We investigate the asymptotic periodicity, L p -boundedness, classical (resp., strong) solutions, and the topological structure of solutions set of strongly damped semilinear wave equations. The theoretical results are well complemented with a set of very illustrating applications.
KEYWORDSasymptotic behavior, boundedness, classical solutions, damped wave equations, strong solutions, topological structure of solutions set where X 1 2 is the fractional power space associated with A as in the work of Henry. 19 Equations like (1.1) have a lot of nontrivial and interesting features and appear in the literature under the name of strongly damped wave equations. An example of mathematical model represented in the form (1.1) is the wave equation with structural damping (see Carvalho and Cholewa 9 and Chen and Triggiani [20][21][22] ). This manuscript is a natural continuation of the work of Cuevas et al, 18 which investigates the existence and uniqueness of asymptotically almost-periodic mild solutions for strongly damped wave equations of type 1.1. Here we are concerned with the asymptotic periodicity, L p -boundedness properties, classical (resp., strong) solutions, and the topologicalProof. The proof requires straightforward modifications in the proof of Lemma 4.1 by Andrede et al. 27 We omit the details.Throughout this paper we always assume that ( , A) is an admissible pair.
Pseudo S-asymptotically -periodic functionsLet Y be an arbitrary Banach space. In this work C b ([0, ∞); Y) denotes the space consisting of the continuous and bounded functions from [0, ∞) into Y, endowed with the norm of the uniform convergence. Definition 2.3. (Pierri and Rolnik[23]) A function f ∈ C b ([0, ∞); Y) is called pseudo S-asymptotically periodic if there is > 0 such that lim h→∞