Fem-test - Departamento de Engenharia Civil · Title: Microsoft PowerPoint - Fem-test.ppt Author: Jorge Created Date: 11/15/2007 10:13:52 PM

November 15, 2007 1

Can we perform tests on materials ?!

M. ‘Rien’ Huurman

November 15, 2007 2

1. Introduction2. Load, Geometry and Material

Examples3. ITT4. DTT5. DSR-mortar6. 4PB

7. Conclusions

INTRODUCTION

November 15, 2007 3

• Simple straight forward > general idea

• Interrupt at any moment

• General effort to get more information from lab. testing

INTRODUCTION

November 15, 2007 4

LOAD, GEOMETRY & MATERIAL

This is a top view of a table.

What is the force in each leg?

This is not a joke!

November 15, 2007 5


This is the 20 cm x 20 cm load area. The load is 100 kg.

November 15, 2007 6


There are 4 legs.

November 15, 2007 7


Indication of thedeformations and the stress within the material.

November 15, 2007 8


The materials!

Steel

Rubber

November 15, 2007 9


LOAD

GEOMETRY (structure)

MATERIAL

November 15, 2007 10


Basically we measure Force and Displacement.

We want to know σ & ε.



F = S x U

σ = E x ε

AF=σ dL

du=ε

Measurement

Transfer function

Material

Strain gauge



Are our transfer functions correct?

Can FEM help?

(Load!, Geometry!, Material?)


EXAMPLES, ITT


EXAMPLES, ITT

0

300

600

900

1200

1500

1800

0 2 4 6 8 10 12 14 16 18Time [s]

Forc

e [N

]

-80

-60

-40

-20

0

20

40

Stra

in [ μ

m/m

]Horizontal strain

Vertical strain

Force


EXAMPLES, ITT

Overview of the full model

Detail showing the InterFace between loading strip and specimen

Overview of the model when making use of symmetry


-9%

-6%

-3%

0%

1456

4241696

Number of elements (full / sym) [-]

Erro

r [-]

784 3136

12164864

16326528

326413056

Horizontal deformation of specimen

Vertical deformation of specimen

EXAMPLES, ITT

-0.9 MPa

0.0 MPa

0.13 MPa


EXAMPLES, ITT

ddrcbdra

+⋅+⋅

=ν with hor

vert

defdef

dr = (1)

( )wdef

FfeEhor ⋅

⋅+⋅=

ν (2)

Where: F: applied vertical force [N] w: width of the specimen [mm] defhor: horizontal deformation [*] defvert: vertical deformation [*] dr: deformation ratio [-] a, b, c, d: parameters [-] e, f: parameters [**] Remark: * strain [-] in case of strain gauges or [mm] in case of LVDTs ** [mm-1] in case of strain gauges or [-] in case of LVDTs


EXAMPLES, ITT

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1Normalised input (-)

Nor

m. e

xpla

ined

val

ue (-

)

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1Normalised input (-)

Nor

m. e

xpla

ined

val

ue (-

)

explained material response v.s. real

material response

E

Pois

Strain gauges LVDTs


EXAMPLES, ITTBy use of TF we can determine VE material behaviour….

150 mm ITT; pulse width: 2 s; temp: 350C

0

20

40

60

80

100

120

140

160

180

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

time [s]

forc

e [N

]

-300

-250

-200

-150

-100

-50

0

50

100

150

stra

in [m

icro

-str

ain]measurement: green,

Burgers’ model fit: red

verticaldeformation

horizontaldeformation

registered force


EXAMPLES, ITTBy going back to FE-model we can check procedure….

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12time [s]

forc

e [N

]

-120

-90

-60

-30

0

30

60

90

stra

in [m

icro

-stra

in]

force

horizontal strain

vertical strain


EXAMPLES, ITTAnd visualise what goes on in the test.

Stress

CAPA-3D


EXAMPLES, DTT

The lab test.


EXAMPLES, DTT

FE modelling.

steel pin

end cap

end cap

steel pin

mortar

interface simulating contact between pin

and end cap

Frictionless contact between pin and

end cap

CAPA-3D ABAQUS


EXAMPLES, DTT

FE modelling & model fit.

CAPA-3D ABAQUS

-0.7 0 0.45


EXAMPLES, DTT

ABAQUS


EXAMPLES, DSR-mortar



CAPA-3D



CAPA-3D




EXAMPLES, 4PB 4 years ago



CAPA-3D

FE modelling.


Strain in longitudinal

direction



Strain in longitudinal

direction



Damage



Damage




-80

-60

-40

-20

0

20

40

60

80

-0.06 -0.03 0 0.03 0.06

verplaatsing [mm]

krac

ht [N

]

-40

-30

-20

-10

0

10

20

30

40

-0.12 -0.08 -0.04 0 0.04 0.08 0.12

verplaatsing [mm]kr

acht

[N]

4pnt 44 x 44 2pnt 70 x 25




•EXAMPLES, 4PB

Disbelieve.We want simple things.What does it bring?It is not exact……….

We don’t want things we do not understand!


EXAMPLES, 4PB

Ad and I shaked hands and are now driving each other crazy.

Busy proving the accuracy of FE modeling via AA verification.

Force feeding?????


EXAMPLES, 4PBaverageel seize

elements over length

elements over height F D (±0.5 H) D (0) D (↓0.5 H) ε (±0.5 H)

[mm] [N] [mm] [mm] [mm] [µm/m]1D, G=9e9 MPa 16 28 n.a. 155.88 n.a. 0.11423 n.a. 168.391D, G=9e9 MPa 8 56 n.a. 155.88 n.a. 0.11423 n.a. 168.391D, G=9e9 MPa 4 113 n.a. 155.88 n.a. 0.11423 n.a. 168.341D, G=9e9 MPa 3 149 n.a. 155.88 n.a. 0.11423 n.a. 168.391D, G=1111.1 MPa 16 28 n.a. 149.23 n.a. 0.11362 n.a. 161.161D, G=1111.1 MPa 8 56 n.a. 149.23 n.a. 0.11362 n.a. 161.161D, G=1111.1 MPa 4 113 n.a. 149.23 n.a. 0.11362 n.a. 161.181D, G=1111.1 MPa 3 149 n.a. 149.23 n.a. 0.11362 n.a. 161.212D, 1-point load 16 28 4 148.00 0.11258 0.11328 0.11258 159.842D, 1-point load 8 56 6 147.81 0.11250 0.11319 0.11250 159.632D, 1-point load 4 113 12 147.52 0.11237 0.11307 0.112374 159.322D, 1-point load 3 149 16 147.40 0.11233 0.113021 0.112325 159.192D, 2-point load 16 28 4 149.83 0.11336 0.11406 0.11336 161.792D, 2-point load 8 56 6 149.61 0.11326 0.11396 0.11326 161.582D, 2-point load 4 113 12 149.28 0.11312 0.11382 0.113117 161.222D, 2-point load 3 149 16 149.14 0.11306 0.11377 0.113061 161.083D, 2-line load 16 28 4 150.15 0.11318 0.11389 0.11318 162.133D, 2-line load 8 56 6 149.92 0.11309 0.11380 0.11309 161.903D, 2-line load 6 76 8 149.78 0.11303 0.11374 0.11304 161.75

Static elastic


EXAMPLES, 4PBDynamic elastic

∆t / cycle ∆t

[-] [s]Ampl[N]

Phase[Degr.]

Ampl[mm]

Phase[Degr.]

Ampl[µm/m]

Phase[Degr.]

1D, G=9e9 MPa 10 0.01 154.95 0.00 0.1141 0.00 168.1 0.001D, G=9e9 MPa 20 0.005 154.99 -0.01 0.1141 0.00 168.1 0.001D, G=9e9 MPa 40 0.0025 154.99 -0.01 0.1141 0.00 168.1 0.001D, G=1111.1 MPa 10 0.01 148.32 0.00 0.1134 0.00 161.0 0.001D, G=1111.1 MPa 20 0.005 148.35 0.00 0.1134 0.00 161.0 0.001D, G=1111.1 MPa 40 0.0025 148.36 0.00 0.1134 0.00 161.0 0.002D, 1-point load 10 0.01 146.92 0.00 0.1123 0.00 159.4 0.002D, 1-point load 20 0.005 146.95 0.00 0.1123 0.00 159.4 0.002D, 1-point load 40 0.0025 146.96 0.00 0.1123 0.00 159.4 0.002D, 2-point load 10 0.01 148.71 0.00 0.1131 0.00 161.4 0.002D, 2-point load 20 0.005 148.74 0.00 0.1131 0.00 161.4 0.002D, 2-point load 40 0.0025 148.75 0.00 0.1131 0.00 161.4 0.003D, 2-line load 10 0.01 148.98 0.06 0.1131 0.00 161.7 0.003D, 2-line load 20 0.005 148.87 0.03 0.1131 0.00 161.7 0.003D, 2-line load 40 0.0025 148.88 0.02 0.1131 0.00 161.7 0.00

Total force U middle Eps middle


EXAMPLES, 4PBDynamic visco-elastic

∆t / cycle ∆t

[-] [s]Ampl[N]

Phase[Degr.]

Ampl[mm]

Phase[Degr.]

Ampl[µm/m]

Phase[Degr.]

2D, 1-point load 10 0.01 147.48 28.92 0.1123 0.00 159.42 0.002D, 1-point load 20 0.005 147.16 29.82 0.1123 0.00 159.42 0.002D, 1-point load 40 0.0025 147.08 30.05 0.1123 0.00 159.42 0.002D, 2-point load 10 0.01 149.27 28.92 0.1131 0.00 161.36 0.002D, 2-point load 20 0.005 148.95 29.82 0.1131 0.00 161.36 0.002D, 2-point load 40 0.0025 148.87 30.05 0.1131 0.00 161.36 0.003D, 2-line load 10 0.01 149.50 29.01 0.1131 0.00 161.68 0.003D, 2-line load 20 0.005 149.15 29.88 0.1131 0.00 161.68 0.003D, 2-line load 40 0.0025 149.04 30.10 0.1131 0.00 161.68 0.00

Total force U middle Eps middle


EXAMPLES, 4PB1D static elastic ≈ AA

ABAQUS


EXAMPLES, 4PB2D static elastic ⇒ AA

ABAQUS



ABAQUS

Why different behaviour at different clamps?



Bending > longitudinal stress.

Material >contract/expand perpendicularly.

Clamp blocks this >Extra system

stiffness


EXAMPLES, 4PB1D dynamic elastic


EXAMPLES, 4PB2D dynamic visco-elastic






EXAMPLES, 4PB

FE ⇒ AA ≠ FE ⇒ real physical test:

•Pulling via clamp•The clamps have no width•There is no clamping force•There is no clamp-beam interaction•…….

FE ⇒ real physical test………


EXAMPLES, 4PB


EXAMPLES, 4PB


EXAMPLES, 4PB

Clamping force

0100200300400500600700800900

1000

0 0.4 0.8 1.2 1.6Time [s]

Forc

e [N

]


EXAMPLES, 4PBClamping moment

-100-80-60-40-20

0204060

0 0.4 0.8 1.2 1.6

Time [s]

Mom

ent [

N.m

m]


EXAMPLES, 4PB


EXAMPLES, 4PB


EXAMPLES, 4PB


CONCLUSIONS

FEM

Test:

GeometryLoadMaterial

Structure:

GeometryLoadMaterial

4PB is basically just an other case.

Pavement design.

What it can do for you depends on your mindset.

Documents

Fem-test - Departamento de Engenharia Civil · Title: Microsoft PowerPoint - Fem-test.ppt Author: Jorge Created Date: 11/15/2007 10:13:52 PM