Electronic Journal of Differential Equations, Vol. 2021 (2021), No. 06, pp. 1-18. Title: Existence and blow up of solutions for a strongly damped Petrovsky equation with variable-exponent nonlinearities Authors: Stanislav Antontsev (Lavrentyev Inst. of Hydrodynamics, Novosibirsk, Russia) Jorge Ferreira (Federal Fluminense Univ., RJ, Brazil) Erhan Piskin (Dicle Univ., Diyarbakir, Turkey) Abstract: In this article, we consider a nonlinear plate (or beam) Petrovsky equation with strong damping and source terms with variable exponents. By using the Banach contraction mapping principle we obtain local weak solutions, under suitable assumptions on the variable exponents p(.) and q(.). Then we show that the solution is global if p(.) ≥ q(.). Also, we prove that a solution with negative initial energy and p(.)<q(.) blows up in finite time. Submitted May 20, 2020. Published January 29, 2021. Math Subject Classifications: 35A01, 35B44, 35L55. Key Words: Global solution; blow up; Petrovsky equation; variable-exponent nonlinearities.