chap93 - Damping Damping dissipates energy from a vibrating...

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1 Damping ± Damping dissipates energy from a vibrating system. ± Therefore, free-vibration amplitude decays in time and the motion dies out.
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2 Viscous and Structural Damping ± V iscous damping resists motion in proportion to the velocity. ± This type of damping is provided by shock absorbers in cars, door-slowing mechanisms in buildings, bicycle pumps, etc. ± Viscous damping is present when a body oscillates in a viscous fluid at a low frequency. ± It is simple to handle mathematically. ± Common sources of damping in structures are not viscous. ± One form of damping in structures is internal friction , called structural or solid damping . ± Coulomb (i.e., dry) friction in joints is another source of damping.
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3 Proportional Damping ± Structural or dry friction damping forces are not proportional to velocity as viscous damping is. ± Damping in structures is small; less than 10 % of elastic (kd) and inertia (ma ) forces. Typical damping ratio ξ is about 0.01-0.10. ± This allows
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chap93 - Damping Damping dissipates energy from a vibrating...

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