Monotonic tensile and fatigue response of continuous silicon carbide fiber reinforced silicon nitride (SiCf/Si3N4) composites has been investigated. The monotonic tensile tests have been performed at room and elevated temperatures. Fatigue tests have been conducted at room temperature (RT), at a stress ratio, R = 0.1 and a frequency of 5 Hz. It is observed during the monotonic tests that the composites retain only 30 percent of its room temperature strength at 1600°C suggesting a substantial chemical degradation of the matrix at that temperature. The softening of the matrix at elevated temperature also causes reduction in tensile modulus, and the total reduction in modulus is around 45 percent. Fatigue data have been generated at three load levels and the fatigue strength of the composite has been found to be considerably high; about 75 percent of its ultimate room temperature strength. Extensive statistical analysis has been performed to understand the degree of scatter in the fatigue as well as in the static test data. Weibull shape factors and characteristic values have been determined for each set of tests and their relationship with the response of the composites has been discussed. A statistical fatigue life prediction method developed from the Weibull distribution is also presented. Maximum Likelihood Estimator with censoring techniques and data pooling schemes has been employed to determine the distribution parameters for the statistical analysis. These parameters have been used to generate the S-N diagram with desired level of reliability. Details of the statistical analysis and the discussion of the static and fatigue behavior of the composites are presented in this paper.

1.
Askeland, D. R., The Science and Engineering of Materials, 3rd Edition, 1994, PWS Publishing Company, Boston, MA 02116-4324.
2.
Bain, L. J. and Englehardt, M., 1991, Statistical Analysis of Reliability and Life-Testing Models, Marcel Dekker, Inc., New York
3.
Daniel
 
I. M.
, and
Anastassopoulos
 
G.
,
1995
, “
Failure Mechanisms and Damage Evolution in Cross-ply Ceramic-Matrix Composites
,”
Int. J. Solids Structures
, Vol.
32
,
3/4
, pp.
341
355
.
4.
Dauskardt
 
R. H.
, and
Ritchie
 
R. O.
,
1987
, “
Fatigue Crack Propagation in Transformation-Toughened Zirconia Ceramic
,”
J. Am. Ceram. Soc.
, Vol.
70
(
10
), pp.
C-248–C-252
C-248–C-252
.
5.
Dauskardt
 
R. H.
,
Marshall
 
D. B.
, and
Ritchie
 
R. O.
,
1990
, “
Cyclic Fatigue-Crack Propagation in Magnesia-partially Stabilized Zirconia Ceramics
,”
J. Am. Ceram. Soc.
, Vol.
73
(
4
), pp.
893
903
.
6.
Dhingra
 
A. K.
,
1986
, “
Aramid Fiber Composites for General Engineering
,”
Journal of Metal
, Vol.
38
, pp.
21
5
, Mar.
7.
Dodson, B., 1994, Weibull Analysis, ASQC Quality Press, Milwaukee, WI.
8.
Evans
 
A. G.
,
1980
, “
Fatigue in Ceramics
,”
Int. J. Fract.
, Vol.
16
(
6
), pp.
485
498
.
9.
Evans
 
A. G.
, and
Linzer
 
M.
,
1976
, “
High Frequency Cyclic Crack Propagation in Ceramic Materials
,”
Int. J. Fract.
, Vol.
12
, pp.
217
22
.
10.
Evans
 
A. G.
, and
Fuller
 
E. R.
,
1974
, “
Crack Propagation in Ceramic Materials under Cyclic Loading Conditions
,”
Metall. Trans.
, Vol.
5
(
1
), pp.
27
33
.
11.
Ewart
 
L.
, and
Suresh
 
S.
,
1992
, “
Elevated-Temperature Crack Growth in Poly-crystalline Alumina under Static and Cyclic Load
,”
Journal of Material Science
, Vol.
27
, pp.
5181
91
, Oct.
12.
Forney
 
R. C.
,
1986
, “
Advanced Composites: Structural Revolutions
,”
Journal of Metal
, Vol.
38
, pp.
18
20
.
13.
Hahn, H. T., 1989, “Fatigue of Composites,” Delaware Composites Design Encyclopedia: Mechanical Behavior and Properties of Composite Materials, Vol. 1, eds., C. Zweben, H. T. Hahn, and T-W Chou, Technomic Publishing Co., Inc., Lancaster, PA, pp. 73–150.
14.
Hale, D. K., and Kelly, A., 1972, “Strength of Fibrous Composite Materials,” Annual Review of Material Science, Vol. 2 R. A. Huffins, R. H. Bube and R. W. Roberts, eds., pp. 405–462.
15.
Holmes
 
J. W.
,
1991
a, “
Influence of Stress Ratio on the Elevated-Temperature Fatigue of a Silicon Carbide Fiber-Reinforced Silicon Nitride Composite
,”
J. Am. Ceram. Soc.
, Vol.
74
(
7
), pp.
1639
45
.
16.
Holmes
 
J. W.
,
1991
b, “
Tensile Creep Behavior of a Fibre-Reinforced Sic-Si3N4 Composite
,”
Journal of Materials Science
, Vol.
26
, pp.
1808
14
, Apr.
17.
James, M. L., Smith, G. M., and Wolford, 1985, Applied Numerical Methods for Digital Computation, 3rd Edition, Harper & Row, Publishers, New York, NY 10022.
18.
Kawakubo
 
T.
, and
Komeya
 
K.
,
1987
, “
Static and Cyclic Fatigue Behavior of a Sintered Silicon Nitride at Room Temperature
,”
J. Am. Ceramic. Soc.
, Vol.
70
, pp.
400
405
, June.
19.
Kishimoto
 
H.
,
Ueno
 
A.
, and
Okawara
 
S.
,
1994
, “
Crack Propagation Behavior of Polycrystalline Alumina under Static and Cyclic Load
,”
Journal of American Ceramic Society
, Vol.
77
, pp.
1324
28
, May.
20.
Mahfuz
 
H.
,
Yu
 
T.
, and
Jeelani
 
S.
,
1993
, “
High Cycle Fatigue Characteristics of Titanium 5Al-2.5Sn Alloy
,”
Journal of Material Science
, Vol.
28
, pp.
138
144
.
21.
Mahfuz
 
H.
,
Maniruzzaman
 
M.
,
Krishnagopalan
 
J.
,
Haque
 
A.
,
Ismail
 
M.
, and
Jeelani
 
S., a
, “
Fatigue Damage and Effects of Stress Ratio on the Fatigue Life of Carbon-Carbon Composites
,”
Journal of Theoretical and Applied Fracture Mechanics
, Vol.
24
(
1995
), pp.
21
31
.
22.
Mahfuz
 
H.
,
Haque
 
A.
,
Yu
 
D.
, and
Jeelani
 
S. b
, “
Response of Resin Transfer Molded (RTM) Composites under Reversed Cyclic Loading
,”
ASME JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY
, Vol.
118
, No.
1
, Jan.
1996
, pp.
49
57
.
23.
Mahfuz
 
H.
,
Das
 
P. S.
,
Jeelani
 
S.
,
Baker
 
D. M.
, and
Johnson
 
S. A.
,
1993
, “
Effect of Mission Cycling on the Fatigue Performance of SiC Coated Carbon-Carbon Composites
,”
Int J Fatigue
, Vol.
15
, No
4
, pp.
283
291
.
24.
Mallick, P. K., 1993, Fiber-Reinforced Composites, Second Edition, Marcel Dekker, Inc., New York, NY 10016.
25.
Mann, N. R., Schafer, R. E. and Singpurwala, N. D., 1974, Methods for Statistical Analysis of Reliability and Life Data, Wiley, New York
26.
Nelson, W., 1982, Applied Life Data Analysis, Wiley, New York.
27.
Press, W. H., Flannery, B. P., Tenkolsky, S. A., and Vetterling, W. T., 1986, Numerical Recipes: The Art of Scientific Computing, Cambridge University Press, Cambridge, U.K.
28.
Prewo, K. M., Brennan, J. J., and Layden, G. K., 1986, “Fiber Reinforced Glasses and Glass-Ceramics for High Performance Applications,” Ceramic Bulletin, Vol. 65(2).
29.
Suresh, S., and Brockenbrough, J. R., 1990, “Cyclic Damage Zones Ahead of Tensile Fatigue Cracks in Ceramic Materials,” Fatigue 90, Vol. II, 4th International Conference on Fatigue, July 15–20, pp. 739–744.
30.
Suresh, S., 1990, “Fatigue Crack Growth in Ceramic Materials at Ambient and Elevated Temperatures,” Fatigue 90, Vol. II, 4th International Conference on Fatigue, July 15–20, pp. 759–768.
31.
Tsai, S. W., 1988, Composite Design, 4th edition, Think Composites, Dayton, Ohio.
32.
Warren, R., 1990, Ceramic-Matrix Composites, Chapmn and Hall, New York, NY 1001–2291.
33.
Whitney, J. M., 1981, “Fatigue Characterization of Composite Materials,” Fatigue of Fibrous Composites, ASTM STP 723, American Society for Testing and Materials, pp. 133–151.
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