prEN ISO 10846-5

SLOVENSKI oSIST prEN ISO 10846-5:2006

PREDSTANDARD
januar 2006
Akustika in vibracije - Laboratorijsko merjenje vibro-akustičnih prenosnih
lastnosti elastičnih elementov – 5. del: Točkovna metoda za določanje
nizkofrekvenčne prenosne togosti elastičnih podpor za translatorno gibanje
(istoveten prEN ISO 10846-5:2005)
Acoustics and vibration - Laboratory measurement of vibro-acoustic transfer
properties of resilient elements - Part 5: Driving point method for determination of
the low frequency transfer stiffness of resilient supports for translatory motion
(ISO/DIS 108
ICS 17.140.01 Referenčna številka
oSIST prEN ISO 10846-5:2006(en)
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD
DRAFT
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2005
ICS
English Version
Acoustics and vibration - Laboratory measurement of vibro-
acoustic transfer properties of resilient elements - Part 5: Driving
point method for determination of the low frequency transfer
stiffness of resilient supports for translatory motion (ISO/DIS
10846-5:2005)
Acoustique et vibrations - Mesurage en laboratoire des
propriétés de transfert vibro-acoustique des éléments
élastiques - Partie 5: Méthode du point d'application pour la
détermination de la raideur de transfert à basse fréquence
en translation des supports élastiques (ISO/DIS 10846-
5:2005)
This draft European Standard is submitted to CEN members for parallel enquiry. It has been drawn up by the Technical Committee
CEN/TC 211.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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 Management Centre has the same
status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN ISO 10846-5:2005: E
worldwide for CEN national Members.

Foreword
This document (prEN ISO 10846-5:2005) 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 document is currently submitted to the parallel Enquiry.

Endorsement notice
The text of ISO 10846-5:2005 has been approved by CEN as prEN ISO 10846-5:2005 without
any modifications.
DRAFT INTERNATIONAL STANDARD ISO/DIS 10846-5
ISO/TC 43/SC 1 Secretariat: DS
Voting begins on: Voting terminates on:
2005-11-17 2006-04-17
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Acoustics and vibration — Laboratory measurement of vibro-
acoustic transfer properties of resilient elements —
Part 5:
Driving point method for determination of the low frequency
transfer stiffness of resilient supports for translatory motion
Acoustique et vibrations — Mesurage en laboratoire des propriétés de transfert vibro-acoustique des éléments
élastiques —
Partie 5: Méthode du point d'application pour la détermination de la raideur de transfert à basse fréquence en
translation des supports élastiques
ICS 17.140.01
ISO/CEN PARALLEL ENQUIRY
The CEN Secretary-General has advised the ISO Secretary-General that this ISO/DIS covers a subject
of interest to European standardization. In accordance with the ISO-lead mode of collaboration as
defined in the Vienna Agreement, consultation on this ISO/DIS has the same effect for CEN
members as would a CEN enquiry on a draft European Standard. Should this draft be accepted, a
final draft, established on the basis of comments received, will be submitted to a parallel two-month FDIS
vote in ISO and formal vote in CEN.
To expedite distribution, this document is circulated as received from the committee secretariat.
ISO Central Secretariat work of editing and text composition will be undertaken at publication
stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
© International Organization for Standardization, 2005

ISO/DIS 10846-5
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ii ISO 2005 – All rights reserved

ISO/DIS 10846-5
Contents Page
Foreword .iii
Introduction.iii
1 Scope.3
2 Normative references.3
3 Terms and definitions .3
4 Principle.3
5 Test arrangements .3
5.1 Normal translations.3
5.1.1 Overview.3
5.1.2 The resilient support under test .3
5.1.3 Static preloading system.3
5.1.4 Force measurement system.3
5.1.5 Acceleration measurement system.3
5.1.6 Dynamic excitation system .3
5.2 Transverse translations.3
5.2.1 Overview.3
5.2.2 Resilient support under test.3
5.2.3 Static preloading system.3
5.2.4 Force measurement system.3
5.2.5 Acceleration measurement system.3
5.2.6 Dynamic excitation system .3
5.3 Suppression of unwanted vibrations .3
5.3.1 General .3
5.3.2 Normal direction.3
5.3.3 Transverse direction .3
6 Criteria for the adequacy of the test arrangement.3
6.1 General requirements .3
6.1.1 Frequency range.3
6.1.2 Limitation due to the acceleration of the output flange .3
6.1.3 Limitation due to unwanted input vibrations.3
6.2 Determination of upper limiting frequency.3
6.3 Force transducers .3
6.4 Accelerometers.3
6.5 Summation of signals .3
6.6 Analysers .3
7 Test procedures.3
7.1 Selection of force measurement system and force distribution plates.3
7.2 Installation of the test element.3
7.3 Mounting and connection of accelerometers.3
7.4 Mounting and connections of the vibration exciter.3
7.5 Source signal .3
7.6 Measurements .3
7.6.1 General .3
7.6.2 Validity of the measurements .3
7.6.3 Measurement uncertainty.3
7.7 Test for linearity.3
8 Evaluation of test results.3
8.1 Calculation of dynamic driving-point stiffness .3
ISO/DIS 10846-5
8.2 One-third-octave-band values of the frequency-averaged dynamic driving-point stiffness.3
8.3 One-third-octave-band values of the frequency-averaged transfer stiffness .3
8.4 Presentation of one-third-octave-band results.3
8.5 Presentation of narrow-band data .3
9 Information to be recorded .3
10 Test report.3
Annex A (informative) Static load-deflection curve.3
Annex B (informative) Measurement uncertainty .3
B.1 General.3
B.2 Level of frequency-averaged dynamic transfer stiffness.3
B.3 Standard uncertainties.3
B.3.1 Signal processing and background noise .3
B.3.2 Instrumentation.3
B.3.3 Installation of the test element.3
B.3.4 Laboratory test rig .3
B.3.5 Difference between driving point stiffness and transfer stiffness .3
B.4 Contributions to combined measurement uncertainty.3
B.5 Calculation of expanded uncertainty for a coverage probability of 95 %.3
Bibliography.3

iv © ISO 2005 – All rights reserved

ISO/DIS 10846-5
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 10846-5 was prepared jointly by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise,
and ISO/TC 108, Mechanical vibration and shock.
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
Annexes A to B of this part of ISO 10846 are for information only.
ISO/DIS 10846-5
Introduction
Passive vibration isolators of various kinds are used to reduce the transmission of vibration. 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 driving point method for measuring the low-frequency dynamic transfer
stiffness function of linear resilient supports. This includes resilient supports with non-linear static load-
deflection characteristics provided that 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 a direct method and on an indirect method. ISO 10846-1 provides global
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, where
appropriate.
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 or to attenuate structure-borne sound in the lower part of the audible
frequency range. The method does not characterize completely resilient supports that are used to attenuate
shock excursions.
vi © ISO 2005 – All rights reserved

DRAFT INTERNATIONAL STANDARD ISO/DIS 10846-5

Acoustics and vibration — Laboratory measurement of vibro-
acoustic transfer properties of resilient elements — Part 5:
Driving point method for determination of the low-frequency
transfer stiffness of resilient supports for translatory motion
1 Scope
This part of ISO 10846 specifies a driving point method for determining the low-frequency transfer stiffness for
translations of resilient supports, under specified preload. The method concerns the laboratory measurement
of vibrations and forces on the input side with the output side blocked, and is called “driving point 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
a) the transmission of vibration in the lower part of the audible frequency range (typically 20 Hz – 200 Hz) to
a structure which may, for example, radiate unwanted fluid-borne sound (airborne, waterborne or others);
b) the transmission of low-frequency vibration (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 available test rig(s) determines restrictions for very small and for very large resilient
supports.
NOTE 2 Samples of continuous supports of strips and mats are included in the 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 method covers the frequency range from f = 1 Hz to the upper limiting frequency f .
1 UL
Typically 50 Hz ≤ f ≤ 200 Hz.
UL
NOTE 1 When a resilient support has no parallel flanges, an auxiliary fixture should be included as part of the test
element to arrange for parallel flanges.
NOTE 2 Arrows indicate load direction.
Figure 1 — Example of resilient supports with parallel flanges
ISO/DIS 10846-5
The data obtained according to the method specified in this part of ISO 10846 can be used for:
 product information provided by manufacturers and to suppliers;
 information during product development;
 quality control, and
 calculation of the transfer of vibration 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
ISO 2041, Vibration and shock – 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
GUM, Guide to the expression of uncertainty in measurement. BIPM/IEC/IFCC/ISO/OIML/IUPAC/
1)
IUPAP,1993
3 Terms and definitions
For the purposes of this part of ISO 10846, 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
[ISO 2041:1990, definition 2.110]
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 under test including flanges and auxiliary fixtures, if any

1) Corrected and reprinted in 2005.
2 © ISO 2005 – All rights reserved

ISO/DIS 10846-5
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 driving point stiffness
k
1,1
frequency-dependent ratio of the complex force F on the input side of a vibration isolator with the output side
blocked to the complex displacement u on the input side during simple harmonic motion, defined by the
following formula
= F / u
k
1,1
1 1
NOTE 1 The indices “1” denote that the force and displacement are measured on the input side.
NOTE 2 The value of k can be dependent on static preload, temperature and other conditions. At low frequencies
1,1
elastic and dissipative forces solely determine k . At higher frequencies inertial forces play a role as well.
1,1
3.6
dynamic transfer stiffness
k
2,1
frequency dependent ratio of the complex blocking force F on the output side of a resilient element to the
2,b
complex displacement u on the input side during simple harmonic motion, defined by the following formula
= F / u
k
2,1
2,b 1
NOTE 1 The indices “1”and “2” denote the input and output sides respectively.
NOTE 2 The value of k can be dependent on static preload, temperature and other conditions. At low frequencies k
2,1 2,1
is solely determined by elastic and dissipative forces and k ≈ k . At higher frequencies inertial forces in the resilient
1,1 2,1
element play a role as well and k ≠ k .
1,1 2,1
3.7
loss factor of resilient element
η
ratio of the imaginary part of k and the real part of k , i.e. the tangent of the phase angle of k , in the low
1,1 1,1 1,1
frequency range, where inertial forces in the element are negligible
3.8
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
3.9
point contact
contact area, which vibrates as the surface of a rigid body
3.10
normal translation
translational vibration normal to the flange of a resilient element
3.11
transverse translation
translational vibration in a direction perpendicular to that of the normal translation
ISO/DIS 10846-5
3.12
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) and x (t); a and b are arbitrary constants.
1 2 1 2
NOTE 2 In practice the above test for linearity is impractical and measuring the dynamic transfer stiffness for a range of
input levels does a limited check of linearity. In effect this procedure checks for a proportional relationship between the
response and the excitation (see 7.7).
3.13
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 vibration isolator blocked
3.14
force level
L
F
defined by the following formula
F
= 10lg  dB
L
F
F
2 -6
where F denotes the mean square value of the force in a specific frequency band and F = 10 N is the
reference force
3.15
acceleration level
L
a
defined by the following formula
a
= 10lg  dB
La
a
where a denotes the mean square value of the acceleration in a specific frequency band and
-6 2
a = 10 m/s is the reference acceleration
3.16
level of dynamic transfer stiffness
L
k
2,1
defined by the following formula:
k 2,1
= 10lg  dB
L
k 2,1 2
k
where |k | is the square magnitude of the dynamic transfer stiffness (see 3.6) at a specified frequency and
2,1
k = 1 N/m is the reference stiffness
4 © ISO 2005 – All rights reserved

ISO/DIS 10846-5
3.17
level of frequency-band-averaged dynamic transfer stiffness
L
k
av
defined by the following formula:
k
av
=10lg  dB
L
k
av 2
k
where k is defined in 3.8 and k = 1 N/m is the reference stiffness
av 0
3.18
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
3.19
upper limiting frequency
f
UL
frequency up to which k can be determined by using the driving point method.
2,1
4 Principle
The measurement principle of the driving point method is discussed in ISO 10846-1. The basic principle is that
the input force and either the input displacement, velocity or acceleration are measured with the output side of
the vibration isolator blocked. From these measurements the driving point stiffness k is determined. At low
1,1
frequencies, up to the frequency f , k is about equal to the transfer stiffness k .
UL 1,1 2,1
The foundation shall provide a sufficient reduction of the vibrations on the output side of the test object
compared to those on the input side.
The mass between the test isolator and the input force transducers causes a bias error in the measurement of
the input force, which limits the frequency range for the correct measurement of k and is one cause of
1,1
deviation between k and k .
1,1 2,1
The inertial properties leading to eigenmodes of the resilient element is another cause of deviation between
k and k
1,1 2,1
This part of ISO 10846 gives a method to determine the frequency limit f up to which the accuracy of the
UL
equivalency between k and k is equal to or within 2dB.
1,1 2,1
The test procedures according to this part of ISO 10846 cover measurements of transfer stiffness for
unidirectional excitations one by one in normal and in transverse directions.
5 Test arrangements
5.1 Normal translations
5.1.1 Overview
In Figure 2 an example is given of a test arrangement for resilient supports exposed to normal translational
vibration. The sketches are schematic. To be suitable for measurements according to this part of ISO 10846,
the test arrangement shall include the items listed in 5.1.2 to 5.1.6.

ISO/DIS 10846-5
5.1.2 The resilient support under test
The test element is positioned on a heavy and rigid foundation table.

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 a hydraulic actuator, which also serves as the vibration exciter. This is mounted in a load frame
together with the test element;
b) Use a frame that provides static preload only, see Figure 2. If such a frame is used, auxiliary vibration
isolators shall also be applied on the input side of the test element to decouple it from the frame.
NOTE In many cases it will be necessary to apply a force distribution plate directly on top of the elastic support.
Besides its function of load distribution, it also provides a uniform vibration of the top flange under dynamic forces.
5.1.4 Force measurement system
The force measurement system on the input side of the elastic support consists of one or more dynamic force
transducers (load cells).
NOTE 1 It may be necessary to apply another force distribution plate, now between the force transducer(s) and the
actuator. Besides its function of load distribution, this latter force distribution plate also provides a high contact stiffness to
the force transducers and to the actuator. Moreover, it provides a uniform vibration of the flange.
NOTE 2 The upper frequency limit f can be a consequence of the fact that above a certain frequency the distribution
UL
plates no longer vibrate as rigid bodies; to prevent against this, one has to use distribution plates as stiff as possible.
5.1.5 Acceleration measurement system
Acceleration measurements shall be made on the input and output sides of the test element. When mid-point
positions are not accessible, making an appropriate signal summation, for example, by taking the linear
average for two symmetrically positioned accelerometers shall perform indirect measurement of mid-point
accelerations.
NOTE 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 appropriate for the suitable 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;
b) one or more electrodynamic vibration exciters (shakers) with connection rods;
c) one or more piezoelectric 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, which 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.
6 © ISO 2005 – All rights reserved

ISO/DIS 10846-5
F
a
a
a
F
a
u
a
a
a) Overview b) Input side (details)

F
5 F
a a
d) Symmetrical set-up of test elements
c) Guiding low friction bearing(s)

Key
1 Exciter 8 Input acceleration measurement (a )
2 Traverse 9 Test element
3 Connection rod 10 Output acceleration measurement (a )
4 Dynamic decoupling spring, static prepoad 11 Rigid foundation
5 Force distribution plate 12 Suspension
6 Input force measurement (F ) 13 Low friction bearing
7 Measurement of unwanted acceleration (a )
u
Figure 2 – Example of laboratory test rig for measuring the dynamic driving point stiffness for normal
translations
ISO/DIS 10846-5
5.2 Transverse translations
5.2.1 Overview
Schematic examples of test arrangements for elastic supports exposed to translational vibrations
perpendicular to the normal load direction are shown in Figures 3 and 4. The test arrangement shall include
the items described in 5.2.2 to 5.2.6.
5.2.2 Resilient support under test
The test element is positioned on a heavy, rigid foundation table (see Figure 3) or between stiff columns on a
rigid foundation (see Figure 4).
5.2.3 Static preloading system
Measurements shall be performed with the test element under a representative and specified normal preload.
Examples of methods for applying the static preload are the following:
a) Use a hydraulic actuator. This actuator is mounted in a load frame together with the test element.
b) Use a frame which provides static preload only.
NOTE In many cases it will be necessary to apply a force distribution plate directly on the input side of the elastic
support(s).
5.2.4 Force measurement system

The dynamic force measurement system shall consist of one of the following options:

a) one or more force transducers for the measurement of dynamic shear forces (see Figures 3);
b) one or more force transducers for the measurement of normal dynamic forces (see Figures 4);
NOTE It may be necessary to apply a force distribution plate between the test element and the dynamic force
transducers (see Figures 3 and 4).

5.2.5 Acceleration measurement system

Acceleration measurements shall be made on the input and output sides of the test element.
The accelerometers on the test element flanges or on the force distribution plate shall be placed on the
symmetry axis of these components. Alternatively taking the linear average of the signals of two symmetrically
positioned accelerometers may make the measurement.
NOTE Provided that their frequency range is appropriate, displacement or velocity transducers may be used instead
of accelerometers.
5.2.6 Dynamic excitation system

The dynamic excitation system shall be appropriate for the suitable excitation level and for the frequency
range of interest. Any type of exciter is permitted. Examples are:
a) hydraulic actuator;
b) one or more electrodynamic exciters with connection rods;
c) one or more piezoelectric exciters.
8 © ISO 2005 – All rights reserved

ISO/DIS 10846-5
F
a
a
a) Overview
F
a
a
u 9
b) Input side (details)
Key
1 Exciter 8 Input acceleration measurement (a )
2 Traverse 9 Measurement of unwanted acceleration (a )
u
3 Connection rod 10 Test element
4 Dynamic decoupling spring, static preload 11 Output acceleration measurement (a )
5 Low friction bearing 12 Rigid foundation
6 Force distribution plate 13 Suspension
7 Input shear force measurement (F)
Figure 3 – An example of laboratory test rig for measuring the dynamic driving point stiffness for
transverse translations
ISO/DIS 10846-5
a
a 2
F
a
Key
1 Exciter 6 Input acceleration measurement (a )
2 Preloading device 7 Nominally equal test elements
3 Connection rod 8 Stiff columns
4 Force distribution plate 9 Rigid foundation
5 Input force measurement (F ) 10 Output acceleration measurement (a )
1 2
Figure 4 – An example of a symmetrical test arrangement for measuring the dynamic driving point
stiffness for transverse translations
5.3 Suppression of unwanted vibrations
5.3.1 General
The test procedures according this part of ISO 10846 cover measurements of transfer stiffness for
unidirectional excitations one by one in normal and in transverse directions.
However, due to asymmetries in excitation, in boundary conditions and in test elements properties, others
than the intended input vibration component may show unwanted strong responses at certain frequencies.
Qualitative measures to suppress unwanted input vibrations are discussed next. A special category of test
arrangements is that in which two nominally equal resilient elements are tested in a symmetrical configuration
(see Figure 4). This may be advantageous to suppress unwanted input vibrations. In 6.1.2 quantitative
requirements are formulated.
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 objects, or of a ‘guiding’ system on the sides of the
excitation mass, for example, roller bearings (see Figures 2c-d).
NOTE When low friction bearings are used as guiding system, the force transducers for measuring the input force F
are to be placed between this guiding system and the test element to avoid errors due to uncertain transmission properties
of these guiding components.
10 © ISO 2005 – All rights reserved

ISO/DIS 10846-5
5.3.3 Transverse direction
For excitation in transverse direction, coupling between transverse and rotational input vibrations will always
occur.
In Figures 3 and 4 examples of measures are shown, which may enhance unidirectional vibrations on the
input side. Figure 3 shows as example, how a guiding system can be used to suppress input rotations.
Figures 4 shows a symmetrical arrangement with two nominally equal test objects.
6 Criteria for the adequacy of the test arrangement
6.1 General requirements
6.1.1 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.
Other limitations follow from the requirements for measuring the acceleration and the input force and from the
unwanted vibration.
6.1.2 Limitation due to the acceleration of the output flange
In Figures 2-4 the following dynamic measurement quantities are indicated:
F input force;
a acceleration of the input flange and the input force distribution plate, which is on the test element;
a acceleration of the output flange.
The stiffness measurements according to this part of ISO 10846 are valid only for those frequencies where
∆ = - ≥ 20dB (1)
L L L
a a
1 2
NOTE A too small value for the level difference ∆L can be explained by insufficient stiffness mismatch between the
1,2
test element and the foundation or by flanking transmission. Use of vibration isolators to decouple the top of the test
element from the load frame (see e.g. Figure 2) and also to decouple the vibration exciter from the frame would reduce
flanking transmission significantly.
6.1.3 Limitation due to unwanted input vibrations
Input accelerations in directions other than those of the excitation shall be suppressed according to 5.3.
Measurements according to this part of ISO 10846 are valid only for those frequencies where the input
acceleration in the excitation direction exceeds that in the other directions perpendicular to it by at least 15 dB,
i.e.
L − L ≥ 15 dB (2)
a(excitation) a(unwanted)
For normal excitation the input acceleration in the excitation direction a is along the line of excitation and at
1Z
the interface between the force distribution plate and the input flange of the resilient element. The unwanted
inputs in perpendicular transverse directions a and a shall be measured at the edge the force distribution
1x 1y
plate between the force transducers and input flange (see Figure 2b).
For transverse excitation (in x- or y-direction) the unwanted inputs a and a or a shall be measured at the
1z 1y 1x
edge of the force distribution plate between the force transducers and input flange (see Figure 3b).

ISO/DIS 10846-5
6.2 Determination of upper limiting frequency
The upper limiting frequency f , above which the dynamic driving point stiffness shall not be used to represent
UL
the dynamic transfer stiffness, is determined by comp
...