2.2.4.2 Vibration

2.2.4.2 Vibration

Vibration is a mechanical phenomenon in which oscillations occur around an equilibrium point. Vibration can be desirable (loudspeaker cones are an example), but in many cases, it is undesirable and wastes energy, creates unwanted sound and causes mating faces to move against or away from one another. Vibration and shock increase the relative movement of parts and materials joined using most traditional methods, causing a loss of clamping force and, ultimately, machine or component failure. Vibration can severely impact the performance and durability of many joining methods. Repeated or continuous exposure can also weaken substrate materials, mainly where localised stresses and material deficiencies are present due to the selected joining method.

Extreme vibration and movement can highlight the harmonic resonance of a component or structure, as seen during the Tacoma Narrows Bridge incident. The Tacoma Narrows Bridge was built in Washington during the 1930s. It was designed to be the most flexible bridge ever constructed. While the design exceeded the calculated ratios of length, depth and width, the aerodynamic forces in play during strong winds were not considered.