Our aim in this paper is to establish the weak existence theorem and find under suitable assumptions sufficient conditions on m; p and the initial data for which the blow up takes place for the following boundary value problem: vertical bar u(t)vertical bar(rho) u(tt) - Delta u - Delta u(tt) + integral(t)(0) g(t - s) Delta u(s)ds + vertical bar u(t)vertical bar(m(x)-2) u(t) = vertical bar u vertical bar(p(x)-2)u. This paper extends some of the results obtained by the authors and it is focused on new results which are consequence of the presence of variable exponents.