EN ISO 10846-2:2008

SLOVENSKI STANDARD
01-november-2008
1DGRPHãþD
SIST EN ISO 10846-2:1999
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Acoustics and vibration - Laboratory measurement of vibro-acoustic transfer properties of
resilient elements - Part 2: Direct method for determination of the dynamic stiffness of
resilient supports for translatory motion (ISO 10846-2:2008)
Akustik und Schwingungstechnik - Laborverfahren zur Messung der vibro-akustischen
Transfereigenschaften elastischer Elemente - Teil 2: Direktes Verfahren zur Ermittlung
der dynamischen Steifigkeit elastischer Stützelemente bei Anregung in translatorischer
Richtung (ISO 10846-2:2008)
Acoustique et vibrations - Mesurage en laboratoire des propriétés de transfert vibro-
acoustique des éléments élastiques - Partie 2: Méthode directe pour la détermination de
la raideur dynamique en translation des supports élastiques (ISO 10846-2:2008)
Ta slovenski standard je istoveten z: EN ISO 10846-2:2008
ICS:
17.140.01 $NXVWLþQDPHUMHQMDLQ Acoustic measurements and
EODåHQMHKUXSDQDVSORãQR noise abatement in general
17.160 Vibracije, meritve udarcev in Vibrations, shock and
vibracij vibration measurements
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 10846-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2008
ICS 17.140.01 Supersedes EN ISO 10846-2:1998
English Version
Acoustics and vibration - Laboratory measurement of vibro-
acoustic transfer properties of resilient elements - Part 2: Direct
method for determination of the dynamic stiffness of resilient
supports for translatory motion (ISO 10846-2:2008)
Acoustique et vibrations - Mesurage en laboratoire des Akustik und Schwingungstechnik - Laborverfahren zur
propriétés de transfert vibro-acoustique des éléments Messung der vibro-akustischen Transfereigenschaften
élastiques - Partie 2: Méthode directe pour la détermination elastischer Elemente - Teil 2: Direktes Verfahren zur
de la raideur dynamique en translation des supports Ermittlung der dynamischen Steifigkeit elastischer
élastiques (ISO 10846-2:2008) Stützelemente bei Anregung in translatorischer Richtung
(ISO 10846-2:2008)
This European Standard was approved by CEN on 12 April 2008.
CEN 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 CEN Management Centre or to any CEN 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 CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10846-2:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 10846-2:2008) has been prepared by Technical Committee ISO/TC 43 "Acoustics" in
collaboration with Technical Committee CEN/TC 211 “Acoustics” the secretariat of which is held by DS.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by February 2009, and conflicting national standards shall be withdrawn
at the latest by February 2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 10846-2:1998.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 10846-2:2008 has been approved by CEN as a EN ISO 10846-2:2008 without any
modification.
INTERNATIONAL ISO
STANDARD 10846-2
Second edition
2008-08-15
Acoustics and vibration — Laboratory
measurement of vibro-acoustic transfer
properties of resilient elements —
Part 2:
Direct method for determination of the
dynamic stiffness of resilient supports for
translatory motion
Acoustique et vibrations — Mesurage en laboratoire des propriétés de
transfert vibro-acoustique des éléments élastiques —
Partie 2: Méthode directe pour la détermination de la raideur dynamique
en translation des supports élastiques

Reference number
ISO 10846-2:2008(E)
©
ISO 2008
ISO 10846-2:2008(E)
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ii © ISO 2008 – All rights reserved

ISO 10846-2:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions. 3
4 Principle. 6
5 Requirements for apparatus. 6
5.1 Normal translations . 6
5.2 Transverse translations . 8
5.3 Suppression of unwanted vibrations. 11
6 Criteria for adequacy of the test arrangement. 12
6.1 Frequency range. 12
6.2 Measurement of blocking force. 12
6.3 Flanking transmission. 13
6.4 Unwanted input vibrations. 13
6.5 Accelerometers . 14
6.6 Force transducers. 14
6.7 Summation of signals. 14
6.8 Analysers. 15
7 Test procedures . 15
7.1 Installation of the test elements . 15
7.2 Selection of force measurement system and output-force distribution plates. 15
7.3 Mounting and connection of accelerometers . 15
7.4 Mounting and connections of the vibration exciter . 16
7.5 Source signal . 16
7.6 Measurements. 16
7.7 Test for linearity. 17
8 Evaluation of test results . 18
8.1 Calculation of dynamic transfer stiffness . 18
8.2 One-third-octave-band values of the frequency-averaged dynamic transfer stiffness. 18
8.3 Presentation of one-third-octave-band results. 19
8.4 Presentation of narrow-band data . 20
9 Information to be recorded . 21
10 Test report . 22
Annex A (informative) Static load-deflection curve . 23
Annex B (informative) Measurement uncertainty . 24
Bibliography . 28

ISO 10846-2:2008(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 10846-2 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise, and
ISO/TC 108, Mechanical vibration, shock and condition monitoring.
This second edition cancels and replaces the first edition (ISO 10846-2:1997), which has been technically
revised.
ISO 10846 consists of the following parts, under the general title Acoustics and vibration — Laboratory
measurement of vibro-acoustic transfer properties of resilient elements:
⎯ Part 1: Principles and guidelines
⎯ Part 2: Direct method for determination of the dynamic stiffness of resilient supports for translatory motion
⎯ Part 3: Indirect method for determination of the dynamic stiffness of resilient supports for translatory
motion
⎯ Part 4: Dynamic stiffness of elements other than resilient supports for translatory motion
⎯ Part 5: Driving point method for determination of the low-frequency transfer stiffness of resilient supports
for translatory motion
iv © ISO 2008 – All rights reserved

ISO 10846-2:2008(E)
Introduction
Passive resilient elements of various kinds are used to reduce the transmission of vibrations. Examples are
automobile engine mounts, resilient supports for buildings, resilient mounts and flexible shaft couplings for
shipboard machinery and small isolators in household appliances.
This part of ISO 10846 specifies a direct method for measuring the dynamic transfer stiffness function of linear
resilient supports. This includes resilient supports with non-linear static load-deflection characteristics, as long
as the elements show an approximate linearity for vibration behaviour for a given static preload. This part of
ISO 10846 belongs to a series of International Standards on methods for the laboratory measurement of
vibro-acoustic properties of resilient elements, which also includes documents on measurement principles, on
an indirect method and on a driving point method. ISO 10846-1 provides guidance for the selection of the
appropriate International Standard.
The laboratory conditions described in this part of ISO 10846 include the application of static preload.
The results of the method described in this part of ISO 10846 are useful for resilient supports that are used to
prevent low-frequency vibration problems and to attenuate structure-borne sound in the lower part of the
audible frequency range. However, for complete characterization of resilient elements that are used to
attenuate low- frequency vibration or shock excursions, additional information is needed, which is not provided
by this method.
INTERNATIONAL STANDARD ISO 10846-2:2008(E)

Acoustics and vibration — Laboratory measurement of vibro-
acoustic transfer properties of resilient elements —
Part 2:
Direct method for determination of the dynamic stiffness of
resilient supports for translatory motion
1 Scope
This part of ISO 10846 specifies a method for determining the dynamic transfer stiffness for translations of
resilient supports, under specified preload. The method concerns the laboratory measurement of vibrations on
the input side and blocking output forces and is called “the direct method”. The method is applicable to test
elements with parallel flanges (see Figure 1).
Resilient elements, which are the subject of this part of ISO 10846, are those which are used to reduce
⎯ the transmission of vibration in the lower part of the audible frequency range (typically 20 Hz to 500 Hz) to
a structure which may, for example, radiate unwanted fluid-borne sound (airborne, waterborne or others),
and
⎯ the transmission of low-frequency vibrations (typically 1 Hz to 80 Hz), which may, for example, act upon
human subjects or cause damage to structures of any size when vibration is too severe.
NOTE 1 In practice, the size of the available test rig(s) can restrict the use of very small or very large resilient supports.
NOTE 2 Samples of continuous supports of strips and mats are included in this method. Whether or not the sample
describes the behaviour of the complex system sufficiently is the responsibility of the user of this part of ISO 10846.
Measurements for translations normal and transverse to the flanges are covered in this part of ISO 10846.
The direct method covers the frequency range from 1 Hz up to a frequency f , which is usually determined
UL
by the test rig.
NOTE 3 Because of the large variety of test rigs and test elements, f is variable. In this part of ISO 10846, the
UL
adequacy of the test rig is not defined for a fixed frequency range, but on the basis of measured data, as described in 6.1
to 6.4.
ISO 10846-2:2008(E)
NOTE 1 When a resilient support has no parallel flanges, an auxiliary fixture is included as part of the test element to
arrange for parallel flanges.
NOTE 2 The arrows indicate the load direction.
Figure 1 — Example of resilient supports with parallel flanges
The data obtained according to the method specified in this part of ISO 10846 can be used for the following:
⎯ product information provided by manufacturers and suppliers;
⎯ information during product development;
⎯ quality control;
⎯ calculation of the transfer of vibration energy through isolators.
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 266, Acoustics — Preferred frequencies
1)
ISO 2041:— , Mechanical vibration, shock and condition monitoring — Vocabulary
ISO 5348, Mechanical vibration and shock — Mechanical mounting of accelerometers
ISO 7626-1, Vibration and shock — Experimental determination of mechanical mobility — Part 1: Basic
definitions and transducers
ISO 10846-1, Acoustics and vibration — Laboratory measurement of vibro-acoustic transfer properties of
resilient elements — Part 1: Principles and guidelines
ISO 16063-21, Methods for the calibration of vibration and shock transducers — Part 21: Vibration calibration
by comparison to a reference transducer
2)
ISO/IEC Guide 98-3 , Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM 1995)
1) To be published. (Revision of ISO 2041:1990)
2) ISO/IEC Guide 98-3 will be published as a re-issue of the Guide to expression of uncertainty in measurement (GUM),
1995.
2 © ISO 2008 – All rights reserved

ISO 10846-2:2008(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2041 and the following apply.
3.1
vibration isolator
resilient element
isolator designed to attenuate the transmission of the vibration in a certain frequency range
1)
NOTE Adapted from ISO 2041:— , definition 2.120.
3.2
resilient support
vibration isolator(s) suitable for supporting a machine, a building or another type of structure
3.3
test element
resilient support undergoing testing, including flanges and auxiliary fixtures, if any
3.4
blocking force
F
b
dynamic force on the output side of a vibration isolator, which results in a zero displacement output
3.5
dynamic transfer stiffness
k
2,1
frequency-dependent ratio of the blocking force phasor F on the output side of a resilient element to the
2,b
displacement phasor u on the input side
k= F / u
2,b
2,1 1
NOTE 1 The subscripts “1”and “2” denote the input and output sides, respectively.
NOTE 2 The value of k can be dependent on the static preload, temperature, relative humidity and other conditions.
2,1
NOTE 3 At low frequencies, k is solely determined by elastic and dissipative forces and kk≈ ( k denotes the
2,1 1,1 2,1 1,1
ratio of force and displacement on the input side). At higher frequencies, inertial forces in the resilient element play a role
as well and kk≠ .
1,1 2,1
3.6
loss factor of resilient element
η
ratio of the imaginary part of k to the real part of k , i.e. tangent of the phase angle of k , in the
2,1 2,1 2,1
low-frequency range, where inertial forces in the element are negligible
3.7
frequency-averaged dynamic transfer stiffness
k
av
function of the frequency of the average value of the dynamic transfer stiffness over a frequency band ∆f
NOTE See 8.2.
3.8
point contact
contact area that vibrates as the surface of a rigid body
ISO 10846-2:2008(E)
3.9
normal translation
translational vibration normal to the flange of a resilient element
3.10
transverse translation
translational vibration in a direction perpendicular to that of the normal translation
3.11
linearity
property of the dynamic behaviour of a vibration isolator, if it satisfies the principle of superposition
NOTE 1 The principle of superposition can be stated as follows: if an input x (t) produces an output y (t) and in a
1 1
separate test an input x (t) produces an output y (t), superposition holds if the input ax (t) + bx (t) produces the output
2 2 1 2
ay (t) + by (t). This must hold for all values of a, b and x (t), x (t); a and b are arbitrary constants.
1 2 1 2
NOTE 2 In practice, the above test for linearity is impractical and a limited check of linearity is performed by measuring
the dynamic transfer stiffness for a range of input levels. For a specific preload, if the dynamic transfer stiffness is
nominally invariant, the system can be considered linear. In effect, this procedure checks for a proportional relationship
between the response and the excitation (see 7.7).
3.12
direct method
method in which either the input displacement, velocity or acceleration and the blocking output force are
measured
3.13
indirect method
method in which the vibration transmissibility (for displacement, velocity or acceleration) of a resilient element
is measured, with the output loaded by a known mass
NOTE The term “indirect method” can be permitted to include loads of any known impedance other than a mass-like
impedance. However, ISO 10846 does not cover such methods.
3.14
driving point method
method in which either the input displacement, velocity or acceleration and the input force are measured, with
the output side of the resilient element blocked
3.15
force level
L
F
level defined by the following formula
F
= 10lg  dB
L
F
F
where
F denotes the mean square value of the force in a specific frequency band and F is the reference
−6
force (F = 10 N)
4 © ISO 2008 – All rights reserved

ISO 10846-2:2008(E)
3.16
acceleration level
L
a
level defined by the following formula
a
= 10lg  dB
L
a
a
where
a denotes the mean square value of the acceleration in a specific frequency band and a is the
−6 2)
reference acceleration (a = 10 m/s
3.17
level of dynamic transfer stiffness
L
k
2,1
level defined by the following formula
k
21,
= 10lg  dB
L
k
2,1
k
where
|k | is the square magnitude of the dynamic transfer stiffness (3.5) at a specified frequency and k is
2,1 0
the reference stiffness (k = 1 N/m)
3.18
level of frequency-band-averaged dynamic transfer stiffness
L
k
av
level defined by the following formula
k
av
= 10lg dB
L
k
av
k
where
k is the frequency-averaged dynamic transfer stiffness (3.7) and k is the reference stiffness
av 0
(k = 1 N/m)
3.19
flanking transmission
forces and accelerations at the output side caused by the vibration exciter at the input side but via
transmission paths other than through the resilient element under test
3.20
upper limiting frequency
f
UL
frequency up to which the results are valid, according to the criteria given in this part of ISO 10846
NOTE See 6.1 to 6.4.
ISO 10846-2:2008(E)
4 Principle
The measurement principle of the direct method for measuring the dynamic transfer stiffness (3.5) is
discussed in ISO 10846-1. The characteristic feature of this method is that the blocking output force is
measured between the output side of the resilient support and a foundation. The foundation must provide a
sufficient reduction of the vibrations on the output side of the test object compared to those on the input side.
5 Requirements for apparatus
5.1 Normal translations
5.1.1 Overview
A schematic representation of a test rig is shown in Figure 2. The test element is exposed to translatory
vibration in the normal load direction. The test element shall be mounted in a way that is representative of its
use in practice.
NOTE The test rig example of Figure 2 is not intended to form a limitation for test arrangements.
To be suitable for the measurements according to this part of ISO 10846, a test rig shall include the items
described in 5.1.2 to 5.1.7.
b)  Input side (details)
a)  Overview c)  Output side (details)
Key
1 vibration exciter 8 rigid foundation
2 traverse 9 static preload
3 connection rod 10 dynamic excitation
4 dynamic decoupling springs, static preload 11 output-force distribution plate
5 excitation mass 12 input acceleration measurement (a )
6 test element 13 output acceleration measurement (a )
′′′
7 output force and acceleration measurement 14 normal output-force measurement FF=+F
(22 2 )
Figure 2 — Example of laboratory test rig for measuring
the dynamic transfer stiffness for normal translations
6 © ISO 2008 – All rights reserved

ISO 10846-2:2008(E)
5.1.2 Foundation
The test element is mounted on a heavy and rigid foundation using a force measurement system [see 5.1.4
and Figure 2 c)].
5.1.3 Static preloading system
Measurements shall be performed with the test element under a representative and specified preload.
Examples of methods for applying the static preload are as follows.
a) Use of a hydraulic actuator, which serves also as a vibration exciter. This is mounted in a load frame,
together with the test element and the foundation table.
b) Use of a frame, which provides static preload only; see Figure 2 a). If such a frame is applied, auxiliary
vibration isolators shall be used for dynamic decoupling of the test object from the frame.
c) Use of a gravity load using a mass on top of the test object (with or without a support frame).
5.1.4 Force measurement system on the output side
A force measurement system consisting of one or more force transducers (load cells) shall be installed on the
output side of the test element; see Figure 2 c).
NOTE It might be necessary to apply a force distribution plate between the test element and the force transducers.
Besides its function of load distribution, the force distribution plate also provides a high contact stiffness to the force
transducers. Moreover, it provides a uniform vibration of the output flange.
5.1.5 Acceleration measurement systems
Accelerometers shall be mounted on the input and output side of the test element and on the foundation of the
test arrangement; see Figures 2 b) and 2 c). When mid-point positions are not accessible, indirect
measurement of mid-point accelerations shall be performed by making an appropriate signal summation, for
example, by taking the linear average for two symmetrically positioned accelerometers.
As an option, instead of accelerometers, displacement or velocity transducers may be used, provided that
their frequency range is appropriate.
5.1.6 Dynamic excitation system
The dynamic excitation system shall be suitable for the excitation level and for the frequency range of interest.
Any type of exciter is permitted. Examples are
a) a hydraulic actuator which also can provide a static preload, or
b) one or more electrodynamic vibration exciters (shakers) with connection rods, or
c) one or more piezo-electric exciters.
Vibration isolators may be used for dynamic decoupling of exciters, to reduce flanking transmission via the
frame for applying static preload. However, in the test rigs that use a hydraulic actuator for both static and
dynamic loading, such a decoupling is usually inconvenient because of its adverse effects on low-frequency
measurements.
ISO 10846-2:2008(E)
5.1.7 Excitation mass on the input side
The excitation mass or force distribution plate on the input side of the test object has one or more of the
following functions:
a) to provide a uniform vibration of the input flange under dynamic forces;
b) to enhance unidirectional vibration of the input flange.
If the test element contains a solid-mass-type input flange, which can provide the above-mentioned functions,
the special excitation mass may be omitted.
5.2 Transverse translations
5.2.1 Overview
Schematic representations of test rigs for resilient supports exposed to transverse vibrations perpendicular to
the normal load direction are shown in Figures 3 to 5. In Figures 3 a) and 3 c), roller bearings are used,
respectively for suppressing unwanted input vibrations and for suppressing unwanted transverse forces on the
output-force distribution plate. See 5.2.7 and 6.1 for further comments on the proper use of such bearings. In
Figures 4 and 5 two symmetrically placed nominally equal resilient elements are used for suppressing
unwanted input vibrations.
The test rig shall include the items listed in 5.2.2 to 5.2.7.
5.2.2 Foundation
The test element is mounted on a heavy and rigid foundation table (see Figures 3 and 4) or between stiff
columns (see Figure 5), using a force measurement system.
5.2.3 Static preloading system
Measurements shall be performed with the test element under a representative and specified preload.
Figures 3 to 5 present some schematic examples.
5.2.4 Force measurement system on the output side
A force measurement system consisting of one or more force transducers (load cells) shall be installed on the
output side of the test element. Two basic options exist.
a) One or more force transducers for the measurement of shear forces; see Figures 3 d), 4 and 5. It may be
necessary to apply a force distribution plate between the test element and the force transducers (see the
notes in 5.1.4),
b) One or more normal force transducers; see Figure 3 c). It may be necessary to apply a force distribution
plate between the test element and the force transducers; see the note in 5.1.4.
5.2.5 Acceleration measurement systems on the input and output sides
Accelerometers shall be mounted on the input and output side of the test element.
The accelerometers on the test element flanges or on the force distribution plate may be placed on horizontal
symmetry axes of these components. When such places are not accessible, indirect measurement of the
acceleration along a symmetry axis may be performed by making an appropriate signal summation, for
example, by taking the linear average for two symmetrically positioned accelerometers.
8 © ISO 2008 – All rights reserved

ISO 10846-2:2008(E)
Provided that displacement or velocity transducers have the appropriate frequency response, they may be
used instead of accelerometers.

b)  Input side (details)
c)  Output side with low friction bearing
(details)
a)  Overview d)  Output with shear force transducers
(details)
Key
1 exciter 8 rigid foundation
2 connection rod 9 input-force distribution plate (excitation mass)
3 traverse 10 output-force distribution plate
4 low-friction bearing 11 input acceleration measurement (a )
5 auxiliary springs to prevent rattling 12 output acceleration measurement (a )
6 test element 13 output transverse-force measurement (F )
′ ′′
7 output force and acceleration measurement 14 output shear-force measurement FF=+F
(22 2 )
Figure 3 — Example 1 of laboratory test rig for measuring the dynamic
transfer stiffness for transverse translation
ISO 10846-2:2008(E)
Key
1 exciter 6 input acceleration measurement (a )
2 connection rod 7 output acceleration measurement (a )
′ ′′
3 traverse 8 output shear-force measurement FF=+F
(22 2 )
4 nominally equal resilient elements 9 rigid foundation
5 input-force distribution plate
Figure 4 — Example 2 of laboratory test rig for measuring the dynamic transfer stiffness for
transverse translation (The lower resilient element is considered as the test element)

Key
1 exciter 6 rigid columns
2 preloading device 7 input acceleration measurement (a )
3 connection rod 8 output shear-force measurement [F = (F′ + F″)/2]
2 2 2
4 input-force distribution plate 9 output acceleration measurement (a )
5 nominally equal test elements
Figure 5 — Example 3 of laboratory test rigs for measuring
the dynamic transfer stiffness for transverse translation
(Test results are for the average transfer stiffness of two nominally equal resilient elements)
10 © ISO 2008 – All rights reserved

ISO 10846-2:2008(E)
5.2.6 Dynamic excitation system
The dynamic excitation system shall be suitable for the excitation level and frequency range of interest.
Examples of vibration exciters are given in 5.1.6.
5.2.7 Excitation mass on the input side
The Input-force distribution plate (mass) has one or more of the following functions:
a) to provide a uniform vibration of the input flange under dynamic forces
b) to enhance unidirectional vibration of the input flange.
If the test element contains a solid-mass-type input flange, which can provide the above-mentioned functions,
the special excitation mass can be omitted.
Predominantly unidirectional translation on the input side of the test element is an essential requirement for
the measurement of dynamic stiffness according to this part of ISO 10846 (see 6.4). For input translations,
predominance of the required translation will be influenced by
a) the symmetry of the vibration excitations and boundary conditions of the excitation mass (see Figures 4
and 5), and
b) the inertial properties of the excitation mass.
In certain cases, it will be necessary to apply external constraints, such as low-friction bearings or some other
guiding system, to prevent vibrations in unwanted directions; see Figures 3 a) and 3 b).
NOTE When, as in the example of Figures 3 a) and 3 b), roller bearings are used between the input side of the test
element and a frame for preloading, the appropriate roller bearings for the applied static preload are necessary. Any
elastic deformation of the bearings, leading to unwanted transverse forces due to the bearing system, needs to be avoided.
Otherwise flanking transmission via the frame structure will occur. This can lead to invalid measurements due to the
serious limitation of the frequency range.
5.3 Suppression of unwanted vibrations
5.3.1 General
The test procedures according to this part of ISO 10846 cover measurements of transfer stiffness for
unidirectional excitations, one by one in the normal and transverse directions.
However, due to asymmetries in excitation, boundary conditions and test element properties, components
other than the intended input vibration component may show unwanted strong responses at certain
frequencies. Qualitative measures to suppress unwanted input vibrations are discussed in 5.3.2 and 5.3.3. A
special category of test arrangements is that in which two nominally equal resilient elements are tested in a
symmetrical configuration; see Figures 4 and 5. This may help to suppress unwanted input vibrations.
Quantitative requirements are given in 6.4.
5.3.2 Normal direction
For excitation in the normal direction, a symmetrical positioning of the exciter, or a pair of exciters, shall be the
favourable method for suppressing transverse and rotational vibrations on the input side.
Nevertheless, the properties of the test object itself may cause coupling between the normal and other
vibration directions. A method of suppressing unwanted input vibrations is the use of a symmetrical
arrangement with two or four nominally identical test elements, or using a “guiding” system on the sides of the
excitation mass, for example roller bearings. These systems are not shown in a figure.
ISO 10846-2:2008(E)
5.3.3 Transverse direction
For excitation in the transverse direction, coupling between transverse and rotational input vibrations will
always occur.
In Figures 3 to 5, examples of measures are shown, which may enhance unidirectional vibrations on the input
side. Figure 3 shows an example of how a guiding system can be used to suppress input rotations. Figures 4
and 5 show symmetrical arrangements with two nominally equal test objects.
In the test set-up of Figure 4, the lower resilient element is the test element.
In the test set-up of Figure 5, the average transfer stiffness of the two resilient elements is determined by
measuring the average blocking force F = (F′ + F″ )/2. It is the responsibility of the user of this part of
b b b
ISO 10846 to ascertain that the two test elements are nominally equal.
An alternative to the application of conventional methods might be the use of active vibration control. Using
multiple actuators and sensors in combination with a control system, the ratio between wanted and unwanted
[6]
input vibration levels can be improved .
6 Criteria for adequacy of the test arrangement
6.1 Frequency range
Each test facility has a limited frequency range in which valid tests can be performed. One limitation is given
by the usable bandwidth of the vibration actuator. Another limitation follows from the requirements for
measuring the blocking output force. In Figures 2, 3 and 4, the following dynamic measurement quantities are
given:
⎯ F blocking output force;
b
⎯ a acceleration of input flange and input-force distribution plate;
⎯ a acceleration of output flange and output-force distribution plate.
The transfer stiffness measurements according to this part of ISO 10846 are valid only for those frequencies
where
∆−L =  W 20dB (1)
LL
aa
1,2
NOTE A level-difference value (∆L ) that is too small can be explained by an insufficient stiffness mismatch
1,2
between the test element and the foundation, or by flanking transmission via the traverse and the columns to the output
side of the test elements or via the air. The use of vibration isolators to decouple the top of the test element from the load
frame (see Figure 2), and also to decouple the vibration exciter from the frame, would reduce flanking transmission
significantly. See the note in 5.2.7 on the risk of improper application of roller bearings on the input side of the test element.
6.2 Measurement of blocking force
The mass between the test isolator and the output-force transducers causes a bias error in the measurement
of the blocking force. Using the symbols in Figure 6, the difference between the approximated blocking force
F′ and the measured force F is equal to the inertia force m a .
b b 2 2
The mass m is the sum of the mass of the output-force distribution plate and half the mass of the force
transducers and shall respect the following inequality:
L /20
F
m u0,06 × kg  (2)
L /20
a
12 © ISO 2008 – All rights reserved

ISO 10846-2:2008(E)
NOTE 1 Inequality (2) is equivalent to the requirement thatLL− u 0,5 dB .
′
F F
2 2
NOTE 2 If Inequality (2) is not respected then either a decrease of m or an increase of force transducer(s) stiffness is
needed. The latter may imply the use of more transducers or a larger transducer.
NOTE 3 When, as in the example of Figure 3 c), a roller bearing is used on the output side of the test element, the
roller bearing needs to be appropriate for the applied static preload. Elastic deformation of the bearing, leading to
unwanted transverse forces due to the bearing system, needs to be avoided.

Key
1 test element
2 output-force distribution plate
3 rigid foundation
Figure 6 — Force and acceleration on output side of the vibration isolator
6.3 Flanking transmission
In many test arrangements, flanking transmission can limit the applicability or accuracy of the test method.
The flanking transmission can be caused by airborne sound or structure-borne sound. Given the large variety
of test arrangements which are allowed, it is in the interest of the user of this part of ISO 10846 to use test rigs
that are robust against invalid measurements caused by flanking transmission. However, obeying
Inequality (2) is sufficient for the validity of test results, also in the presence of flanking transmission.
6.4 Unwanted input vibrations
Input accelerations in dir
...