  Advances in material architectures have enabled endowing materials with
exotic attributes not commonly available in the conventional realm of
mechanical engineering. Twisting, a mechanism whereby metamaterials are used to
transform static axial load into twist motion, is of particular interest to
this study. Herein, computations based on the finite element method,
corroborated by an analytical approach derived from applying Lagrange's
equations to a monoatomic spring-mass system, are employed to explore the
longitudinal-twist (L-T) conversion exhibited by a chiral tetragonal-beam
metamaterial. Firstly, we perform an eigenvalue analysis taking into account
the polarization states to highlight the potential contribution of the
longitudinal mode in the L-T conversion. We contrast the twisting behavior of
the chiral cell with that of other homogeneous medium, octagonal-tube, and
non-chiral cells. Moreover, we demonstrate the influence of the cell's
chirality on the L-T conversion using both time-domain and frequency-domain
studies. The findings indicate that at least a portion of the longitudinally
propagating wave is transformed into twist throughout a broad frequency range
and even quasi-totally converted at distinct frequencies.
