In this paper, we considered the propagation wave in transversely isotropic piezoelastic medium based on the nonlocal strain gradient theory. Two kinds of scale parameters, namely, the nonlocal parameter and the strain gradient parameter are introduced to account for the size effect of mechanical properties of nanostructures. | Vietnam Journal of Mechanics Vol. 45 No. 4 2023 pp. 358 375 DOI https 0866-7136 19604 WAVE PROPAGATION ANALYSIS IN TRANSVERSELY ISOTROPIC PIEZOELASTIC MEDIUM BASED ON NONLOCAL STRAIN GRADIENT THEORY Trinh Thi Thanh Hue1 Do Xuan Tung2 1 Faculty of Building and Industrial Construction Hanoi University of Civil Engineering 55 Giai Phong Street Hanoi Vietnam 2 Faculty of Civil Engineering Hanoi Architectural University Km 10 Nguyen Trai Street Thanh Xuan Hanoi Vietnam E-mail tungdx2783@ Received 07 December 2023 Revised 24 December 2023 Accepted 30 December 2023 Published online 31 December 2023 Abstract. The purpose of this research is to study the propagation of surface waves in transversely isotropic piezoelastic medium based on nonlocal strain gradient theory. A characteristics equation for the existence of surface waves is discussed. This equation could be easily reduced to the ones of the gradient strain theory nonlocal theory and classical theory. It has also been concluded that there exist cut-off frequency for the wave propagating in size-dependent materials based on the nonlocal strain gradient theory. The dispersion equation which surface wave speed satisfies is derived from the free traction condition on the surface of half-space with consideration of electrically open circuit condi- tions. The effect of the nonlocal parameter the strain gradient parameter on the existence of surface waves as well as the Rayleigh wave propagation is illustrated through some numerical examples. Keywords dispersion equation nonlocal gradient transversely isotropic piezoelectric. 1. INTRODUCTION The piezoelectric medium has found many applications in the area of signal process- ing transduction and frequency control. Both theoretical and experimental studies on wave propagation in piezoelectric materials have attracted the attention of scientists and engineers during last two decades. The survey of literature can be found in many related texts and .
