Material Designer offers two methods for the analytical homogenization of the coefficients of thermal expansion of a unidirectional composite, namely Schapery and Mori-Tanaka methods.
Schapery's Method
Consider a unidirectional composite with inclusions transversely isotropic in the x direction. In the Schapery's method [Schapery, (1968)], the thermal expansion coefficient in the longitudinal direction is computed as
(3–8) |
and the thermal expansion coefficient in the transverse directions is computed as
(3–9) |
Here the Young moduli and Poisson ratios of the matrix and fiber constituents are denoted by E and ν.
Note that in the Schapery's method inclusions are modeled as infinitely long cylinders.
Mori-Tanaka Method
Following the formalism in [Lu P., (2013)], the thermal expansion coefficients predicted by the Mori-Tanaka method read
(3–10) |
where
(3–11) |
and is the Eshelby tensor introduced in the section above, Homogenization of Unidirectional Composites.
In case of a composite with misaligned fiber orientations, the orientation averaged thermal expansion coefficients are given by [Camacho et al., (1990)]
(3–12) |
where
the constants R 1 and R 2 depend on the stiffness tensor and thermal expansion coefficients of the unidirectional composite
and denote the second order orientation and identity tensors in Voigt notation, respectively;
the orientations averaged stiffness tensor is computed as described in the section above, Orientations Averaging.