  The Bonnor-Swaminarayan solutions are boost-rotation symmetric space-times
which describe the motion of pairs of accelerating particles which are possibly
connected to strings (struts). In an explicit and unified form we present a
generalised class of such solutions with a few new observations. We then
investigate the possible limits in which the accelerations become unbounded.
The resulting space-times represent spherical impulsive gravitational waves
with snapping or expanding cosmic strings. We also obtain an exact solution for
a snapping string of finite length.
