In 1954, two crashes involving the world’s first commercial airliner, the de
Havilland Comet, brought the words “metal fatigue” to newspaper headlines
and into long-lasting public consciousness. The aircraft, also one of the first to
have a pressurized cabin, had square windows. Pressurization combined with
repeated flight loads caused cracks to form in the corners of the windows, and
those cracks widened over time until the cabins fell apart. As well as being a
human tragedy in which 68 people died, the Comet disasters were a wake-up
call to engineers trying to create safe, strong designs.
Since then, fatigue has been found at the root of failure of many mechanical
components such as turbines and other rotating equipment operating under
intense, repeated cyclical loads.
The primary tool for both understanding and being able to predict and avoid
fatigue has proven to be finite element analysis (FEA).