  In this paper we propose some kinds of two-dimensional square zigzag lattice
structures and study their bandgaps and directional propagation of elastic
waves. The band structures and the transmission spectra of the systems are
calculated by using the finite element method. The effects of the geometry
parameters of the 2d-zigzag lattices on the bandgaps are investigated and
discussed. The mechanism of the bandgap generation is analyzed by studying the
vibration modes at the bandgap edges. Multiple wide complete bandgaps are found
in a wide porosity range owing to the separation of the degeneracy by
introducing bending arms. The bandgaps are sensitive to the geometry parameters
of the systems. The deformed displacement fields of the transient response of
finite structures subjected to harmonic loads are presented to show the
directional wave propagation. The research work in this paper is relevant to
the practical design of cellular structures with enhanced vibro-acoustics
performance.
