  This work investigates wave propagation in undulated square structural
lattices. The undulated pattern is obtained by imposing an initial curvature to
the lattice's elements. The study considers both periodic undulated structures,
in which the undulation is uniform throughout the structure as well as graded
undulated patterns, in which the undulation is modulated within the lattice.
Undulation is specifically considered in relation to its ability to induce
anisotropy in the equivalent mechanical properties and to break the symmetry of
the straight square lattice. Results show that wave motion is inhibited within
specified frequency ranges owing to the generation of band gaps, and in
specific directions as a result of the undulation-induced anisotropy.
