Widespread fatigue damage

Widespread fatigue damage (WFD) in a structure is characterised by the simultaneous presence of fatigue cracks at multiple points that are of sufficient size and density that while individually they may be acceptable, link-up of the cracks could suddenly occur and the structure could fail.

The objective of a designer is to determine when large numbers of small cracks could degrade the joint strength to an unacceptable level.

[2] The in-flight loss of part of the fuselage from Aloha Airlines Flight 243 was attributed to multi-site fatigue damage.

Several factors can influence the occurrence of WFD, like Design issues and Probabilistic parameters like manufacturing, environment etc.

[1] LOV is defined as “the period of time (in flight cycles, hours or both) up to which WFD will not occur in aeroplane structure.” The steps followed are:

Widespread fatigue caused the in-flight failure of the fuselage on Aloha Airlines Flight 243