room temperature flexure fixture for adv ceramics

7/24/2019 Room Temperature Flexure Fixture for Adv Ceramics

1/22

Room Temperature Flexure

Fixture for dvanced

Ceramics

ST R

8

George

D

Quinn

U S DEP RTMENT OF COMMERCE

Technology Administration

National Institute of Standards

and Technology

ceramics Division

Gaithersburg MD

2 899

August

992

U S DEPARTMENT OF COMMERCE

Barbara Hackman Franklin secretary

TE HNOLOGY DMINISTR TION

Robert M White Under Secretary for Technology

NATIONAL INSTITUTE OF STANDARDS

AND TECHNOLOGY

John W Lyons Director


2/22


3/22

ROOM TEMPER TURE FLEXURE FIXTURE FOR DV N ED CER MICS

George Quinn

Ceramics Division

BSTR CT

A t e s t f i x t u r e for the measurement

of the

f lexure

strength

of

advanced

ceramic specimens

i s presented.

The f ixture meets the

requirements

of

several American and

in ternat ional

standards.

INTRODUCTION

This

report

presents a four-point f l e x u r e f ixture t h a t i s

in

accordance

with

the

requirements

of u.s. Army MIL ST 1942 [1]

and

STM C 1161

[2] . These

standards prescribe

specif ic specimen and

f i x t u r e

s i z e s

tolerances, and

alignment

requirements.

The

standards

specify

t h a t

the

f ixture

must have

s u f f i c i e n t

a r t i c u l a t i o n t o

ensure

even

l ine- loading onto the

specimen surface

and equal loading a t

the

fo ur loading

pins. Machined

specimens

wil l usually meet

t h ~ p r l l l i s m

specif icat ions and therefore

may

be t e s t e d

with

a simple

semi-art iculat ing

f i x t u r e . A fUlly

a r t i c u l a t i n g f i x t u r e i s no t necessa ry . As-fired specimens can even

be used

with

the f i x t u r e i n some instances [3].

Many f i x t u r e

designs have emphasized

unnecessarily the need t o

have

f u l l a r t i c u l a t i o n .

This

i s usually done

a t

the cost of having

f ixed-load bearing

pins, o r

simple s l o t s

i n t o which

the

load pins

r e s t . The l a t t e r are

not

re l iable fo r ensuring t h a t

load

pins

w i l l r o l l sin ce th e r o l l e r s may r e s t against e i t h e r shoulder

of

the

s l o t .

Both

schemes

can cause

f r i c t i o n a l

constraints

as the

specimen

i s loaded and w i l l cause s i g n i f i c a n t experimental error

[ 4 5 ] .

C 1161 and

MIL ST 1942

show several general schematics of possible

f ixture designs. A v a r i e t y

of

design

wil l meet the requirments of

th e s ta nd ar ds .

This repor t

shows

one successful design for the

three-

and four-point

B sizes specif ied i n

the standards.

The

f i x t u r e has been shown previously i n Reference [3] which summarized

r e s u l t s of a successful

four

nation

round-robin

exercise.

The

f i x t u r e

i s

designed

so

t h a t

can be s e t up

and aligned

easi ly

and

quickly -30

minutes).

The alignment

system i s quite

simple

and

r e l i e s upon

the

use

of

a

single

6.35

1/4 inch)

locating

hole

or

pin

i n

each p a r t .

n

a l t e r n a t e diameter

could also

be

used

provided

t h a t a l l p a r t s a re adju sted accord ingly .) This will

ensure t h a t the f i x t u r e s

are a li gned proper ly from l e f t

to r i g h t

and

from

f ront

to back. The s e t up procedure i s given in Appendix

A

The

f i x t u r e

shown i n t h i s

report

i s intended for use

with

f l a t

and

p a r a l l e l

specimens. I f

specimens are twisted or warped,

then

a


4/22

Figure

The

f ou r po in t f le xu re f ix ture

with

an alumina specimen

place

4-PT FLEXURE FIXTURE

CONFIGURATION B

FOR 4 5 mm

R ll RS

~ SeeNotes

1 2 . 2 5 ~ 1 2 . 2 5 ~

- - - S - = P ~ E = C I - E N - B - - - - .

1 . . - 1 7 . 7 5 ~ 1 - 1 7 . 7 5 ~

LL

D PTE

PL TE

LO DING

PL TFORM

UPPE

BEARING

PL TE

LOWER BEARING

PL TE

UPPER

D PTER

PL TE

Figure

2

n assembly drawing fo r the

f ix ture

All dimensions

rom


5/22

fUlly-ar t iculat ing f ix ture i s necessary. References [6]

and

[7]

give designs for fu l ly -a r t icu la t ing

f ixtures which also

have

rol l ing-loading

pins .

L XUR IXTUR

Figures 1 and 2 i l lus t ra te the f ixture with a specimen in place.

The f ix ture i s for

s ize

B specimens 3 x

4

x 45-50

rom

tha t are

f l a t

and

para l le l

within t he sp ec if ic at ion of

ASTM

C 1161 and MIL

STD 1942. The adaptor p la te s w ill vary with the te s t ing machine.

One not shown below)

i s

needed to attach the upper bearing plate

to the crosshead.

Another

i s

needed

to

attach the

lower

bearing

pla te

to the load

ce l l

or

a

platform attached to the load ce l l

such as shown l a te r .

The following parts are i l lus t ra ted as Figures

3-6 :

a.

Upper bearing pla te

b.

Lower

bearing

pla te

c . Ball adaptor pla te

d.

Three-point adap to r

The f i r s t two should

be

made of a s tee l tha t suff ic ient ly hard

to re s i s t

plas t ic

deformation a t

the

ba l l sea t and

th e poin ts

where

the

loading

ro l lers contact them. A

Rockwell

C

R

c

hardness of

30

or

higher

i s required and wil l permit te s t ing f lexural specimens

with strengths up

to

3000 MPa. Maraging 18-250

or

18-300 steels*

are qui te good

since they have th i s

hardness in

the annealed

s ta te

and wil l not

require a

heat

treatment) ,

are

quite

machinable,

and

are

oxidation

res i s tant . An al

t e rna t i

ve wrought s ta inless

s tee l

grades

17-4

PH AISI

630),

PH

13-8 Mo,

or

15-5 PH .

These

have

R

c

=

30-32

in

the solut ion

t rea ted

s t a t e .

The

Maraging

or

wrought

s ta inless

s tee ls can be obtained from a tool s tee l

supplier .

Note t ha t most common s ta in less s tee ls are re la t ively

sof t

and are not

s at is fa ct or y t o

sustain

the concent ra ted Hertz ian

con ta ct lo ad s.

The

three-point adaptor and

the bal l

adaptor

plate can

be

made of

any grade s t ee l with R

c

12

since Hertzian

s t resses

are

smaller in

these par ts . Common s ta in le ss s te e ls

such

as a

316 grade)

are

adequate.

The bal l adaptor pla te

i s

designed to

e i

ther attach

direc t ly to the

load

ce l l

or

to a

platform

which i s

attached to

the

load ce l l . On one side has a 6.35

1/4 inch)

hole for

alignment and

centering

purposes.

On the

other

side

has

a

countersink

to

hold

and

center

the

bal l .

The

countersink

and

the

centering hole

must

be

well

aligned with respect

to each

other .

VASCOMAX Stee l . co . An 18 n icke l

s t ee l .

The second

number

re fe r s to

th e y ie ld

s t r e ss in

ks i . The i d en t i f i c a t i on

o f mater ia l s

in t h i s r epor t

does no t

imply

an endorsement by th e

Nat ional I ns t i t u t e of

Standards

and

Technology

ARMCO Stee l .


6/22

L

O

W

E

B

N

P

A

S

Z

B

R

F

O

4

5

m

P

N

~

N

1

;

I

-

I

I

I

I

/

I

I

\

I

I

f

I

I

\

_

I

I

\

~

I

I

I

I

I

I

I

I

'

_

_

I

I

I

I

I

I

1

1

C

e

s

n

3

0

u

s

d

A

p

o

h

e

p

t

o

2

4

I

s

m

e

I

I

3

1

3

1

I

1

7

1

7

M

\

=

1

L

1

G

R

U

1

t

U

T

O

.

2

3

1

1

1

1

1

~

3

1

[

A

1

1

u

r

m

*

D

M

O

0

U

E

O

H

W

I

S

N

F

g

e

3

L

w

b

n

p

a

e

A

l

d

m

e

o

i

n

r

o

m


7/22

6

D

A

4

7

D

.

6

3

T

H

H

E

I

1

1

C

B

O

7

1

D

E

E

P

2

H

E

I

-

(

+

)

j

i

L

1

-

-

1

-

,

0

I

-

U

B

N

P

A

S

Z

B

R

3

F

O

4

5

m

P

N

I

1

L

1

2

~

i

I

1

1

2

1

0

,

I

2

4

I

I

0

1

4

I

I

I

I

N

S

O

E

R

A

I

U

S

I

I

I

G

U

P

O

.

1

i

t

U

P

T

O

2

I

I

I

h

r

I

I

T

I

i

I

I

I

I

I

~

I

Z

Q

T

I

I

'

,

I

3

9

1

0

0

1

1

I

3

9

1

0

*

A

D

M

O

0

U

E

O

H

W

I

S

N

g

e

4

U

p

b

n

p

a

e

d

m

e

o

i

n

r

o

m


8/22

T

H

H

E

A

U

T

O

M

T

H

P

A

O

A

A

O

O

T

H

L

O

C

7

8

1

D

A

7

1

D

A

D

1

1

.

1

1

C

B

O

7

1

5

D

4

H

E

E

U

L

Y

6

.

3

5

:

8

8

C

B

O

4

0

5

D

N

C

B

O

@

A

1

C

N

C

R

C

W

I

T

H

N

.

0

1

6

4

0

1

C

e

s

n

4

7

d

A

p

o

h

e

o

4

0

I

s

p

m

e

.

I

-

_

-

,

0

0

1

q

_

,

I

7

,

-

,

I

-

I

:

A

D

M

O

1

U

E

O

H

W

I

S

N

F

g

e

5

B

a

a

o

p

l

t

e

T

s

i

s

a

e

m

p

e

O

t

h

a

o

d

g

a

e

p

b

e

d

n

u

t

h

t

e

s

t

s

y

e

m

.

T

k

f

e

u

e

i

s

t

h

a

g

m

e

h

e

a

p

n

m

u

b

w

e

c

e

e

w

i

h

r

e

p

t

o

t

h

c

e

n

T

m

o

n

b

h

e

s

h

d

h

a

m

p

e

c

e

a

t

o

p

m

i

p

o

a

u

m

e

s

A

l

d

m

e

o

i

n

r

o

m


9/22

Three

Point

daptor

Size B

2 4 4 6 ~ : g ~ l i ~ ~ 1

12 23 2

coy

R

Figure Thr ee p oin t a da pto r

which

i s in se rted in to th e

upper

bear ing

p l a t e

l l dimensions

in


10/22

I t

i s

important

tha t the adaptor plates

have

suff ic ient play so

t ha t the i r

posi t ion

can be adjusted. Their mounting

holes

should

have

ample

clearance

fo r the mounting

bolts .

For example,

Figure

5 shows four mounting holes

of

7.14 r diameter which are intended

to be used with 6.35 r diameter socket head bolts .

The

adaptor

pla tes

must

be

able

to

align

the

upper

and

lower

f lexure-f ix ture

pieces. The

whole system eas i ly aligned by the

use

of

6.35

r

(1/4

in ch ) d iameter

holes and locat ing

pins

in

each

par t

as shown

in

Figure

2.

A

long

6.35 r (1/4 inch)

diameter rod

i s used

to i n i t i a l l y align the system during setup .

The f ix ture i s designed

to

be used

with lo ad ing

ro l lers (bearings)

tha t are 4.5 r in

diameter

t ha t are

about

25

r

long.

They

should

have a

hardness of

R

c

40

or

higher. Hardened

dowel

pins

have hardnesses

a t leas t

as

high

as

th is

and

are

as

high

as R

c

60.

Rubber

bands are needed to hold the ro l lers a ga in st th e shoulders.

The

rubber bands should be 12

s ize

and are

avai lable

from any

sta t io ne ry o r

office supply s tore . Smaller bands wil l be too

t ight ;

la rger

ones,

too loose.

A

-10

r diameter

s tee l

ba l l

i s also needed.

The exact diameter

i s

not

important.

I t

need only have a hardness of

about

R

c

12, but

chrome s t ee l

bal ls

of R

c

60 are r ead il y ava ilabl e off the shelf .

A 13 r diameter ba l l

could

be

used, but doesn t ar t iculate

as

well .

Wood

or

aluminum shims can be inserted under the

f ix ture ,

so tha t

when the specimen breaks,

the lower

bearing

pla te

wi l l not topple

off

the bal l .

This fac i l i ta tes se t t ing up

the

next specimen.

The

lower

bearing

pla te

can

rota te around the ver t ica l axis

such

tha t

the

loading

ro l le rs

are

not

para l le l .

A

l i t t l e

homemade

guide

block can be made and afixed with

epoxy

glue

to f ix ture

base

to

res t r ic t th i s unwanted rotat ion.

Fixtures of

th i s typ e w ith ad aptors have been prepared a t costs

ranging from 2000- 3000.

ON LUS ONS

A

simple f ix ture

fo r

measuring

the

flexure strength

of advanced

ceramics presented. I t

a

semi-art iculat ing

design for

f l a t

and

para l le l specimens. The f ixture meets the requirements of

several

standard

t e s t

methods,

and

when

used

in

accordance

with

these

standards, wil l measure flexure

strengths

accurate to within

approximately 1 [4] .

Alternate

diameter ro l l e r s

are

sa t i s f ac tory except

the lo ca tio n o f

the

shoulders in

the bearing

pla tes Figures 3

and

4,

must

be

revised

accord ingly .

C-1161 and

MIL STD 1942

speci fy

t ha t

the

ro l l e r diameter

s ha l l

be

approximately

4.5 rom


11/22

KOWLEDGEMEHT

Par t i a l suppor t fo r

t h i s

projec t

was provided

by the Ceramic

Technology

Pro jec t , U.

S. Department of Energy, Office of

Transpor ta t ion Technologies ,

under

con t rac t D E A C 5 ~ 8 4 R 2 1 4 with

Martin

Mar ie t t a

Energy Systems, Inc .

REFEREN ES

1. MIL STD

1942

MR and MIL STD 1942 (A),

F le xu ra l S tr en gth

of

High

Performance Ceramics

a t

Ambient

Temperature,

Avai l .

from

Standardizaion

Documents, Order

Desk, Bldg.

4,

Sect ion D 700

Robbins

Ave.,

phi ladelphia ,

PA

19111-5094.

(The

A vers ion i s

an 1990 update to the ea r l i e r MR vers ion .

2.

C-1161-90,

Standard

Test

Method fo r

Flexura l S trength of

Advanced

Ceramics a t

Ambient Temperature, Annual Book of ASTM

Standards , Vol. 15.01, ASTM, Phi ladelphia , PA

3.

G

D.

Quinn,

Flexure

Strength

of

Advanced

St ruc tu ra l

Ceramics: A

Round

Robin.

J .

Am Ceram. Soc. ,

Vol.

73, [8]

(1990)

2374-84.

4. F. I .

Barat ta , G D

Quinn,

and W.

T.

Matthews,

Errors

Associated

with

Flexure Test ing of Br i t t l e

Mater ia ls ,

U S.

Army MTL Technical

Report ,

TR

87-35, July 1987.

5.

G

Quinn, Twist ing and

Fr ic t ion

Errors

in

Flexure Testing,

Ceram. Eng.

and S ci . P roc .,

July-Aug. (1992)

319-330.

6. R.

G

Hoagland, C.

W. Marschal l , and W.

H.

Duckworth,

J .

Am.

Ceram.

Soc . ,

Vol. 59, [5-6] (1976) 189-192.

7. U S. Army MTL Art icu la t ing Flexure Test Fixture ,

U.S.

Paten t 4,941,359, July

17, 1990. (Available

from

U

S.

Army

MTL,

Watertown, Mass.

o r G

Quinn,

NIST)


12/22

PPEN IX

SET

UP PROCEDURE

1 . Mount a compression load

c e l l to th e base o f th e t e s t

machine.

Attach t

loose ly . See Figure

A1.

2.

Mount

a load

c e l l

platform

onto

th e

load ce l l .


13/22

ITION L OT S

1.

Fragments

can

sometimes drop into the coun tersink-bal l se t in

the b l l adaptor pl te This can cause

a

misalignment.

Check

the

countersink per iodical ly . Clean

the

f ix ture

f ter

each

batch

of

specimens i s broken.

2.

The f ix ture can be e s i ly converted to a

three-point

f ixture

by the insert ion

of

the three-point adaptor Figure

6 into

the upper bearing pl te as

shown

in Figure

A

om caution

should be exercised

when

insert ing specimens, however, since

the

system

does not r t icul te

as well as

the

four-point

arrangement. J iggle th e sytem carefully in step 12.

3.

The system l tern t ively can be se t up with the

load

ce l l

attached

to the

crosshead, provided

the

correct

adaptor plates

are available.


14/22

Figure

Aligning the system

in

a universal test ing

machine.

he

load

e l l i s on the bottom. 6.35 r

1/4

inch rod i s

passed

through the ent i re system to line up the load e ll

platform and

adaptor

pl te under the crosshead.


15/22

upper

e a r i l ~

igure loseup of the

i ns t l l ed

f ix tu re


16/22

Figure

Fixture with

three point

adaptor

in

place Extra care

must be exercised

with

th i s arrangement

since

the fixture

does

not

r t i ul te as well


17/22

PPEHDIX

E n gl is h E q ui va le nt Drawings

F o r

c o n v e n i e n c e , th e

f o l l o w i n g

engl ish

dimension

d r a w i n g s are

furnished

Note

t h a t

these

a re d e s i g n e d to b e u sed

w i t h

3/16 i n c h

4 .7 6 d i a m e t e r

loading

ro l l e r s and the re fo re th e s h o u l d e r

d i m e n si o n s

a re

d i f fe ren t

than

t h o s e

fo r

th e

m e t r i c

drawings

which

u se 4.S mm

d i a m e t e r

ro l l e r s The dr wings and

p rts re

therefore

n ot in te rch n ge b le w ith the metric p rts


18/22

L

O

W

B

N

P

L

T

S

z

B

R

H

E

I

I

I

t

I

I

\

_

g

I

I

~

L

\

I

/

I

I

C

-

J

\

i

-

1

C

S

.

1

P

L

O

U

T

O

D

I

A

P

M

I

T

.

I

5

0

I

1

1

.

.

1

1

1

~

,

W

J

~

0

,

l

t

-

L

-

G

R

O

O

V

R

U

8

1

1

8

U

T

.

0

t

O

O

I

.

6

,

,

I

A

Q

1

A

l

o

D

M

O

6

U

E

O

H

W

i

S

N

F

g

e

B

L

w

e

b

n

p

l

t

e

A

l

d

m

e

o

i

n

i

n


19/22

.

.

U

P

N

P

S

z

B

R

c

~

3

.

2

D

I

A

.

.

3

D

E

E

P

t

T

H

H

C

B

R

D

E

P

2

H

O

L

-

J

/

.

I

I

I

I

_

I

\

I

I

I

~

\

r

-

T

-

I

~

\

/

I

I

I

I

-

.-

-

L

L

I

1

0

1

0

I

-

1

1

1

o

I

l

O

l

o

_

-

1

-

I

-

N

S

D

E

R

A

I

U

S

U

P

T

O

.

0

-

G

R

A

I

U

S

U

T

O

.

0

t

m

O

i

I

t

O

1

3

.

1

3

.

1

6

U

N

L

E

O

H

W

I

S

N

F

g

e

B

U

p

b

n

p

a

e

l

d

m

e

o

i

n

i

n


20/22

Three oint daptor

Size 8

.000

1 ~ I f - - - - - - 974

.001 J

487

001

t

500

:t.005

010

3 [J Y

--rl--

\ V ; I ~

9

18

L

-------------_.

~

c

Figure

Three po in t adaptor All dimensions in inches

I

/


21/22

NIST-114A

REV. 3 89

U S DEPARTMENTOF COMMERCE

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY L

BIBLIOGRAPHIC

DATA SHEET

I

PUBUCATION OR REPORT NUMBER

NISTIR 4877

PB95 210498

AuQUSt

1992

RTN

4 TITLEAND SUBTITLE NIST r.11; r1Q mes

Room Temperature Flexure

Fixture for

Advanced Ceramics

5.

AUTHOR(S)

George

D.

Quinn

6. PERFORMING ORGANIZATION (IF

JOINT

OR OTHER THANNIST, SEEINSTRUCTIONS)

U.S. DEPARTMENTOF COMMERCE

NATIONALINSTITUTEOF STANDARDS AND TECHNOLOGY

GAITHERSBURG,MD 20899

9.

SPONSORING ORGANIZATION

NAME

AND COMPLETE ADDRESS (STREET, CITY, STATE,

ZIp

10 SUPPLEMENTARY NOTES

7

CONTRACT/GRANT

NUMBER

8 TYPEOF REPORTAND PERIOD COVER

f \ l IST CATE oR f 4

n

DOCUMENT

DESCRIBES A COMPUTER PROGRAM; SF-l85 FIPS SOFTWARE SUMMARY, IS ATTACHED.

ABSTRACT

A

~ W R OR LESS FACTUAL SUMMARY OF

MOST

SIGNIFICANT INFORMATION. IF DOCUMENT INCLUDESASIGNIFICANT 81BUOGR

UTERATURE SURVEY, MENTION IT HERE;)

A

test fixture

for the measurement

of the flexure strength

of advanced ceramic specimens

presented The fixture meets the requirements of MIL STD 1942 and ASTM C

1161

and

severa

interna t ianal

standards

12

KEY

WORDS

(6

TO

12

ENTRIES;ALPHABETICAL ORDER; CAPITAUZE ONLY PROPER NAMES; AND SEPARATE

KEY

WORDSBY SEMICOLONS)

Ceramics; Flexure; Strength; ASTM Standard C 1161; MIL

STD

1942

MR. ;

Set up; alignment

~ I L B l U T Y

UNUMITED

FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE TO NATIONALTECHNICALINFORMATIONSERVICE(NTIS).

ORDER FROM SUPERINTENDENTOF DOCUMENTS, U.S. GOVERNMENT PRINTING OFFICE,

WASHINGTON, DC 20402.

7

ORDER FROM NATIONAL TECHNICAL INFORMATION SERVICE INTIS), SPRINGFIELD,VA

22161.

ELECTRONIC fORM

14.

NUMBEROF PRINTED P

21

15.

PRICE

A03


22/22