Glossary

Table of Contents

0-9
1/3 octave band 		

E
4

A
Abrasion in mm3
Airborne noise 		
Ambient temperature in °C
Amplitude 		
Amplitude dependence
Amplitude of vibration
Angle of loss δ in degrees

4
4
4
4
4
4
4

Bedding modulus in N/mm3

4

B

C
Center of gravity
Coefficient of friction
Complex e-modulus in N/mm2
Compression in %Compression set in %Crest factor 		

2

4
5
5
5
5
5

Elastic force in N
Elasticity 		
Elongation at rupture under tensilestress in % 		Elongation at tear in %Emission isolation
Energy absorption in Nm
Energy dissipation in Nm
Energy equivalent mean level
Evaluation level in dB
Excitation frequency in Hz

7
7
7
7
7
7
7
7
7
7

F
Fatigue test 		
Finite Elements Method (FEM)
Footfall noise level in dB
Form factor q		
Frequency in Hz

7
7
7
7
8

H
Hooke’s Law 		

D

I

Damping 		
5Damping coefficient in 1/s
5Damping ratio D
5
Decade 		5
Decibel in dB 		
6
Deflection in mm
6
Deformation energy in Nm
6
Degree of freedom
6
Degree of transmission in dB
6
Density in kg/m3
6
Design load in N/mm2
6
Design value of resistance in N/mm2 6
Disturbing frequency in Hz
6
Dynamic load 		
6
Dynamic range of use
6

Immission isolation
Impact noise level in dB
Impact		Impedance in Ns/m
Insertion loss 		
Insertion loss in dB
Isolating vibration
Isolation 		
Isolation efficiency
Isolation factor 		
Isolation of impact noise in dB

8

8
8
8
8
8
8
8
8
8
9
9

L

S

Level in dB 		
Load deflection curve
Load peaks in N/mm2
Loss factor  		
Loss modulus 		

9
9
9
9
9

Mass-spring system
Mechanical loss factor
Modal analysis 		
Modulus of elasticity in N/mm2
Multiple mass oscillator

9
9
9
9
9

M

N
Natural frequency in Hz
Natural mode 		Noise emission 		
Noise immission
Noise pollution 		

10
10
10
10
10

O
Octave 		

10P
Periodic duration in s
Plasticity 		
Poisson Number 
Polyurethane 		Pre-load in N 		

Q

10
10
10
10
10

Secant modulus in N/mm3
Secant stiffness in kN/mm
Shear modulus in N/mm2
Shearing stress in N/mm2
Shock 		Shock absorbing elements
Shock absorption
Shock isolation 		
Shore hardness 		
Single-mass oscillator
Sound 		Sound isolation in dB
Sound pressure in Pa
Sound pressure level in dB
Sound spectrum
Sound wave 		
Specific load in N/mm2
Spectrum 		Spring deflection in mm
Static range of use in N/mm2
Static creep behaviour in %Stationary loading
Stiffening factor
Stiffness in kN/mm
Storage modulus
Structure-borne noise
Structure-borne noise isolation in dB
Sum level Ltot 		

Ultimate limit states

15

V
Velocity level in dBv
Vibration isolation
Vibrations 		
Volume resistivity in Ωcm

15
15
15
15

T

Tangent modulus in N/mm3
10 Tangent stiffness in kN/mm
11 Tensile strength in N/mm2
Tensile stress at rupture in N/mm2
Thermal conductivity in W/mK
R
Resistance to strain in N/mm2
11 Transmission function
Resistance to tear propagation in N/mm 11 Tuned mass damper
Resonance 		
11 Tuning frequency in Hz
Resonant frequency in Hz
11 Tuning ratio 		
Quasi-static deformation
Quasi-static load deflection curve

U
11
11
11
11
12
12
12
12
12
12
12
12
12
12
13
13
13
13
13
13
13
13
13
14
14
14
14
14

14
14
14
14
14
14
14
14
15

3

A-C

1/3 octave band
The range (bandwidth) between two
frequencies, which are at a ratio ofroughly 4:5, to be more precise
fo = 3 2fu; in a logarithmic representation the width of a 1/3 octave band is
one-third of the width of an ¬octave.

Abrasion in mm3
Parameter for the assessment of abrasion (abrasive wear) against abrasive
loss; abrasion is the loss in volume in
mm3 of a defined testing body on atest emery surface with a defined attack strength, defined contact pressure over a pre-defined path.
Abrasion only reflects actual wear behavior under field conditions to a limited extent.

Airborne noiseSound propagated in the air in theform of ¬sound waves, as opposed tosound transmission through liquids orsolid bodies.

Ambient temperature in °C
The working temperature for elastomers manufactured by Getzner is between -30 °C and +70 °C. The data listed in the material data sheets is valid
for room temperature. The mechanical4

properties of elastomers are dependent on the temperature.

Sylodyn® materials exhibit a negligible
amplitude dependence. The dynamic
stiffness of other elastic materials,
At temperatures above the maximum
such as compact, foamed and bonded
limit permanent damage can occur torubber products (rubber granule), howthe elastomer, and at temperatures
ever, is significantly dependent on the
below the minimum limit the elastomer amplitude of excitation.
may freeze.
The maximum working temperature
limit denotes the maximum temperature at which the material can be usedwithout beginning to age, i.e. without
an excessive loss of elastic properties.
Minimum working temperature: lowtemperatures reduce the mobility ofthe molecular chains, causing the elastomer to lose elasticity (this process isreversible for Sylomer® and Sylodyn®).

Amplitude
A quantity characterizing a ¬vibration;
it is the maximum magnitude of variation of a physical quantity from its
zero value to a positive or negativevalue; amplitude refers to a physicalquantity (e.g. force, displacement).

Amplitude dependence

Amplitude of vibrationSee ¬amplitude.

Angle of loss  in degrees

The angle of loss  indicates the phasedifference between the stress andstrain in an oscillatory test and can beused as a measurement of material
damping.
The relation between the mechanicalloss factor  and the angle of loss  ischaracterised by  = tan().

Bedding modulus in N/mm3
Also: Surface ¬stiffness; ratio of the¬specific load to the resulting ¬deflection; a distinction is made between the¬secant modulus and the ¬tangent
modulus.

Amplitude dependence describes thedependence of the dynamic stiffness
on the amplitude of vibration.

Center of gravity

This characteristic is highly specific to
the particular material. Sylomer® and

The point to which the entire mass of asystem can be reduced; the center ofgravity is extremely important for thedesign of elastic equipment bearings.

C-D

Coefficient of friction

Compression set in %Damping coefficient in 1/s

The coefficient of friction represents
the relationship between frictional
resistance to normal forces.

Measures the recovery capacity of anelastomer; ratio of the sample bodyheight before and after compression;
testing procedure as per EN ISO 1856;
test conditions: deformation to 50 %at 23 °C, duration of load 72 h andmeasurement 30 min after load removal.

Unit for characterizing the dampingof a free oscillator with speed-proportionate damping; it is calculated as
time-related amount of damping;“” describes the (exponential) timerelated damping of an oscillationfrom the initial value “A0“ (t = 0) to the.
value “A” at the time “t” A=A0 . e- t

The coefficient of friction of an elastomer can be determined for materials
such as steel, concrete, wood, etc.
A distinction is made between static
friction and dynamic friction; in thematerial data sheets the values arestated for static friction.

Complex e-modulus
in N/mm2
Describes the properties of “spring”
and “damping” in a complex notation
E*=E (1 + i . ); the real portion of thecomplex ¬e-modulus modulus is referred to as the storage modulus E(spring component), while the imaginary portion is referred to as the loss
modulus (i . E . , damping component).

Compression in %The ratio of deformation of the elastomer under load to the unloaded thickness of the elastomer.

Crest factor

Note: not the same as spatial damping
coefficients  (e.g. degree of absorpRatio of the crest value to the effective tion in acoustics).
value of a vibration. For sinusoidal
vibrations it is 2 = 1.41.

Damping ratio D

Damping

Unit of measurement for characterizing the damping of a free oscillator
with a speed-proportionate damping;also known as the degree of damping.

Transformation of kinetic energy intoanother form of energy which is nolonger relevant (reusable) for the oscilThe damping ratio D is directly
latory system (e.g. heat via abrasion,plastic deformation,…); damping (dissi- related to the ¬loss factor  by theequation
pation of energy) takes energy out of
the mechanical system.
D=
In order to limit resonant vibration toan acceptable range, a mechanicalsystem requires adequate damping.
DecadeVibration damping and ¬vibration isolation are two different measures for
The interval at which the upper interisolating vibrations.
val limit is 10 times higher than thelower limit; decades are used for time
See also ¬loss factor, ¬damping
and also for frequencies. For example,
ratio.
an interval of 100 to 1000 has a bandwidth of one decade, while an intervalof 50 to 5000 has a bandwidth of two
decades.

5

D

Decibel in dB
Unit for expressing the ratio against
some physical quantity in terms of
the base 10 logarithm of that ratio
10 log(v1/v2). Logarithmic ratios aredescribed as levels or amounts, e.g.
¬velocity level, ¬insertion loss, etc. For
example, sound pressure levels areusually put in ratio as a square equation. The 2 of the square equation in
the Log will be set in front of the same
becoming 20 log (…).

In respect of ¬vibration isolation characterizes the isolation efficiency as aratio of input and response forces and/or input and output amplitudes.

The elastomer is subject to a forced
sinusoidal vibration. The test parameters are ¬frequency, ¬pre-load and¬amplitude.

Deflection in mm

The density (volume weight or specificmass) is the ratio of the mass to thevolume for elastomers; testing procedure as per DIN 53420.

The energy necessary to cause deformation of an elastomer; can be determined based on the surface area under
the force-deformation curve (¬load
deflection curve).

Degree of freedom
Describes the possible directions of
motion of an oscillatory system; there¬Frequency applied to excite an oscillatory system, e.g. cyclical forces generated by a machine.

Dynamic loadDensity in kg/m3

Deformation energy in Nm

Disturbing frequency in Hz

Degree of transmission
in dB

Example: the ¬velocity level:
Lv = 10 . log(v2/v02) = 10 . log(v/v0)2 =20 . log(v/v0)dB.

The distance which an elastomer iscompressed under a specific ¬load orforce.

6

are 3 translational degrees of freedom
in the 3 spatial axes and 3 rotational
degrees of freedom around the 3 spatial axes.

Based on the force and deformation
result, the dynamic ¬stiffness, the dynamic ¬modulus of elasticity or dynamic ¬bedding modulus and the¬ mechanical loss factor can bederived.

Design load in N/mm2

The data sheets usually use the frequencies 10 and 30 Hz with a ¬velocity
level of 100 dBv. Testing procedures
similar to DIN 53513.

To verify the ¬ultimate bearing capa­
city, characteristic loads Ek will be subject to partial safety factors ψ.

Dynamic range of use

Design value of resistancein N/mm2

The characteristic bearing resistanceRk, needs to be reduced by a material
property safety factor γm to verify the¬ultimate limit bearing states.

This is the load range for an elastomer
bearing, which includes both the ¬static loads and the ¬dynamic loads; static
loads should be lower than the upper
limit of the ¬static load range of use;
dynamic loads should fall in the range
between the maximum static load limit
and the maximum dynamic load limit.
Elastomer bearings are particularly
elastic in this range, i.e. the ¬vibration

E-F

isolating effect of the elastomer is utilized to the fullest extent.

Elastic force in N
Recovery force of an elastomer from anexternal force due to its elastic property.

Elasticity
Material property which causes elastomers to return to the original form
following deformation.

Elongation at rupture
under tensile stress in %Also: Elongation at tear; maximum
elongation at which a standardized
cross-section of the material tears;
elongation at rupture is a minimum
value; testing procedure as per
DIN EN ISO 527.

Elongation at tear in %See ¬elongation at rupture.

Emission isolation

Energy absorption in Nm

periodic levels for a defined reference
period (evaluation period). The evaluation level is compared to certain referThe energy absorption is defined asence values as a basis for evaluating
dissipated kinetic energy during impact or intense dynamic load. The elas- the noise situation.
tic material is able to convert a largepart of the kinetic input energy into
inelastic energy by inner damping
Excitation frequency in Hz
mechanism, which is an irreversible
See ¬disturbing frequency.
process. See also ¬shock isolation.

Energy dissipation in Nm
The energy dissipation is the loss ofenergy per cycle of motion in an oscillatory test due the conversion of mechanical energy into thermal energy(area of displacement-force hysteresisloop). See also ¬loss factor.

Energy equivalent meanlevel
An energy equivalent mean level depicts
the temporally different noise events in
an individual numeric value. The energy
equivalent mean level includes thestrength and duration of each individual
sound during the evaluation period.

Evaluation level in dB

Vibration isolation consisting of an elastic bearing system for an oscillatory
The ¬energy equivalent mean level issystem, so that no disturbing vibrations frequently used to describe and evaluare emitted into the surroundings.
ate immission situations; the energy
equivalent mean level is calculated
averaging the individual frequency and

Fatigue test
A method of testing the long-term behavior of an elastomer by subjecting it
to a static and simultaneous dynamicload; for rail applications up to 12.5
million load cycles (oscillations) areusually necessary.

Finite Elements Method(FEM)
The Finite Elements Method is a method for numerical modeling of problems
in various physical disciplines, in particular strains and deformations of all
kinds in elastic and plastic spaces.

Form factor q
Form factor is a geometric measurement for the form of an elastomer
bearing and is defined as the quotientof the loaded surface to the exterior
housing surface of the bearing. An elastomer with a form factor of greaterthan 6 can be characterized as a plane.

7

F-I

Cellular materials, such as Sylomer®
SR11, SR18 and SR28, are volume compressible and hence the influence ofthe form factor on ¬stiffness can beneglected.

Impact noise level in dB

Measurement of disturbing noise fromstructure-borne noise generation inceilings, indicated in dB; in this respect
it should be noted that high values
represent a lower level of protection
By contrast, the form factor plays an
increasingly important role as the com- against impact noise.
pactness of the elastomer increases,
because in such cases a compression
load can lead to bulging of the elastoImpact
mer resulting in transverse forces in
See ¬shock.
the elastomer. This in turn can meanthat the force or the compression required to deform the elastomer can
Impedance in Ns/mvary, depending on the form factor.
Also known as ‘characteristic acoustic
impedance’. The greater the difference
between the characteristic acoustic imFrequency in Hz
pedances of two media, the more soundNumber of oscillations per second in a energy will be reflected at the boundary
surface between the two media, i.e. lessperiodic signal.
sound energy is transmitted.

Hooke’s Lawtransmitted when an elastic element
or mounting is present.
Note: insertion loss is only independent of the selected site of measurement if the boundary conditions (e.g.
subgrade, building design, tunnel design, etc.) are identical.

Insertion loss in dB
10 base decade logarithm of ¬insertion
loss. Core quantity for characterizing
the efficiency of measures to reduce
structure-borne noise.
Insertion loss can be measured as thedifference between the level of structure-borne noise with and without resilient mounting. Insertion loss is frequency dependent.

Conversely, this also represents better¬vibration isolation; For good damping
there is a so-called ‘jump in impedDescribes the linear relationship between ¬specific load and ¬strain; valid ance’, i.e. a significant difference befor Sylomer® and Sylodyn® in the linear tween the characteristic acoustic impedance of the two media involved.
range of the ¬load deflection curve.

Isolating vibration

Immission isolation

Insertion loss

Isolation efficiency

Vibration isolation of a system (recipient) against disturbing vibrations fromthe surroundings.

Ratio of the power of the vibrations(e.g. power of the structure-borne
noise) which is transmitted into theadjacent structure without an elastic
element or mounting to that which is

See ¬vibration isolation.

IsolationSee ¬vibration isolation.

See ¬isolation factor.

8

I-M

Isolation factor in %absorb load peaks of 5 to 10 times thestatic load range.

In respect of ¬vibration isolation thisfactor characterizes the ¬isolation
efficiency as a ratio of input and response forces and/or input and output
amplitudes.

A method to experimentally determine
modal quantities such as ¬natural frequencies and natural damping of a comThe mechanical loss factor η is a meas- plex ¬multiple mass oscillator (oscillating system); the quasi-numerical counure of mechanical damping of viscoeterpart of modal analysis is ¬FEM anallastic materials. With respect to harysis (Finite Elements Method).
monic loads, the mechanical loss factor η can be calculated by the dissipated energy per cycle (hysteresis) related to stored energy during loading byModulus of elasticity
the following formula η = dissipatedin N/mm2
energy / (2 . π . stored energy).
The modulus of elasticity (e-modulus)
Furthermore the mechanical loss facis a material property and describes
tor η can be derived by measuring the the relationship between ¬specific load
angle of loss δ, when harmonic loads
and ¬strain (¬Hooke’s Law). ). The eare applied. The tangent of angle ofmodulus is dependent on the ¬specificloss δ corresponds to the mechanicalload and load acceleration.
loss factor η (η = tan(δ)). Test methods
in accordance to DIN 53513; see also
A distinction is made between static¬damping ratio, angle of loss.
e-modulus (¬quasi-static deformation)and the dynamic e-modulus (¬dynamicload). Testing procedures similar to
DIN 53513. See also ¬complex
Loss modulus
e-modulus.
See ¬complex e-modulus.

Isolation of impact noisein dB
Measurement for the efficiency of
dampening by a partition element
which is located between the concrete
sub base and the flooring material;
dampening of impact noise is frequency dependent.

Level in dB
Logarithmic ratio of a quantity to a reference quantity of the same dimension,
See ¬decibel.

Load deflection curve
See ¬quasi-static load deflection curve.

Load peaks in N/mm2
Load peaks are maximum loads which
occure for short-term and infrequentand can be absorbed by the material
without relevant changes of the material properties. Cellular elastomers canabsorb load peaks of well over 20 times
the ¬static range of use stated in thematerial data sheets without sufferingdamage. More compact elastomers canModal analysis

Loss factor 

Mass-spring system

Multiple mass oscillator

A mass-spring system is a type ofsuperstructure for permanent way
consisting of a reinforced concrete
trough or slab and a spring (for example an elastomer bearing). The large
mass of the concrete trough allows forvery low tuning frequencies.

An oscillatory system consisting ofseveral linked oscillating sub-systems
with various masses and springs,
whereby each sub-system consists of amass and a spring (¬single mass oscillator); a multiple mass oscillatory system has as many ¬natural frequencies
as it does sub-systems.

Mechanical loss factor
See ¬loss factor.
9N-Q

Natural frequency in Hz

Noise pollution¬Frequency of a system’s free vibration after one excitation; the period of
the vibration is dependent on the¬damping.

Noise is defined as ¬airborne sound,which may be disturbing, annoying,hazardous or damaging. Perception ofsounds and noise depends to a great
degree on the individual and is thus
subjective.

Natural mode
Vibratory systems have natural modes,
which can be described by ¬natural
frequency, natural damping and vibratory form. A system can have naturalmodes in the form of translation, rotation or bending as well.

OctaveAn octave is the range (frequencyband) between a ¬frequency and twiceor one-half of that frequency, i.e.
fo= 2 . fu bzw. fu= 1/2 . fo .

Noise emission refers to ¬structureborne noise or ¬ airborne noise emitted
by a sound source; the sound source islocated at the emission location.

For example, one octave above andbelow the frequency 1000 Hz is covered by the intervals to 2000 Hz and
500 Hz. In acoustic measurements,
standardized mean octave frequencies(fm) are usually used (fm = 16, 31.5, 63,
125, 250, 500, 1000, 2000 Hz).

Noise immission

Periodic duration in s

Noise emission

Noise immission is the ¬structureTime duration of one whole harmonicborne noise or ¬airborne noise striking oscillation; the reciprocal value is ¬frea recipient, regardless of the locationquency.
of the ¬noise emission (source of thestructure-borne or airborne noise).

Plasticity

The location of the recipient is referred to as the immission location and Material property which leaves an elasthe level of sound measured there is
tomer in a deformed state following
known as the immission level.
deformation.

10

Poisson Number 

Ratio of the lateral deformation to theaxial deformation; for elastomers the
Poisson number (also: Poisson’s ratio)
depends to a great degree on the cellular structure and load.

Polyurethane
Abbreviation: PUR. Polyurethanes are
manufactured by poly addition of isocyanates and polyalcohols and can beproduced with cellular structures orcompact structures. A distinction ismade between polyether urethanes
and polyester urethanes.

Pre-load in N
Static load which is applied to an elastomer before the application of a dynamic load.

Quasi-static deformation
One time application of a load onto anelastomer, whereby the time period for
application of the maximum load is
20 s; see ¬quasi-static load deflection
curve.

Q-S

Quasi-static load
deflection curve
Describes the relationship between¬specific load and ¬deflection ingraphic form; depending on the load
speed; depending on load acceleration,a distinction is drawn between quasistatic and dynamic load deflection
curves.
In the data sheets the load deflection
curve is usually depicted with compression deformation of 40 %, with
20 s rise and decay duration of theload ramp. The elastomer is usually
pre-stressed with two preliminary­cycles, and measurements are carriedout for the third cycle.

Resistance to strain
in N/mm2¬Specific load that is necessary tocompress an elastomer to a certain¬compression set.

Resistance to tearpropagation in N/mm
Maximum tensile strength of a standardized sample that resists the propagation of a tear; denotes a minimum
value; testing procedure as per DIN
53515.

Resonance

points (forces) with the ¬load deflection curve; the rise in the secant isreferred to as the secant stiffness.

When the ¬disturbing frequency of asystem is equal to the natural frequency of the system, resonance occurs.
Occurrence of resonance can lead to
Shear modulus in N/mm2
the destruction of the entire oscillating
system.
Elastomer bearings are able to absorb
shearing forces and ¬shearing stress.
By ¬damping the vibratory system it ispossible to limit resonance vibrations
The ratio between shearing stress andto an acceptable degree. Flexibility to a horizontal deflection of the elastomer
changing force is particularly strong
is referred to as the shear modulus.
with the resonance range.
Fundamentally speaking, an elastomer
bearing is softer with regard to shearResonant frequency in Hz ing loads than with regard to compression loads. The relationship of compression to shearing stiffness ranges
Frequency, at which ¬resonancebetween factor 4 and 10, depending on
occurs.
the cellular structure and geometry of
the bearing. The quasi-static shearing
Secant modulus in N/mm3 deflection curve exhibits relatively
linear deformation behavior. A dynamDenotes the surface-related ¬stiffness ic shearing modulus can be calculated
from the dynamic shearing load.
of an elastomer bearing; a secant isdrawn through the interface points ofTesting procedures similar to DIN ISO
two defined secant points (¬specificloads) with the ¬load deflection curve. 1827.
The rise in the secant is referred to as
the secant modulus or ¬bedding
modulus.
Shearing stress in N/mm2

Secant stiffness in kN/mm

Shearing force per unit of surface areaof the elastomer.

Denotes the ¬stiffness of an elastomer
bearing; a secant is drawn through theinterface points of two defined secant

11

Sh-SoShock
Sudden occurred impact force between
two or more bodies; the impact force
is defined by the shock duration, maximum impact force and the impact shape(half-sine, triangle, rectangle, trapezoidal,...). See also ¬shock isolation.

elastic material is able to convert alarge part of the kinetic input energy
into inelastic energy by inner damping
mechanism, which is an irreversible
process. See ¬energy absorption.

Shore hardness

Shore hardness is a measurement for
the hardness of rubbers for example
and can only be used to a limited deComponents which are used to reduce gree with foamed elastomers. The
measurement of Shore hardness is thethe force, path or delay associatedresistance to indentation of a body ofwith individual or repetitive shock
defined shape with force applied by apulses and to transform the impact
energy of the impacting mass into heat calibrated spring.
and additional ¬deformation energy.
There are two hardness scales: the“Shore A” scale for soft (rubbery) materials and the “Shore D” scale for
Shock absorption
harder materials. The measurement
See ¬shock isolation.
for the hardness or elasticity of
foamed elastomers is the ¬modulus ofelasticity.
Shock isolation

Shock absorbing elements

Shock isolation is a special case of thevibration isolation, where the transmission of sudden impact forces (see¬shock) is reduced by the installationof elastic components; the short impact force with a relatively high force
peak gets transformed into a longerterm pulse with lower forces.
The energy absorption is defined as
the dissipated kinetic energy during
impact or intense dynamic load. The

12Single-mass oscillator
Applications for vibration isolation areoften postulated on an oscillatory system with ¬one degree of freedom consisting of a mass and a spring.

Sound
Smallest pressure and density oscillations in an elastic medium in the audible range of humans from approxi-

mately 16 Hz to 20,000 Hz, e.g. airborne sound, structure-borne noise,sound transmitted through liquids.
Lower frequencies are referred to as
infrasound and higher frequencies as
ultrasound.

Sound isolation in dB
The level of sound isolation is definedas the 10 base logarithm of the ratio of
the sound energy striking a component (exterior) (power: W1) to theamount of sound energy transmitted
by the components (power: W2).
R = 10 • log(W1/W2)Sound pressure in Pa
Changes in the static air pressure due
to oscillation of the air molecules in asound field.

Sound pressure level in dB
is twenty times the 10 base logarithmof the ratio of the instantaneous soundpressure to the reference sound pressure (audible threshold); For practicalapplications in noise abatement andevaluation, the frequency sensitivity ofthe ear is realized via the so-called“A-weighting”, and reference is madeto the “A-weighted sound level (alsoknown as “sound level in dB A”).

So-StIn addition to this frequency weighting, Specific load in N/mm2
there are also three different time averaging options that can be selected in Force per unit of surface area.
the measurements.

Static creep behaviour in %Increase in deformation under steady,long-term load. When Sylomer® and
Sylodyn® are subjected to loads as
These three options are: Fast: Rise
stated in the ¬static range of use, theSpectrumduration = 125 ms; Decay duration =deformation is lower than 20 % even
125 ms; Slow: Rise duration = 1.0 s; Deafter 10 years. Deformations of thisGraphic representation of a physicalcay duration = 1.0 s; and impulse: Riseorder of magnitude have also been
quantity (ordinate) as a function ofduration = 35 ms; Decay duration =¬frequency (abscissa). A pure sinusoi- observed in elastomer bridge bearings.
1.5 s; it is particularly important to indi- dal vibration, for example, is represent- Testing procedure as per DIN ISO 8013.
cate the time averaging for impulse
ed as a line in a line spectrum.
and burst sound events.
Naturally occurring vibrations are rare- Stationary loading
ly pure sinusoidal vibrations; therefore,
in order to determine the frequencies
Sound spectrum
The elastomer is subject to a static
comprising the largest portion of theload which does not vary over time. If
the ¬specific load and the resulting
A graphic representation of sound as a vibration it is expedient and/or necessary to represent it graphically as a¬deflection are known, it is possible tofunction of frequency. Depending on
determine the static ¬stiffness, thethe type of frequency filter used in the spectrum. The largest portions are
static ¬modulus of elasticity or the
analysis, one can primarily distinguish visible at the ¬natural frequencies.
static ¬bedding modulus. Normally,
between ¬spectra in ¬octaves, ¬1/3
elastomers begin to experience creep
octave bands or narrow band spectra.
after a load is applied.
Spring deflection in mm
In comparing various spectra, it is imSee ¬deflection.
portant to take into account the bandwidth of the filter used in the analysis.
Stiffening factor

Sound wave
A motion with periodic changes in theposition of molecules (vibration),whereby the energy of this ¬vibration
propagates at the speed of sound while
the individual molecules (e.g. air molecules) oscillate around a static point.

Static range of use
in N/mm2

The maximum compression stress forstationary loads up to which the elastomer will retain its elastic properties;
resilient bearings are generally designed for the upper limit of the static
range of use in order to achieve maximum ¬vibration isolation.

The spring deflection properties ofelastomers depend on the accelerationof deformation. The ratio between the
dynamic and static ¬stiffness stiffness
is referred to as the stiffness factor (orratio of dynamic to static).

13

St-T

Stiffness in kN/mm
Describes the elasticity of an elastomer to deformation; can be determined using force-displacement measurement; the steepness of the forcedisplacement curve (see ¬load deflection curve) represents the stiffness;
stiffness is dependent on load acceleration (quasi-static or dynamic).

stress at rupture is a minimum value;
Note that structure-borne noise isolation should not be confused with struc- testing procedure as per DIN EN ISO 527.
ture-borne noise damping.

Sum level Ltot

Is formed from the addition of n partial
levels Li levels (sound pressure levels)
according to the formula Ltot =10 log
100,1Li, expedient for multiple soundA distinction is drawn between ¬secant sources.
stiffness and ¬tangent stiffness.

Storage modulus
See ¬complex e-modulus.

Structure-borne noise
Are ¬vibrations transmitted via solid
or liquid bodies

Structure-borne noise
isolation in dB
Structure-borne noise isolation involves the prevention of the propagation of ¬structure-borne noise by reflection at an impedance jump, inpractice usually at an elastic layer. In
general, it can be stated that the softer the elastic layer, i.e. the lower the¬impedance (in relation to the impedance of the adjacent media), thegreater the isolation of the structureborne noise.

14

Tangent modulus in N/mm3
See ¬tangent stiffness, but the stiffness pertains to the elastomer surface.

Tangent stiffness in kN/mm

Thermal conductivity
in W/mK
Is determined by the thermal conductivity in watts through a 1 meter thickflat layer of a material with a surface
area of 1 m2, when the temperature
difference of the surface in the direction of conductivity is one Kelvin, testing procedure as per DIN IEC 60093.

Transmission function
In respect of ¬vibration isolation theisolation efficiency as a ratio of input
and response forces and/or input andoutput amplitudes.

Denotes the ¬stiffness of an elastomer
bearing at a certain working point; thesteepness of the tangent is determined Tuned mass damper
in relation to the ¬load deflection
curve at the working point.
A method of vibration reduction involving the removal of energy from an
oscillatory system by the attachment
Tensile strength in N/mm2 of an vibration dampener; the dampener consists of an oscillatory system
See ¬elongation at rupture.
(e.g. mass, spring and damper) andvibrates at its resonance.

Tensile stress at rupturein N/mm2

The force that must be applied per unitof a standardized cross-section tocause the elastomer to rupture; tensile

Tuning frequency in Hz
Lowest vertical ¬natural frequency ofan elastically-mounted system (ma-T-Vchine, track superstructure, building,etc.); the lower the tuning frequency,
the higher the level of ¬vibration isolation.

Tuning ratio

A velocity level of 100 dBv at a ¬frequency of 10 Hz represents an oscillation amplitude (crest value) of approximately 0.1 mm, or at a frequency of
100 Hz of approximately 0.01 mm.

mer and the distance between the twoelectrodes; specific volume resistancedepends strongly on temperature andhumidity. Testing procedures similar to
DIN IEC 93.

Vibration isolation

Ratio of the ¬disturbing frequency tothe ¬tuning frequency of an elastically-mounted system; also known as frequency ratio; the disturbing frequency
and the tuning frequency must be separated by at least a factor of 2 toachieve isolation of the system.

Reduction of the transmission of mechanical vibrations by the installationof elastic components; a distinction isdrawn between the reduction of vibration transmission from a source ofvibration into the surroundings (reduction of emissions, isolation of the emission source) and the shielding of an
object from the impact of vibrations
Ultimate limit statesfrom the surroundings (reduction of
Structural safety as well as the durable immissions, isolation of an object). See
also ¬immission isolation and ¬emisintegrity of a construction must be
sion isolation.
given. Therefor the ultimate bearing
capacity needs to be verified with­¬design loads on the action side Ed
smaller-equal than the ¬design value
Vibrationsof resistance Rd. This method bases on
the semi-probabilistic safety concept
Vibrations are processes in which a
according to EN 1990.
physical quantity changes periodicallydepending on time; these physicalquantities can be displacements, accelerations, forces, momentum.
Velocity level in dBv
Used in acoustics to denote vibration
velocity in the form of a ¬level (logarithmic ratio); it is defined as twenty
times the logarithm of the ratio of theeffective vibration velocity to the reference velocity of 5 . 10-8 m/s.

Volume resistivity in Ωcm

Is determined by resistance of an elastomer which is placed between twoelectrodes with a defined voltage, multiplied by the thickness of the elasto-15

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