Читать книгу Engineering Acoustics - Malcolm J. Crocker - Страница 68

For steel we have E = 210 × 10⁹ N/m² and ρ = 7800 kg/m³. The cross‐sectional moment of inertia of a rectangular beam is I = ab³/12 = 0.006 × (0.01)³/12 = 5 × 10⁻¹⁰ m⁴. The cross‐sectional area of the beam is S = 0.006 × 0.01 = 6 × 10⁻⁵ m². Then,

If the beam is now simply supported, we use Eq. (2.64) with n = 1,

Figure 2.16 First four mode shapes of a cantilever beam.