Sound system equipment - Electroacoustic transducers - Measurement of suspension parts

IEC 62459:2010(E) applies to the suspension parts of electroacoustic transducers (for example, loudspeakers). It defines the parameters and measurement method to determine the properties of suspension parts like spiders, surrounds, diaphragms or cones before being assembled in the transducer. The measurement results are needed for engineering design purposes and for quality control. Furthermore, this method is intended to improve the correlation of measurements between suspension-part manufacturers and loudspeaker manufacturers. The measurement methods provide parameters based on linear and nonlinear modelling of the suspension part and uses both static and dynamic techniques. It cancels and replaces IEC/PAS 62459 published in 2006. It constitutes a technical revision. The main changes are: - descriptions of the methods of measurement are adjusted to the state of the technology; - addition of Clauses 5 to 13; - integration of Annex A in the main body of the standard; - overall textual review.

Elektroakustische Geräte - Elektroakustische Wandler - Messung der Aufhängungsteile

Equipements pour systèmes électroacoustiques - Transducteurs électroacoustiques - Mesure des pièces de suspension

L'IEC 62459:2010 s'applique aux pièces de suspension des transducteurs électroacoustiques (haut-parleurs, par exemple). Elle définit les paramètres et la méthode de mesurage pour déterminer les propriétés des pièces de suspension comme les spiders, les suspensions périphériques, les diaphragmes ou les cônes, avant leur assemblage dans le transducteur. Les résultats de mesurage sont nécessaires pour la conception technique et le contrôle qualité. En outre, cette méthode a pour objet d'améliorer la corrélation des mesures entre les fabricants de pièces de suspension et de haut-parleurs. Les méthodes de mesurage fournissent des paramètres déterminés par une modélisation linéaire et non linéaire de la pièce de suspension; elles reposent sur des techniques statiques et dynamiques. L'IEC 62459:2010 annule et remplace l'IEC/PAS 62459 parue en 2006. Elle constitue une révision technique. Les principales modifications sont les suivantes: – la description des méthodes de mesurage a été adaptée à l'état de la technologie; – les Articles 5 à 13 ont été ajoutés; – l'Annexe A "Code de pratique" a été intégrée à la partie principale de la norme; – le texte a été revu dans son intégralité.

Oprema zvokovnega sistema - Elektroakustični pretvorniki - Meritve obesnih delov (IEC 62459:2010)

Ta mednarodni standard velja za obesne dele elektroakustičnih pretvornikov (na primer zvočniki). Določa parametre in metode merjenja za določevanje lastnosti obesnih delov, kot so pajki, ogrodja, diafragme ali stožci, vgrajeni v pretvornike. Rezultati merjenja so potrebni za tehnično projektiranje in za nadzor kakovosti. Poleg tega je ta metoda namenjena izboljšavi korelacije meritev med proizvajalci obesnih delov in proizvajalci zvočnikov. Merilne metode zagotavljajo parametre, zasnovane na linearnem in nelinearnem modeliranju obesnih delov ter uporabljajo statične in dinamične tehnike.

General Information

Status
Published
Publication Date
24-Mar-2011
Current Stage
6060 - Document made available
Completion Date
25-Mar-2011

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SLOVENSKI STANDARD
SIST EN 62459:2011
01-julij-2011
2SUHPD]YRNRYQHJDVLVWHPD(OHNWURDNXVWLþQLSUHWYRUQLNL0HULWYHREHVQLKGHORY
,(&
Sound system equipment - Electroacoustic transducers - Measurement of suspension
parts (IEC 62459:2010)

Elektroakustische Geräte - Elektroakustische Wandler - Messung der Aufhängungsteile

(IEC 62459:2010)

Equipements pour systèmes électroacoustiques - Transducteurs électroacoustiques -

Mesure des pièces de suspension (CEI 62459:2010)
Ta slovenski standard je istoveten z: EN 62459:2011
ICS:
17.140.50 Elektroakustika Electroacoustics
33.160.50 Pribor Accessories
SIST EN 62459:2011 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 62459:2011
---------------------- Page: 2 ----------------------
SIST EN 62459:2011
EUROPEAN STANDARD
EN 62459
NORME EUROPÉENNE
March 2011
EUROPÄISCHE NORM
ICS 33.160.50
English version
Sound system equipment -
Electroacoustic transducers -
Measurement of suspension parts
(IEC 62459:2010)
Equipements pour systèmes Elektroakustische Geräte -
électroacoustiques - Elektroakustische Wandler -
Transducteurs électroacoustiques - Messung der Aufhängungsteile
Mesure des pièces de suspension (IEC 62459:2010)
(CEI 62459:2010)

This European Standard was approved by CENELEC on 2011-01-02. CENELEC members are bound to comply

with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard

the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on

application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CENELEC member into its own language and notified

to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,

the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,

Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,

Spain, Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 62459:2011 E
---------------------- Page: 3 ----------------------
SIST EN 62459:2011
EN 62459:2011 - 2 -
Foreword

The text of document 100/1625/FDIS, future edition 1 of IEC 62459, prepared by IEC TC 100, Audio,

video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and was

approved by CENELEC as EN 62459 on 2011-01-02.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent

rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
(dop) 2011-10-02
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2014-01-02
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 62459:2010 was approved by CENELEC as a European

Standard without any modification.
__________
---------------------- Page: 4 ----------------------
SIST EN 62459:2011
- 3 - EN 62459:2011
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
IEC 60268-1 - Sound system equipment - HD 483.1 S2 -
Part 1: General
---------------------- Page: 5 ----------------------
SIST EN 62459:2011
---------------------- Page: 6 ----------------------
SIST EN 62459:2011
IEC 62459
Edition 1.0 2010-01
INTERNATIONAL
STANDARD
colour
inside
Sound system equipment – Electroacoustical transducers – Measurement of
suspension parts
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
ICS 33.160.50 ISBN 978-2-88910-734-6
® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 7 ----------------------
SIST EN 62459:2011
– 2 – 62459 © IEC:2010(E)
CONTENTS

FOREWORD...........................................................................................................................4

INTRODUCTION.....................................................................................................................6

1 Scope...............................................................................................................................7

2 Normative references .......................................................................................................7

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

4 Test conditions ...............................................................................................................10

5 Clamping of the suspension part ....................................................................................10

5.1 General .................................................................................................................10

5.2 Destructive measurement......................................................................................10

5.3 Non-destructive measurement ...............................................................................10

5.4 Clamping position..................................................................................................10

5.5 Guiding the inner clamping part.............................................................................11

5.6 Reporting the clamping condition...........................................................................11

6 Methods of measurement ...............................................................................................11

6.1 Static measurement...............................................................................................11

6.2 Quasi-static measurement.....................................................................................11

6.3 Incremental dynamic measurement .......................................................................11

6.4 Full dynamic measurement....................................................................................11

7 Static displacement x (F ) .......................................................................................12

static dc

7.1 Characteristic to be specified ................................................................................12

7.2 Method of measurement ........................................................................................12

7.2.1 General .....................................................................................................12

7.2.2 Test equipment..........................................................................................12

7.2.3 Procedure..................................................................................................12

7.2.4 Presentation of results...............................................................................13

8 Static stiffness K (x ) ...........................................................................................13

static static

8.1 Characteristic to be specified ................................................................................13

8.2 Method of measurement ........................................................................................13

8.3 Presentation of results ..........................................................................................13

9 Lowest cone resonance frequency, f .............................................................................13

9.1 Characteristic to be specified ................................................................................13

9.2 Method of measurement ........................................................................................14

9.2.1 General .....................................................................................................14

9.2.2 Test equipment..........................................................................................14

9.2.3 Procedure..................................................................................................14

9.2.4 Presentation of results...............................................................................15

10 Dynamic stiffness K(x ) .................................................................................................15

10.1 Characteristic to be specified ................................................................................15

10.2 Method of measurement ........................................................................................15

10.2.1 General .....................................................................................................15

10.2.2 Test equipment..........................................................................................15

10.2.3 Procedure..................................................................................................16

10.2.4 Presentation of results...............................................................................17

11 Coefficients of the power series expansion of K(x)..........................................................17

11.1 Characteristics to be specified...............................................................................17

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SIST EN 62459:2011
62459 © IEC:2010(E) – 3 –

11.2 Presentation of results ..........................................................................................17

12 Effective stiffness K (x )...........................................................................................17

eff peak

12.1 Characteristic to be specified ................................................................................17

12.2 Method of measurement ........................................................................................17

12.3 Presentation of results ..........................................................................................18

13 Mechanical resistance R .................................................................................................18

13.1 Characteristic to be specified ................................................................................18

13.2 Method of measurement ........................................................................................18

13.3 Presentation of results ..........................................................................................18

Bibliography..........................................................................................................................19

Figure 1 – Measurement of static displacement ....................................................................12

Figure 2 – Measurement of lowest cone resonance f ...........................................................14

Figure 3 – Pneumatic excitation of the suspension part.........................................................16

Figure 4 – Magnitude response of the normalized transfer function, H(f)/H(0), versus

frequency, f...........................................................................................................................17

---------------------- Page: 9 ----------------------
SIST EN 62459:2011
– 4 – 62459 © IEC:2010(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SOUND SYSTEM EQUIPMENT –
ELECTROACOUSTICAL TRANSDUCERS –
MEASUREMENT OF SUSPENSION PARTS
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

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

International Standard IEC 62459 has been prepared by IEC technical committee 100: Audio,

video and multimedia systems and equipment.

This first edition cancels and replaces the IEC/PAS 62459 published in 2006. It constitutes a

technical revision. The main changes are listed below:

– descriptions of the methods of measurement are adjusted to the state of the technology;

– addition of Clauses 5 to 13;
– integration of Annex A “Code of practice” at the main part of the standard;
– overall textual review.
---------------------- Page: 10 ----------------------
SIST EN 62459:2011
62459 © IEC:2010(E) – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
100/1625/FDIS 100/1648/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

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

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

the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The “colour inside” logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct understanding

of its contents. Users should therefore print this publication using a colour printer.

---------------------- Page: 11 ----------------------
SIST EN 62459:2011
– 6 – 62459 © IEC:2010(E)
INTRODUCTION

The properties of the suspension parts such as spiders and surrounds have a significant

influence on the final sound quality of the loudspeaker. This International Standard defines

measurement methods and parameters required for development and quality-assurance by

suspension-part manufacturers and loudspeaker manufacturers.

Static and dynamic methods have been developed for measuring the suspension parts at

small and high amplitudes. Due to the visco-elastic properties of the suspension material

(fabric, rubber, foam, paper) the measurement results depend on the measurement conditions

and are not comparable between different methods. For example, the properties measured by

static method significantly deviate from the dynamic behaviour of the suspension material

when excited by an audio signal. This standard defines the terminology, the characteristics

which should be specified and the way the results should be reported. The goal is to improve

the reproducibility of the measurement, to simplify the interpretation of the results and to

support the communication between manufacturers of suspension parts and complete drive

units.
---------------------- Page: 12 ----------------------
SIST EN 62459:2011
62459 © IEC:2010(E) – 7 –
SOUND SYSTEM EQUIPMENT –
ELECTROACOUSTICAL TRANSDUCERS –
MEASUREMENT OF SUSPENSION PARTS
1 Scope

This International Standard applies to the suspension parts of electroacoustic transducers (for

example, loudspeakers). It defines the parameters and measurement method to determine the

properties of suspension parts like spiders, surrounds, diaphragms or cones before being

assembled in the transducer. The measurement results are needed for engineering design

purposes and for quality control. Furthermore, this method is intended to improve the

correlation of measurements between suspension-part manufacturers and loudspeaker

manufacturers.

The measurement methods provide parameters based on linear and nonlinear modelling of

the suspension part and uses both static and dynamic techniques.
2 Normative references

The following referenced documents are indispensable for the application of this document.

For dated references, only the edition cited applies. For undated references, the latest edition

of the referenced document (including any amendments) applies.
IEC 60268-1, Sound system equipment – Part 1: General
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
suspension part

surround of the cone made of rubber, foam, paper and fabric and the spider which is usually

made out of impregnated fabric
3.2
displacement
perpendicular direction at the inner rim of the suspension part
3.3
peak displacement
peak

peak value of the displacement occurring during a dynamic measurement at resonance

frequency
3.4
driving force

total effect of the restoring force, friction and inertia of both the suspension part and the inner

clamping parts at the neck of the suspension
---------------------- Page: 13 ----------------------
SIST EN 62459:2011
– 8 – 62459 © IEC:2010(E)
3.5
transfer function
H(f)
amplitude response given by
(1)
X()jω
Hf() =
F()jω

between the displacement spectrum X(jω) = FT{x(t)} and the force spectrum F(jω) = FT{F(t)}

3.6
dynamic stiffness
K(x )

reciprocal of the dynamic compliance C(x ); it is the ratio of instantaneous force F to

ac ac

instantaneous displacement x for an a.c. excitation signal at point x , given by the

ac, ac
following equation
(2)
1 F
Kx==
Cx() x
ac ac

NOTE The dynamic stiffness K(x ) corresponds to the secant between origin and working point defined by x in

ac ac
the force-displacement curve.
3.7
incremental stiffness
K (x )
inc dc

reciprocal of the incremental compliance C (x ); it is the ratio of a small a.c. force F to the

inc dc ac

small a.c. displacement x produced by it at working point x under steady-state condition as

ac dc
given by the following equation
(3)
1 F
Kx==
inc dc
Cx() x
inc dc ac

NOTE The incremental stiffness K (x ) corresponds to the gradient at the working point defined by x in the

inc dc dc
force-deflection curve.
3.8
static stiffness
K (x )
static dc

reciprocal of the static compliance C (x ); it is the ratio of a d.c. force F and the d.c.

static dc dc

displacement x produced by it at the working point x under steady-state condition; the

dc dc

static stiffness K (x ) corresponds to the secant between origin and working point in the

static dc
force-displacement curve, given by the following equation
(4)
1 F
Kx==
static dc
Cx() x
static dc dc
3.9
moving mass
defined by
(5)
mm=+δ m
where
m is the mass of the suspension part,
m is the additional mass of the inner clamping parts,

δ is the clamping factor (with 0 < δ ≤ 1), describing the fraction of the suspension which

contributes to the moving mass.
---------------------- Page: 14 ----------------------
SIST EN 62459:2011
62459 © IEC:2010(E) – 9 –

NOTE If factor δ is not known, the moving mass is approximated by using the total weight of the suspension part

(δ = 1) and ensuring that the mass, m , of the inner clamping part dominates the moving mass, m (m >> m ).

c c s
3.10
resonance frequency

frequency of an a.c. displacement x at which the restoring force, F = K(x )x of the

ac K ac ac

suspension part equals the inertia of the moving mass, m, given by the following equation

(6)
d x
F = K(x )x = m
K ac ac
3.11
lowest cone resonance frequency
frequency at which the cone mass and suspension stiffness resonate
NOTE The lowest cone resonance frequency can be approximated by
1 (7)
f ≈
2(πδKxm)
off s

using the stiffness K(x ) at the offset x due to gravity, the clamping factor δ and the cone mass m .

off off s
3.12
effective stiffness
eff
stiffness given by
(8)
K()xf=2πm
eff peak R

describing the conservative properties of the suspension part performing a vibration at the

resonance frequency, f , using the moving mass, m

NOTE The effective stiffness, K (x ), or the reciprocal, compliance, C (x ) = 1/K (x ), are integral

eff peak eff peak eff peak

measures of the corresponding non-linear parameters, K(x) and C(x), in the working range used, defined by the

peak value, x . The effective parameters are directly related to the resonance frequency and may be measured

peak

with minimal equipment. However, the effective parameters can only be compared if the measurements are made

at the same peak displacement, x
peak.
3.13
loss factor
factor estimated by the ratio
(9)
H()f
Q =
Hf()

between the magnitude of the transfer function, H(f ), at resonance frequency, f , and the

R R

magnitude of the transfer function, H(f ), at very low frequencies, f (with f << f ).

dc dc dc r

NOTE If the losses are sufficiently high (Q > 2), the transfer function, H(f), has a distinct maximum (peak) at the

resonance frequency, f .
3.14
mechanical resistance
given by
2π f m (10)
R =
---------------------- Page: 15 ----------------------
SIST EN 62459:2011
– 10 – 62459 © IEC:2010(E)
where
m is the moving mass,
f is the resonance frequency f ,
R R
Q is the Q-factor.
3.15
inner clamp dimension

diameter at the neck of the suspension part which is clamped by inner clamping parts (for

example, cone and cap)
3.16
outer clamp dimension

inner diameter of the outer rim of the suspension part which is clamped by the outer clamping

parts (for example, the upper and lower clamping rings)
4 Test conditions

The test should be made at 15 °C to 35 °C ambient temperature, preferably at 20 °C, 25 % to

75 % relative humidity and 86 kPa to 106 kPa air pressure, as specified in IEC 60268-1.

Prior to the measurement the suspension part under test should be stored under these

climatic conditions for 24 h.
5 Clamping of the suspension part
5.1 General

The suspension part should be clamped during the dynamic testing in a similar way as

mounted in the final loudspeaker.
5.2 Destructive measurement

In some cases, it may be convenient to use adhesive and original loudspeaker parts (voice

coil former, frame) for clamping.
5.3 Non-destructive measurement

However, non-destructive testing is preferred for comparing samples, storing reference units

and for simplifying communication between manufacturer and customer. Since tooling of

special clamping parts fitted to the particular geometry of the suspension is costly and time-

consuming, a more universal clamping system comprising a minimal number of basic
elements (for example, rings, caps and cones) may be preferred.

The moving mass, m, depends on the mass of the moving parts of the suspension, the air load

and the mass of the inner clamping parts. If the mass of the inner clamping part is much

higher than the mass of the suspension, the total moving mass, m, can be approximated by

the total weight of the suspension together with inner clamping parts, (δ = 1). In this case, the

mass of the clamped areas at the outer rim of the suspension and the influence of the air load

can be neglected.
5.4 Clamping position

A vertical position of the suspension part during measurement (displacement in horizontal

direction) is mandatory if the weight of the inner clamping parts or the weight of the

suspension part is not negligible. A horizontal position (displacement in vertical direction) may

cause an offset in cone displacement due to gravity, giving a higher stiffness value.

---------------------- Page: 16 ----------------------
SIST EN 62459:2011
62459 © IEC:2010(E) – 11 –
5.5 Guiding the inner clamping part

An additional guide for the inner clamping parts may be used to prevent eccentric deformation

or tilting of the suspension and to suppress other kinds of vibration (rocking modes).

5.6 Reporting the clamping condition

The clamping factor according 3.9 shall also be stated; if not, the default value, δ = 1, is used.

It is strongly recommended that the inner clamping dimension, D , and the outer clamping

dimension, D , as well as the geometry of the inner clamping parts be reported. The

orientation of the suspension part (which side of the suspension part is used as front and

back side in the measurement jig) should also be reported. The repeatability of the

measurement can be improved by using the same clamping parts and the same orientation of

the suspension.
6 Methods of measurement
6.1 Static measurement

This technique for measuring the static stiffness according to Equation (4) uses a d.c. signal

of certain magnitude (for example, a constant force F ) as stimulus and measures a d.c.

) under steady-state
response of the suspension part (for example, the displacement x

condition. The measurement time required to get a steady-state response depends on the

visco-elastic behaviour of the suspension material (creep) which is usually much longer than

the settling time for an a.c. signal corresponding to the resonance frequency f .

6.2 Quasi-static measurement

This technique is similar to the static measurement as described in 6.1, using a relatively

short measurement time T. The ratio of d.c. force F and d.c. displacement x is the quasi-

T T

static stiffness K (x ) at the working point x . Since the suspension part has not reached

quasi T T

the final equilibrium the quasi-static stiffness is usually higher than the static stiffness

(K (x) > K (x)). Settling/reading time that has a great influence on the results shall be

quasi static
stated with the results.
6.3 Incremental dynamic measurement

This technique for measuring the incremental stiffness K (x ) according to Equation (3)

inc dc

uses a superposition of a d.c. signal of certain magnitude (for example, constant displacement

x ) and a small a.c. signal (e.g. displacement x ) as stimulus and measures the a.c.

dc ac
response of the suspension part (e.g. the a.c. part of the restoring
...

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