  Tissue engineering aims to grow artificial tissues \emph{in vitro} to replace
those in the body that have been damaged through age, trauma or disease. A
recent approach to engineer artificial cartilage involves seeding cells within
a scaffold consisting of an interconnected 3D-printed lattice of polymer fibres
combined with a cast or printed hydrogel, and subjecting the construct
(cell-seeded scaffold) to an applied load in a bioreactor. A key question is to
understand how the applied load is distributed throughout the construct. To
address this, we employ homogenisation theory to derive equations governing the
effective macroscale material properties of a periodic, elastic-poroelastic
composite. We treat the fibres as a linear elastic material and the hydrogel as
a poroelastic material, and exploit the disparate length scales (small
inter-fibre spacing compared with construct dimensions) to derive macroscale
equations governing the response of the composite to an applied load. This
homogenised description reflects the orthotropic nature of the composite. To
validate the model, solutions from finite element simulations of the
macroscale, homogenised equations are compared to experimental data describing
the unconfined compression of the fibre-reinforced hydrogels. The model is used
to derive the bulk mechanical properties of a cylindrical construct of the
composite material for a range of fibre spacings, and to determine the local
mechanical environment experienced by cells embedded within the construct.
