Abstract:

The effective electrical permittivity and thermal conductivity is investigated.  A two-scale asymptotic homogenization scheme is used to formulate electrostatic and steady state thermal boundary value problems (BVP’s) at the micro-scale for each effective orthotropic property. The BVP’s are solved analytically, using three dimensional series parallel nets and numerically, using finite element methods.  Effective properties are determined as functions of the constituent material properties, fiber volume fraction and the geometric parameters of the reinforcement fabric.  The dielectric constant is determined analogous to thermal conductivity, by neglecting the contribution from the constituent materials?loss tangents which are order(s) of magnitude lower than the respective dielectric constants.  The effective loss tangent is obtained analogous to mechanical viscoelastic problems as a linear combination of the constituent loss tangents.  The predicted effective properties are compared with experimentally obtained values for E-glass/epoxy laminates and with predictions from other available models in the literature.

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