tpc lectures 02 - univerzitet u zenicipomacom.unze.ba/pdf/tpc/tpc_testing polymers_02.pdf · impact...

UNIVERZITET U ZENICI

Mašinski fakultet

Aleksandar KaračMFZE, room 1111Tel: 449 120, ext. 140Email: [email protected] TESTING PRODUCT CHARACTERISTICS

Testing polymeric materials and products

PART II:

TESTING PRODUCT CHARACTERISTICS

A. Karač 2/68


About polymeric materials and products

Thermosetting resins - liquefy when heated and solidify with continued heating; the polymer undergoes permanent cross-linking and retains its shape during subsequent cooling/heatingcycles.

Large organic molecule formed by combining many smaller molecules (monomers) in a regular pattern

Thermoplastic resins - when heated during processing, soften and flow as viscous liquids; when cooled, they solidify. The heating/cooling cycle can be repeated many times with little loss in properties.


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Major benefits:

- Low production and maintenance costs

- Low weight (=easy transport)

- Very good hydraulic characteristics

- Chemicaly resistant (=do not corrode)

- Relatively small modulus of elasticity (=flexibility) with high ductility (deformations up to 20% without loss of bearing capacity)

About polymeric materials and products


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Properties and Standard Methods of Measurements1)

1) Encyclopedia of Polymer Science and Technology


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NDT methods - classes1)


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Mechanical testing

Tensile tests (steady-state, high strain-rate, …)

Compression tests

Impact tests (impact resistance)

……..

……..


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Mechanical testing

Experiemntal set-up


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Mechanical testing

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0

Nom

inal

str

ess

Extension

(a)

(b)

(c) (d)

a)

b)

c)

d)

Engineering curve

Tensile tests2)

2)Hillmansen S., Large strain bulk deformation and brittle-tough transitions in polyethylene, PhD, 2001


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Mechanical testing

0

20

40

60

80

100

0 0.5 1 1.5 2

PE3PE4PE5PE6

Tru

e st

ress

(M

Pa)

True strain

Linear polyethylenes

Strain rate = 10-3s-1

24°C

0

5

10

15

20

25

30

35

0 0.1 0.2 0.3 0.4 0.5

PE3PE4PE5PE6

Tru

e st

ress

(M

Pa)

True strain



24°C

40

60

80

100

120

140

1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2

PE3PE4PE5PE6

Tru

e st

ress

(M

Pa)

True strain



24°C

True-stress-true strain curve

Tensile tests2)


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Mechanical testing

Temperature and stran-rate effects

0

2 0

4 0

6 0

8 0

100

0 0.5 1 1.5 2

Tru

e st

ress

(M

Pa)

True strain

MDPE = 24°C

HDPE (dashed line)MDPE (solid line)

HDPE = 36°C

HDPE = 75°CMDPE = 66°C

MDPE = 98°CHDPE = 96°C

0

20

40

60

80

100

0 0.4 0.8 1.2 1.6T

rue

stre

ss (

MP

a)True strain

HDPE Strain rate = 10-2s-1

3.2 x 10-3s-1

10-3s-1

3.2 x 10-4s-1

Tensile tests2)


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Roll-down process

(d)(c)

(b)(a)


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Compression Plates Specimen

Mechanical testing

(Uniaxial) compression tests3)

UC specimen at bore

UC specimen at outside diameter

0

10

20

30

40

50

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

PSC, PlaqueUC, 110UC, 250UC, 400

True

Stre

ss (M

Pa)

True Strain

3) Paizis A., Orientation and Strain Cycle Effects on the RCP Resistance of Polyethylene Resins, PhD, 2003


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Mechanical testing

Plain-strain compression tests3)

z

x

y

Plane strain compression rig employed by Williams

z

y

x

Base

Plunger

Direction of Compression

Direction of ExtrusionSpecimen Position

Experimental set-up of the channel die (plane strain) compression rig


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(a) (b)

Mechanical testing

Plain-strain compression tests3)


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Mechanical testing – high strain-rate tests4)Split – Hopkinson pressure bar at ICL

4) Maneeratana K.., Development of the finite volume method for non-linear structural applications, PhD, 2000


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Mechanical testing – high strain-rate tests (SHPB)4)


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Mechanical testing – high strain-rate tests (SHPB)4)


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Impact resistance1)

Impact resistance is a measure of the ability of a material, specimen, or structure to withstand a sudden load without failure.

Standard tests


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Impact resistance1)


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Izod-type pendulum impact machine, ASTM D256

ES = EI − ER − EF − EwImpact resistance1)


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Charpy-type pendulum impact machine, ASTM D256

Impact resistance1)


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Typical drop-weight testing machine

Impact resistance1)


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Three-point-bend testing2)

Conventional Charpy test( )

CUG aBD

wφ

=

5-10 mm

10-12mm

Razor notch

Specimen supports

Striker

0

0.5

1

1.5

2

0 0.002 0.004 0.006 0.008 0.01

Load

(kN

)

Displacement (m)


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Side-notched Charpy test

10-15 mm

10-12mm

Razor notch

Specimen supports

Striker

0

0.5

1

1.5

2

0 0.005 0.01 0.015

Load

(kN

)

Displacement (m)

a

c

b

d



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Inverted Charpy test

10-12mm

10-12mm

Deep razor notch

Specimen supports

Striker

0

5 0

100

150

200

250

300

350

0 0.001 0.002 0.003 0.004 0.005 0.006

Load

(N

)

Displacement (m)



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Concept of Essential Work of Fracture (EWF) method

W

l

h Ht

plastic zone

process zone

a) b) clamped zone tlwltwW pef2 β+=

lwwlt

Ww pe

ff β+=⎟⎟

⎠

⎞⎜⎜⎝

⎛=

Specimen Basic equations

Measuring fracture toughness for thin plastic sheets


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HM5411EA – test speed 1 mm/s


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HM5411EA –test speed mm/s

0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

Displacement, mm

For

ce, N Increase in ligament size

6.98.6

10.812.5 13.2

0

20

40

60

80

100

120

140

160

180

200

0 2 4 6 8 10 12 14 16

Ligament length, mm

Sp

eci

fic w

ork

of

fra

ctu

re,

kJ/m

2

DataLinear (Data)Data

Linear (Data)

Determination of fracture toughness


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Determination of Cohesive Zone parameters – maximum displacement method

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16

Ligament length, mm

Ma

xim

um

str

ess

, M

Pa

DataLinear (Data)

0

2

4

6

8

10

12

14

16

0 2 4 6 8 10 12 14 16

Ligament length, mm

Separa

tion d

ispla

cem

ent, m

m

Data

Linear (Data)

Data

Linear (Data)


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δ

F

increase inligament length

δ

σ

δc( l )δc(0)0

A’A

BB’

CC’

0 (0,0)A [δm(l), σm(l)]A’[δm(0), σm(0)]B [δx(l), σy( l )]B [δx(0), σy(0)]C [δc(l), 0]C’[δc(l), 0]

σm(0)

⎥⎦

⎤⎢⎣

⎡=⎥

⎦

⎤⎢⎣

⎡=

)()0()()0(

)()0()()0(

ll

ll

c

cxx

m

myy δ

δδδσσσσ




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0

5

10

15

20

25

30

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Displacement, mm

Str

ess,

MP

a

wf =20.35 kJ/m2




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Profile analysis of deformation zone

Width, mm

Gre

y va

lue

Width, mm

Gre

y va

lue

Width, mm

Gre

y va

lue

d i

d j

d k

minimum width = min (d i ), i – line index in a ROI


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HD5502XA – test speed 20 mm/s


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0

100

200

300

400

500

0 1 2 3 4 5 6 7 8 9 10

Displacement, mm

Forc

e, N

Increase in ligament size

0

20

40

60

80

100

120

140

160

0 2 4 6 8 10 12 14 16

Ligament length, mm

Speci

fic w

ork

of fr

act

ure

, kJ

/m2

DataLinear (Data)

Data

Linear (Data)5.2

7.28.9

10.9

13.1

HD5502XA – test speed 20 mm/s


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HD5411EA – test speed 1 m/s


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• From sixties intensive use of polymeric materials in pipe production (conveying gases and fluids) in Europe – PE and PVC

• Problems with potential catastrophic accidents

• Use of HDPE and MDPE materials – PE-63, PE-80, PE-100

Testing plastic pipes


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Technical programme (ISO): TC 138/SC 5ISO/DIS(CD) 1167 (1-4) Resistance to internal pressureISO/DIS 2505 Longitudinal reversion ISO/DIS 7686 Determination of opacity ISO/CD 11673.2 Determination of the fracture toughness properties ISO/CD 13477 Determination of resistance to rapid crack propagation ISO/CD 13478 Determination of resistance to rapid crack propagation (RCP)

- Full-scale test (FST)ISO/AWI 13968 Determination of ring flexibilityISO/DIS 17454, 17455, 17456 Multilayer pipe systems – various tests

Commonly used standardsISO 3126:1974, 3127:1994, 11173:1994, 4433:1997, 6259:1997, 7361:1991, 9854:1994, 1167:1996


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• High propagation speed with potential catastrophic consequences

• Type of tests (chronologically)

Full-scale (FT) test – ISO 13478 – British Gas

- Pipe length up to 20 m, 50 bar

- First 2 m cooled to -70ºC, the rest 0ºC

- Crack propagates more than 90%of length, pressure is above critical

- Extremely slow and expensive testing

Modified Robertson’s test – Belgium standard – 1981

S4 test – ISO 13477 – Imperial College London – 1987

- Possible parametric analysis due to low costs (temperature, pressure, material)

- Determination of critical pressure and temperature

Determination of resistance to RCP



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before during after

Full-scale testDetermination of resistance to RCP



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Small-scale steady-state (S4) testDetermination of resistance to RCP

Video: A. Paizis, A. Karac



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Pressure (bar)

Temperature (°C)

Crack ArrestCrack Propagation

Crack Arrest

PCS4

TBT

Determination of critical pressure and brittle-to-tough transition temperature


2

4

6

8

10

12

14

-15 -10 -5 0 5

Pre

ssur

e (b

ar)

Temperature (ºC)

TBT


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Testing plastic pipesOpenFOAM simulation


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Testing plastic pipesOpenFOAM simulation


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Testing plastic bottles

ASTM D2463-95

“Provides measures of the drop impact resistance of blow-moulded thermoplastic containers as a summation of the effects of material, manufacturing conditions, container design, and perhaps other factors.”

r v

v =0

r v 1

?p =p0

H

a) b) c)


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a) b)

c) d)


Standard tests

H

container

platform

hard surface

• Static drop height method• Bruceton staircase (up-and-down) method


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Standard tests


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Modified standard tests

H

to image analyser

quick-release mechanism

bottle

high-speed camera

to charge amplifier


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non-failure failure


RT6 container


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a) b) c) d)

e) f) g) h)

v =0, p =pmax

t = 0 0< t<L/c t = L/c

L/c< t<2L/c t = 2L/c 2L/c< t<3L/c

p =p0

H

L

v =0

p =p0

v =0, p

v =0 p =pmax

v =0, p =pmax

c

v v

v1

v v

c

c



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SR1 container


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RT6 container


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SR1

RT6

Fractures containers


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Experimental set-up

KistlKistlKistl

Nicolete 500

Oscilloscope SG amplifiers PT amplifiers Drop rig

U-profile guide

PC - WinNicolete

Instrumented rig

Quick-release mechanism


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Strain gauges

Pressure transducers

PT3

PT1

PT2

Upper cap

Water-filled bottle

Lower cap

Jubilee clip

PT holder

Tie bars Rubber O-ring

Rubber cushion

SG1 SG2

SG1

SG2 PT3

Instrumented rig


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All sensors Pressure transducer histories

0 2 4 6 8 10 12 14Time, ms

−4

−2

0

2

4

6

8

10

Pre

ssur

e, b

ar

Pressure transducer 1Pressure transducer 2Strain gauge 1Strain gauge 2

0 2 4 6 8 10 12 14Time, ms

−20

−10

0

10

20

30

Pre

ssur

e, b

ar

recorded historysmoothed history


Pressure histories


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0 2 4 6 8 10 12 14Time, ms

−2

−1

0

1

2

3

4

Pre

ssur

e, b

ar

SG2SG1

0 2 4 6 8 10 12 14Time, ms

−2

0

2

4

6

Pre

ssur

e, b

ar

SG1SG2

Strain histories

Bottle without bottom-end Bottle with original bottom-end


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Numerical procedures

Fluid domain

Analysis method I

Interface program

Solid domain

Analysis method II

a)

Fluid

domain

Analysis method

Solid domain

b)

Fluid

Analysis method Solid

domain

+

c)

Strongly coupled – interactingSolids relatively flexible: plastic pipelines,containers, tanks/reservoir sloshing, airbags, cardiovascular flows

Fully coupled – coupledSolid-fluid phase transformations: material processing/forming (moulding, casting, extrusion, welding, …)

Two-system approach: One-system approach:


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Two-system approach:

START OF TIME STEP

END OF TIME STEP(implicit scheme only)

1. Solve fluid domain (or 3.)

3. Solve structure domain (or 1.)

2. Pass infromation from the fluid to solid domain (or 4.)

4. Pass infromation from the solid to fluid domain (or 2.)

Fluid domain

Analysis method

Solid domain


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Strain gauges

Pressure transducers

PT3

PT1

PT2

Upper cap

Water-filled bottle

Lower cap

Jubilee clip

PT holder

Tie bars Rubber O-ring

Rubber cushion

SG1 SG2

SG1

SG2 PT3


Numerical ‘set-up’

Solid domain

Impact end ( V=0, U=0) Fluid domain

Free surface (p=const=1bar)

50 cells

20 cells 3 cells

Flat base

Curved base

Simple geometry


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OpenFOAM simulation – simple geometry


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OpenFOAM simulation – base shape effect


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Some quantitative results

0 1 2 3 4 5Time, ms

-8

-6

-4

-2

0

2

4

6

8P

ress

ure,

bar

experimentFV, two-systemFV, one-system


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Some quantitative results

0 1 2 3 4 5Time, ms

-4

-3

-2

-1

0

1

2

3

4

5

6

Pre

ssur

e, b

ar

experimentFV, two-systemFV, one-system

0 1 2 3 4 5Time, ms

-5

0

5

10

Pre

ssur

e, b

arexperimentFV, two-systemFV, one-system


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Simulations with fracture – numerical domains

Free surface (fixed pressure and zero velocity gradient) Symmetry plane Interface – fluid Crack interface – fluid

Cohesive zone model

Symmetry plane

Interface – solid

Outside – traction free

Crack interface – solid

Base – direction mixed


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Simulations with fracture – OpenFOAM simulation


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Simulations with fracture – OpenFOAM simulation

0 1 2 3 4 5Time, ms

0

2

4

6

8

10

Pre

ssur

e, b

ar

constant thicknessvariable thickness

0 1 2 3 4 5 6 7 8Time, ms

0

2

4

6

8

Pre

ssur

e, b

ar

no CZM appliedCZM applied

Pressure histories

UNIVERZITET U ZENICI

Mašinski fakultet

Aleksandar KaračMFZE, room 1111Tel: 449 120, ext. 140Email: [email protected] TESTING PRODUCT CHARACTERISTICS

PART III:

Testing adhesives and adhesively bonded joints

tpc lectures 02 - univerzitet u zenicipomacom.unze.ba/pdf/tpc/tpc_testing polymers_02.pdf · impact...

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