Residual stresses in composites are induced during fabrication and by environmental exposure. The theory formulated can describe the shrinkage commonly observed after a thermal expansion test. Comparison between the analysis and experimental data for [02/± 45]s laminates of various material systems indicates that the residual stress-free temperature can be lower than the curing temperature, depending on the curing process. Ef fects of residual stresses on ply failure including the acoustic emission characteristics are discussed.
Get full access to this article
View all access options for this article.
References
1.
D.R. Doner and R.C. Novak, "Structural Behavior of Laminated Graphite Filament Composites," 24th Annual Tech. Conf, SPI, Inc., 1969, paper 2-D.
2.
R.C. Novak and M.A. DeCrescente , "Fabrication Stresses in Graphite Resin Composites ," J. Engineering for Power, Vol. 92 (1970), p. 377.
3.
C.C. Chamis and T.L. Sullivan, "A Computational Procedure to Analyze Metal Matrix Laminates With Nonlinear Lamination Residual Strains ," Composite Reliability, ASTM STP580, 1975, p. 327.
4.
M.A. Wright , "The Effect of Thermal Cycling on the Mechanical Properties of Various Aluminum Alloys Reinforced with Unidirectional Boron Fibers," Met. Trans. A., Vol. 6A (1975), p. 129.
5.
H.T. Hahn and N.J. Pagano, "Curing Stresses in Composite Laminates," J. Composite Materials, Vol. 9 (1975), p. 91.
6.
N.J. Pagano and H.T. Hahn, "Evaluation of Composite Curing Stresses," Presented at ASTM 4th Conf. on Composite Materials, May 1976 .
7.
R.A. Schapery , "Thermal Expansion Coefficients of Composite Materials Based on Energy Principles," J. Composite Materials , Vol. 2 (1968), p. 380.
8.
Z. Hashin, "Theory of Fiber Reinforced Materials," NASA Contract NAS1-8818, Nov. 1970.
9.
G. Marom and A. Weinberg, "The Effect of the Fiber Critical Length on the Thermal Expansion of Composite Materials," J. Mat. Sci., Vol. 10 (1975), p. 1005.
10.
H.T. Hahn and D.H. Morris, "Anisotropic Photoelasticity with Application to Composites," Presented at 1976 SESA Spring Meeting, May 1976 .
11.
Proceedings of the AFOSR Workshop, " The Influence of Relative Humidity and Elevated Temperature on Composite Materials and Structures," Univ. of Delaware, Mar. 1976.
12.
C.-H. Shen and G.S. Springer, "Moisture Adsorption and Desorption of Composite Materials," J. Composite Materials, Vol. 10 (1976), p. 36.
13.
W.T. Freeman and M.D. Campbell, "Thermal Expansion Characteristics of Graphite-Reinforced Composite Materials," Composite Materials: Testing and Design (Second Conf.), ASTM STP497, 1972, p. 121.
14.
K.E. Hofer , N. Rao, Jr., and D. Larsen, "Development of Engineering Data on the Mechanical and Physical Properties of Advanced Composite Materials ," AFML-TR-72-205 Parts I and II, Air Force Materials Lab. , Sept. 1972 and Feb. 1974.
15.
K.E. Hofer , D. Larsen, Jr., and V.E. Humphreys, "Development of Engineering Data on the Mechanical and Physical Properties of Advanced Composite Materials," AFML-TR-74-266, Air Force Materials Lab., Feb. 1975.
16.
Y. Weitsman , "Diffusion with Time-Varying Diffusivity, with Application to Moisture-Sorption in Composites," To be published in J. Composite Materials, 1976.
17.
I.M. Daniel and T. Liber, "Lamination Residual Stresses in Fiber Composites," NASA CR-134826, Mar. 1975.
18.
S.W. Tsai and H.T. Hahn, "Failure Analysis of Composite Materials," Inelastic Behavior of Composite Materials, AMD-Vol. 13, ASME1975.
19.
S.W. Tsai, "Strength Characteristics of Composite Materials," NASA CR-224, Apr. 1965.
