Flow-induced vibration

Article By:

Weaver, David S. Department of Mechanical Engineering, McMaster University, Hamilton, Ontario, Canada.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.757565

Structural vibrations caused by a flowing fluid. Whenever a structure is exposed to a flowing fluid, the fluid forces may cause the structure to vibrate. In many cases, such as a gentle wind rustling the leaves of a tree, the structural response does not produce any damage. However, in other cases, the structural motion can couple with the fluid excitation in such a way that the energy from the flowing fluid is transferred to the structure and damaging vibrations can occur. One of most spectacular examples of this is the 1940 collapse of the Tacoma Narrows Suspension Bridge. In this case, the 2800-ft (850-m) central span oscillated wildly for several hours before finally failing at a relatively modest wind speed just over 40 mi/h (65 km/h). In fact, a similar catastrophe had occurred nearly 100 years earlier with the Wheeling Suspension Bridge in Ohio. This bridge had a span of 1000 ft (305 m), the longest in the world at the time (1854). Any lessons learned from this experience had apparently long been forgotten when the Tacoma Narrows Bridge was designed. Fortunately, not all excessive flow-induced vibrations lead to failure if they are recognized and appropriate action is taken. The Golden Gate Suspension Bridge was completed in 1937 and has a central span of 4200 ft (1280 m). During a wind storm in 1951, the bridge deck suffered peak-to-peak vibration amplitudes of 12 ft (3.5 m) and peak-to-peak rotational oscillations of 22°. Subsequent torsional stiffening of the deck stabilized the bridge response to acceptable levels. See also: Bridge; Fluid mechanics; Mechanical vibration; Vibration

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