NASA Technical Memorandum 102302 

Metal Matrix Composite Micromechanics : 

In-Situ Behavior Influence on 

Composite Properties 

P.L.N. Murthy, D.A. Hopkins, 

and C.C. Chamis 

Lewis Research Center 

Cleveland, Ohio 

Prepared for the 

Third Joint Mechanics Conference 

cosponsored by the ASCE and ASME 

San Diego, California, July 9-12, 1989 

-- - - 

(NASA-TR-102302) METAL HA TEIX COHPOSIIE N89-26924 

flICROHECHABICS: IN- SITU BEHhYIOB IIIFLUEICE 

ON COHPOSITE PROPERTIES [NASL Lewis 

Research Center) 21 p CSCL 11D Unclas 

G3/24 0225950 
TA13LE OF CONTENI’S 

A13S‘IKAC’I’ ............................................................ 1 

SYMIKlI. S AND NO’I’A‘I‘ION ............................................... 2 

I N’IROI>IJCI’I ON 7 

COX S’l’l ‘IIJ I {Nl’ M 1J I. TI . I;.4C‘L‘OK M A‘II; K 1.4 I. MODE I. ......................... 4 

CASES S~I’~JD11iD ........................................................ 5 

R13SUL‘IS AND I>ISCIJSSION .............................................. 7 

.............. 7 

IO 

SIJMMARY ........................................................... 11 

R13I~I~RENCIJS ......................................................... 13 

....................................................... 

Influence of in-situ matrix strength on unidircctional conipositc bchavior 

Influence of interpliasc property dcgradation on unidirectional conipositc hchavior ...... 

. 
M ETA L MATRIX COM POSI'I'E R.1 ICKOR.1 EC ti AN I CS: 

IN-SITU BEHAVIOR INFLUENCE ON COMPOSITE 1'ROI'F:RTI ES 

P. I,. N. Murthy', I). A. Ilopkins*, iind C. C. Chatnis2 

National Aeronautics and Space Administratioti 

1,cwis Research Center 

Cleveland, Ohio 44 135 

ABSTRACT 

Recent cfforls in compulational nwchanics methods for simulating the nonlineur behuvior of rnetal rnatrix 

composites huve culniinuted in thc implementation of the Metal ,Mutrix CotnpoJita it na[Lcxr (.\!ETCA N 1 conipuler code. In M.YI'CAN material nonlinearity is treated at the constituent (fibcr, mcctrix. and interphase) Ic-vel 

where [he current mdterial model ciercribes a iirne-tcmpc~rature-strc~ss depcntiency of the condtrtent propertic>s 

in a "material behtsior space." 1 Yic composite properties are synthesizcd frorn the cons lititent insttinttineous 

properties by virtue of composite micromechanics and macromechanics models. The behavior of metul niatrix 

composites depend on fubrication process variables, in-situ fiber and matrix properties, bonding betwecn the fiber 

and matrix, and/or the properties of an interphase between the fiber and matrix. The present paper focuses on 

various aspects of in-situ property influence on composite behavior. Spec$cal(y, the inflwnce of in-situ matrix 

strength and the interphase degrudution on the unidirectional composite stress-strain behavior is excitrtined. 

These lypes of studies provide inJight into micromechanical behavior that may be helpful in resolving diwrcpcincies bchveen experimentally obsoved composite behavior and predicted response. 

*lZerospace Research Enginccr, Structures Division 

2Senior Aerospace Scientist, Structures Ilivision 

-1- 
I SYhlBOLS AND NOTATION 

subscripts 1 I 

subscripts 2 2,3 3 

subscripts I’,m,c 

subscripts o,F 

E 

G 

S 

11, 

-I-M 

-I’, 

NVI. 

N,,, 

7‘ 

L’F 

P 

R 

S 

t 

a 

P 

V 

U 

0 

Dircction along the fiber 

Dircctions transvcrsc to the fiber 

Fiber, Matrix, and Composite 

Rcfcrcncc and Final values 

Dianietcr of the fiber 

Shear A40dulus 

Strengths 

Mclting temperature 

Room tcriipcraturc 

Currcnt or use tcinperature 

l’hcrnial cyclic liniit 

Mechanical cyclic limit 

l’hcrnial and Mechanical cyclcs 

Pro pcr t y 

Reaction 

Stress rate 

lime 

1’t icrma 1 ex pans i o n c oe f TIci cn t 

Poisson’s Ratio 

W ei gh t tien sit y 

Stress 

Stress rate 

Young’s Modulus 

INTROIIUCTION 

I ligh temperature metal matrix composites (1 ITM .MC) are emerging as niatcrials with potcnI tially high payoffs in aerospace structural applications. Rcalization of these pityofh dcpcnds on 

the parallcl and synergistic dcvclopment of: (I) a technology base for hbricating H‘I‘M MC 

structural components, (2) c\pcrimcritiil techniques for nicasuring their tlicrmal rind rncchanical 

churacteristics, and (3) computational mcthodologics for predicting their nonlinear bchavior in 

coinplcv scrvice cnvironmcnts. In fact, it niight be argucd that the dcvclopnicnt of computational 

mcthodologics should prcccdc the othcrs bccausc the structural intcgrity and durability of 

I1I.M MMC can bc computationally simulated, and the potential payoff‘ for a spccific application can 

be assessed, at least qualitati\fely. In this way, it is possible to minimi/e the costly and the conI 

I 

~ ‘ 

I -2- 
suniing cspcrimcntal cffort that would othcnvisc be rcyuirctl in the absence of a predictive capability. 

Recent research at N.4SA 1,cwis is dircctcd toiviirds thc dcvelopment of a computational capability to predict thc nonlincar behavior of I II’M h4C. ‘I‘his capability is schernatically depicted 

in figurc I. As sccn in this figure, thc capability consists of scvcral computationid modules cncompassing the matcrial coristitutivc behavior (bottom), composite inicro,’niacro mechanics 

(sides), and the finite clcmcrit analysis of structural coniponcnts (top). ‘l’hc Iclt part of the figurc 

represents the synthcsis of composite thcrmal/mcchanical property variables. n.hilc thc right part 

represents the tfccomposition of compositc responsc variables. In the svnthcsis, the propertics 

needed for structural aniilysis are gcncratcd while in thc decomposition the locd stresses nccdccl 

to update thc constituent instantancous propertics arc calculated. ’Ihc local stresses arc used to 

calculate the ply microstrcsscs (thc stresses in thc constituents). ‘I’he clcpctidcncc of the constituent material propertics on tcmpcraturc, strcss, anti several additional fiictors is dcfincd in ;I “JIUtcrial behavior space” as depicted at the bottom center of the ljgurc. The simulation (synthesis 

and dccornposition) is performed using an incrcnicntal-itcrativc nonhciir :inal}sis whcrc convcrgencc is enforced at every scalc (ply, laminate, and structurc) of the simulation. A detailed dcscription of this multi-scalc simuIation stratcgy is givcn in rcfcrcncc [I]. A stilnd alone computer 

codc has bccri developed to cxpctlitc the computational simulation process from thc constituent 

materials lcvel up to the laminate lcvel. This simulation capability is encircled with the dashed line 

in figurc 1. ‘l’he stand-alonc computcr codc is identified as MIi‘1’C:rZN for Mctal Matrix Corn- 

% 

positc Analyzer. 

-3- 
CO NSTl TlJ ENT MU LTI-F ACTO It MAT ERl A L MO DEL 

'I'hc various factors, which influence the constituent ITliitcriLll behavior and ultimately thc 

I ITiM .hi(: bchavior, arc incorporated through a multi-fiictor interaction relationship shown in 

figure 2 whcre the rationale for adopting this type of rclatioriship is summari/ctl. Additional discussion on this rclationship and its application can be found in rcfcrcnce [2]. Ilccausc of the 

I uniquc rcprcsentation of the unit cell with differcnt iiitralaminar subrc'gioris, the model has ii utility 

for studying the influences of thc individual constitucrit in-situ behavior on thc global response. 

Jn the prcscnt cfrort thc in-situ matrix strength and thc intcrphasc rncchanical propcrtics arc sclcctcd for thc parametric studies. 

A limitcd amount of predicted results has bcen gcnerntcd using thc METC.4Y codc in ordcr 

to verify, validate the multihctor interaction relationship with experimental data. These results 

can bc found in rcfercnce [3]. Some of. the conccrris with thc I IFfMhlC pcrforrnancc arc the low 

cxperinientally measured transverse strength?, low thermal fitiguc life and fiibrication induced 

rcsidLIii1 thcrmal strcsscs clue to the cocflicicnt of thcrmal expansion mismatch bctwcen the fibcr 

and matrix. The unanticipated poor performance observcd from these materials could be duc to 

a lack of knowledge of propcr in-situ constitucnt behavior, improper consolidation betwcen thc 

constituents, or an interphase growth due to a chemical reaction between the libcr and matrix 

icading to a weak bond bctwccn thc constitucnts. To undcrstand the causcs of poor I I-fMMC 

performance, one nccds insight into the composite hchavior sensitivity to in-situ constitucnt 

properties. Such insight can be rcadily gaincd cithcr by pcrforrning routine parametric studies 

using computational simulation or bq conducting costly experiments. 

I 

In the prcscnt work the VIYl~CAS computcr codc is used to study thc behavior at room and 

high tcmpcrature of SiC,'Ti- 15-3-3-3 (where Sic: stands for Silicon Carbide fibcr and Ti- 1.5-3-3-3 

stands for an alloy ofTitanium with 15% Vanadium, 3% Aluminum, 3% Chromium, and 3Y'n Tin) 

I 

I metal matrix composite. The motivation in selccting this particular cornpositc for the study is 

~ -4- 
provided by the wide recognition it has already received as a Liable candidate for some of the high 

temperature ;ipplications as5ociatctl with the h'ational Aerospace Plane (SASI'). Also, additional 

eiperirncrital testing is currently uncleway at NASA Lewis I<csearch Center bvliich will provide 

;in opportunity for the verification,'validation of the M 13'1'<:AN codc. 'I'hc specific objectives for 

the present work are: (1) to study the influence of the in-situ Iniitris strength on the room, high 

temperature response of unidirectional metal rnatrix composites, and (2) to study the influcncc of 

the interphase and its degradation on the room'high tenipcrature response of unidirectional rnctal 

matrix composites. 

CASES STUDIED 

'The metal matrix system, Sic, Ti-1.5-3-3-3 , is selected as the candidate for the present study. 

All the nunicrical results arc obtaincd for ;I unidirectional lanlinate made of thc above mentioncd 

nietal matrix composite. 'lhe fiber volume fraction is chosen to be 0.40 throughout the study. 

'Ihe nominal properties of Si(: fiber and Ti- 15-3-3-3 matrix used in the prescnt study arc given 

in 'I'able I. Also presented in 'I'able I arc the room temperature composite properties predicted 

by ME'I'CAN. The study is divided into two parts; for the first part no interphase is taken into 

account, for the second part ;I distinct interphase is iissunied. In the lirst part of the study, three 

difl'crent values for the in-situ matrix strength are used in the analysis. 'fhe in-situ strength values 

considered are 100% of the reference (room temperature) matrix strength, 50% of the rcl'ercncc 

strength, and 2.59:) of the reference strength. Thus the matrix normal strengths chosen are 130, 

65, and 32.5 ksi (tensile arid compressive) respectively. The matrix shcar strengths chosen are 9 1, 

45.5, ancl 22.8 ksi respectively. For the second part of the study an interphasc with a thickness 

equal to one percent of the fiber clianieter is assumed to exict. 'I'hree sets of niechanical properties 

for the interphase are considered in the study, as follows: (1) interphase properties arc the sanie 

as the matrix properties, (2) interphase properties are 5CY% of the rnatrix properties, arid (3) 

-5- 
I interphase properties are 2.5';" of the matrix properties. In this manner, the effect of interphase 

degradation on the composite behavior can be assessed. 

The uniaxial stress-strain bchavior of the metal matrix composite is exarnined as an indicator 

of composite response and is obtained at two different use temperatures; ambient or room ternperature (70" I:) and elevated temperature ( 1200" I:). 'the composite stress-strain response is 

examined under five separate nionotoriic loading conditions; longitudinal tension, longitudinal 

compression, transvcrsc tension, transverse compression and in-plane shear. '1'0 account for the 

composite residual stresses induced by thc processing conditions, the cool-down history from the 

consolidation tcmpcrature (zero stress state) to room temperature (70" I:) is simulated prior to the 

application of mechanical loading in all the cases studied. I:or the high tcmpcrature stress-strain 

behavior, heat-up from room temperature to I2OO"I~ is simulated, as well, prior to the application 

of mechanical loading. The (lata necessary to plot the stress-strain behavior under tlilrercnt loading conditions is generated using Ml131'CAN. The thermal, mechanical load is applied incrcmentally until global failure is indicated. For each step the local cumulative microstresses in each 

region are checked against the respective strength limits. When a particular stress cxcecds the limit 

the corresponding stiffness (modulus) is set to a low value (0.01 psi) to cflectivcly represent zero 

: :fTness. For example, if the local stress in matrix region A ((T,,,,,) exceeds its allowable strength 

limit, then the value for modulus IimllA is set to 0.01 psi. The incremental analysis is continued in 

this manner until the damage accurnulatcd is sufficient enough to cause global failure of the 

structure. In the present study global failure is considered to occur at that point in the loading 

history where: (1) further load increase would cause an ordcr of magnitude increase in strain, or 

(2) an abrupt change occurs in the slope of the stress-strain curve. c 

-6- 
RESULTS AND DISCUSSION 

'I'hc results of the study are shown ;is stress (ksi) vcrsus strain (5,j curves in ligurcs 3-12. Ilach 

figure contains tivo scts of curves. 'I-he solid lincs represent room tcrnpcraturc stress-strain response whcrcas the dashed lines represent high tcniperatiire ( 1200" 1:) response. 1;ach sct consists 

of thrcc ciirvcs (,4,ll,C) that rcprcscrit the thrcc tlifrcrcnt ciiscs of in-situ matrix strength in figs. 

3-7 and the thrcc tliIrcrent scts 01' propcrtics assurncd Tor the iliterphiisc in figs. 8-12 

Influence of in-situ matrix strength on iiiiidirectionnl composite bcliavior 

Figures 3 and 4 show the behavior under lo~igitudi~iiil tension and cornpression loading respcctivcly of a unidirectional SiC/'l'i- 15-3-3-3 cotnpositc. 'I'hc ciirvcs show ;in initial negative 

(compressive) strain at nxo load due to the processing inducctl residual strains. I;roni these results 

the follotving observations itrc nindc: 

(1) 'I'hc roorrirhigh temperature plots show similar trends. 130th scts start at difrcrent initial 

compressive strains. The initial strain in room tcnipcraturc predictions is due to proccssing. Additional strains duc to heat-up arc also prcscnt in the second set which corresponds to thc 1200" 

I' stress-strain prcdictions. I Icrc, thc heating has allcviatctf thc initial residual strain due to processing. Both cases show a slight decrease in the ultiniate strength at 1200" 1:. 

(2) For cach set, the ultimate strcngth in tcnsion!comprcssion is rcachcd at approximately the 

same strain level. I lowever. thc stress level at lhilure is substantially sniallcr for the tensile loiidirig 

case than it is for the comprcssivc loading casc. Also to be notcd is thc higher strcngth ~x~dictions 

in compression than in tension. The primary reason Tor this is that thc fibcr iillowablc strength 

in tcnsion is assumed to bc 500 ksi u.hcreas its comprcssivc strength is assumctl to be 650 ksi 

(Table I). 'I'hc present modcl docs not account for the fiber microbuckling fliilure niodc which 

-7- 
may actually he the governing failure mode in compression. The fiber microbuckling will rcducc 

the compresivc strength substantially and thcrefore, the coinprcssive strength predicted by the 

prcwnt model may be overly optimistic. 

(3) About 10 to 20 percent rcduction in the composite longitudinal strength resulted as ;L 

consequence of the in-situ nilitrix strength degradation. ’[he bchavior of the cornpositc is csscntially fiber dominated for this t>pc of loading. This explains why the composite strength does not 

show degradation in the sanie proportion ;is the matrix strength degradation. 

(3) ‘Hie initial tangent modulus for all three cases of each tcmpcrature sct appears to be the 

samc for the longitudinal compression loading bcha\.ior. There appears to be ii slight decrease in 

thc initial tangcnt modulus (of the room tcriipcraturc sct) for the longitudinal tension loading. 

Also, the bchavior in longitudinal compression exhibits more pronounccd reduction in initial tangent modulus due to the increase in use temperature. 

I3ased upon the abovc observations it can be concluded that in the absence of an interphase 

the longituclinal strength of the unidirectional coniposite exhibits only iibout a 10 to 20 percent 

loss cven though the matrix strength has bcen reduced drastically. llence, one can infer that X 

experimentally observed strengths arc substantially lower than those predicted, then it is niore 

than likely that fibers wcrc damaged during the proccssing of‘ thc compositc. Also, a film 

microbuckling fdurc mode needs to be incorporated into the model in order to obtain more realistic comprcssivc strengths. 

1:igurcs 5 and 6 show the behavior of the compositc under trans,crsc tension and coniprcssion 

loading. Following is a list of significant observations that can be madc from the results. 

(1) Sinular to thc longitudinal loading case, thc room,’high temperature strcss-strain behaviors 

show similar trends, however, the reduction in strcngth is quite substantial due to transverse 

-8- 
loading. Iloth the ultimatc strength and strain suf‘fer scvcrc dcgriidatio11 duc to ;in increasc in thc 

usc temperature cxccpt for casc C of figure 5. ‘I’his is duc to the matrix doniinancc on compositc 

hchavior and matrix sensitivity to clcvatcd temperature. 

(2) ‘fhc strain and thc ultimate stress at which global fitilurc occurs show drastic reduction with 

thc dccrcase in matrix strength. ‘his is tluc to the matrix dominated bchiivior of the unidirectional 

composite in trunsvcrsc tciision’comprcssion. As with the longitudinal tcnsion,lconipression 

loading cam, the stress limits predicted arc much higher for the loading in cornpression as opposed to thc loading in tension. 

(3) ‘Hie reduction in composite trrinsvcrsc strcngth is almost in the same proportion ;is thc rcduction in matrix strength. 

(4) ’I’hc initial tangent modulus also shows significant rcduction with the reduction in thc 

strength ol‘ niatrix for the rooni tcrnperaturc curves. 

An iniportant gencral conclusion from the above observations is that tlic trans\ crsc rcsponsc 

is very sensitive to thc in-situ matrix strcngth variations. I Icnce, onc can expect a significant 

scatter in expcrirncntal data for transvcrse strcngths as wcll as extremely low values for the conipositc strcngth in the transvcrsc dircction. ‘I’hcrcforc, the in-situ matrix propcrtics must he known 

prcciscly in order to correlate expcrirncntal data and prcdictions with acccptablc accuracy. 

The behavior of the compositc in in-plane shear loading is dcpictcd in figure 7. It is sccn from 

the figurc that the ultimate stress and strain are reduced significantly ivith reduction iri rnatris 

strength as well as with the incrcasc in usc tcnipcraturc. ‘I’hc initial tangent modulus nppcars to 

he unalTcctct1 by the reduced matrix strength. I lowcver, uith the increLise in use tcniper;itiire this 

initial tangcnt modulus docs show significant dcgradation. All thc plots start at xro strain whcrc 

no load is applied. This is to be expected because there is no residual shear strain present due to 

-9- 
the processing induced rcsidusl stresses. Note that the sanic general conclusion nicntioncd abovc 

for transverse tcnsionjcornpression applies to the composite bchavior in in-planc shear as well, 

narncly that in-plane shear is vcq‘ scnsitivc to in-situ matrix strength degradations. 

Influence of‘ interphase property degradation on unidirectional coniposite behavior 

‘I‘he influence of intcrphasc property degradation on the behavior of a unidirectional 

SiC;Ti- 15-3-3-3 composite in longitudinal tensionicompression is shown in figures 8 and 9 rcspcctivcly. ‘I’hc tlifrercnccs among curvcs A, B arid (1 appear to be minor. The residual strain tluc 

to proccssirig is sccn to be difkrcnt for each case A, I3 and C. This results in a slight lateral shift 

of tlic response. I lighcr use tcrnperaturc has alleviatctl the residual strain significantly. ‘I‘hc ultimate strength in coniprcssion is seen to be higher than in tension. This is due to the higher fiber 

strength assumed in conipression than in tension. The reduction in thc ultimate strength due to 

the interphiise dcgraclation is ncgligihle. 

Figures IO and 11 show the influcncc of the interphase degradation on thc transverse strcssstrain response in tcnsionicompressiori respectively. The ultimate strcngth exhibits substantial 

rcduction due to the degradation in the interphase propcrtics. Also, the behavior in transverse 

compression appears to be afrectcd much more severely than the transverse tcnsion. The higher 

use tcmpcrature has primarily resulted in substantial rcductions in the ultimate strengths for case 

A. Cases B arid C show degradation due to higher use tcrnperaturc only for tension loading. In 

addition, there is a significant reduction in the initial tangent modulus duc to higher use tcniperI 

I 

I aturc in thc case of transverse coniprcssion loading. 

I The behavior due to in-plane sliear loading is shown in figure 12. I Icre, it is secn that the 

interphase has almost negligible inlluence on the response. The ultimate strain shows a minimal , 

I increase with the interphase degradation. The higher use temperature response shows similar I 

I I - 10 - 
trends with significant rcdcctions in t he ovcrall shear modulus and thc ultimate in-planc hear 

strength. 

'lhc intcrphasc in metal niatrix compositcs can be caused by a chcnucul rcaction bctwcen film 

atid matrix, or by an intcntional introduction of ;I compliant coating 011 the fiber whicli CJI~ he 

thought of a$ ;in intcrphasc for the prctcnt discusvion. Ihscd on the results in figurcs 8- 12. it can 

be concluded that the longitucfinal and in-plane shear behavior ofthc composite is riot significantlj 

alrectctl. l'hc transverse behavior is drasticiilly altcrccl due to thc intcrphasc tlcgratlation. I Icncc, 

a low tran\vcrsc strcngth obscrvcd expcrirncntally may be indicative of ;i lvcak intcrphasc or iinpropcr consolidation between thc fiber and matrix. 

SUMMARY 

I~ascd on the coniputational studies pcrfornicd with 34 IXCAX for the SiC''1'i- 15-3-3-3 

uniclircctional compositc the following conclusions are rcachctl: 

(I) The in-situ matrix strength substantially influcnccs the transverse tcnsilc,'cotnpressive 

strcngths. ]:or the range of matrix strcngths consitlcred, the reduction in composite transverse 

strengths is in direct proportion to the rcduction in matrix strength. 

(2) The longitudinal terisilc,'comprcssivc strcngth of the compositc exhibits about a 10 to 20 

percent reduction duc to the reduction in matrix strength. for the range consicicrcd. 

(3) The in-plane shcar strength is severely reduced due to the in-situ matris strcngth variations. 

A maximum of SO percent reduction in in-planc shcar strength occurs for the range of in-situ 

matrix strengths considered. 

- 11 - 
(4) The inllucncc ol' thc iritcrphrisc tlcgratliition on tlic longitudinal tension compression and 

in-planc shcar bchavior is ncgligiblc. 

(5) l'hc behavior in transvcrsc tciision,'coniprcssion is affcctcd drastically by the intcrphasc 

dcgraclation. 130th thc ultimatc strcngth ;ind strain reduce substantially. 

(6) The priniary effect of highcr usc temperature spccific to intcrphasc tlcgradation casts is li 

rcduction in cornpositc strength with the exception of thc bchitvior undcr trmsvcrsc comprcssion 

loading whcrc thc rcduction in strcngth occurs only for casc A curvcs. I;or coniprcssion and inplanc shcar loading a rcduction in the initial tangcntial modulus occurs. ;is well as thc reduction 

in the ultima tc strcngth. 

(7) In gcncral. dcgradation in in-situ matrix strength and the prcscncc ol' a wcak intcrphasc 

dramatically allcct the matrix doniinatcd conipositc bchavior and haw ncgligihlc efrccts on the 

filscr dorninatcd cornpositc bch;ivior. 

- 12 - 
R EFE; R EN (1 ES 

1. 

2. 

3. 

I Iopkins, I). A., 1984, “Nonlinear Analysis of I ligh-’l’enipcraturc Multilaycrctl Fiber Conipositc Structurcs,’’ NASA l‘.\?1-S3754. 

Chamis, C.C., and I Iopkins, I). A., 1985, “~l’hermoviscoplastic h‘onlincar Constitutivc Rclationships for Structural Aniilysis of I ligh ‘I‘crnpcraturc Metal Matrix Cornposites,” NASA 

‘I-~-s729 I. 

Chamis, C. C., Murthy, 1’. 1,. N., and I Iopkins, I). A., IOSS, ”Computationid Simulation of 

I Iigh Temperature Metal Matrix Composites Cyclic Rchavior.” Prcscntetl at the AS’1-M 

Symposium or1 Thcrrnal and ,Vcchanical Ikhayior of Ccramic and Metal hl atris (’ompositcs. 

Atlanta, Georgia. 

- 13 - 
I'ABLE 1. Nominal Constituent Properties and Predicted Composite Propcrties 

at Room 'Temperature 

.1 1 Ib'in' 

62 Mpsi 

.3 in'in 

23.S Mpsi 

l.S pprn 

3870 deg. 1: 

500 hsi 

6.50 ksi 

500 ksi 

6.50 ksi 

300 k<i 

5.6 rriils 

Ti-15-3-3-3 Matrix Composite 

. I72 Ib'in' 

12.3 ,Mp4 

.32 inlin 

4.7 hlpsi 

-1.5 ppm 

1SOO dcg. F 

130 hsi 

I30 ksi 

91 ksi 

31.2 Mpsi 

IS.5 Mpsi 

1S.5 ,Mpsi 

7.7 Mpsi 

0.9 Mpsi 

7.7 Mpsi 

.31 in'in 

.-)-> 11. in.:in . 

.31 in,'in 

2.0 pprn 

3.2 pprn 

3.2 pprri 

- 14 - 
COMPONENT 

I 

I 

I 

I 

I 

I 

f 

LAMINATE 

I 

I 

I 

I 

I4 '\ \\ "SYNTHESIS" t I 

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\ 

\ 

\ 

\ 

\ 

\ 

I 

I 

MATERIAL PROPERTIES I 

P (0, T, 1) I 

I 

I GLOBAL i I STRUCTURAL I 

ANALYSIS I L------J LAMINATE 

P 

I 

I 

THEORY 

/ 

/ 

/ 

/ PLY 

/ 

/ 

/ COMPOSITE / 

t NONLINEAR 

MATERIAL 

MODEL 

MICROMECHANICS ,/ THEORY / 

CONSTITUENTS / H' 

\ PLY \ 

\ \ 

\ 

\ 

\ COMPOSITE 

\, MICROMECHANICS \. THEORY 

Figure 1. - Integrated multi-scale approach to metal matrix composite analysis. 

RATIONALE: 

r MATRIX 

I r INTERPHASE 

SUBREGIONS OF 

INTRALAMINAR 

NONUNIFORMITYp._ +- \\ i, 

0 GRADUAL EFFECTS DURING HOST RANGE. RAPIDILY DEGRADING NEAR FINAL STAGES 

0 REPRESENTATIVE OF THE IN-SITU BEHAVIOR FOR FIBER, MATRIX, INTERPHASE. COATING 

0 INTRODUCTION OF PRIMITIVE VARIABLES (PV) 

0 CONSISTENT IN-SITU REPRESENTATION OF ALL CONSTITUENT PROPERTIES IN TERMS OF PV 

0 ROOM TEMPERATURE VALUES FOR REFERENCE PROPERTIES 

0 CONTINUOUS INTERPHASE GROWTH 

0 SIMULTANEOUS INTERACTION OF ALL PRIMITIVE VARIABLES 

0 ADAPTABILITY TO NEW MATERIALS 

0 AMENABLE TO VERIFICATION INCLUSIVE OF ALL PROPERTIES 

0 READILY ADAPTABLE TO INCREMENTAL COMPUTATIONAL SIMULATION 

Figure 2. - Multifactor interaction relationship for in-situ constistuent material behavior. 

15 
IN-SITU MATRIX STRENGTH 

A: 100% OF REFERENCE VALUE 

B: 50% OF REFERENCE VALUE 

300 ,- C: 25% OF REFERENCE VALUE 

270 

240 

21 0 

180 

150 

120 

90 

60 

30 

n 

at 70 OF t- ---- at 1200 4 

- 

-.w -.& -.32 -.la -.04 .io 24 .M .52 .ai .m 

LONGITUDINAL STRAIN, (%) 

Figure 3. - Influence of In-situ matrlx strength on the 

response of Sil-153-3-3 unldlrectional canpOSite 

In longitudinal tension. 

IN-SITU MATRIX STRENGTH 

A: 100% OF REFERENCE VALUE 

8: 50% OF REFERENCE VALUE 

C: 25% OF REFERENCE VALUE 

- at 70 OF 

at 1200 OF 160 - ---- 

144 

128 

112 

- 

- 

- 

-60 -.24 .12 .48 .84 120 

TRANSVERSE STRAIN, E= (%) 

Flgure 5. - Influence of In-situ matrix strength on the 

response of SICfli-15-3-3-3 unldirectlonal composite 

In trimwema DnJon. 

IN-SITU MATRIX STRENGTH 

A: 100% OF REFERENCE VALUE 

B: 50% OF REFERENCE VALUE 

C: 25% OF REFERENCE VALUE 

0 -.% -.72 -.i.o8 -1.44 -1.80 

Figure 4. - Influence of In-situ matrix strength on the 

LONGITUDINAL STRAIN, (%) 

response of SICfli-15-3-3-3 unldlrectknal compaslte 

in longitudinal canpression. 

IN-SITU MATRIX STRENGTH 

A: 1009c OF REFERENCE VALUE 

B: 50% OF REFERENCE VALUE 

C: 25%OFREFERENCEVALUE A 

- at70OF 

---- at 1200 OF 

-25 

1111111~ 

0 -.3 -.6 -.9 -12 -1.5 -1.8 -2.1 -2.4 -2.7 -3.0 

TRANSVERSE STRAIN. eZ(%) 

response of SlCml53-3-3 unkllrectlonal mposlte 

In transverse compresdon. 

Flgure 6. - InWenoe of in-dtu maMx strength on the 

r 

16 
. 

IN-SITU MATRIX STRENGTH 

60 - A: 100% OF REFERENCE VALUE 

9 - B: 50% OF REFERENCE VALUE A 

IKPLANE SHEAR 

STRESS,ol2 36 - 

30- (KSi) 

IIlllllI 

0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1.0 

IKPLANE SHEAR STRAIN, E~~(%) 

response of SiUrI-15-3-3-3 unidirectional mmposite 

in in-plane shear. 

Figure 7. - Influence of in-situ matrix strength on the 

LONGITUDINAL 

STRESS, o1 

(KSI) 

-320 

-288 

-256 

-224 

-1 92 

-160 

-1 28 

-96 

-64 

-32 

0 

INTERPHASE PROPERITES 

A: SAMEASMATRIX 

B: 50%OF MATRIX 

C: 2596OFMATRlX 

-.2 -.4 -.6 -.8 -1.0 -1.2 -1.4 -1.6 -1.8 -2.0 

LONGITUDINAL STRAIN, (%) 

Figure 9. - Influence of interphase property degradatlon on the response of SiC/Ti-153-3-3 unldlrectlonal 

composite in bngitudinal compression. 

LONGITUDINAL 

STRESS, oll 

(KSI) 

TRANSVERSE 

STRESS, 022 

(KSI) 

INTERPHASE PROPERITES 300 

- A: SAM AS MATRIX 

270 8: 50% OF MATRIX - 

240 - C: 25% OFMATRIX 

210 

180 

150 

120 

- - 

- 

- 

- 

90- 

60- 

30- 

0 

-60 -.46 -.32 -.18 -.04 .10 .24 .38 52 .66 .80 

LONGITUDINAL STRAIN, (%) 

Figure 8. - Influence of interphase properly degradation on the response of SIUrI-153-3-3 unidlrectkmai 

cunpcndte in bn~lludlnal tension. 

150 

135 

120 

105 

INERPHASE PROPERITES 

A: SAMEASMATRIX 

8: W9bOFMATRlX 

C: 25%OF MATRIX 

---- at70OF 1200 OF /A 

" 

-.60 -.46 -32 -.18 -.04 .10 .24 .38 52 .66 .80 

TRANSVERSE STRAIN, E~(%) 

Figure 10. - Influence of interphase property degradatlon 

on the response of SWI-153-3-3 unidlrectlonal 

composite in tfwuverse tendon. 

17 
50 -T -25 

INTERPHASE PROPERITES 

A: SAME AS MATRIX 

B: 50%- MATRIX 

C: 25%OFMATRIX 

at 70 OF 

---- at 1200 T 

,‘E fi 

1,fC CI I I I1 I I I 

0 -.3 -.6 -.9 -1.2 -1.5 -1.8 -2.1 -2.4 -2.7 -3.0 

TRANSVERSE STRAIN, €22 (%) 

Figure 11. - Influence of Interphase property degradation on the response of SMi-153-3-3 unldlrectlonal 

composite In trsnwuse CanPnrJan. 

INTERPHASE PROPERITES 

A: SAMEASMATRIX 

B: 50%OFMATRlX 

C: 259LOF MATRIX 

- at 70 OF 

42 A 

rlllrrrII 

0 .I .2 .3 .4 .5 .6 .7 .8 .9 1 .O 

INPUNE SHEAR STRAIN, E 12 (%) 

Figure 12. - Influence of interphase property degndaion on Uw response of SICITI-153-3-3 unidirectlonal composite In IIl-plPro Ihepr. 

. 

I 

18 
m 

National Aeronautics and 

1. Report No. 

NASA TM-102302 

Report Documentation Page 

2. Government Accession No. 

17. Key Words (Suggested by Author@)) 

Metal matrix composite; Nonlinear behavior; Interphase 

degradation; In-situ matrix strength; Local response; 

Global response; Computational simulation 

4. Title and Subtitle 

Metal Matrix Composite Micromechanics: In-Situ Behavior 

Influence on Composite Properties 

18. Distribution Statement 

Unclassified - Unlimited 

Subject Category 24 

7. Author(s) 

P.L.N. Murthy, D.A. Hopkins, and C.C. Chamis 

19. Security Classif. 20. Security Classif. (of this page) 21. No of pages (of this report) 

Unclassified Unclassified 20 

9. Performing Organization Name and Address 

National Aeronautics and Space Administration 

Lewis Research Center 

Cleveland, Ohio 44135-3191 

22. Price’ 

A03 

2. Sponsoring Agency Name and Address 

National Aeronautics and Space Administration 

Washington, D.C. 20546-0001 

3. Recipient’s Catalog No. 

5. Report Date 

6. Performing Organization Code 

8. Performing Organization Report No. 

E-4982 

10. Work Unit No. 

505-63-1 1 

11. Contract or Grant No. 

13. Type of Report and Period Covered 

Technical Memorandum 

14. Sponsoring Agency Code 

5. Supplementary Notes 

Prepared for the Third Joint Mechanics Conference cosponsored by the ASCE and ASME, San Diego, California, 

July 9-12, 1989. Invited paper. 

6. Abstract 

Recent efforts in computational mechanics methods for simulating the nonlinear behavior of metal matrix composites have culminated in the implementation of the Metal Matrix Composite Analyzer (METCAN) computer code. 

In METCAN material nonlinearity is treated at the constituent (fiber, matrix, and interphase) level where the 

current material model describes a time-temperature-stress dependency of the constituent properties in a “material 

behavior space. ” The composite properties are synthesized from the constituent instantaneous properties by virtue 

of composite micromechanics and macromechanics models. The behavior of metal matrix composites depend on 

fqbrication process variables, in-situ fiber and matrix properties, bonding between the fiber and matrix, and/or 

the properties of an interphase between the fiber and matrix. The present paper focuses on various aspects of insitu property influence on composite behavior. Specifically, the influence of in-situ matrix I-- strength and the 

interphase degradation on the unidirectional composite stress-strain behavior is examined.:,These)types of studies 

provide insight into micromechanical behavior that may be helpful in resolving discrepancies-6etween experimentally observed composite behavior and predicted response.