Читать книгу Engineering Acoustics - Malcolm J. Crocker - Страница 72

The numerical results for the velocity level at the coordinate point (x,y) = (0.04, 0.03) for a plywood board with properties E = 6 × 10⁹ N/m², ρ_S = 6.5 kg/m², a × b = 0.7 × 0.6 m², ν = 0.293 and η = 0.01 are presented in Figure 2.19. The reference velocity is 10⁻¹⁸ (m/s)². It is observed that excitation close to a corner excites more modes in the plate. Excitation at the middle point of the plate excites mostly the modes (m,n) where m and n are both even, while no contribution to the velocity level is included from modes having nodal lines passing through the center of the plate.

Figure 2.19 Computed velocity level of a simply‐supported rectangular plate excited: ______ at a corner; _ _ _ _ at the center.

(Source: from Ref. [16].)