  Advancement in manufacturing methods enable designing so called metamaterials
with a tailor-made microstructure. Microstructure affects materials response
within a length-scale, where we model this behavior by using the generalized
thermomechanics. Strain gradient theory is employed as a higher-order theory
with thermodynamics modeled as a first-order theory. Developing multiphysics
models for heterogeneous materials is indeed a challenge and even this
``simplest'' model in generalized thermomechanics causes dozens of parameters
to be determined. We develop a computational model by using a given
microstructure, modeled as a periodic domain, and numerically calculate all
parameters by means of asymptotic homogenization. Finite element method (FEM)
is employed with the aid of open-source codes (FEniCS). Some example with
symmetric and random distribution of voids in a model problem verifies the
method and provides an example at which length-scale we need to consider
generalized thermoeleasticity in composite materials.
