  We investigate the dynamical effects of an interaction between an initially
barred galaxy and a small spherical companion using an N-body/SPH algorithm. In
the models described here the small companion passes through the disc of the
larger galaxy near-perpendicular to its plane. The impact positions and times
are varied with respect to the phase of the bar and the dynamical evolution of
the disc.
  The interactions produce expanding ring structures, offset bars, spokes,and
other asymmetries in the stars and gas. These characteristic signatures of the
interaction are present in the disc for about 1 Gyr. We find that in some cases
it is possible to destroy the bar while keeping the disc structure. In general
the central impacts cause larger damage to the bar and the disc than the
peripheral ones. The interaction tends to accelerate the transition from a
strongly barred galaxy to a weakly or non-barred galaxy. The final disc
morphology is determined more by the impact position relative to the bar rather
than the impact time.
