Effects of Changing Environment and Loading Speed on Mechanical Behavior of FRP Composites

Abstract

Durability of fiber reinforced polymer composites (FRP) are controlled by the durability of their constituents: reinforcement fibers, resin matrices, and the status of interfaces. A great deal of research has been focused on attempting to assess the relationship between interfacial structure and properties of fiber-matrix composites. It is at the interfacial area where stress concentration develops because of differences in the thermal expansion coefficients between the reinforcement and the matrix phase. A significant mismatch in the environmentally induced degradation of matrix and fiber leads to the evolution of localized stress and strain fields in the FRP composite. The present investigation aims to study the effects of changing hygrothermal conditioning cycles (either by changing relative humidity (RH) and keeping the temperature constant, or by changing the temperature while RH the same is maintained) on moisture gain/loss kinetics and on interlaminar shear strength (ILSS) of varied weight fraction glass fiber reinforced epoxy and polyester matrices composites. The mechanical assessment is extended to evaluate the loading rate sensitivity of hygrothermally shocked glass/epoxy and glass/polyester laminates at 2 and 50 mm/min crosshead speeds, respectively. Observations on absorption/desorption kinetics are noticed to be dependent on the nature of hygrothermal shock cycle and on the weight fraction of fiber reinforcement. The results of mechanical performance are statistically significant at different stages of conditioning. Shear values are found to be greater at higher crosshead speed for all undertaken situations. Mechanical responses are observed to be dependent on the matrix resin and the type of hygrothermal shock cycle. Very little and limited literature is open to address the important interactions of polymer composites with this kind of realistic environmental situation.

Keywords

glass fiber epoxy polyester hygrothermal shock absorption/desorption mechanical behavior crosshead speed

Get full access to this article

View all access options for this article.

References

Bockenheimer, C. , Fata, D. and Possart, W. (2004). New Aspects of Aging in Epoxy Networks. I. Thermal Aging , Journal of Applied Polymer Science, 91(1): 361-368 .

Jang, B. Z. (1994). Interfaces and Interphases in Composites, Advanced Polymer Composites, ASM International, Materials Park, OH .

Gonzalez-Benito, J. (2003). The Nature of the Structural Gradient in Epoxy Curing at a Glass Fiber/Epoxy Matrix Interface using FTIR Imaging , Journal of Colloid and Interface Science, 267(2): 326-332 .

Canavate, J. , Pages, P. , Saurina, J. , Colom, X. and Carrasco, F. (2000). Determination of Small Interactions in Polymer Composites by means of FTIR and DSC , Polymer Bulletin, 44(3): 293-300 .

Fllyin, F. and Rohrbacher, C. (2003). The Influence of Aqueous Environment, Temperature and Cyclic Loading on Glass-fiber/Epoxy Composite Laminates , Journal of Reinforced Plastics & Composites, 22(7): 615-635 .

Omiya, M. , Kishimoto, K. and Yang, W. (2002). Interface Debonding Model and its Application to the Mixed Mode Interface Fracture Toughness , International Journal of Damage Mechanics, 11(3): 263-286 .

Smith, B. L. , Schaffer, T. E. , Viani, M. , Thompson, J. B. , Frederrck, N. A. , Kindt, J. , Belchers, A. , Strucky, G. D. , Morse, D. E. and Hansma, P. K. (1999). Molecular Mechanistic Origin of the Toughness of Natural Adhesive, Fibres and Composites , Nature, 399(6738): 761-763 .

Sanders, B. (ed.). (2004). Characterization and Failure Analysis of Plastics, ASM International, Materials Park, OH .

Nairn, J. A. (2000). Matrix Microcracking in Composites, In: Kelly, A. and Zweben, C. (ed.), Comprehensive Composite Materials, Vol. 2, pp. 403-432, Elsevier, Oxford .

10.

Pagano, N. J. and Schoeppner, G. A. (2000). Delamination of Polymer Matrix Composites: Problems and Assessment, In: Kelly, A. and Zweben, C. (ed.), Comprehensive Composite Materials, Vol. 2, pp. 433-436, Elsevier, Oxford .

11.

Schutte, C. L. (1994). Environmental Durability of Glass-fiber Composites , Materials Science and Engineering, R13(7): 265-324 .

12.

Roy, S. , Xu, W. , Patel, S. and Case, S. (2001). Modeling of Moisture Diffusion in the Presence of Bi-axial Damage in Polymer Matrix Composite Laminates , International Journal of Solids and Structures, 38(42-43): 7627-7641 .

13.

Vaddadi, P. , Nakamura, T. and Singh, R. P. (2003). Inverse Analysis for Transient Moisture Diffusion through Fiber-reinforced Composites , Acta Materialia, 51(1): 177-193 .

14.

Herrera-Franco, P. J. and Drzal, L. T. (1992). Comparison of Methods for the Measurement of Fiber/Matrix Adhesion in Composites , Composites, 23(1): 3-26 .

15.

Drzal, L. T. , Rich, M. J. and Lloyd, P. F. (1982). Adhesion of Graphite Fiber to Epoxy Matrices. I. The Role of Fiber Surface Treatment , Adhesion, 16(1): 1-30 .

16.

Bockenheimer, C. , Fata, D. and Possart, W. (2004). New Aspects of Aging in Epoxy Networks. II. Hydrothermal Aging , Journal of Applied Polymer Science, 91(1): 369-377 .

17.

Gaur, U. and Miller, B. (1990). Effects of Environmental Exposure on Fiber/Epoxy Interfacial Shear Strength , Polymer Composites, 11(4): 217-222 .

18.

Reinhart, T. J. (Technical Chairman). (1998). Composites, In: Engineered Materials Handbook, Vol. 1, 5th Printing, ASM International, Metals Park, OH .

19.

Ray, B. C. (2004). Thermal Shock on Interfacial Adhesion of Thermally Conditioned Glass Fiber/Epoxy Composites , Materials Letters, 58(16): 2175-2177 .

20.

Ray, B. C. (2004). Effects of Crosshead Velocity and Sub-zero Temperature on Mechanical Behavior of Hygrothermally Conditioned Glass Fiber Reinforced Epoxy Composites , Materials Science and Engineering, A379(1-2): 39-44 .

21.

Zafeiropoulos, N. E. , Baillie, C. A. and Hodgkinson, J. M. (2002). Engineering and Characterisation of the Interface in Flax Fiber/Polypropylene Composite Materials. Part II. The Effect of Surface Treatments on the Interface , Composite: Part A, 33(9): 1185-1190 .

22.

Yano, O. and Yamaoka, H. (1995). Cryogenic Properties of Polymers , Progresses in Polymer Science, 20(4): 585-613 .

23.

Dutta, P. K. and Hui, D. (1996). Low-temperature and Freeze-thaw Durability of Thick Composites , Composites, Part B, 27B(3-4): 371-379 .

24.

Gu, W. , Wu, H. F. , Kampe, S. L. and Lu, G.-Q. (2000). Volume Fraction Effects on Interfacial Adhesion Strength of Glass-fiber-reinforced Polymer Composites , Materials Science & Engineering, A277(1-2): 237-243 .

25.

Jacob, G. C. , Starbuck, J. M. , Fellers, J. F. and Simunovic, S. (2004). Strain Rate Effects on the Mechanical Properties of Polymer Composite Materials , Journal of Applied Polymer Science, 94(1): 296-301 .

26.

Liu, C. T. and Smith, C. W. (1996). Temperature and Rate Effects on Stable Crack Growth in a Particulate Composite Material , Experimental Mechanics, 36(3): 290-295 .

27.

Ray, B. C. (2005). Thermal Shock and Thermal Fatigue on Delamination of Glass-fiber-reinforced Polymeric Composites , Journal of Reinforced Plastics & Composites, 24(1): 111-116 .

28.

Gilat, A. , Goldberg, R. K. and Roberts, G. D. (2002). Experimental Study of Strain-rate-dependent Behavior of Carbon/Epoxy Composite , Composites Science and Technology, 62(10-11): 1469-1476 .

29.

Okoli, O. I. and Smith, G. F. (2000). The Effect of Strain Rate and Fiber Content on the Poisson’s ration of Glass/Epoxy Composites , Composite Structures, 48(1-3): 157-161 .

30.

Spathis, G. and Kontou, E. (2004). Non-linear Viscoplastic Behavior of Fiber reinforced Polymer Composites , Composites Science and Technology, 64(15): 2333-2340 .

31.

Merdas, I. , Thominette, F. , Teharkhtchi, A. and Verdu, J. (2002). Factors Governing Water Absorption by Composite Matrices , Composites Science and Technology, 62(4): 487-492 .

32.

Ray, B. C. (2005). Effect of Hydrothermal Shock Cycles on Shear Strength of Glass Fiber-Polyester Composites , Journal of Reinforced Plastics & Composites, 24(12): 1335-1340 .

33.

Ray, B. C. (2005). Hydrothermal Fatigue on Interface of Glass-epoxy Laminates , Journal of Reinforced Plastics & Composites, 24(10): 1051-1056 .

34.

Ray, B. C. (2005). Effects of Thermal and Cryogenic Conditionings on Mechanical Behavior of Thermally Shocked Glass Fiber-Epoxy Composites , Journal of Reinforced Plastics & Composites, 24(7): 713-717 .

35.

Lekatou, A. , Faidi, S. E. , Ghidaoui, D. , Lyon, S. B. and Mewman, R. C. (1997). Effect of Water and its Activity on Transport Properties of Glass/Epoxy Particulate Composites , Composites Part A, 28(3): 223-236 .

36.

Hancox, N. L. (1998). Thermal Effects on Polymer Matrix Composites: Part 1. Thermal Cycling , Materials & Design, 19(3): 85-91 .

37.

Mukherjee, N. and Aditya, P. K. (2002). A Micromechanical Model to Study Hygrothermal Shocks at the Fiber-matrix Interface , Journal of Reinforced Plastics & Composites, 21(14): 1271-1283 .

38.

Kasen, M. and Santoyo, R. (1995). Interfacial Residual Thermal Strain , Cryogenics, 35(11): 731-733 .

39.

Tang, X. , Whitcomb, J. D. , Li, Y. and Sue, H.-J. (2005). Micromechanics Modeling of Moisture Diffusion in Woven Composites , Composites Science and Technology, 65(6): 817-826 .

40.

Hull, D. and Clyne, T. W. (1996). The Interface region, An Introduction to Composite Materials, 2nd Edn, p. 138-138, Cambridge University Press, Cambridge .

41.

Tang, J. M. and Springer, G. S. (1988). Effect of Moisture and Temperature on the Compressive and Short Beam Shear Properties of Fiberite T300/976 Fabric , Journal of Reinforced Plastics & Composites, 7(2): 120-135 .