initiated in 2008 and a first proposal was prepared in

2011. It was developed out of the existing standard IEC 60068-2-64:2008 which contains a

technically similar test method and modified accordingly. This facilitates usage and

maintenance of both standards.

Differences are that this document relies on a specified time history. A test spectrum is not

specified.

This part of IEC 60068 deals with long time history replication vibration testing intended for

general application to components, equipment and other products, hereinafter referred to as

”specimens”, that may be subjected to vibrations of an arbitrary nature not covered by the other

existing methods for vibration testing. The methods and techniques in this document are based

on digital control of vibration in the time domain which allow a more flexible definition of the

vibration input signal to suit individual cases that are specified in the relevant specification.

Compared with most other tests, test Fj is based on deterministic techniques, and the time

history is supposed to have a long duration. There are nearly no restrictions to the vibration

characteristics besides the technical limitations of the test apparatus.

As the vibration input signal in this test is specified by a digital time history stored in a file, there

are no general methods for comparing two different test severities. The vibration tolerances

cannot be given in a single measure, as this depends on the purpose of the test. Therefore, it

is emphasized that long time history replication testing always demands a high degree of

engineering judgement by the user and specifier. The writer of the relevant specification is

expected to select the testing procedure, test time history and its severity, tolerances and

analysis methods, 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.

Long time history replication vibration testing can 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, can be used to assess the

acceptability of specimens.

If the specimens are subjected to vibration of a deterministic transient or periodic nature

resulting from transportation or real life environments that are covered by other test methods,

these are generally preferred. See IEC 60068-3-8 [1] for estimating the dynamic vibration

environment of the specimen and based on that, selecting the appropriate test method.

Annex A provides guidance and a list of details that can be considered for inclusion in

specifications.
___________
Numbers in square brackets refer to the bibliography.
---------------------- Page: 7 ----------------------
– 6 – IEC 60068-2-85:2019 © IEC 2019
ENVIRONMENTAL TESTING –
Part 2-85: Tests – Test Fj: Vibration –
Long time history replication
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 vibration test requirements as defined by a time history (long time history

replication). These can either be recorded in measurement exercises or generated artificially.

In both cases, this method allows for generating a test tailored to very specific applications.

Typical applications are tests in which very specific deterministic transient, periodical or random

excitation is necessary and the characteristics of the motion are not covered by other test

standards. This includes time histories not sufficiently represented by the standard shock tests

of IEC 60068-2-27 [2] or a general description by a shock response spectrum as in

IEC 60068-2-81 [3], periodical vibration that is not covered by a sinusoidal waveform as in

IEC 60068-2-6, and random vibration that is not covered by the description of Gaussian or non-

Gaussian (high kurtosis) broad-band random vibration of IEC 60068-2-64. However, the user is

made aware that long time history replication uses a deterministic time history. Simulation of

random vibration of any kind is approximated by quasi-random.

In addition, additional mixed mode tests are possible with this test method by generating time

histories that are representations of the required test signals. This includes tests of high

complexity.

The purpose of this test is different from IEC 60068-2-57 [4]. The purpose of IEC 60068-2-57

is an evaluation for a transient vibration using mainly a synthesized time history. A long time

history test is mainly used for a durability and functionality test using an actual time history

measured in a real field environment. It can also be used as a method to apply a simulated non-

gaussian time history.

This document is applicable to specimens which can be subjected to vibration of a very specific

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 can 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 document can be used in

conjunction with IEC 60068-2-47, for testing packaged products.

Although primarily intended for electrotechnical specimens, this document is not restricted to

them and can be used in other fields where desired (see Annex A).
This document is applicable for single axis excitation.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 60068-2-6, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)

---------------------- Page: 8 ----------------------
IEC 60068-2-85:2019 © IEC 2019 – 7 –

IEC 60068-2-47, Environmental testing – Part 2-47: Tests – Mounting of specimens for vibration,

impact and similar dynamic tests

IEC 60068-2-64:2008, Environmental testing – Part 2-64: Tests – Test Fh: Vibration, broadband

random and guidance
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

NOTE The terms used are generally defined in IEC 60050-300 [5], IEC 60068-1 [6], IEC 60068-2-6, and

IEC 60068-5-2 [7] and ISO 2041 [8].
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 1 to entry: The cross-axis motion should be measured close to the fixing points.

[SOURCE: IEC 60068-2-64:2008, 3.1]
3.2
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 to entry: 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.
[SOURCE: IEC 60068-2-64:2008, 3.3]
3.3
measuring points
specific points at which data are gathered for conducting the test
Note 1 to entry: These points are of three types, as defined in 3.4 to 3.6.
[SOURCE: IEC 60068-2-64:2008, 3.6]
3.4
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

[SOURCE: IEC 60068-2-64:2008, 3.7, modified – The notes to entry have been deleted.]

3.5
control point

point, chosen from amongst the checkpoints, whose signal is used to control the test, such that

the requirements of IEC 60068-2-85 are satisfied
---------------------- Page: 9 ----------------------
– 8 – IEC 60068-2-85:2019 © IEC 2019

[SOURCE: IEC 60068-2-64:2008, 3.8, modified – The term “reference point (single-point

control)” has been replaced with "control point" and in the definition "this standard" has been

replaced with "IEC 60068-2-85".]
3.6
response points

specific points on the specimen from which data is gathered for the purpose of the vibration

response investigation
Note 1 to entry: These points are not the same as checkpoints or control points.
[SOURCE: IEC 60068-2-64:2008, 3.10]
3.7
preferred testing axes

three orthogonal axes that correspond to the most vulnerable axes of the specimen

[SOURCE: IEC 60068-2-64:2008, 3.11]
3.8
specified time history

data file containing digital acceleration values varying with time to be replicated during the test

Note 1 to entry: The specified time history is usually based on recorded ‘real life’ digitized data, properly modified

(e.g. filtered) for reproducibility on a shaker.
3.9
control time history
time history measured at the control point simulating the specified time history
3.10
error time history
difference between the specified time history and the control time history
3.11
equalization
minimization of the RMS of error time history
3.12
RMS value
root-mean-square value

square root of the average of the squared values of all functions over the total frequency interval

f and f
1 2

[SOURCE: IEC 60068-2-64:2008, 3.33, modified – The definition has been simplified.]

3.13
test frequency range

frequency range to use for processing control, as given in the relevant specification

3.14
probability density function

at a specified amplitude, ratio of the probability that the amplitude will be within a given

incremental range, to the size of the incremental range
---------------------- Page: 10 ----------------------
IEC 60068-2-85:2019 © IEC 2019 – 9 –
3.15
maximum response spectrum

curve giving the value of the highest peak of the response of a linear single degree of freedom

system (SDOF system) to vibration, according to its natural frequency, for a given damping ratio

Note 1 to entry: The response is described by the relative movement of the mass of this system in relation to its

support.
3.16
fatigue damage spectrum
FDS

spectrum obtained by tracing the fatigue damage experienced by a linear single degree of

freedom system (SDOF) according to its natural frequency, for a given damping ratio and for a

given value of parameter b

Note 1 to entry: Parameter b comes from the Basquin law representing the Wöhler curve of the material constituting

the structure.
Note 2 to entry: This note applies to the French language only.
4 Requirements for test apparatus
4.1 General

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.

The standardized test method consists of the following test sequence normally applied in each

of the mutually perpendicular axes of the test specimen:

1) an initial vibration response investigation, with low level sinusoidal excitation, or low level

random excitation, (see 8.2 and Clause A.1);
2) the long time history replication as the mechanical load or stress test;

3) a final vibration response investigation to compare the results with the initial one and to

detect possible mechanical failures due to a change of the dynamic behaviour
(see 8.2 and 8.5).

Where the dynamic behaviour is known, and it is not considered relevant, or sufficient data can

be gathered during the test at full level, the relevant specification may not require pre and post

test vibration response investigations.
4.2 Basic motion

The basic motion of the fixing points of the specimen shall be specified by the relevant

specification. The fixing points shall have substantially identical motions in phase and amplitude

and shall be rectilinear relative to the direction of excitation.
4.3 Cross-axis motion

Cross-axis motion shall be checked, if required by the relevant specification, either before the

test is applied by conducting a sine or random investigation at a level specified by the relevant

specification, or during testing by utilizing additional monitoring channels in the two

perpendicular axes.

The maximum cross axis amplitude at the control point shall not exceed 50 % of the value of

the specified axis. With large-size or high mass specimens it may be difficult to achieve this

requirement. In such cases, the relevant specification shall state which of the following

requirements applies:

a) any cross-axis motion in excess of that given above shall be stated in the test report;

---------------------- Page: 11 ----------------------
– 10 – IEC 60068-2-85:2019 © IEC 2019

b) a cross-axis motion which is known to offer no hazard to the specimen need not be

monitored.
4.4 Mounting
The specimen shall be mounted in accordance with IEC 60068-2-47.
4.5 Measuring systems

The characteristics of the measuring system shall be such that it can be determined whether

the value of the vibration as measured in the intended axis at the control point is within the

tolerance required for the test.

The frequency range for long time history replication needs to extend to higher frequencies than

the conventional vibration test.

The frequency response of the overall measuring system, which includes the transducer, the

signal conditioner and the data acquisition and processing device, has a significant effect on

the accuracy of the measurements. The frequency response of the m
...

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