Determination of Fracture Toughness of small ceramic discs and plate using the ball on three balls test.

Programme

3 !

E

E

t

'E

tt

:t

eE g$ F FI rg {

H

ii

It

Ei

5i

lr

€ }F

ii

6 :

t!^!{E

is:+i

iit

_F!

!"ii

!E:tld

iii$i

uili

;iaf!

il

ir

'i

5Flit

,r

'*

ttH!

ir

'Fifl

+i*;

iig

I

i€$i;

{+{i

;I:P

EIFi

t;:i

rgi

.trtr-rt!

i,li;

5Ct{t!

ii*{i

t

t!:

'ii$18

TiES

'ftriii

l'

€-sEgtEFiF

F$iii:

r

titf,:

E

liilt{

r,€

ii!

iii

t

EI!19

fB t

cll

$

algi:t

{uE

f

! I

iFr

r{riE

F'it

[$t

!

f'EEiiF

I

:il

\

:tF

$i:

E

E?!

it*r

.

tgttl

$siii

'r

tia{

!rt

E

FE+f

it5:!e

'!

!iiE

'iEi

i.;

i

itattF

!IE 1F

t!ttE

FF

ir!

1-riF

t-iF{r;tr

ii[EF

3 F6i E

5

F!i

*i

istF!

Eqtti

e

"F"

ir;l:

F

;t!{R

!1iii.

ntili

a

!t4t5;

t:iiF

"eEit

!::

;

taf

ii5

lFg

r$tiE

Fiit

ECoS 2015 -r4dr ieodoGl co6r.ic Fr.@

cdic

sci.lyl ..

ltDttuw&arrlt@$1ffi

ieJctdk

lrcal

Organising

Committee

le&*&NeeA4.lfu*%Frc

Intemational Advisory Board

tud.@ddrerdttuee

Deternination of fracture totrghngs ofsmall cenmic discs aDd platB Dsitrg the ball-on-tbree-bslls tesa

Tdia Luber. Stefe R4chc1, TjototdacdeTirlaNindhia:, Srefd SFoblr

\n$itut ffir Shkrur lnd FunklionskeEnik. Monbuiversibel

k

bh, ler.Tunne.Sftn 5.

3700 L€6b€n,

Aufir

Depdnen orVRhdE. tn8leen _& I dr)aM I r.teriry.l'nbrm. Ba i. lndone.is Mr'e'ialsce re' Leoben l-o$lungCmbH, Ro*scebrmle l2,3 00 kokn,Ausma Ketryods: ball{n-three-bails l€s! Facturc toueiDes, ninjatuied d@h ical testirs.

Abstmcl: Fmcnn€ bDghr6s

m*wnals

on cemic

conpo!{ts

d mt€rials

e

sudly lqfomed on alatively ldge, b&-shap€d specinem (3 r 4

:

45 _nm"l), whicb de

ofi€n mEh bissq the conlonents or the

eomi

ol naterial that is available fron lab scale

prcesing uits, Suitdble sDecinens thu have to be nelfactued spdtely md oflen with

a diff@nt prcc*sing route.Then nicrosb@tft dd theEfoe th€n mechdical b€havior cm

vrry lor tnis reaon. A new nactre ntruelness tesl h pEsenled. w[ich @ be applied to din

di$ or plateihaped sp€cinetr (0.5

m

thickrcs). lt is

bsd

on the ballon-lnree-balls (B3B) test, which is a bidial srrengd t$l n€ihod Rll-suited fof lhe stength

nedwnot

of llin circule discs o! r€cllngdd plates. If the sp€cinec

e

pepd€d *ith a o@k of well

denned _{e€onetry, the B3B} test

@

be used for n&hre tougnness hebu€nenls too. In

dalog/ b tne surfm cmck in flexue (SCF) detho4 atificial semi€lliptical surfrc€ cEks

e

inaoduced irlo the enler oflhe discs with a (n@p in.lenter ddre plalicolly dofomed zone is rnoved by edndine or polishirg. Tnen the sp4ines @ loaded bidiallyin the B3B

t€st jie. The cnck is opeftd in node I duing loading.

Ai6

$e tes! the @ck sizes

re

n*uEd

on the

6etw

surfac6. The evalution of stes inlensiry f&tos is basd on finile elmenl cahdatioN.lir sol$ioG for the Fet@ sEess ed tle _seon€tric frclor calcdat€d

fo! pnctic.lly elevel mges of spdmem ed crok dimeNios

e

provided loeelbo silh

M0ilTAl{

ul{vtnstrAl

Determination

of

fracture toughness

of

small

ceramic

discs

and plates

using

the

ball-on-three-balls

test

Tanja Lubel, Stefan Raschel, Tjokorda Gde

llrta

Nindhiar,

Stefan Strobll,

qnsdtlt _{for s!!kb)r und Fuktlonslcdmib Mont nunisldt Lebe., Arstda}

,DeparFmnt of Medrail€l Engln4dng, udat"M unlwEity, lhb€En, Ball, hdoaia

:t'4at!ials cent€r Lshen FlRhurc GmbH, L6ben, aLskl:

ECERS XN, 2l _- 25, June 2015, Toledo

Motivation

stnndard KFspecimen

available material & components

Material properties depend

on

consolidation and

sintering conditions

WfiNTED

test

method

for

fracturc

toughness

applicable

to

small

material

pieces

++

+

+

ball-on-three-balls

test

B3B test

Principle

Knoop

zone: grind off

/-\

K,.="","

yl:,i,;,,)ra

--xtp"F#

Goals

support R"

-(t

R-

\

F

=,Ia,i,,

)e

(1)

Fit-formulae

for

geometric

function

f

easy

evaluation

of

the

tests

further

calculations

possible

(sub-critical

crack

groMh,

btigue,

...)

(2)

Error

analysis

.

errors

from

B3B

test

('

1olo,

Poisson's

ratio!!!)

.

errors

from

cmck

position

.

errors

from

crack shape

determination

(3)

Experimental

validation

Parametric

FEM

full

3D

FEM

model

simulations

disc

&

f

support radius

&

I

dE

AE

EE

tl

0.4

0.5

0.05

0.10

0,1

0.2

0.1

0.2

0.6

0.7

0.15

0.2 0,3

0.3

0.4

0.8

Db

D= 2R

13.8s6mm

20mm

8mm

200GPa

6,

F...

-(r R \

F

f

l

.e .v

-\R'R' )

T

result of FEl4 simulation

a

c*

K,

along

the

crack

front

cc,

4

t=

0.15 and 4R.= 0.2

c

non-symmetric

poisition of maximum depends

on

--

crack shape

-

Poisson's ratio

Ya=

Y(a=0o)

rc=maxr(85"<p<90')

,']=

"....Gi

K\

response

s

urface

Fit-formulae

for

model

Y

inear terms interaction terms quadratic terms

3.s6 .

10j

-0.013779

0.0t6227

0.005191 s.96 . 105

-0.0074s0

0.007435

0.002684

Error

analysis

-

position

-\

out

of

/al (a\ (t\

r. + c'

l;

l-',

[i

J-

c.l&

J

+'.

'+

..

t:

lt:

I

.,t:l(+).

"f

:1..

"

t

:l[;l..

|

:)..

*[i

J

tat'

lat'

lt\

6',1;

I

+

c'

ttJ +."[4J

--rllSFK

errors

in plane shift,

\ _^.

plane _{shift, Arl}

t

alh.

,"

,.,.

K

rotation, ct

Experimental validation

-.I

ffiMHIH

,..

0.545

'"'

+ o.oo3

H

@

E

0.23

85 + 7 110:! 5

7.5

9_5 ₊ 1.802

0.012

o.zt

7a

!

1

140+1

5

3,5 + 0.2

(sEvNB)

5.1+ 0.2

(scD

5.0 + 0.2

(SEVNB)

ft-

Experimental validation

-

position

.rrorc

-\

5,5

5,0

3,5 3,0

x-Ofbet = 750pm

(-

3c

-

o,2

Ra)

fracture does NOT

sta.t

at indentation crack

no influence of rctation

3.5 + 0.1

5.0 + 0.3

s. shbr 4 ar,

r6e

ra42 (2014)

a

FE

Summary

M

simulations

-

fit

formulae for geometry function at two positions

Error analysis

-

Poisson's ratio is important

-

shift away from the central point causes signmcant

eror

-

rotation causes no significant

effor

-

crdck

which are clitical at A are less affected by errors

-

suiirable for smallsp€cimens:

a

D"B

mm,

t"o.5mm:

error +10o/o, larger specimens: similar

to

standard /ar. m

Experimental

validation

excellent agreement of B3B-KC wi bends of error analysis validated applicable to discs and plates