Divin i Cell

8/11/2019 Divin i Cell

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H Manual - 0903 - 1

55555GRADE

Technical Manual

E


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DISCLAIMER

DIVINYCELL H

H Manual - 0903 - 2

This manual and the data contained herein may be subject to revision and changes due to

development and changes of the material. The data is derived from tests and experience.

The data is average data and should be treated as such. Calculations should be verified

by actual tests. The data is furnished without liability by the company or its agents anddoes not constitute a warranty or representation in respect of the material or its use. The

company reserves the right to release new replacement data. Customers should check

that they have the latest issue which can be downloaded from the DIAB web site -

http://www.diabgroup.com


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GENERAL INFORMATION

DIVINYCELL H

H Manual - 0903 - 3

E 5

the ultimate core for sandwich construction

Divinycell H grade has all the properties expected of a high-performance, lightweight construction material. It is a partiallycross-linked, structural cellular material expanded according toa CFC free process.

High ductility and resilience give excellent dynamic behaviour

under shock and impact. Compatibility with a wide range ofmatrix materials, low water absorption, self-extinguishing andexceptionally good thermoforming properties are other basicfeatures.

OTHER DIVINYCELL GRADES

In addition to H, Divinycell is available is range of grades to suitspecific application parameters.

Divinycell HCP, with its high hydraulic crush point, is usedin various subsea applications.

Divinycell HT is formulated to suit various prepreg systemsand the process temperatures involved.

Divinycell HD has extremely good dynamic propertiesand high ductility. It is intended for use in primary marine

structures subjected to slamming and shock loads.

Divinycell IPN insulation materials exhibits low water vapourpermeability for extreme cold to hot environments.

Divinycell HPS has been specially developed for use withepoxy prepregs. It is suitable for high temperature proc-esses up to 120C.

Specific information on these other grades of Divinycell isavailable upon request.

DIAB - AN INTERNATIONAL MARKET LEADER

DIAB develops and sells products and services based onadvanced polymer and composite technologies.

Over twenty years of experience combined with continuous

research and development have made us an internationalmarket leader in multi-functional sandwich constructions.

Our philosophy is to supply our customers with structural coresfor sandwich construction of the highest quality. To this end allDIAB operations are certified to ISO 9001.

We strive for excellence not only in materials but also in

technical assistance and documentation. Long-term involve-ment enables us to give strong support to our customerswhenever and wherever needed.


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AVERAGE PHYSICAL PROPERTIES

DIVINYCELL H

H Manual - 0903 - 4

Table shows average values for the nominal densities and minimum values withinthe brackets for the minimum density.

* = Measured on maximum size, trimmed blocks with a typical thickness of 50-70mm. Sheets, especially in low thickness, may have lower or higher density than specified above.

Low density sheets will still meet the minimum properties stated above.

** = Perpendicular to the plane.

*** = Parallel to the plane.

Operating temperature is -200C to +70C. Lifetime must be taken into consideration for the very low and high temperatures. Maximum processing temperature is dependent on time,

pressure and process conditions. Normally Divinycell H can be processed up to 80C without dimensional changes. Please contact DIAB for advice before use.

Coefficient of linear expansion ASTM D 696: Approx. 35 10-6

/ C. Poissons ratio: 0.32

Property Unit H 45 H 60 H 80 H 100 H 130 H 160 H 200 H 250

Density*, nominal 48 60 80 100 130 160 200 250Density*, maximum kg/m3 55 69 92 115 149 180 230 290Density*, minimum 43 55 72 90 120 145 180 230

Compressive strength**MPa

0.55 0.8 1.2 1.7 2.6 3.4 4.5 5.8 ASTM D 1621 (0.4) (0.7) (1.0) (1.4) (2.2) (2.8) (3.7) (4.9)

Compressive Modulus**MPa

40 60 85 125 175 230 310 400(extens.) ASTM D 1621 (30) (45) (65) (95) (130) (175) (235) (300)

Tensile strength **MPa

1.2 1.6 2.2 3.1 4.2 5.4 7.0 8.8 ASTM D 1623 (0.9) (1.1) (1.8) (2.6) (3.4) (4.0) (5.5) (6.5)

Tensile Strength ***MPa

1.1 1.4 2.0 2.4 3.0 3.9 4.8 6.4

ISO 1926 (0.8) (1.0) (1.6) (1.9) (2.4) (3.2) (3.9) (5.2)Shear Strength ***

MPa0.5 0.7 1.0 1.4 2.0 2.6 3.3 4.5

ASTM C 273 (0.4) (0.6) (0.9) (1.2) (1.7) (2.2) (2.8) (3.8)

Shear Modulus***MPa

18 22 31 40 55 73 90 108 ASTM C 273 (12) (15) (23) (30) (40) (50) (70) (87)

Shear Strain***

%

10 13 20 24 29 30 30 30

ASTM C 273 (6) (8) (12) (14) (19) (20) (20) (20)


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TECHNICAL DATA - GRAPHS

DIVINYCELL H

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Compressive strength parallel to the plane at +23C as a function of

density according to ASTM D 1621 and ASTM D 1622.

COMPRESSIVE STRENGTH

DIVINYCELL H 45 - H 250

0

1

2

3

4

5

6

0 50 100 150 200 250 300

COMPRES

SIVESTRENGTH

(MPa)

DENSITY (kg/m3)


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DIVINYCELL H

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Compressive modulus perpendicular to the plane at +23C as a function of

density according to ASTM D 1621 (crosshead movement) and ASTM D 1622.

COMPRESSIVE MODULUS


0

25

150

200

0 50 100 150 200 250 300

COMPRESSIVEMODULU

S(MPa)

DENSITY (kg/m3)

50

125

75

100

175


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DIVINYCELL H

H Manual - 0903 - 8

Compressive modulus perpendicular to the plane at +23C as a function of

density according to ASTM D 1621 (extensometer) and ASTM D 1622.

COMPRESSIVE MODULUS


0

100

400

500

0 50 100 150 200 250 300

COMPRESSIVEMODULUS

(MPa)

DENSITY (kg/m3)

200

300


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DIVINYCELL H

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Compressive modulus parallel to the plane at +23C as a function of

density according to ASTM D 1621 (crosshead movement) and ASTM D 1622.

COMPRESSIVE MODULUS


0

25

50

75

100

125

175

0 50 100 150 200 250 300

COMPRES

SIVEMODULUS(MPa)

DENSITY (kg/m3)

150


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DIVINYCELL H

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Tensile strength perpendicular to the plane at +23C as a function of

density according to ASTM D 1623 and ASTM D 1622.

TENSILE STRENGTH


0

4

8

10

0 50 100 150 200 250 300

TENSIL

ESTRENGTH(MPa)

DENSITY (kg/m3)

6

2


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DIVINYCELL H

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Tensile strength parallel to the plane at +23C as a function of

density according to ISO 1926 and ASTM D 1622.

TENSILE STRENGTH


0

1

2

3

4

5

7

0 50 100 150 200 250 300

TENSILESTRENGTH(MP

a)

DENSITY (kg/m3)

6


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DIVINYCELL H

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Tensile strain parallel to the plane at +23C as a function of

density according to ISO 1926 (extensometer) and ASTM D 1622.

TENSILE STRAIN


0

2

4

6

8

10

12

0 50 100 150 200 250 300

TENSILESTRAIN(%)

DENSITY (kg/m3)


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DIVINYCELL H

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TENSILE MODULUS


0

50

100

150

200

250

350

0 50 100 150 200 250 300

TENSILEMODULUS(MP

a)

DENSITY (kg/m3)

300

Tensile modulus perpendicular to the plane at +23C as a function of

density according to ASTM D 1623, ASTM D 1621 procedure B and ASTM D 1622.


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DIVINYCELL H

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Tensile modulus parallel to the plane at +23C as a function of

density according to ISO 1926 (extensometer) and ASTM D 1622.

TENSILE MODULUS


0

50

100

150

200

250

350

0 50 100 150 200 250 300

TENSIL

EMODULUS(MPa)

DENSITY (kg/m3)

300


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DIVINYCELL H

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Shear strength at +23C as a function of

density according to ASTM C 273 and ASTM D 1622.

SHEAR STRENGTH


0

1

2

3

4

5

6

0 50 100 150 200 250 300

SHEARSTRENGTH(MP

a)

DENSITY (kg/m3)


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DIVINYCELL H

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Shear strain at +23C as a function of


SHEAR STRAIN


0

5

30

40

0 50 100 150 200 250 300

SHEARSTRAIN(%)

DENSITY (kg/m3)

10

25

15

20

35


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DIVINYCELL H

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Shear modulus at +23C as a function of


SHEAR MODULUS


0

20

40

60

80

100

120

0 50 100 150 200 250 300

SHEA

RMODULUS(MP

a)

DENSITY (kg/m3)


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DIVINYCELL H

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Water absorption at 23C as a function of density

acc. to ASTM D 2842 and ASTM D 1622.

WATER ABSORPTION


0

0.02

0.12

0.16

0 50 100 150 200 250 300

WATERABSORPTION(kg/m2)

DENSITY (kg/m3)

0.04

0.10

0.06

0.08

0.14


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DIVINYCELL H

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Water vapour permeability at 22C as a function of density

acc. to SS 02 15 82 and ASTM D 1622.

WATER VAPOUR PERMEABILITY


0.5

1.0

6.0

7.0

0 50 100 150 200 250 300

WVP1

0-8

(g/m.s.Pa)

DENSITY (kg/m3)

2.0

5.0

3.0

4.0


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DIVINYCELL H

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Dissipation factor at 8-12 GHz as a function of density.

DISSIPATION FACTOR


0

0.002

0.005

0 50 100 150 200 250 300

DISSIPATIONFACTOR

DENSITY (kg/m3)

0.001

0.004

0.003


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DIVINYCELL H

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Dielectric constant at 8-12 GHz as a function of density.

DIELECTRIC CONSTANT


1.00

1.05

1.10

1.15

1.20

1.25

1.35

0 50 100 150 200 250 300

DIELEC

TRICCONSTANT

DENSITY (kg/m3)

1.30


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DIVINYCELL H

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Open cells as a function of density

acc. ISO 4590 and ASTM D 1622

OPEN CELLS


0

4

8

10

0 50 100 150 200 250 300

OPENCELLS(%)

DENSITY (kg/m3)

6

2


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DIVINYCELL H

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Cell size as a function of density.

CELL SIZE


0.0

0.4

0.8

1.0

0 50 100 150 200 250 300

C

ELLSIZE(mm)

DENSITY (kg/m3)

0.6

0.2


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TECHNICAL DATA - TABLES

DIVINYCELL H

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CHARACTERISTICS - H 45

Value Unit Test Procedure

Density 48 kg/m3 ASTM D 1622Compressive strength * 0.55 MPa ASTM D 1621

Compressive strength ** 0.4 MPa ASTM D 1621

Compressive modulus * 19 MPa ASTM D 1621 (crosshead movement)

Compressive modulus * 40 MPa ASTM D 1621 (extensometer)

Compressive modulus ** 15 MPa ASTM D 1621 (crosshead movement)

Tensile strength * 1.2 MPa ASTM D 1623

Tensile strength ** 1.1 MPa ISO 1926Ultimate tensile strain ** 5.5 % ISO 1926 (extensometer)

Tensile modulus * *** 42 MPa ASTM D 1623

Tensile modulus ** 45 MPa ISO 1926 (extensometer)

Shear strength 0.5 MPa ASTM C 273

Shear strain 10 % ASTM C 273

Shear modulus 18 MPa ASTM C 273

Thermal conductivity -10C 0.025 W/(m .C) ASTM C 177

+10C 0.026

+37C 0.028

Water absorption 0.10 kg/m2 ASTM D 2842

Water vapour permeability 2.8 m2/(s . 10-8) SS 02 15 82

Coefficient of linear expansion 35 .10-6/C ASTM D 696

Continuous temp. range -200 +70 C

Max. processing temp. +80 C

Dissipation factor 0.0008 8-12 GHzDielectric constant 1.065 8-12 GHz

Open cells 4.5 % ISO 4590

Cell size 0.7 mm

* = Perpendicular to the plane ** = Parallel to the plane ***= Calculation of modulus based on ASTM D 1621 (extensometer)

TECHNICAL DATA TABLES


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DIVINYCELL H

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Density 60 kg/m3 ASTM D 1622Compressive strength * 0.8 MPa ASTM D 1621




Compressive modulus ** 20 MPa ASTM D 1621(crosshead movement)


Tensile strength ** 1.4 MPa ISO 1926Ultimate tensile strain ** 6 % ISO 1926 (extensometer)







+10C 0.027

+37C 0.029







Open cells 4 % ISO 4590

Cell size 0.6 mm




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DIVINYCELL H

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Density 80 kg/m3 ASTM D 1622

Compressive strength * 1.2 MPa ASTM D 1621






Tensile strength ** 2.0 MPa ISO 1926Ultimate tensile strain ** 6.5 % ISO 1926 (extensometer)







+10C 0.030

+37C 0.032








Cell size 0.5 mm




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DIVINYCELL H

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+10C 0.032

+37C 0.034








Cell size 0.45 mm




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DIVINYCELL H

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Value Unit Test ProcedureDensity 130 kg/m3 ASTM D 1622



Compressive modulus * 85 MPa ASTM D 1621(crosshead movement)



Tensile strength * 4.2 MPa ASTM D 1623Tensile strength ** 3.0 MPa ISO 1926

Ultimate tensile strain ** 8 % ISO 1926 (extensometer)






Thermal conductivity -10C 0.034 W/(m .C) ASTM C 177+10C 0.036

+37C 0.038








Cell size 0.35 mm



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DIVINYCELL H

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Tensile strength ** 4.8 MPa ISO 1926

Ultimate tensile strain ** 10 % ISO 1926 (extensometer)






Thermal conductivity -10C 0.042 W/(m.C) ASTM C 177+10C 0.045

+37C 0.048








Cell size 0.3 mm





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DIVINYCELL H

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+10C 0.050

+37C 0.054








Cell size 0.3 mm




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FATIGUE PROPERTIES


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DIVINYCELL H

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FAILURE MODES FOR DIFFERENT TYPES OF PLASTICS

Type Failure mode

Rigid PVCUrethane CrackPhenolic propagationEpoxy

PMMA Crack

PET propagation orAlkyd thermalPolycarbonate failure

PolypropylenePolyethylene ThermalNylon failure

FATIGUE TESTING

Four-point bending test until fracture

The fatigue properties have been determined by cycling sand-wich beams in four-point bending. All tests were carried out in aSchenck 40 kN servo-hydraulic machine, an MTS 50 kN servo-hydraulic machine and an Intsron 100 kN universal testing

machine.

A state of dominant shear stress was achieved, by using a four-point bending test. The face material and the dimensions of thetest beam were selected such that the core material, rather thanthe face material, was the limiting factor.

The four-point bending tests were carried out with the stressrations

R = 0.05, R = 0.5 and R = 1 where R = min/max

Figure 1: Illustration of R values

The frequency has been 5 Hz (5 load cycles/second).

A higher frequency will increase the temperature due to hystereticheating and cause a failure due to softening.

min

max

0 N

R = 0.05

min

max

0 N

R = 0.05

FATIGUE PROPERTIES


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DIVINYCELL H

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Figure 2

Four-point bending test:

The maximum normal stress in the face material is:

The maximum shear stress in the core is:

The ratio of shear stress in the core to the normal stress in theface is:

Hence, the ratio b/t should be low enough (we assume a safety

factor of 2) so that fracture does not occur in the face material:

With respect to the discussion above, the following values werechosen: b = 180 mm (7 in), a = 80 mm (3.1 in) and L = 500 mm(20 in). The thickness of the core material was 60 mm (2 3/8 in).

The width of the beam should not influence the resultssignificantly, but was selected to be large enough to preventlateral buckling, d = 60 mm (2 3/8 in). The loads P must beapplied in such a way that local failure under the load points isavoided. Therefore, the length of the load plates was set equalto the core thickness c.

The test programme starts with determination of the ultimateshear strength in a static four-point bending test. The beams arethen tested in fatigue at different stress-ratios of the ultimate

shear strength. The test is stopped when the shear crackpropagation is in a macro stage, and the number of load cyclesis recorded. At least three beams need to be tested at each levelof stress ratio.

The result is presented in a S/N curve with stress on the y-axisand the number of load cycles on the x-axis.

As can be seen from the curves the S/N relationship for Diviny-

cell is essentially linear. At a stress-ratio of 40 % Divinycell canbe subjected to 5-25 million load cycles before failure. We havenot tested at higher numbers of load cycles, but normally aplastic material will tend to level off and become asymptotic toa characteristic stress level. This stress is call the endurancelimit.

FOUR-POINT BENDING, RESIDUAL STRENGTH AFTER CY-

CLING

The tests were carried out in accordance with the procedures inFatigue Testing, Four-point bending test until fracture, with thefollowing exceptions:

1. The tests were carried out in a 250 KN servo hydraulicmachine.

max =

Mmax

= P . b max

= P

P . bc . d . t

max

= Pc . d

max

/max

= b / t

(b / t)max

= 0.5 . max

/max

FATIGUE PROPERTIES


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DIVINYCELL H

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2. The deflection (d) was measured with an electric gauge.

3. Bending stiffness EI =

4. Beam dimensions.

After determination of the static properties the beams werecycled 106-107cycles with a stress ratio of 20-30%. The bendingstiffness was checked during and after the test.

None of the beams showed any decrease in physical propertiesafter cycling. The results are presented in appendices III-V.

SLAMMINGIntroduction

Bottom slamming at the bow of ships due to repetetive dynamicloading is a frequent reason for repair of ships. This occurs inrough seas when the conditions are such that the fore of the shipemerges from the water and at the re-entering the relativevelocity between the ship and the water surface is so high that

an impulse water pressure arises. The time for the impulsepressure is very short; it is in the range of a few milliseconds.

The literature on slamming is rather extensive. Each scientist

has his own theory, but the most commonly used and adoptedamong designers and classification societies are those by Ochiand Motter.

Slamming frequency

In accordance with the definitions of Ochi and Motter slammingoccurs under the following conditions.

1. Bottom emergence, i.e. the relative motion between the shipand the waves, is larger than the draught at the location

considered.2. The relative velocity at the re-entry is larger than a certainthreshold velocity.

For a ship with constant speed and heading in a certain seastate, the relative motion and relative velocity are stationaryGaussian processes with amplitudes that are Rayleigh distrib-uted.

Ochi has shown that the threshold velocity is assumed to followFroudes scaling law for ships with different lengths (i.e. propor-tional to ).

The frequency of slamming is given by the following equation:

The significant value is defined as the average of the one-thirdlargest amplitudes.

b . L2.

P

16

L

!

"

#$

%

&'(() *

v

g

s

21/2

v

ss

r

v

r

de

r

r

2

1F

+

FATIGUE PROPERTIES


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DIVINYCELL H

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The significant value is defined as the average of the one-thirdlargest amplitudes.

Slamming pressure

The local pressure at the bottom plating at slow impacts isproportional to the square of the impact velocity.

rs = significant amplitude of relative motion

rv = significant amplitude of relative velocity

= threshold velocityd = ship draught at location consideredv

g

= density of water

= impact angle

v= impact velocity

Considering a ship in pure long-crested head seas with no rollmotion, the section shape coefficient can be regarded as constant.However, in oblique sea or short-crested head sea the ship willroll more or less, which means that the angle of impactinstantaneously will have different values.

p

=1

. . .

v2

2 tan


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FATIGUE PROPERTIES


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DIVINYCELL H

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APPENDIX 2 - FOUR POINT BENDING TEST - H 130

0.0

0.2

0.4

0.6

1.0

1.2

1.4

1.6

1.8

2.0

101

102

SHEARSTRESS(M

Pa)

NUMBER OF CYCLES (N)

X

104

103

105

106

R = 0.05 F = 5 Hz

R = 0.5 F = 5 Hz

R = -1 F = 1.5 Hz

1 100

X

XXXX

XX X

XXXXX

XXXX

XX

X

XX

0.8

FATIGUE PROPERTIES


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DIVINYCELL H

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APPENDIX 3 - FOUR POINT BENDING TEST - H 250

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

10 100 1,000

SHEARSTRESS(MPa

)

NUMBER OF CYCLES (N)

X R = 0.05 Frequency = 1 - 2 Hz

1 10,000 100,000 1,000,000 10,000,000

X

X

XXX

X

XX

X

X

XX

X

FATIGUE PROPERTIES


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DIVINYCELL H

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APPENDIX 4

DETERMINATION OF RESIDUAL STRENGTH AFTER FOUR POINT BENDING FATIGUE TEST

Beam design

Core H 130 - 60 (2 x 30)

Density 150 kg/m3

Skin GRP

Face thickness 11 mm

Beam dimensions 2000 x 300 mm

Static bending

Bending stiffness/width 330 MN mm2/mm

Tensile strength, faces 115 MPa

Shear strength, core 2.87 MPa

Fatigue test

Number of cycles, N 107

Pmax/Pult 21 %

R 0.17

Frequency 1.4 Hz

Bending stiffness,

N = 0 99,000 MN mm2

N = 106 108,000 MN mm2

N = 107 113,000 MN mm2

Static bending, residual strength



FATIGUE PROPERTIES


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DIVINYCELL H

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Beam design

Core H 130 - 40 GS

Density 137 kg/m3

Putty Divilette 600

Skin GRP

Face thickness 6 mm


Static bending


Tensile strength, faces 169.6 MPa


Fatigue test

Number of cycles, N 106

Pmax/Pult 26 %

R 0.05

Frequency 2 HzBending stiffness,

N = 0 28,000 MN mm2

N = 3 .105 25,000 MN mm2

N = 5 .105 26,000 MN mm2

N = 1 .106 26,000 MN mm2

APPENDIX 5


FATIGUE PROPERTIES


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DIVINYCELL H

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APPENDIX 6


Beam Design

Core H 250 - 60 (2 x30)

Density 247 kg/m3

Skin GRP

Face thickness 9.3 mm


Static bending




Fatigue test Beam 1

Number of test cycles, N 106

Pmax/Pult 25 %

R 0.05

Frequency 2 Hz

Bending stiffness,

N = 0 64,800 MN mm2

N = 106 65,600 MN mm2




Fatigue test Beam 2

Number of test cycles, N 106

Pmax/Pult 30 %

R 0.05

Frequency 2 Hz

Bending stiffness,

N = 0 66,800 MN mm2

N = 106 68,800 MN mm2





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FIRE, SMOKE & TOXICITY PROPERTIES (FST)


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DIVINYCELL H

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AIRCRAFT

FAR (Federal Aviation Requirements)

The FAR is the set of rules and requirements established by theFAA (Federal Aviation Administration). FAR deals with aircraftsafety, and concerns everything from upholstery and curtains inthe cabin to panels for cargo compartments.

Airbus 1000 (ATS-1000.001)

Airbus ATS 1000 is a company standard drafted by AirbusIndustries regarding fire, smoke, and toxicity in their aircraft.

ATS 1000.001 follows FAR closely, except that ATS is morerestrictive in certain areas. These restrictions are often dictatedby their suppliers.

Typeof test Requi.Unit H 45 H 80 HT 50 HT 110 FRG 80

mm 12.5 25 12.5 25 6.3 12.5 6.3 12.5 12.5 25

Vertical A1ii (12 s) < 203 mm Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass

Burn A1i (60 s) < 152 mm Fail Pass Fail Pass Pass Pass Pass Pass Pass Pass

Heat HR < 65 kWmin/m2 Fail Fail Fail Fail Fail Fail Fail Fail Fail FailRelease HRR < 65 kWmin/m2 Fail Fail Fail Fail Fail Fail Fail Fail Fail Fail

Smoke Ds (90s) < 100 - Fail Fail Fail Fail Fail Fail Fail Fail Fail FailDensity Ds (240s) < 200 - Fail Fail Fail Fail Fail Fail Fail Fail Fail Fail

CO < 3000 ppm Pass Pass Pass Pass Pass Pass Pass Pass Pass PassHF < 50 ppm Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass

Toxicity HCl < 50 ppm Fail Fail Fail Fail Fail Fail Fail Fail Fail Fail(1.5 min) NOx < 50 ppm Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass

SO2 < 50 ppm Pass Pass Pass Pass Pass Pass Pass Pass Pass PassHCN < 100 ppm Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass

BMS and BSS (Boeing Material Specifications)

BMS and BSS are standards, for Boeing Aircraft, and are alsobased on FAR. The requirements in BMS are generally moreconservative than those in FAR.

The main criteria for use as an interior material in all threestandards are vertical burn, heat release, smoke density andtoxicity.

The table below shows the requirements and whether a particu-

lar Divinycell grade passes or fails.


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THERMAL INSULATION

FORMULAS FOR CALCULATION OF THERMAL PROPERTIES


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DIVINYCELL H

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FORMULAS FOR CALCULATION OF THERMAL PROPERTIES

Symbol Formula Unit

t t = T 273.15 C

T T = T1 T

2C

T1 = T on warm surface

T2 = T on cold surface

= g .A W

g g = T .k W/m2

G G = /T = A .k W/K

R R = 1/G = 1/A .k K/W

Mn

Mn= 1/k m2.K/W

(d = thickness in m or ft)

Ma

Ma= 1/ m2.K/W

k W/(m2.K)

1= a on warm surface

2= a on cold surface

d = d1= thickness of first layer d

2= etc.

= 1= of first layer

2= etc.

C C = c .m J/K(m = mass in kg or lb)

1

1

2

3

2

k = 1 d1

d2

d3

1

1

+ + + +

WATER VAPOUR PROPERTIES

DEFINITION OF WATER VAPOUR PROPERTIES


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Designation Symbol UnitThermodynamic temp. T K

Celsius or Fahrenheit temperature t C

Temperature diff. 1) T K

Water vapour permability 2)

Water vapour content v m2/s

Water vapour pressure p kg/(m .s .Pa)

Water vapour permeance 3) WV

m/s

Water vapour resistance ZV

s/m

Water vapour transmission rate 4) D kg/(m2.s)

Water vapour difference

Water content v kg/m3

Water pressure p Pa

Insulation thickness d m

Water vapour flow g kg/(m2.s)

1. K (Kelvin) can be changed to C (Celsius) or F (Fahrenheit) in all units whereK occurs since all units refer to a temperature difference.

2. The water vapour permeability is the amount of water vapour per second atsteady state that passes through 1 m2of a material with 1 m thickness when adifference in water vapour content between the two sides of the material is 1 kg/m3.

(The definitions are in accordance with SS 02 15 82)

3. The water vapour permeance is the amount of water vapour per second atsteady state that passes through 1 m2of material with a given thickness whenthe difference in water vapour content between the two sides of the material is1 kg/m3.

4. The water vapour transmission rate is the amount of water per second at steadystate that passes through 1m2of a material when the difference in water vapourcontent between the two sides of the material is 1 kg/m 3.

WATER VAPOUR PROPERTIES

FORMULAS FOR CALCULATING WATER VAPOUR PROPERTIES


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Symbol Formula Unit

t t = T 273.15 C

T T = T1 T

2K

T1= T on warm surface

T2= T on cold surface

v v = d/Z m2/s

p p = dv .7.33 .10-6 kg/m .s .Pa

Wv

Wv= 1/Z m/s

Zv

Zv= s/m

g g = kg/(m2.s)

Zp Zp = Zv/7.33 .10-6 m2.s .Pa/kg

FORMULAS FOR CALCULATING WATER VAPOUR PROPERTIES

v

D

vZv+ (d/v)

WATER ABSORPTION

The values in the data sheet are determined in accordance with cells cut open during specimen preparation has to be taken into


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The values in the data sheet are determined in accordance withASTM D 2842-69. This method covers the determination of thewater absorption of rigid cellular plastics by measuring the

change in buoyant force resulting from immersion under a 5.1cm head of water for 96 h.

The purpose of this method is to provide a means for comparingrelative water absorption tendencies between different cellularplastics. It is intended for use in specifications, product evalua-tion and quality control. It is applicable to specific end-use designrequirements only to the extent that the end-use conditions are

similar to the test conditions.

The water absorption is measured as a result of direct contactexposure to the water. The volume error associated with surface

cells cut open during specimen preparation has to be taken intoaccount when calculating the true specimen volume.

This is, however, complicated and is often a reason for errors.Both internal and external tests have shown negative waterabsorptions due to miscalculation of the volume of the cells cutopen on the surface.

The results are reported in terms of amount of water absorbedper unit of surface area. The unit is kg/m2 .

ISO 2896 could also be used for determination of water absorp-

tion. We do not recommend ASTM C 272-53 since it does nottake the volume of the cells cut open on the surface into account.

GLASS TRANSITION TEMPERATURE

All amorphous as opposite to crystalline polymers have a point A low T does not necessarily mean that the polymer or the


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All amorphous, as opposite to crystalline, polymers have a pointwhere the physical properties are changed due to temperature.At this point, i.e. temperature range, the mobility of the polymer

chains increases and the material softens. This softening pointis called the glass transition temperature (T

g).

Tgis different for different polymers and relates to the structure

of the polymer.

The Tgis +85 - +88 C for the H-grade and +84 - +86 C for the

HT-grade.

A low Tgdoes not necessarily mean that the polymer, or the

material, has bad thermal stability. This is pronounced concern-ing the HT-grade. HT has a lower T

gthan H-grade but a better

thermal stability. HT consists partly of crystalline areas whichhave a high melting point, approx +250 C.

These crystalline areas give HT-grade good thermal stabilitycompared with H-grade. Such materials are called semi-crystal-line materials.

DIELECTRIC PROPERTIES

INTRODUCTION


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O UC O

A dielectric material is defined as a non-conductor of electricityand a medium that lets electrical fieldlines through.

The dielectrical properties of a material are measured in terms ofdielectric constant or permittivity and dissipation factor.

When we talk about the dielectric constant in common usage wemean the relative dielectric constant. It is the ratio of theequivalent capacitance of a given configuration of electrodeswith a material as a dielectric to the the capacitance of elec-

trodes with vacuum (or air for most practical purposes) as thedielectric. Since the relative dielectric constant is a ratio it has nounit.

Table 1 - Typical dielectric constants

Material Dielectric constant

Vacuum 1.0000

Air (1 atm +20 C) 1.0006

Water (+20 C) 80

Divinycell 1.1

Rubber 3

Glass 510

Porcelain 68

Teflon 2.1

Polyethylene (PE) 2.3

The lower the dielectric constant, the lower the conductingcapacity. The reduction can be understood in terms of polariza-

tion. It is the alignment of atomic or molecular dipoles in thedielectric when an electric field is applied. An electric dipole is aconfiguration of equal amounts of positive and negative chargeswith the positive charge displaced relative to the negativecharge.

The dissipation factor is a measure of the A/C loss in thedielectric. The A/C loss shall generally be small, both in order to

reduce the heating of the material and to minimize its effect onthe rest of the network. In high frequency applications, a lowvalue of loss index is particularly desirable, since for a givenvalue of loss index the dielectric loss increases directly withfrequency.

FACTORS AFFECTING THE DIELECTRIC PROPERTIES

Dielectric materials are used over the entire electromagneticspectrum from direct current to radar frequencies. There areonly a few materials whose dielectric constants are even ap-proximately constant over the frequency range. It is thereforenecessary either to measure the dielectric constant at thefrequency at which the material will be used or to measure it atseveral frequencies suitably placed, if the material is to be used

over a frequency range.


Table 2 - Electromagnetic spectrum Radio and radar waves are produced in electrical oscillating


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Wave length Frequency Designation

500 mm 1.5 GHz Radio waves500 mm 10 mm 1.5 GHz 30 GHz Radar waves

10 mm 0.1 mm 30 GHz 3 THz mm wave

0.1 mm 0.001 mm 3 THz 300 THz Infrared light

8000 4000 Visible light

4000 1 UV-light

100 0.01 X-ray

1 0.01 Gamma radiation

1 (ngstrm) = 10-10m

p gcircuits. Infrared, visible and UV-light and X-rays are due tochanges in energy in the electron layers of the atoms in the

material that transmits the radiation. Gamma radiation is cre-ated by changes in energy in the atom cores.

Another very important parameter that affects the dielectricconstant is water vapour permeability and water absorption.The major electric effect is a great increase of the interfacialpolarization, thus increasing the dielectric constant and theconductivity.

The dielectric constant also increases with increasing density.


O S O C C O S


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Designation Symbol SI Unit

Quantity of electricity Q C, As

Electric flow density D C/m2

Voltage U V

Electric field strength E V/m

Capacitance C F

Permittivity, capacitivity or dielectric constant

Permittivity of vacuum o

F/M

Relative permittivity r

Dissipation factor, loss tangent or tan d

Loss index or loss factor r"

Wave length m

Frequency f Hz

Velocity of light in air m/s

DEFINITIONS OF DIELECTRIC PROPERTIES



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Symbol Formula Unit

C C = Q/U F

E E = U/d v/m

D D = Q/A C/m2

= D/E F/m

F/m

o F/m

r

r"

d1)

rad/s

=/f m

f f = 1/T s-1

= 3 .108 m/s

Formulas for calculations of dielectric properties

N.B. The normal presentation of the dielectric loss is to represent a capacitorat a single frequency by capacitance Cp parallel to a resistance Rp. Butit is occasionally desirable to represent it by a capacitance Csin serieswith a resistance Rs.

= C .dA

= 8.854 .10-12

r= /

r" =

r .d

dp = .Cp.Rp1

= 2.f

ds =.Cs.Rs

MACHINING

INTRODUCTION SAWING


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There are a number of ways to machine Divinycell. This sectioncovers the most commonly used methods, namely:

Sawing

Cutting

Horizontal sawing

Sanding

Milling

Turning

Drilling

This part of the manual is in no way a complete set of instructionsfor machining Divinycell. The intention, based on our internalexperiences, is a guide when making the first attempts tomachine the materials in various ways. The contents will cover

the basic parameters and principles and give the user a fairchance of getting close to a good result at the first try, becausealmost always some trials must be made before choosing a finalsetup.

Divinycell is a fairly easy to machine but its low thermal conduc-tivity and other plastic properties can be a source of problems.Several measures can be taken to ensure a good cut. A very

important part is the checking and maintenance of the machinesand machining tools. The final result is highly dependent onthese factors.

If in doubt concerning machining, please contact DIAB and wewill advise you in this area.

Depending on the operation and the density of the material thereare two types of sawing: Cross-cut sawing and band sawing.

They will be dealt with separately because of their differences.

CROSS-CUT SAWING

This type of sawing can be used on any density and on manysandwich panels. Please note that the feed speed must bedecreased on sandwich panels and on higher densities. The

main parameters when cross-cut sawing are:- Cutting speed 50-60 m/s.

- Carbide-tipped sawing blades.

- 350-400 mm blades, 54-96 teeth.

- Alternately or trapezoidally sharpened teeth. (See fig. 1-4)

BAND SAWING

This type of machining can be used on the lower densitieswithout problems. On higher densities (>200 kg/m3) the feedspeed must be considerably decreased. When sawing sand-wich panels, great emphasis must be put on trials. The machin-ing parameters are:

- Cutting speed 30-35 m/s.- Carbide tipped blades.

- 10-13 mm wide blades.

MACHINING

30


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30

Figure 2. Alternatelly sharpened blade, side view.

Figure 4. Trapezoidally sharpened blade, side view.

Figure 1. Alternatelly sharpened blade, rear view.

Figure 3. Trapezoidally sharpened blade, rear view.

40

15

MACHINING

CUTTING HORIZONTAL SAWING


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CUTTING

When cutting the speed must be 50 m/s and the blades have a

configuration as in figures 5 and 6. The feed speed is very highlydependent on what density to machine. A first try with 6 m/min ofspeed should give a good indication of how to proceed. Onhigher densities (>100 kg m3) use an initial feed rate of 2 m/min.

NOTE: Be sure to keep the blades well sharpened. The amountof material that can be machined off in one pass highly dependson the density, feed speed and the condition of the blades. A

starting value of 1 mm per cylinder and pass as a first try will givea good indication of what can be achieved.

HORIZONTAL SAWING

This type of sawing is done using a standard sawing blade and

the following main parameters:

20 mm wide blade.

- 3 teeth per inch.

- Standard setting (every other tooth) to 1.5 mm.

- Hook-shaped teeth. (See fig. 7)

- Carbide-tipped blades.- Cutting speed 45-50 m/s.

- Feed speed 0.5-2 m/min depending on density.

20

40

10positive

SANDING

When sanding, the resulting surface is different from one cuttedor horizontally sawed. The surface consists of deformed cellswith a distinct direction. This can be felt when passing ones handin different directions on the sheet.

Figure 7. Band-saw blade, top and side view.

Figure 6.

Cutter knife, side view.

Figure 5.

Cutter cylinder, side view.


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MACHINING

Quality H 45-200 HT & HCP To compensate for the springback of Divinycell, the mouldradius should be 5-10 % smaller than the final radius


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Temperature (C) +85 +100

The time from removal from the heating unit until the pressureis applied must not exceed 0.5 minutes to avoid the Divinycellcooling down.

DIMENSIONAL STABILITY

Divinycell will change its dimensions when heated in accord-ance with temperatures and times mentioned above. The fol-lowing typical figures as percentages of the original dimension

are valid

- Length/width = 3 %

- Thickness = -3 - 0 %

radius should be 5 10 % smaller than the final radius.

It should also be noted that the edges of thermoformed pieceshave a tendency to straighten out.

Care must also be taken to avoid springback during storage.Specially designed boxes or pallets may need to be used.

EFFECT ON PHYSICAL PROPERTIES

The Divinycell is affected in two ways during thermoforming

1) Decrease in density during heating.

2) Stretching of the outer radius.

Both will decrease the physical properties slightly. Typicaldecrease is 0-5 %. From design standpoint 10 % should beused.


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Head Office

DIAB AB

Box 201S-312 22 LAHOLM

Sweden

Tel +46 (0)430 163 00

Fax +46 (0)430 163 95

E-mail: [email protected] Web Site: http://www.diabgroup.com

SwedenTel +46 (0)430 163 00Fax +46 (0)430 163 95

E-mail:[email protected]

USATel +1 (972) 228-7600Fax +1 (972) 228-2667

E-mail:

[email protected]

Australia

Tel +61 (0)2 9620 9999Fax +61 (0)2 9620 9900


France

Tel +33 (0)2 38 93 80 20Fax +33 (0)2 38 93 80 29


Germany

Tel +49 (0)511 42 03 40

Fax +49 (0)511 42 03 438

E-mail:

[email protected]

Denmark

Tel +45 48 22 04 70Fax +45 48 24 40 01


NorwayTel +47 66 98 19 30Fax +47 66 84 64 14


United KingdomTel +44 (0)1452 50 18 60Fax +44 (0)1452 30 70 31

E-mail:

[email protected]

Italy

Tel +39 0119 42 20 56Fax +39 0119 47 35 53


Operating Companies

Divinycell is a registered trademark of DIAB AB.

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Divin i Cell