An algorithm was developed based on diffusion and hygrothermal expansion theories to quantify the real-time hygrothermal deformation of a composite structure. The algorithm can be used to calculate the dynamic hygrothermal strain of composite laminates that is caused by constantly changing environmental humidity and temperature. Experiments were performed on carbon/ epoxy laminates in a conditioning chamber where relative humidity and temperature were set to vary stepwise and the hygrothermal strains of the specimens were monitored. The hygrothermal strains were calculated theoretically from humidity and thermal history throughout each experiment and confirmed experimentally.
Daniel, I.M. and Ishai, O. (2006). Engineering Mechanics of Composite Materials: Hygrothermal Effects, Oxford University Press, New York.
2.
Gazit, S. and Ishai, O. (1977). Hygroelastic Behavior of Glass-Reinforced Plastics Exposed to Different Relative Humidity Levels. In: Proceedings of Conference on Environmental Degradation of Engineering Materials, pp. 383-392, Virginia Polytechnic Inst., Blacksburg, VA.
3.
Tsai, C.-L., Chang, T.-W., Yeih, W. and Chang, J.-J. (2007). Tracking the Moisture Expansion of Carbon/Epoxy Composite Exposed to Varying Humidity, Accepted by Journal of Composite Materials, JCM#0612244.
4.
Crank, J. (1975). The Mathematics of Diffusion, 2nd edn, Oxford University Press, New York.
5.
Pierron, F., Poirette, Y. and Vautrin, A. (2002). A Novel Procedure for Identification of 3D Moisture Diffusion Parameters on Thick Composites: Theory, Validation and Experimental Results, Journal of Composite Materials, 36(19): 2219-2243.
6.
Tsai, C.-L., Cheng, M.-C., Hwang, S.-F. and Tsai, Y.-S. (2004). Characterizing the Hygric Behavior of Composites by Suspending Method. Journal of Composite Materials, 38(9): 757-768.
7.
Loos, A.C. and Springer, G.S. (1979). Moisture Absorption of Graphite-Epoxy Compositions Immersed in Liquids and in Humid Air, Journal of Composite Materials, 13: 131-147.
8.
Shen, C.-H. and Springer, G.S. (1976). Moisture Absorption and Desorption of Composite Materials, Journal of Composite Materials, 10: 2-20.
9.
Tsai, C.-L. and Chiang, C.-H. (2002). Pneumatic Strain of Woven Glass/Epoxy Composite Laminate Induced by Fluctuating Air Pressure, Composite Science and Technology, 62: 451-456.
10.
Tsai, C.-L. , Cheng, M.-C. and Chang, S.-L. (2007). Gradient-Dependent Model for Moisture Diffusion in Polymer Matrix Composite Laminate, Journal of Composite Materials, 41: 419-434.
11.
Tsai, C.-L. and Daniel, I.M. (1994). Method for Thermal-Mechanical Characterization of Single Fibers, Composites Science and Technology, 50: 7-12.
