Effect of Fiber Orientation and Sample Geometry on the Effective Thermal Conductivity of a Uniaxial Carbon Fiber-Reinforced Glass Matrix Composite

Abstract

From solutions for the thermal conductivity of anisotropic solids, it is pre dicted that the effect of fiber angle on the thermal conductivity of uniaxial fiber-reinforced composites is a function of sample geometry. Experimental data for the effect of fiber an gle on the thermal conductivity of a uniaxial carbon fiber-reinforced aluminoborosilicate glass matrix composite taken from three different sample geometries are presented in sup port of this conclusion. The thermal conductivity of the center portion of samples with a thickness in the direction of heat flow much smaller than their width agreed very well with the corresponding effect predicted for a composite plate of infinite extent. Similar results were obtained for "angled" samples, with a geometry such that the net direction of heat flow was parallel to the fiber direction. In contrast, for samples of rectangular geometry with a thickness of the order of the width, the thermal conductivity data for fiber angles greater than about 45° agreed very well with those predicted for a narrow composite strip with thermally insulated sides. At lower fiber angles, the data for these latter samples were intermediate to those predicted for the infinite composite plate and the insulated strip. The results of this study imply that care needs to be taken in the selection of specimen geom etry when measuring the effect of fiber orientation on thermal conductivity of uniaxial composites, and when using such data in the thermal analysis of composites with different shape and boundary conditions.

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References

Rayleigh, Lord. 1892. "On the Influence of Obstacles Arranged in Rectangular Order upon the Properties of a Medium," Phil. Mag., 34:481.

Maxwell, J.C. 1904. A Treatise on Electricity and Magnetism. 3rd Ed., Oxford University Press.

Bruggeman, D.A.G. 1935. "Dielectric Constant and Conductivity of Mixtures of Isotropic Materials," Annalen Physik, 24:636.

De La Rue, R.E. and C.W. Tobias. 1959. "On the Thermal Conductivity of Dispersions," J. Electrochem. Soc., 106:827.

Behrens, E. 1968. "Thermal Conductivities of Composite Materials," J. Comp. Mat., 2:2.

Hashin, Z. 1968. "Assessment of the Self Consistent Scheme Approximation: Thermal Conductivity of Particulate Composites," J. Comp. Mat., 2:284.

Cheng, S.C. and R.I. Vachon. 1969. "The Prediction of the Thermal Conductivity of Two and Three Phase Solid Heterogeneous Mixtures," Int. J. Heat and Mass Transfer, 12:249.

Budiansky, B. 1970. "Thermal and Thermoelastic Properties of Isotropic Composites," J. Comp. Mat., 4:286.

Nir, A. and A. Acrivos. 1976. "The Effective Thermal Conductivity of Sheared Suspension," J. Fluid Mech., 78:33.

10.

Maewai, A. , T.C. Bache and G.A. Hegemier. 1976. "A Continuum Model for Diffusion in Laminated Composites," J. of Heat Transfer, 98:133.

11.

Crane, R.A. and R.I. Vachon. 1977. "Prediction of the Bounds on the Effective Thermal Conductivity of Granular Materials," Int. J. Heat and Mass Transfer, 20:711.

12.

Willes, J.R. 1977. "Bounds and Self-Consistent Estimates for the Overall Properties of Anisotropic Composites," J. Comp. Mat., 25:185.

13.

Nomura, S. and T.W. Chou. 1980. "Bounds of Effective Thermal Conductivity of Short-Fiber Composites," J. Comp. Mat., 14:120.

14.

Han, L.S. and A.A. Cosner. 1981. "Effective Thermal Conductivities of Fibrous Composites," J. of Heat Transfer, 103:387.

15.

Hatta, H. and M. Taya. 1986. "Thermal Conductivity of Coated-Filler Composites," J. Appl. Phys., 59:1851.

16.

Shih-Yuan Lu and S. Kim. 1990. "Effective Thermal Conductivity of Composites Containing Spheroidal Inclusions," J. Am. Inst. Chem. Eng., 36:927.

17.

Hasselman, D.P.H. and L.F. Johnson. 1987. "Effective Thermal Conductivity of Composites with Interfacial Thermal Barrier Resistance," J. Comp. Mat., 21:508.

18.

Benveniste, Y. 1987. "Effective Thermal Conductivity of Composites with a Thermal Contact Resistance between the Constituents: Non-Dilute Case," J. Appl. Phys., 61:2840.

19.

Chiew, Y.C. and E.D. Glandt. 1987. "Effective Conductivity of Dispersions: The Effect of Resistance at the Particle Surfaces," Chem. Eng. Sci., 42:2677.

20.

Nye, J.F. 1957. Physical Properties of Crystals. Oxford : Clarendon Press.

21.

Carslaw, H.S. and J.C. Jaeger. 1959. Conduction ofHeat in Solids, 2nd Ed. Oxford: Clarendon Press.

22.

Havis, C.R. , G.P. Peterson and L.S. Fletcher. 1989. "Predicting the Thermal Conductivity and Temperature Distribution in Aligned Fiber Composites," J. Thermophysics, 3:416.

23.

Parker, W.J. , R. J. Jenkins, C. P. Butler and G.L. Abbott. 1961. "Flash Method for Determining Thermal Diffusivity, Heat Capacity and Thermal Conductivity," J. Appl. Phys., 32:1679.

24.

Heckman, R.C. 1973. "Finite Pulse-Time and Heat Loss Effects in Pulse Diffusivity Measurements," J. Appl. Phys., 44:1450.

25.

Hasselman, D.P.H. and K.Y. Donaldson. 1990. "Effects of Detector Non-Linearity and Specimen Size on the Apparent Thermal Diffusivity of NIST 8425 Graphite," Int. J. of Thermophysics, 11:573.