Table Of ContentCOMPUTATION OF VARTABILITY IN THE AVERAGE THERMAT. ANT) MECHANICAL
PROPPRTIES OF A MBLT-INFILTRATED SIC:SIC COMPOSITE,
Seeerumesh Kelli Anthony M. Caloming
Ohio Aerospace Tino: NASA Glenn Rescarch Center
NASA Glenn Research Center 210% Brookpark Road M'S 49-7
21000 Brookpark Road M'S 49-7 Bruck Park, Ohio 44135,
Brook Park, Ohio 44135,
David N. Brewer
US Army Research Tshuratory
‘NASA Gloun Research Comer
21000 Brookpark Road M'S 49.7
Brook Park, Ohio 44135,
ABSTRACT
Thermal conductivity and tensile properties (elutic modulus, proportional limit stength, in-
plane tensile strength, aad strain #9 failure) of a SIC/SIC compowite were experimentally
determined at $16 and 1204°C. Tests were potformed at 190m temperature om uhe same material
to obisin interlaminar shear and tensile srengihs, For each thoanal and mechanical properly 24
test were conducted (o capture the variaton. A random sampling method was used t quutlify
the variability extibited by the mean values of the thermal und tnechanical properties. ‘The
‘minimaur number of tests required In characterize tho mean valve of each thermal ar mechanical
Property for the composite was determined by varying the group size ofthe random sample
ANLRODUCTION
Ceramic matrix composites (CMCS) arc under considerulion ay vombustor Lincr materials in
aircraft gas turbine engines in ander to sustain higher engine operating temperatures and achieve
eater cngine cycle efficiencies. A woven SiC/SiC composite, manufactured by # slorry-cast,
‘melin filtration process, was developed ns « potential sandidate material [1], Robust kerma aud
mechunical property dats bases for the CMC. ave mecessery for the design of combustor
‘components. In particular, rcfiable estimations of the average values of thermal and mechamieal
properties are required Fram the experimentally generated data bases
Variatility exhibited in the userage thermal and mechanical properties of « silicon carbide
‘axed CMC was tletomined as a function of the number of repeated tests with a previously
developed simulation technique invalving random sampling of test data '2). The CMC.
investigated was the 9:99 MI SiC/SIC composite ounufaclured by General Electic Power
Systoms Composites, LLC. Tes! spevimens were sclected from theee separate manaficturing 1ots
of the CMC 49 incorporate Torio-lol siaistical variations, ‘The number of tests required 10
entimate the average valuc of either a thermal or mochanical property to within 1 § and 10%
exror bunds was levermined with the simaularion tecinique,
MATERIAL AND EXPERTMBNTAL DETAILS
For the 999 MI SiC/SIC campusile, the fiber pre-torm consisted nf Sylramic™ fiber woven
(oa SHS wenve. 20 BPI configuration with a [090].s lay-up. ‘The material kad & CVT silioon-
doped GN interphase and a CV SiC mar fully dsnsified by the slurry-cast well infiltration
Thigis aust
‘onforones. Because:
Publi iam
ol be eid or op a
pit at paper nso fr prserfnton a4
922 ay bomade belts tral
vale wih the undertandrg tat il
ad wthout to pernlan oe #her
process. Specimens for througheths-thickness thermal conductivity, tease, ierleinar shear
and tensile stengts tents were machined feom the as-manwfactard CMI plates (dimensions: 229
zum lengsh, 152 mm width, and 2 mm thickness). Geometry o€ te lemile leat specimens was
reported previously [3]. interlaminar shear strength {ILSS) testy vere conducted by
compressively loading specimens with two notches that weee offet (alony the length of the
specimen) whereas interlaminar tensile sneugth (ILTS) fests wore conduosed on eisular diske
shaped specimens. For determining» gion tral or mechnieal propery ofthe CMC, Aiur test
specimens per plate and tw plates pet lot foreach of the thraelened lls were selected to obisin
4 totel population of 24 specimens. Additonal deus on testing are urate n Ref [S|
‘THERMAL AND MECHANICAL PROPERTIES
‘Thermal conductivity and tensile tosts were conducted at 816°C and 1204°C, ILSS aud ILTS
testk were conducted at exire wemperalure (RT), Average thermal conductivity, & values 1 816
‘and 1204°C and the standand deviations (SDx) are Usted in Table I, Tn-plane tensile properties a?
the 9°99 material at 416 and 1204°C were previously reported [2, 3], Moana and SDs off fur
tensile proportics (clastic modulus, #: proportionl Lic steength, PLS (0.005% aftse0 in-plane
tensile shengrh, TTS; and strain to ue, SF) at both temperatures ate shown in Table J for the
CMC. Moreover, average valups and SDs of ILSS aud ILTS at 1 are also listed in Table I.
Tablet
of Propesies for 9°99 M) SiC'SIC Composite In = 24
® E PLS SSE u ILTS.
[Work] [GP] [MPs] MPa] 4d (Mpa [MPa]
RY
BOC 176 (13; 208 14 177 9} 342 1325 O48 40.06),
Tange 14.8 11} 182 {14} 106 28} 307 I? w4S 4OOT,
472 (Ey 8S At
First number iy mene value and the second number in ;} denotes SI
SIMULATION OF GROUPS WITH RANDOM SAMPLING
‘Variations in the means of the theenval and raechatical properties of the CMC were computed
will previvusly developed simulation mothod [2], For each thermal or mechanical property, the
data base af 24 points represented the total population in the simulation. Krom this population
sample groups wete randomly selected and their means and SDy were celeulated. Sample sizes
fiom 3 to 12 weie investigated. In the previous study (21, a teil of 200 rmndoorly selected
independent groups (no duplication of data within ench group) wece determined to be sufficient
to axtimate the varighility in the means for each property, The maximum and rinianm means
among the randomly selecled groups with different sample sot sizes (m~ 3 te 12) were uscd to
estimate the rainimum number af samples meguired 1 characterize the means af the thermal and
anechanical properties to within $ and 10% oT the woreespondinus pupulation mans (Table I)
Jt hss bocn shown thar the means of the randomly selected yroups fallow a normal
Jsribution regardless ofthe distibution followed by the patent population [6]. For ILTS at RT,
these distributions are shown in Fig. | for group sizes, m= 4, 8, and 12, Note the decrowse in the
variation of these distributions asa increases from 4 ly 12, Variability in the group averages of &
a 816°C ate plotted against the proup size in Tig. 2, Similar plows for B, PLS, ITS, aud SF wt
1204°C and ITSS snl W.TS st RT are shown in Figs. 308, respectively. Tn theve figures, only
the maximum and miaimum group averages are ideutified with points and the fine connecting
these points represents a divibulion. In general fora given property, variability in wean value
eareases as the group size increases from 3 us 12, Tn Figs, 3 108, population means {i} and error
bunds (& § and + 10%) about are also ploted. Minimum mumber of eats ncoded to determine
the mean thermal and rnechanival propertics of the CMC to within 5 and 10% of the respentive
population means are Usted in Table TI. For the MU SiCISiC composite, at least £2 tesln were
required to estimate the means of thermal and mechanical propertics 10 within 10% of the
averages of tho populatious. However, more thin 12 tesls would be required to estimate the
‘mean of he propertos to within
able UL. Minimum Number of Thermal and Mechanical Tests Requined far the CMC Matera
cm. Peroent Error Iss ngs ets
12 > 12
10 8
‘SUMMARY
‘Thermal conductivity axd tensite properties (clastic mosinlus, proportional Limit strength, im-
plane tensile stroagth and strain © failure) oF a of woven, melt-infitrared. SICSIC composite
(9999) were experimentally characterized at 816 andl 204°C Iricrlaminar shear and tensile
strengris of the same CMC were also determined at rom temperature, Ths minimum number of
testa, required Io entitle thy average waluc of either a thermal or mechanical property of the
CMC to within a conuin perveriage uf the corresponding population avernge, was determined hy
simulating groups with random sarapling. The random sampling siraulation with ditfecent group
sizes is applicable for any type of parent poputation distribution (i.e, normal, Jog-netmal, aud
Weibull ete),
ACKNOWLEDGEMENTS
‘This work was funded by NASA Glenn Research Centar (NASA-GRC) under cooperative
sagreeinent NCC-3-1041 through the Ultra Efficient Frgine Technology Program, Mr. fobn D.
Zima conducted the tensile tests at MASA-GRC. Therinul vonduetivity and ILSS de ILI'S tests
‘wore performed ut Thermophysics, Ine, and Cincinnati Testing Laboratories, respectively.
REFERENCES
[1] D. Brower, “HSI/EPM Combustor Viakrials Develepmcnt Progran” Mazuriale Sefence
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2004.
[B]S. Kallor, A.M. Coloming, and D. N. Brewer, “High Temperature Tensile Properties and,
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Strucnmres" A, Ceramic Eng. and Sci. Proc., Vol. 23, sue 3, 1.-T. Lin and M. Singh, Fas. pp.
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[6] FR, Ou, “Variables Data: An Intreduetion.”, pp. 17-23 in Process Quality Conirut
Troubleshooting cord inerpretaion of Dara, MeGras-Hill Book Company, 1975,
[5 Group Ste, maa
2 Group size, m=
[5 _Group Slze,m= 12
Cuntlatve Probability,
@ 4 rn 8 re
Strength LTS [4]
x for Interlaminar Tensile Strength at RL
‘average KW)
so 4
Group Ste, m
gute 2: Variability in che Group Averages for Thermal Conductivity «t 816°C
mo
mo
‘Average E (GP)
140
‘Group Size,
Figure 3: Varlabi
‘Average PLS (HP)
Group Size, m
«
& nu)
£ 48]
i= 4
eiaeepesegeer
Eom k at
“
*
‘Group Slee,
Figure 5: Vorishility in tho Gromp Averages for In-Plane Tensile Strength at 1204°C
avetage SF (8)
24 6 8 0 Md
Group Size, m
Figure 6: Variubility in the Group Averages for Strain to Future ut 12045
‘Average 1L88 (MPa
3
»
Group Sie, m
Figure 7: Variability in the Group Averages for Interlaminar Shear Strength at RT
2
average ILTS (Ps
Group Size, m
Figure §: Variuhility in the Group Averages for Imerlaminar Tensile Sirengih al RT
