  The problem of blow up of solutions to the initial boundary value problem for
non-autonomous semilinear wave equation with damping and accelerating terms
under the Robin boundary condition is studied. Sufficient conditions of blow up
in a finite time of solutions to semilinear damped wave equations with
arbitrary large initial energy are obtained. A result on blow up of solutions
with negative initial energy of semilinear second order wave equation with
accelerating term is also obtained.
