ISO 5344:2004

INTERNATIONAL ISO
STANDARD 5344
Second edition
2004-07-01


Electrodynamic vibration generating
systems — Performance characteristics
Systèmes électrodynamiques utilisés pour la génération de
vibrations — Caractéristiques de performance




Reference number
ISO 5344:2004(E)
©
ISO 2004

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ISO 5344:2004(E)
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ISO 5344:2004(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 2
4 Structure of this International Standard. 6
4.1 General. 6
4.2 Subclause coding . 6
4.3 Symbol coding . 7
5 Systems. 7
5.1 General. 7
5.2 System specifications (S,a). 7
5.3 System performance. 8
5.4 Calculated system performance. 9
6 Electrodynamic vibration generators . 10
6.1 Vibration generator specification (C,a). 10
6.2 Vibration generator performance . 11
6.3 Vibrator drive requirements. 12
6.4 Vibrator maintenance (A,a) . 15
7 Power amplifiers . 15
7.1 Amplifier specification (C,a). 15
7.2 Amplifier test loads. 16
7.3 Amplifier performance. 17
7.4 Amplifier maintenance (A,a). 19
8 Tests and measurements. 19
8.1 General. 19
8.2 Conditioning before data runs. 19
8.3 Endurance tests . 20
8.4 Spill-over limits . 21
8.5 Distortion tests. 22
8.6 Impulse generation . 24
Annex A (informative) Additional equipment characteristics . 25

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ISO 5344:2004(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 5344 was prepared by Technical Committee ISO/TC 108, Mechanical vibration and shock, Subcommittee
SC 6, Vibration and shock generating systems.
This second edition cancels and replaces the first edition (ISO 5344:1980), which has been technically revised.
Considered responses to all of the proposed substantive changes to ISO 5344:1980 are incorporated in this
second edition. Changes favouring the specific design of individual sources were rejected. Regarding
endurance testing, a compromise is incorporated, providing a less expensive, but hopefully adequate,
assurance of reliability.
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ISO 5344:2004(E)
Introduction
Users want their equipment to operate for long period without malfunction. A major purpose of this
International Standard is to establish procedures to measure performance and to provide ways to ensure the
reliability of electrodynamic vibration generation equipment and systems. Some assurance of reliability, but
not conclusive, is provided by endurance tests on the vibrator, amplifier and the system as a whole.
If all sources of electrodynamic vibration generation equipment and systems use the same procedures, these
procedures define the meanings of the performance statements and reliability statements. Comparisons of the
performance and reliability statements of the different sources become useful.
Many of these procedures are suitable for incorporation in a purchase specification to state the acceptance
testing to be carried out upon delivery.
Others, particularly those related to endurance testing, are lengthy and expensive, and typically are performed
by the source at the end of the product development process, before the start of series production. These
procedures typically are used to establish and confirm the rated performance stated in the sales literature.
After discussions with the proposed sources, the writer of the purchase specification may propose abbreviated
procedures for equipment acceptance testing, or alternatively, may propose to accept written assurances that
the full procedures have been performed by the source with mutually satisfactory results.

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INTERNATIONAL STANDARD ISO 5344:2004(E)

Electrodynamic vibration generating systems — Performance
characteristics
1 Scope
This International Standard specifies the performance characteristics and performance test conditions for
electrodynamic vibration generator systems and provides a list of additional equipment characteristics (see
Annex A) that can be declared by the equipment manufacturer. This information can be used by the user or
the writer of specifications for equipment for the selection of such a system, taking into account its application.
This International Standard establishes procedures for calculating the system performance of a system
comprising an amplifier from one source and a vibrator from a different source. Such a calculated system
performance is less precise than performance measured on a system comprising the actual vibrator and
amplifier, and a reserve of calculated force is recommended. It can be desirable to specify separately the
acquisition of needed vibrator and/or amplifier interface data, particularly if a vibrator or amplifier is to be
acquired to add to an existing installation. It can also be desirable to specify the responsibility for the
calculation of performance.
This International Standard is applicable to equipment producing sine, random and impulse rectilinear
vibration. It is implied that all systems are usable for sine testing at least at a low level, since sine capability is
needed for specimen response evaluation and transfer function measurements for random and impulse
testing. When random capability is specified, it is implied that some sine capability is also available. Similarly,
when impulse capability is specified, it is implied that some sine, but not necessarily random, capability is
available.
NOTE Three groups of people are expected to use this International Standard: the supplier of the equipment, the
purchaser of the equipment, and the organization that tests the equipment. The supplier of the equipment states that
“rated” performance is available, typically as stated in sales literature. The purchaser states the “specified” performance of
the equipment that he will accept, typically less than or equal to the rated performance. The test organization “provides”
the results of its tests and observations, typically by a written report, which may include the conditions and accuracy of
each measurement, and illustrations such as waveforms, performance graphs and tables of values.
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.
ISO 2041:1990, Vibration and shock — Vocabulary
ISO 15261, Vibration and shock generating systems — Vocabulary
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ISO 5344:2004(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2041, ISO 15261 and the following
apply.
3.1
electrodynamic vibration generator
vibrator
vibration generator which derives its vibratory force from the interaction of a magnetic field of constant value,
and a coil of wire contained in it which is excited by a suitable alternating current
[ISO 2041:1990]
NOTE 1 Unless specifically restricted to the moving element, body and base of the vibrator machine, this includes the
flexible field, control and drive cables, coolant hoses, field supply, and cooling, demagnetizing, protective and safety
systems.
NOTE 2 In this International Standard, the subscript “ v ” is used to indicate vibrator, short for electrodynamic vibration
generator. The word vibrator, which has the same meaning, is the term commonly used in industry.
3.2
power amplifier
amplifier
power electronic device capable of providing the voltage and current used to drive the vibrator
NOTE Unless otherwise specified, this includes the cooling, protective and safety systems.
3.3
system
combination of a power amplifier and an electrodynamic vibration generator to provide vibratory force
NOTE The following are excluded from this International Standard, but are included in the more inclusive
electrodynamic vibration test facility system:
 the input signal source and control (typically providing controlled sinusoidal, random or shock simulation signals);
 specimen mounting fixtures and auxiliary tables;
 measuring instrumentation (e.g. accelerometers and conditioning and analysis electronics);
 mains electrical power cables and coolant hoses, or piping to and between the power amplifier, vibrator field supply,
and vibrator and amplifier cooling supplies;
 air conditioning to remove generated heat not removed by the cooling systems;
 a vibration-isolated inertia block to inhibit the transmission of vibratory forces from the vibrator to the surroundings.
3.4
equipment source
source
supplier of the equipment being acquired or to be used in the system
NOTE 1 When a system is purchased from a single source, that source usually is the manufacturer or his agent. When
the components of a system are being purchased from more than one source, the sources are usually the manufacturers
of the individual components or their agents. When an organization wishes to acquire a new component (e.g. a switching
amplifier) to be combined with an existing component (e.g. a vibrator in the test laboratory of the organization), the source
of the vibrator is the vibration test laboratory.
NOTE 2 The vibration test laboratory, or other similar non-commercial source, may have difficulty acquiring the data
needed to assure that the resulting system achieves the desired system specifications.
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ISO 5344:2004(E)
3.5
drive coil
component of the electrodynamic vibration generator, designed to provide, by means of interaction between
the alternative current in the drive coil and the static magnetic field, the vibratory force proportional to the drive
coil current
NOTE For most electrodynamic vibration generators, the drive coil is attached to the moving element. For
transformer coupled vibrators, the drive coil is stationary and is coupled by transformer action to a shorted ring on the
moving element.
3.6
linear power amplifier
power amplifier having an output proportional to the input
NOTE 1 Typically, the large linear power amplifiers designed to drive vibrators have low distortion (0,1 % to 0,3 %)
when they are new or well maintained, but have high internal power dissipation, so necessitate a way of disposing of the
excess heat, and are more expensive than switching power amplifiers.
NOTE 2 Small vibrators are sometimes driven by linear audio-power amplifiers or arrays of linear audio-power
amplifiers. Moderately priced units typically have 0,1 % distortion, and higher performance and price units are available
with 0,01 % distortion.
3.7
switching power amplifier
power amplifier having an output that switches alternately between a negative value and a positive value at a
high frequency
NOTE 1 If the output is positive for a greater fraction of the high frequency cycle than it is negative, the mean output is
positive. Filtering, including the effects of the drive coil inductance and the moving mass, serves to smooth the current
through the drive coil. The technique results in low internal power dissipation. Switching power amplifiers typically are
smaller and less expensive than linear power amplifiers of the same output capability, but may have higher distortion.
NOTE 2 The earlier switching power amplifiers used to drive vibrators had switching frequencies around 40 kHz and
distortions of about 5 % to 15 %. Modern switching power amplifiers are available with switching frequencies of about
150 kHz and distortion of about 1,5 % to 5 %. As faster switching transistors become available, higher switching
frequencies will be possible, and the distortion will be reduced further. When switching frequencies reach the megahertz
region, substantial feedback around the output stage is possible, and the switching amplifier distortion will reach the 0,1 %
to 0,3 % range of the linear power amplifiers.
3.8
force
vibratory force resulting from a varying current, in a steady magnetic field, which is applied to the structure of
the moving element and the attached specimen
NOTE Due to losses, resonances and travel limitations, not all of this force is available to accelerate the moving
element and attached specimen and/or to deflect the moving element suspension springs. The magnitude of the force is
defined by the resulting acceleration:
F=+mm a
( )
et
where m and m are the masses of the moving element and attached load, respectively, and a is the resulting
e t
acceleration. This definition applies to sine, random and impulse functions of a and F .
3.9
frequency range f to f
min max
frequency range over which the full rated performance of a variable can be achieved
NOTE 1 Since the frequency range for one variable differs from the frequency range of another variable, the frequency
range should be separately specified for each variable and for each load.
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ISO 5344:2004(E)
NOTE 2 With regard to the force-generating capability, the values of f and f should be individually specified
min max
for both vibrator and system rated sine, random and impulse forces for each of the masses m , and for the amplifier rated
t
sine, random, and impulse output. If factors other than the force-generating capability limit the frequency range of
operation, they should be specified.
EXAMPLE
a) At low frequencies, examples of areas that may cause problem are
 ratio of body mass to moving mass,
 the pedestal-body suspension stroke limitations,
 distortion,
 transverse motion,
 the moving element stroke limitations,
 moving element side load capability, and
 moving element suspension heating.
b) At high frequencies, examples of areas that may cause problems are
 moving element mechanical resonance,
 diaphragmatic effect of the moving element table (diaphragming),
 distortion,
 transverse motion, and
 moving element to load stiffness.
3.10
test mass
m
t
mechanical mass used for the testing of systems and electrodynamic vibration generators
NOTE Except for the special case of m , the subscript “ t ” indicates the magnitude of the mass by the magnitude of
0
the sinusoidal acceleration achievable with the mass:
m is the special case of zero load, where only the moving element is driven;
0
2
m means that 10 m/s ( ≈ 1g ) is achievable;
1 n
2
m means that 40 m/s ( ≈ 4g ) is achievable;
4 n
2
m means that 100 m/s ( ≈ 10g ) is achievable;
10 n
2
m means that 200 m/s ( ≈ 20g ) is achievable;
20 n
2
m means that 400 m/s ( ≈ 40g ) is achievable.
40 n
Unless otherwise specified, only m , m and m are used.
0 10 40
3.11
amplifier test load
Z
a,t
electric load of the amplifier, designed to be used when testing as a system is not possible (usually because
the amplifier and vibrator sources differ)
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ISO 5344:2004(E)
NOTE Tests with the loads Z are used to acquire data for the prediction of system performance. The subscript t
a,t
indicates the operation mode: s for sine, r for random, and i for impulse. See 7.2 for properties and the calculation of load
magnitudes.
3.12
amplifier apparent power
product of the amplifier output current and the amplifier output voltage under specified conditions
NOTE See Note to 7.1.2 for improved size designation.
3.13
standard random spectral shape
random motion spectrum of the following shape, unless otherwise specified:
Φ ( f ) = 0 for f < 20 Hz;
2
f

ΦΦ()f = for 20 Hz u f < 100 Hz (20 dB per decade)
0

100

ΦΦ( f ) = for 100 Hz u f < 2 000 Hz (constant)
0
4
2000
−4
ΦΦf < or 10Φ for fW 2 000 Hz (allowable spill-over)
()
00
f

NOTE Φ f is the magnitude of the acceleration spectral density function, defined as the limit as ∆f approaches 0
( )
2
of af∆ , where a is the root-mean-square value of a narrow-band random acceleration of bandwidth ∆f centred
n n
about the frequency f .
3.14
impulse
short-duration waveform used to provide a shock excitation to the specimen
NOTE 1 There should be agreement on the acceleration time history of the impulse to be used before any of the
impulse clauses of this International Standard may be used.
NOTE 2 An impulse is specified by an acceleration time history. For electrodynamic systems, the frequency
components of the acceleration time history or of the wavelets used to produce an acceleration response spectrum are
specified over the frequency range.
NOTE 3 Typically, the high frequency spill-over problems of impulse testing are more severe than for random vibration
testing because the high amplifier output, and clipping, generate larger distortion components.
NOTE 4 Vibrators with transformer driver coils sometimes are used for high acceleration impulses. Typically, such
vibrators have the advantage of very strong moving elements. As a disadvantage, they have displacement limits that are
particularly serious for the smaller vibrators. Moving element cooling of the strongest types of these vibrators is difficult,
which may be a problem if the same vibrator is to be used for sine and random testing as well as for impulse testing.
3.15
spill-over
undesired vibration (or signal) in the frequency range higher than the specified frequency range
EXAMPLE For vibration tests specified only to 2 000 Hz, spill-over is vibration excitation above 2 000 Hz.
NOTE Typically, spill-over is caused by loose elements of the moving element or test load, inadequate filtering, or by
excessive current distortion.
3.16
distortion
undesired change in the waveform
[ISO 2041:1990]
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ISO 5344:2004(E)
NOTE 1 Distortion is distinguished from noise and hum, which are dealt with separately in this International Standard.
NOTE 2 For a good electrodynamic vibration generating system, the presence of distortion is a very sensitive indication
that something is wrong. Excessive distortion is a signal calling for corrective action. The user is advised to find the
problem, and correct it, before running an environmental test that would be invalid. The cause of the distortion may be
anywhere, including a loose bolt mounting the specimen to the table, a failed amplifier output transistor, an obstruction in a
cooling system, or an attempt to drive the amplifier or vibrator beyond its limits.
NOTE 3 For properly maintained electrodynamic vibration generation systems, a major cause of distortion is non-
linearity or clipping in the power amplifier. Some of the low frequency distortion, below 50 Hz to 100 Hz, is typically caused
by suspension stiffness non-linearity and/or the non-uniformity of the field in the magnetic gap. In this frequency range,
these distortions can exceed those due to power amplifier non-linearity.
NOTE 4 The distortion process generates harmonics of the input signal which excite higher frequency resonances of
the specimen. Both distortion products in the operating band, typically 20 Hz to f , and distortion products which
max
cause excitation above f are troublesome (see 3.15).
max
NOTE 5 Distortion may be specified for any variable of the system: current, voltage, acceleration, velocity or
displacement. Current distortion is the most useful distortion measure for vibration test systems. It is used to predict
system distortion and spill-over.
NOTE 6 It is tempting to specify the measurement of acceleration distortion directly, but such a measurement is unique
to the particular moving element/load combination being measured, and does not provide data that are useful for the
prediction of distortion with other table loads.
3.17
standard acceleration due to gravity
g
n
value for the acceleration due to gravity as defined for shock and vibration use in ISO 2041
2
NOTE 1 According to ISO 2041, g equals 9,806 65 m/s .
n
NOTE 2 In vibration testing, acceleration magnitude is often expressed as a multiple of g .
n
4 Structure of this International Standard
4.1 General
Clauses on the electrodynamic vibration generator, power amplifier and system as a whole include
subclauses giving information that the specification writer may include in his relevant specification for the
acquisition of a complete system or for components of a system.
A single relevant specification is unlikely to include all of the subclauses. For example, if only an amplifier is to
be acquired, some of the system subclauses are not necessary, and only a few of the vibrator subclauses are
needed for interface information. It is suggested that the writer of a specification read the entire standard
before selecting the subclauses needed for a particular application.
4.2 Subclause coding
A code appears after the title of each subclause as an aid to the reader and to the writer of relevant
specifications. This code has the form (X,y).
The entry at position X specifies the type of acquisition for which the subclause is applicable:
 A for all acquisitions,
 S only for system acquisitions, and
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ISO 5344:2004(E)
 C only if a component, vibrator or amplifier, is being acquired, but not if both are being acquired.
The entry at position y specifies the type of use for which the subclause is applicable:
 a for all,
 s for sine,
 r for random, and
 i for impulse.
4.3 Symbol coding
Symbols used frequently in the text are coded as K :
g,h
 symbol K means F for force, t for time to temperature stabilization, I for current, V for voltage, Z for
amplifier load, and d for distortion;
 subscript g means s for system, v for vibration generator, and a for amplifier;
 subscript h means s for sine, r for random, and i for impulse.
5 Systems
5.1 General
The performance of both vibrators and amplifiers deteriorates as the operating temperature increases. When
performance is specified for continuous operation, as is typical for sine and random testing, the performance
tests shall be taken after a conditioning heat run to stabilize the temperature of the equipment. Exceptions to
continuous operation shall be clearly stated. For example, not all air-cooled systems will operate at high
altitudes. Also, for some vibrators, overheating and failure will occur if continuous sine operation is attempted
at certain pedestal to body suspension resonances or certain body to moving element suspension resonances.
5.2 System specifications (S,a)
The major characteristic to be specified for an electrodynamic vibration generator system is its
force-generation capability for the desired type of use (sine, random or impulse). Be sure to include the mass
of the necessary fixtures when calculating the needed force.
The system force generation capabilities shall be specified as follows:
 for sine operation
...