  Strain gradient theory is an accurate model for capturing the size effect and
localization phenomena. However, the challenge in identification of
corresponding constitutive parameters limits the practical application of the
theory. We present and utilize asymptotic homogenization herein. All parameters
in rank four, five, and six tensors are determined with the demonstrated
computational approach. Examples for epoxy carbon fiber composite, metal matrix
composite, and aluminum foam illustrate the effectiveness and versatility of
the proposed method. The influences of volume fraction of matrix, the stack of
RVEs, and the varying unit cell lengths on the identified parameters are
investigated. The homogenization computational tool is applicable to a wide
class materials and makes use of open-source codes in FEniCS. We make all of
the codes publicly available in order to encourage a transparent scientific
exchange.
