Material Properties andVibration Isolation
Technical Information

General information on Sylomer®
Sylomer® is a special PU elastomer manufactured by
Getzner, which features a celled, compact form and isused in a wide range of applications in the construction
and mechanical engineering industries. In most cases,
Sylomer® is used as a compression-loaded elastic support element. The characteristics of the elastic support
can be adjusted to the structure, construction method
and load requirements by selecting the specific type of
Sylomer®, the load-bearing area and the thickness.
Sylomer® materials are available as a continuous roll andare particularly well suited as flat, elastic layers. Aboveand beyond this, engineered moulded parts made ofSylomer® are also available.

Quasi-static load deflection curve
Fig. 2 shows the typical pattern of the load deflection
curve for Sylomer® under compression load.
In the lower load ranges, there is a linear relationshipbetween tension and deformation. For elastic bearings,
the permanent static load should fall in this range. The
load range is specified in the individual data sheets.
After the linear load range, the load deflection curve
moves on a degressive path; the material reacts toadditional static and dynamic loads in a particularly“soft” manner, thus allowing for highly effective vibration
isolation. In the data sheets, the area of the deflection
curve in which a high degree of efficiency is achieved
with a relatively small degree of spring deflection,marked with the lighter shading in the diagram.

SR
220
SR
110
SR
55

12.5 mm

25 mm
37.5 mm

0,16
0.16

50 mm
0,12
0.12
0.11 N/mm2

0,08
0.08

SR
42
SR
28

0,04
0.04

SR
18
SR
11
10

1

0,1
0.1

0,01
0,001
0.01
0.001
Specificload inN/mm2]2
Pressung
[N/mm

0
0
0

1

2

3

4

5

6

7

Dynamikbereich
Dynamic
range of use

SR
450

0.20
0,20

Staticrange of Einsatzbereichuse
Statischer

SR
850

Specificload in[N/mm
N/mm2]2
Pressung

SR
1200

8
9
1010
Einfederung
Deflection
in[mm]
mm

Fig. 2: Load deflection curve, using the example of Sylomer® SR 110

Fig. 1: Sylomer® product series

For specific applications, special types can be manufactured with precisely defined stiffness. The material’s finecelled structure provides the necessary deformation volume under static and dynamic loads. As a result, elastic
bearings with full-surface load transmission are possible.
This offers major engineering and economic advantages,
especially in the construction industry.

www.getzner.com

For loads and deformations exceeding the degressive
range, the deflection curve is progressive (the darker
shaded area). The material becomes stiffer. As a result,
reduced vibration isolation efficiency can be expected inthis load range. Sylomer® is not affected by overloading.
After load removal, the material recovers almost completely even after very significant deformations resulting
from brief, extreme load peaks. No damage is caused tothe material. The compression set as per EN ISO 1856 forSylomer® is less than 5 %.

Behavior under dynamic load
Fig. 3 shows the load dependence of the static and dynamic modulus of elasticity (at 10 Hz and 30 Hz). Just
like all elastomers, Sylomer® reacts to dynamic loads
more stiffly than to static loads. The stiffening factor
depends on the Sylomer® type, the load and the frequency,
and ranges between 1.4 and 4. In keeping with the pathof the deflection curve, the quasi-static and the dynamic
moduli of elasticity exhibit minimum levels. Sylomer®
features particularly good vibration isolation properties
in this load range. Accordingly, by using Sylomer® it has
been possible to realize vibratory systems, which resultin a high degree of isolation despite relatively small
amounts of static subsidence.

Modulus of E-Modul
elasticity[N/mm
N/mm2]2

Static Statischer
range of use
range of use
Einsatzbereich Dynamic
Dynamikbereich
3

0.11 N/mm2

30 Hz
10 Hz
Quasi-static
1

Impact of the shape factor
Low density, celled Sylomer® materials are volume-compressible. This means that, compared to more compact
elastomers, elastic Sylomer® elements do not expand
very much transverse to the direction of the load. On theother hand, Sylomer® bearings with a low shape factor q(defined as the ratio of the load-bearing surface to theperiphal surface of the bearing, see Fig. 4) exhibit greater subsidence than can be derived from the deflection
curves on the data sheets (pages 2 and 3 show the deflection curves for shape factor 3).

Definition:
0

0,04
0.04

0,08
0.08

0,12
0.12

0,20
0,16
0.16
0.20
Pressung
Specificload in[N/mm
N/mm2]2

Fig. 3: Load dependence of the quasi-static and dynamic modulus of elasticity, using the example of Sylomer® SR 110

2

Behavior with shearing loads
Fundamentally speaking, a Sylomer® bearing is softerwith regard to shearing loads than with regard to compression loads. The relationship of compression to shearing stiffness ranges between factor 4 and 10, dependingon the celled structure and geometry of the Sylomer®
bearing. The quasi-static shearing deflection curve exhibits relatively linear deformation behavior.

Page 4 of the data sheets shows the dependence of thesubsidence, the dynamic modulus of elasticity and thenatural frequencies on the shape factor. These dependencies can be used as correction factors for the deflection curves on pages 2 and 3 of the data sheets for different shape factors.

200Loss factor
When Sylomer® materials are subjected to dynamic
loads, some of the mechanical work applied is transformed into heat by dampening effects. The dampening
behavior of Sylomer® materials can be described by themechanical loss factor, which ranges between 0.09 and0.25 for Sylomer® materials. The specific values areshown on the data sheets.

Shape factor =Load area
Perimeter surface area

Blockq=hl

The bulk of the increase in deformation due to creeping
occurs after a relatively short period of time. Subsequent
to this short phase, the increase in deformation over alonger period of time is very small.

w·l
2 · h (w + l)w

Getzner’s 45 years of experience and numerous reference projects using Sylomer® bearings have repeatedly
confirmed this pattern of behavior by the bearings under
static long-term load.

D

CylinderD
4·hDynamic properties under long-term load
A change in the dynamic properties under long-term loadconditions can be critical for elastic vibration-isolation
bearings in particular. The recommendations for the static range of use have seen selected in such a manner that,
under the maximum load for the static range of use, thenatural frequency of the system does not change during
the load period. Fig. 6 illustrates these relationships:hDdHollow Cylinder
q=

D-d
4·h

h

Fig. 4: Definition of the shape factor, block, cylinder, hollow cylinder

Static long-term durability
As is the case with all elastomers, certain creep effects
occur under long-term load. Creep refers to a reversible
increase in deformation under unchanging, long-termload conditions. Fig. 5 shows the behavior typical for
Sylomer®:

Change in der
naturalfrequency overinÄnderung
Eigenfrequenzüber times
die Zeit
relation
thedendata
sheet values in[%]%bezogentoauf
Datenblattwert

q=

10 %
8%
%
8
6%
4%
2%
%
2
0%
-2 %
-4 %
-6 %
-8 %

1 Month

1 Year10 Years

-10 %
%
-10
Springin %of the thicknessofRelative Einfederung[% deflection
der Dicke derunbelasteten
Probe]
the unloaded sample

0,1
0.1
25 %

1

10

100

10.0001.000
1,000
10,000Dauer
derof
BelastungDuration
impact in[Tage]
days

Fig. 6: Dynamic long-term durability of Sylomer®
20 %Full load

15 %Half load

10 %

5%

1 Month

1 Year10 Years0%0 1 2 3 4 5 6 7 10

100
100

10.0001.000
1,000
10,000
Load duration in[Tage]
days
Belastungsdauer

Fig. 5: Static long-term durability of Sylomer®
3

Poisson’s ratio
Poisson’s ratio can only be stated with adequate precision for materials which are loaded in the linear range.
In general, however, Sylomer® is also subject to loads inthe non-linear range, as a result of which disclosure of
the Poisson’s ratio as a discrete “single value” is not realistic.
The higher the density and hence the stiffness of the
Sylomer®, the lower the degree of volume compressibility(ideally incompressible ¬ Poisson’s ratio 0.5).
Determination of the Poisson’s ratio for Sylomer® is subject to corresponding fluctuations, depending on the material type (density) and the load (or testing method). The
values for Sylomer® have been found to be between 0.3
and 0.5.

Influence of temperature
The working temperature range for Sylomer® materials
should be between -30 °C and 70 °C. The glass transition
temperature of Sylomer® is around -50 °C, and the melting temperature range spans from 150 °C to 180 °C. The
maximum temperature to which Sylomer® can be briefly
exposed to without permanent loss of the properties
stated in the data sheet depends strongly on the specificapplication in question. Please contact the Support department at Getzner Werkstoffe for exact information.
The data listed in the data sheets is valid for room temperature.

4

Amplitude dependence
Sylomer® shows a low degree of dependency on amplitude, and as a result this can generally be disregarded in
the calculations. This is a very important factor, in particular in the field of mounting systems for buildings andthe related amplitudes.

Inflammability
Sylomer® materials are categorized in flammability class
B2 as per DIN 4102 (normal flammable). No corrosive
gases are generated in the event of combustion. The gases produced are similar in composition to those producedby the combustion of wood or wool.

Resistance to environmental conditions and chemicals
Sylomer® materials are resistant to substances such as
water, concrete, oils and fats, diluted acids and bases. A
detailed list of resistance to various materials is contained in the data sheet on chemical resistance.

Vibration isolation
Vibration isolation and isolation of structure-borne noise
serve to reduce mechanically transmitted vibrations. This
involves the reduction of forces and vibration amplitudes
by the use of special visco-elastic construction elements
which are aligned in the path of propagation of the vibrations. In the case of structure-borne noise isolation, in
addition to the reduction in mechanical vibration, thesecondary airborne noise generated by structure-borne
noise is also mitigated.

The respective dependencies for the individual material
types with regard to temperature can be found in thedetailed datasheet.

For structure-borne noise isolation, the tuning frequencies are generally higher than those for vibration isolation. Vibration and structure-borne noise isolation is divided into

Frequency dependency
The modulus of elasticity and the loss factor of Sylomer®
are dependent on the deformation velocity, and thus on
the frequency in cases of dynamic load. The dependency
of Sylomer® on frequency can be found in the detailed
datasheet.

Emission isolation
with the goal reducing the forces transmitted by a machine or other source into the environment.

Targeted use of visco-elastic construction elements andthe possible deployment of additional masses generally
allows for the realization of optimum solutions for vibration isolation for all applications.

The amplitude of this vibration fades over time:
Deflection x
Auslenkung

Immission isolation
to shield machines, equipment or buildings against vibrations from the environment.

An
An+1

One-dimension mass-spring systems
Many vibration problems can be approximated with asimple physical model, the so-called mass-spring system(see Fig. 3). If the mass is disturbed from the equilibrium
position by a brief, external force, the mass oscillates ata natural frequency of f0 (see Fig. 4)

T = 1/f0
Zeit tTime

Fig. 8: Fading behavior of a free vibration displacement x

1

ƒ

0

1
2π

1
T

c

m

How quickly the amplitude fades depends on the dampening of the spring. For Sylomer® materials, dampening
is described by the mechanical loss factor. Depending on
the product type, the loss factor for Sylomer® ranges
from η = 0.09 to η = 0.25.

T = Period duration in s
ƒ 0 = Natural frequency in Hz
c = Spring constant in N/m
m = Oscillating mass in kg

The relationship between the mechanical loss factor ηand the so-called dampening ratio D is the following:
F
m
2

C

D

2D

The relationship between dampening and the ratio of twoconsecutive maximum amplitudes is described by theequation:

3

Fe

η

A n+1
An

e

-2Dπ

e

-ηπ

Fig. 7: One-dimensional mass-spring system

5Transmission function
The isolation effect of the elastic bearing is describedwith the transmission function V(f). This refers to theforce transmission function for the force excitement(emission isolation), and the amplitude transmissionfunction for immision isolation.

Degree of transmission / isolation factor
The isolation effect is often presented logarithmically ina level form. In this case, the term used is degree oftransmission L(f) in dB.

5

1+η2·( f0 )

V(ƒ)

2 2

L(ƒ)

2

(1– ( ) ) +η ·( )
f
f0

2

f
f0

Übertragungsfunktion
Transmission function V(f)V(f)

The transmission function describes the mathematical relationship between the system response (amplitude of thevibration) and the impact (amplitude of excitation) and isgenerally rendered as a function of the frequency ratio f/f0.
1020·log2 22(1-( ff ) ) +η ·( ff )
2

2

0

0

3

5
4
Frequency ratio f/f0
Frequenzverhältnis

2Übertragungsmaß
Degreeof transmission in[dB]
dB

f

4

f

1+η2·( f0 )

η = 0.120η =0.115

η =0.210η =0.3

5
0
-5
-10

9
-15
8
8
-20
7
7
-25
-25

6
-30

5

0

1

2

η = 0.24
η =0.3

3

Fig. 10: Degree of transmission

2
11
0
0

0

1

2

3

4
5
Frequency ration f/f
f/f0
Frequenzverhältnis
0

Another useful variable is the isolation factor l(f), which
presents the reduction in the transmitted excitation
factor in %:Fig. 9: Transmission functionf

6

An isolation effect only occurs in the frequency range
f/f0 > 2. So-called low frequency tuning occurs when thenatural frequency f0 of the system is around a factor of
1.41 lower than the lowest frequency f of the mechanicalvibrations.
In the resonance range f/f0 < 2 there is an amplificationof the mechanical vibration in all cases, independent of
the dampening.

6

I(ƒ)

100· 1-

1+η2·( f0 )2 2

2

(1-( ff ) ) +η ·( ff )
0

2

0

2

Calculation of natural frequency and dampening effectwith systems using Sylomer®
If only one type of Sylomer® is used, the natural frequency of the free vibration in line with the static design canbe found in the data sheets. In this regard, the natural
frequency of the system depending on the surface pressure for various material thicknesses is presented in
Point 3. Calculation of the natural frequency occurs inline with (1).
The dynamic spring constant of the bearing is
calculated by:

7

c

E·A
d

0

15.76

Estimation of the natural frequency from the static subsidence as per the following formula (9) cannot be employed for Sylomer®.

ƒ0

As an alternative to (1), it is also possible to use thefollowing formula:ƒMoreover, both values are presented in dependence on
the natural and excitation frequency in the data sheets
under point 4.

9

E = Dynamic modulus of elasticity in N/mm 2
A = Bearing surface in mm 2
d = Material thickness mm

8Insertion loss and the isolation factor of the elastic bearing are dependent on the ratio of the excitation frequency to the natural frequency and the loss factor. They canbe calculated using equations (5) and (6).

Edσ

σ = Surface pressure in N/mm2

The dynamic modulus of elasticity can be found for thesurface pressure under Point 2 in the diagrams in thedata sheets. In all cases the material thickness of the
Sylomer® bearing in the unloaded state is to be used for
calculation of the dynamic spring constant as per (7). If
various types of Sylomer® are combined, then it is necessary to use the overall stiffness of the bearing as a basis
for the calculation of natural frequency as per (1). The
overall stiffness is derived from the sum of the individual
stiffnesses as per (7).

5xx = Static subsidence in cm

Modeling
Calculation of the real oscillatory system occurs on thebasis of a mechanical dummy model for many real vibration problems, it is sufficient to use one-dimensionalmodeling as a mass-spring system. If one wishes to examine the oscillatory system more precisely, then one
must allow for further movement possibilities which are
relevant for the real system. Moreover, the oscillating
mass can be represented by various discrete individual
masses which are linked by springs or dampeners. The
number of independent movement possibilities allowed
for by the system are referred to as degrees of freedom.
The number of degrees of freedom is identical to thenumber of possible natural frequencies.
For measuring vibration isolation, in general the lowest
natural frequency is relevant. As this frequency is approximately the same for all models, a one-dimensionalmodeling as a mass-spring system is often sufficient.

All information and data is based on our current knowledge. The data can beapplied for calculations and as guidelines, are subject to typical manufacturing
tolerances, and are not guaranteed. We reserve the right to amend the data.

For bearings which are also subjected to shearing forces,
it is necessary to use the dynamic shearing modulus inthis regard, instead of the dynamic modulus of elasticity.
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