NASA Technical Memorandum 102 1 15 

J 

Computational Simulation of High 

Temperature Metal Matrix 

Composites Cyclic Behavior 

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

Nutional Aeronautics arid Spuc*e Administration 

Lewis ResearcSi Center 

Clet yeland, Oh io 

Prepared for the 

ASTM Symposium on Thermal and Mechanical Behavior 

of Ceramic and Metal Matrix Composites 

Atlanta, Georgia, November 7-8, 1988 

__~ 

1 N~SA 3H- IO 21 IS)-? oKPUTA TI ON A L-SIBUL A TI ON- Ha 9 0 27 9s 

OF HIGH TEHPEEATURE METAL flATBIX COHPOSITES 

CYCLIC BEHAVIOR (NASA. Lewis Research 

Center) 15 p CSCL 11D Unclas 

G3/24 0225955 
COMPUTATIONAL SIMULATION OF HIGH TEMPERATURE METAL MATRIX 

sf 

I w 

COMPOSITES CYCLIC BEHAVIOR 

C.C. Chamis*, P.L.N. Murthyt, and D.A. Hopkinst 

National Aeronautics and Space Administration 

Lewis Research Center 

Cleveland, Ohio 44135 

SUMMARY 

A procedure was developed and is described which can be used to computationally simulate the cyclic behavior of high temperature metal matrix composites (HTMMC) and its degradation effects on the structural response. This 

procedure consists of HTMMC mechanics coupled with a multifactor-interaction 

constituent material relationship and with an incremental iterative nonlinear 

analysis. The procedure is implemented in a computer code which can be used 

to computationally simulate the thermomechanical behavior of HTMMC starting 

from the fabrication process and proceeding through thermomechanical cycling, 

accounting for the interfacelinterphase region. Results show that combined 

thermal/mechanical cycling, the interphase and in situ matrix properties have 

significant effects on the structural integrity of HTMMC. 

INTRODUCTION 

Structural components made from high temperature metal matrix composites 

(HTMMC) will be subjected to both monotonic and cyclic thermal and mechanical 

loads. The cyclic loads degrade the composite structural integrity in terms 

of stiffness and strength. What is of interest is either (1) the degradation 

rate or (2) the value to which characteristic properties have degraded after a 

specified number of cycles. Experimental determination of these degradations 

is frequently prohibitive in cost and may not be tractable because of the 

numerous contributlng factors such as constituent material properties, fabrication process variables, and the continuously changing nonlinear behavior with 

each cycle. 

Recent research by the authors indicates that the degradation can be 

described at the constituent materials level, including the interphase, by 

using a multifactor-interaction relationship of product series form. 

responding degradation at the composite level is described by using composite 

micro- and macro-mechanics incorporated into a computer code. This computer 

code Is used to computationally simulate the cyclic behavior of HTMMC. 

objective of the present paper is to describe the computational procedure and 

illustrate its application by presenting typical results. 

The corThe 

GLOBAL STRUCTURAL RESPONSE 

A brief description of global structural analysis provides the background 

for the need to computational ly simulate the thermal/mechanical behavior of 

*Senior Aerospace Scientist, ASTM Member. 

?Aerospace Research Engineer, Structures Division. 
HTMMC. The process of "computational simulation" is summarized in the following section. A schematic summarizing equations for global structural analysis, 

through which global structural response variables and local variables a.re 

obtained to assess the adequacy of the design, is depicted in figure 1. Computational simulation is used to generate the elements (terms) in the structural matrices: [MI, [CI, [Kl, CDI, and {SA}. The vector {F(t)} includes the 

loading conditions while {u} includes the calculated global displacements, {u} 

includes the local stresses and w represents the natural frequencies of the 

structure. Variables with the subscript A denote allowable values of the 

respective variables set by the design requirements. Comparable equations are 

used for thermal analysis where composite micro- and macro-mechanics are used 

to generate the structure's thermal properties required for heat transfer and 

the procedure to generate the properties needed for local/global thermostructural analysis of HTMMC. 

I 

I for thermal stress analysis. The sections that follow describe the details of 

I 

COMPUTATIONAL SIMULATION OF THERMALIMECHANICAL PROPERTIES 

For the computational slmulation to be representative of the physics of 

HTMMC behavior, it must account for the fabrication process starting with the 

constituent materials and ending with the structural component. A schematic 

depicting the fabrication process of HTMMC is shown in figure 2. The integrated multiscale computational simulation strategy is shown in figure 3. The 

left part of the figure represents the behavior synthesis, while the right 

part represents the response decomposition. In the synthesis the properties 

needed for structural analysls are generated, while in the decomposition the 

local stresses are calculated. 

The dependence of the constituent material properties on time, temperature, and stress, is defined in a materials space shown at the bottom center 

of the figure. The ply stresses are used to calculate the local microstresses 

(the stresses in the constituents and in the interface). The simulation (synthesis and decomposition) is performed using an incremental-iterative nonlinear 

analysis where convergence is enforced at every level (ply, laminate, and 

global) of the simulation. A detailed description of this simulation including requisite equations is found in reference 1. A stand-alone computer code 

$as been developed to perform the computational simulations from the constituent materials level to the laminate level. This stand-alone code encompasses 

all the capabilities shown within the dashed line in figure 3 and is identified 

as METCAN (Metal Matrix Composite Analyzer). METCAN is patterned after and has 

many of the features of the ICAN computer code (ref. 2). I 

The various factors, which influence constituent material behavior and 

ultimately the HTMMC behavior, are incorporated through a multifactorinteraction relationship as shown In figure 4 where the rationale for adopting 

this type of relationship is summarized. Additional discussion on this relationship and its application to a specific structural component fabricated 

from HTMMC is found in reference 3. The important points to note in figure 4 

are: (1) the individual effects of the thermal and mechanical load cycles 

NT,NM are explicitly included; (2) the temperature T and the stress u 

induced by these cycles are also explicitly included; (3) the combined 

thermomechanical cyclic effects on the thermomechanical behavior of HTMMC's 

are, therefore, automatically included; and (4) the various effects are 

2 
normalized with respect to reference properties which are usually taken as room 

temperature properties. 

The important points of the above discussion are (1) METCAN can be used 

to computationally simulate the high temperature nonlinear behavior of HTMMC's 

from the fabrication process through service and from global structure response 

to local constituent response including the interface/interphase regions, and 

(2) METCAN can be used as a preprocessor to any global structural (thermal) 

analysis with anisotropic material capability and also as a postprocessor to 

this same global structural analysis. METCAN is a comprehensive and continuously evolving computer code. In this respect, it is difficult at present to 

verify all of its predictive capabilities since most of the necessary data do 

not exist. Even so, the code is continuously validated (compared with other 

computational predictions) and verified (compared with available or currently 

acquired experimental data). The room temperature constituent properties used 

to generate the results that follow are given in Table I. Verification compari sons of room temperature stresslstrain response for tungsten/copper HTMMC are 

shown in figure 5 for two fiber volume ratios. Similar results for graphitel 

copper, but only at one fiber volume ratio, are shown in figure 6. The experimental data was obtained by J. Diaz, Materials Division, NASA Lewis Research 

Center. Note that METCAN predicts higher stress and strain to fracture for 

the graphite/copper which could indicate fiber damage during the fabrication 

process. Verification and validation comparisons for borsic/titanium metal 

matrix composite are shown in figure 7. The agreement is good i n a l l these 

comparisons, except as already noted. Validation comparisons for room temperature thermal and mechanical properties for a specific graphite fiber (P100)/ 

copper matrix (Cu) HTMMC with four different fiber volume ratios are summarized 

in table 11. These comparisons also show excellent agreement. Though these 

comparisons are admittedly limited, they do indicate that one can computationally simulate the thermomechanical behavior of HTMMC using METCAN with some 

confidence. 

COMPUTATIONAL SIMULATION OF CYCLIC BEHAVIOR 

The thermal/mechanical cyclic behavior of HTMMC is computationally simulated by using the following procedure: 

(1) Calculate the microstresses from global thermal and structural analyses using the respective cyclic loads as inputs to these global analyses. Note 

the global analyses are performed using finite element analysis of the structural component (top part (undashed) fig. 3). 

(2) Enter the magnitude of these microstresses and the respective number 

of thermal and mechanical cycles in the multifactor relationship in figure 4. 

(3) Apply the next cycle loads to the structure and/or laminate and simulate the desired behavior using the incremental-iterative procedure mentioned 

previously. See references 1 and 3 for more detailed descriptions. 

All of the above steps and the required convergences are automatically performed in METCAN and are transparent to the user. 

3 
METCAN predicted longitudinal stresslstrain responses for four ply 

[0/90/90/01 PlOO/Cu after a specific number of accumulated mechanical cycles 

are shown in figure 8. These curves were generated by assuming that: (1) the 

limit number of mechanical load cycles was 1 million, and (2) the cyclic stress 

amplitudes were the following ratios of the reference stress (static fracture 

stress): 85 percent for 100 000 cycles, 65 percent for 500 000 cycles, and 50 

percent for 800 000 cycles. It is interesting that the reference curve and the 

100 000 cycles curve exhibit some nonlinear behavior while the other two curves 

are practically linear. The important observations from the results shown in 

figure 8 are: (1) mechanical cyclic loading degrades the cyclic stress magnitude but does not induce any discernable nonlinearities on the stresslstrain 

behavior; and'(2) the curves do not'start at zero strain because of residuals 

due to fabrication. Corresponding results for thermal load cycling are shown 

in figure 9. The number of accumulated thermal load cycles and the temperature 

range are shown in the figure. Note that the curves start at nonzero strains 

because of the fabrication residuals already mentioned and because the curve 

is generated at the elevated temperature. The limit number of thermal cycles 

was assumed to be 400 for generating these curves. Similarly METCAN predicted 

thermal cyclic load results are shown in figure 10 for a tungsten/copper HTMMC 

and in figure 11 for silicon-carbide/titanium-aluminide. The important point 

to be observed from the thermal cycling load curves is that thermal cycling has 

severe degradation effects on the endurance of HTMMC's. 

SIGNIFICANCE OF THE INTERPHASE AND IN SITU PROPERTIES 

HTMMC either have no metallurgical bond at the interface or develop an 

interphase as a result of the fiber-matrix reaction (interdiffusion). The 

micromechanics model in METCAN incorporates the interphase as a separate constituent with independent properties. As such the effects of bond integrity 

on HTMMC behavior can be evaluated with judicious use of METCAN by using an 

interphase with suitable properties. Results from one such evaluation are 

shown in figure 12. As would be expected, both the interface and the in situ 

properties of the matrix have dramatic effects on the transverse tensile 

strength of this particular HTMMC. It is noted that the average experimentally measured strength is about 2 ksi which corresponds to the lowest value 

shown in figure 12. This value was obtained by assuming no interface and 

dlinealed at yield in situ matrix conditions as inputs to METCAN. The important 

observation in figure 12 is that METCAN can be used to assess the fabrication 

process as well as the effects of variable constituent in situ behavior on 

HTMMC performance. For example, the lowest value indicates inadequate fabrication quality and inefficient use of copper as a matrix; 

value indicates that there is considerable room for improvement. This type of 

information is routinely obtained using METCAN, which provides an expedient 

capability for conducting a variety of parametric studies. 

while the highest 

~ 

SIMULATION OF COMBINED THERMOMECHANICAL CYCLING AND INTERFACE EFFECTS t 

METCAN simulations of the effects of combined thermomechanical cycling are 

shown in figure 13 for a SiC/Ti HTMMC. Comparisons with experimental data of 

the half cycle stress-strain response for a unidirectional composite and for an 

angleplied [+3012s laminate are also shown. The dip in the experimental data 

represents, in part, the onset of excessive nonlinearities caused by high 

4 
. 

intralaminar shear stress in the 30° plies under displacement control testing. 

The experimental data were obtained by Dr. 6. Lerch, Structures Division, NASA 

Lewis. The individual load cyclic effects are included for comparison purposes. As can be seen, combined cycling (lower right curves) degrades the 

mechanical behavior of HTMMC at a faster rate than do either of the individual 

loadings or their algebraic superposition. The important observation from the 

above discussion is that traditional isothermal cyclic data will be inadequate 

and even misleading for assessing the combined thermomechanical cyclic loading 

degradation effects on the behavior of HTMMC. 

The effects of an interphase on thermal load cycling (fatigue), assuming 

400 maximum thermal cycles between 70 and 1000 OF, are shown in figure 14. 

Comparisons to those without the interphase at the end points are summarized 

in the following table. 

Number of Without interphase With 5-percent interphase 

accumulated stress (strain), stress (strain), 

cycles ksi (percent) ksi (percent) 

1 78 (0.44) 

100 69 (0.42) 

200 69 (0.42) 

300 43 (0.43) 

66 (0.44) 

60 (0.42) 

49 (0.42) 

40 (0.46) 

About the only observation to be made from these results is that the presence 

of the interphase tends to progressively degrade the stress magnitude at fracture, but not the fracture strain level for all practical purposes. Other 

tentative observations are: (1) the interphase has negligible effect on the 

fracture stress magnitude at relatively high thermal cycles, and (2) it has 

moderate degradation effects (about 16 percent) at relatively low number of 

thermal cycles. Again, the important conclusion is that METCAN can be used, 

rather routinely, to evaluate these effects which are complex and difficult to 

expcrimentally measure. 

tegic experiments to selectively measure some of these effects. 

Also METCAN can be used to aid the planning of straCONCLUDING REMARKS 

The significant conclusions of an investigation to develop a procedure 

which can be used to computationally simulate the cyclic behavior of HTMMC are 

as follows: 

1. The cyclic behavior of HTMMC can be computationally simulated by using 

high temperature composite mechanics in conjunction with a multifactorinteraction relationship and with an incremental/interative nonlinear solution 

procedure. 

cation process, through thermomechanical cyclic loadings, and accounting for 

the interphase. 

2. The computational simulation can be performed starting with the fabri3. A computer code has been developed to perform these types of computational simulations in an effective and routine manner. 

5 
4. Results from this compu,zr code show that combined thermomechanical 

cycling degrades the HTNMC structural integrity at a faster rate than the 

algebraic superposition of the two individual effects. 

5. The interphase mainly affects the fracture stress at practically all 

levels of thermal cycling; it minimally effects the fracture strain, and then 

only at relatively high numbers of thermal cycles. 

6. The interface has dramatic effects on the transverse tensile strength 

as do the in situ properties of the matrix. 

itive variab.les, which contribute to these effects can be quantified. 

The ranges of values of the prim7. The type of computational simulation (or the respectively computer 

code) described herein can and should be validated and verified continuously 

in order to ascertain its predictive adequacy. 

REFERENCES 

1. Hopkins, D.A. and Chamis, C.C., "A Unique Set of Micromechanics Equations 

for High Temperature Metal Matrix Composites," NASA TM-87154, National 

Aeronautics and Space Administration, Washington, D.C., 1985. 

2. Murthy, P.L.N. and Chamis, C.C., Journal of Composites Technology and 

Research, Vol. 8, No. 1, Spring 1986, pp. 8-17. 

3. Chamis, C.C. and Hopkins, D.A., "Thermoviscoplastic Nonlinear Constitutive 

Relationships for Structural Analysis of High Temperature Metal Matrix 

Compos1 tes," NASA TM-87291, National Aeronautics and Space Administration, 

Washington, D.C., 1985. 

. 

6 
I Property type 

TABLE I. - ROOM TEMPERATURE CONSTITUENT PROPERTIES 

USED IN THE CURRENT STUDY 

' Mat 

Property type 

- 

PlOO 

6600 

105 

0.9 

1.1 

0.7 

0.2 

0.25 

-0.9 

5.6 

7.5 

0.75 

325 

200 

25 

25 

25 

12.5 

SiCA 

4870 

62 

62 

23.8 

23.8 

0.3 

0.3 

1.8 

1.8 

0.75 

0.75 

500 

650 

500 

650 

300 

300 

Fiber 

Borsic 

6000 

58 

58 

29 

29 

0.2 

0.2 

2.8 

2.8 

1.9 

1.9 

510 

600 

100 

200 

100 

100 

Tmm, OF 

E,, mpsi 

V,, in./in. 

am* PPm 

K,, Btu/hr/in./OF 

Sm~, ksi 

S,c, ksi 

S,s, ksi 

Copper 

1980 

17.7 

0.3 

9.8 

19.3 

32 

32 

19 

ix 

Ti 

1800 

12.3 

0.32 

4.5 

0.39 

130 

130 

91 

~ 

Tungsten 

6170 

59 

59 

22.7 

22.7 

0.29 

0.29 

2.5 

2.5 

8.3 

8.3 

390 

390 

390 

390 

236 

236 

7 
TABLE 11. - GRAPHITE/COPPER ROOM TEMPERATURE MECHANICAL AND THERMAL PROPERTIES: 

COMPARISON OF METCAN PREDICTIONS AND 3-0 FINITE ELEMENT ANALYSIS 

[PlOO/Cu at four different fiber volume ratios (FVR).] 

Property type 

0.063 

METCAN 

23.7 

13.8 

13.8 

5.8 

5.6 

5.8 

.29 

.30 

.30 

6.8 

10.4 

10.4 

19.7 

15.6 

15.6 

3-OFEM 

23.1 

14.9 

14.9 

6.0 

5.8 

5.8 

.30 

.30 

.30 

6.6 

10.5 

10.5 

20.6 

17.3 

17.3 

FVR 

0.2234 

METCAN 

37.3 

10.2 

10.2 

4.5 

4.2 

4.5 

.28 

.30 

.30 

3.3 

11.0 

11.0 

20.6 

11.8 

11.8 

3-OFEM 

36.7 

11.0 

11.0 

4.8 

4.5 

4.5 

.30 

.26 

.26 

3.7 

10.9 

10.9 

21.6 

13.5 

13.5 

0.466 

METCAN 

58.4 

6.5 

6.5 

3.2 

2.8 

3.2 

.25 

.30 

.30 

1 .o 

11.2 

11.2 

22.0 

7.8 

7.8 

CONSTITUTIVE I.1 = [DI[BlIul 

EQUATION % l.1 5 IS3 

NATURAL 

FREQUENCY 

EIGENPROBLEM \ USWA 

3-OFEM 

58.0 

6.9 

6.9 

3.4 

2.7 

2.7 

.29 

.22 

.22 

1.40 

11.1 

11.1 

23.2 

8.8 

8.8 

0.622 

METCAN 

72.0 

4.6 

4.6 

2.5 

2.1 

2.5 

.24 

.30 

.24 

.18 

11.1 

11.1 

22.8 

5.8 

5.8 

3-DFEM 

71.8 

5.0 

5.0 

2.6 

1.8 

1.8 

.28 

.19 

.22 

.42 

10.9 

10.9 

24.0 

6.3 

6.3 

FIWE 1. - OVERVIEW OF STRUCTURAL ANALYSIS. 

8 
MIX 

MATRIX 

POWDER 

+ 

TEFLON 

BINDER 

t 

STODDARO 

SOLUTION 0 

HEAT ROLL POWDER 

CLOTH 

67 0 0 0 00 0 00 

COMPOSITE 

LAY UP AND HOT PRESS 

FIGURE 2. - ETAL-MTRIX CWOSITE FABRICATION PROCESS. 

COMPONENT 

FINITE ELEMENT FINITE ELEMENT 

/ TOP-DOWN 

UPWARD \, CONSTITUENTS 

INTEGRATED \ 

OR 

"SYNTHESIS" 

MATERIAL PROPERTIES , TRACED 

I OR P (u. T, t I I --- __ - - -- "DECOMPOSITION" '1. 

FIGURE 3. - INTEGRATED MILTI-SCALE CWUTATIW S1IUUTIO)I. 

9 
RATIONALE: 

,- MATRIX 

I rINTERPHASE 

SUBREGIONS OF 

INTRALAMINAR 

NONUNIFORMITY 7.. . 

2, +t 

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

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

0 INTRODUCTION OF PRIMITIVE VARIABLES (PV) 

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 

NOTATIONS: 

P - PROPERTY: T - TEMPERATURE; S - STRENGTH: R - METALLURGICAL REACTION: N - NUMBER OF CYCLES; t - TIME: 

OVER DOT - RATE; SUBSCRIPTS: 0 - REFERENCE; F - FINAL; M - KCHANICAL; T - THERMAL 

FIGURE 4. - MULTIFACTOR INTERACTION RELATIONSHIP FOR IN SITU CONSTITUENT MATERIAL BEHAVIOR. 

- 

0 EXPERIMENTAL DATA FIBER VOLUME 

METCAN PREDICTION FRACTION, 

PERCENT 

LONGITUDINAL STRAIN, PERCENT 

FIGURE 5. - UNIDIRECTIONAL TUNGSTEN/COPPER MC ROOM EMPERATURE STRESS-STRAIN RESPONSE. 

0 .I .2 . .3 .4 .5 

STRAIN EPS XX. PERCENT 

FIGURE 6. - Gr/CU CWOSITES ROON TEMPERATURE STRESSSTRAIN BEHAVIOR (UNIDIRECTIONAL MIIIATE AT .4 FVR). 

10 
. MEASURE0 ’ 

0 THREE-DIMENSIONAL 

FINITE ELEMENT SIMULATION 

METCAN 

LONGITUDINAL TRANSVERSE 

FIGURE 7. - UNIDIRECTIONAL BORSIC/TITANIUN MC ELASTIC 

MODULI AT ROOM TWERATURE. 

75 - 

[0/90/90/01 

60 - 

- 

v) X

(70 - 500 F)-t 

E 45- 

s 

v) 

v) (70 - loo0 F) v) 30- 

si 

kY 

I 

-.080 .076 .182 .288 .394 .500 

STRAIN EPS XX. PERCENT 

FIGURE 9. - THERMAL CYCLIC EFFECTS OF PlOO/CU CWOSITE 

(AT .4 FVR). 

STRESS EPS XX. PERCENT 

FIGURE 8. - MECHANICAL CYCLIC LOAD EFFECTS (P100/Cu AT .4 

FVR), 

STRAIN EPS XX, PERCENT 

FIGURE 10. - THERNAL CYCLIC EFFECTS OF TUNGICU COMPOSITE 

(AT .4 FVR). 

11 
200- 

[0/90/90/01 

160 - 

- 

v) x

(70 - 1000 F) 

1 

-.60 -.34 -.08 -18 .44 .70 

STRAIN EPS XX. PERCENT 

FIGURE 11. - THERHAL CYCLIC EFFECTS OF sica/Tils CofposITE 

(AT .4 FVR). 

WITHOUT INTERFACE 

WITH INTERFACE 

H 2ot 

YIELD FRACTURE YIELD FRACTURE 

FIGURE 12. - UNIDIRECTIONAL GRAPHITE/COPPER MC TRANSVERSE 

STUEWGTH BOUWDS. 

12 
CYCLIC BEHAVIOR 

4 

250 

200 

150 

100 

50 

EXP' [O' 

0 

1/2 CYCLIC r UNIAXIAL BEHAVIOR 

0 .24 .48 .72 .% 1.20 

I 

0 .24 .48 -72 .% 1.20 

STRAIN EPS XX, PERCENT 

FIGURE 13. - PETCAN PREDICTIONS FOR THE-CHANICAL CYCLING OF mC tSiC/ll 15 333 AT .36 FVR). 

64 - M 

X v) 

E 48- 

B 

LI 

32- 

ln W 

V) 

e 

16 - 

n I 

-.lo .02 .14 .26 .38 .50 

STRAIN EPS XX. PERCENT 

FIGURE 14. - [0/90/90/01 PlOO/CU WITH 5 PERCENT INTERPHASE THEW FATIGUE EFFECTS. 

13 
National Aeronautics and Report Documentation Page 

Space Administration 

1. Report No. I 2. Government Accession No. 

17. Key Words (Suggested by Author(s)) 

Graphite/copper; Tungstedcopper; 

Silicon-carbide/Ti-A1; Stress; Strain curves; 

Interface; Interphase; In-situ effects; 

ThermaUmechanical cycling 

NASA TM-102115 I 

18. Distribution Statement 

Unclassified - Unlimited 

Subject Category 24 

I 

4. Title and Subtitle 

Computational Simulation of High Temperature Metal Matrix 

Composites Cyclic Behavior 

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

Unclassified Unclassified 14 

7. Author(@ 

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

22. Price' 

A03 

9. Performing Organization Name and Address 

National Aeronautics and Space Administration 

Lewis Research Center 

Cleveland, Ohio 44135-3191 

12. 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-4888 

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 

15. Supplementary Notes 

Invited paper presented at the ASTM Symposium on Thermal and Mechanical Behavior of Ceramic and Metal 

Matrix Composites, Atlanta, Georgia, November 7-8, 1988. 

16. Abstract 

A procedure was developed and is described which can be used to computationally simulate the cyclic behavior 

of high temperature metal matrix composites (HTMMC) and its degradation effects on the structural response. 

This procedure consists of HTMMC mechanics coupled with a multifactor-interaction constituent material relationship and with an incremental iterative nonlinear analysis. The procedure is implemented in a computer code 

that can be used to computationally simulate the thermomechanical behavior of HTMMC starting from the fabrication process and proceeding through thermomechanical cycling, accounting for the interfacehnterphase region. 

Results show that combined thermal/mechanical cycling, the interphase, and in situ matrix properties have 

significant effects on the structural integrity of HTMMC.