0(0) Figure 5.1 A rod of circular cross section with a diameter of Scm and length of I m possesses a polar moment of inertia, lạ, and (shear) modulus of rigidity, G (sce table 5.1 for steel and aluminium) and a mass moment of inertia of 0.5 kg m² of the disc. For the case of a wire or shaft of diameter d, l, = «d*/32. The modulus of rigidity has units N/m². The torsional stiffness is used to describe the vibration problem illustrated in Figure 5.1, where the mass of the shaft is ignored. In the figure, 0(t) represents the angular position of the shaft relative to its equilibrium position. The disk of radius r and rotational moment of inertia / will vibrate around the equilibrium position @(0) with stiffness Gl9/l. Table 5.1 Physical Constants for some common materials Density, (kg/m²) Material Young's modulus, Shear modulus, G(N/m²) Steel Aluminium E(N/m²) 2.0 x 10" 7.1 x 10 7.8 x 10 2.7x 10' 8.0 x 10 2.67 x Calculate the natural frequency of oscillation of the torsional system for both steel and aluminium.
A rod of circular cross section with a diameter of 5cm and length of 1 m possesses a polar
moment of inertia, ?0, and (shear) modulus of rigidity, ? (see table 5.1 for steel and
aluminium) and a mass moment of inertia of 0.5 kg m2 of the disc. For the case of a wire
or shaft of diameter ?, ?0 = ??
4⁄32. The modulus of rigidity has units ? ?2 ⁄ . The
torsional stiffness is used to describe the vibration problem illustrated in Figure 5.1, where
the mass of the shaft is ignored. In the figure, ?(?) represents the angular position of the
shaft relative to its equilibrium position. The disk of radius ? and rotational moment of
inertia ? will vibrate around the equilibrium position ?(0) with stiffness ??0⁄?.
Calculate the natural frequency of oscillation of the torsional system for both steel and
aluminium
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