Fatigue failure is a common challenge in machine design. For engineers and designers alike, addressing fatigue failure is key to ensuring the integrity of structures an
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Scooped by
Richard Platt
onto Internet of Things - Technology focus February 11, 8:44 PM
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Fatigue failure is a common challenge in machine design. For engineers and designers alike, addressing fatigue failure is key to ensuring the integrity of structures and components throughout the lifecycle.
1/- An overview of fatigue failure and how it affects mechanical systems.
2/- How FEA software enables engineers to predict fatigue failure points on structural designs, before the manufacturing process.
From the dawn of the Industrial Revolution, humanity has become increasingly reliant on machines in daily life. This frequent use results in mechanical structures having to compete not only with the erosion of time, but also the fatigue stemming from repetitive loads being placed on them. Defined as the initiation and propagation of cracks due to cyclic loads, fatigue failure can affect even the most well-built contraptions. If left unnoticed for long enough, these cracks can snowball into much larger structural deformities, leading to severe damage in mechanical components that might otherwise seem to be operating well within their limits. This article provides an overview of what fatigue failure is, explores notable real-world examples and outlines the critical principles that every engineer should understand to help prevent this pervasive issue. It will also look at the relationship between fatigue failure and FEA software.
-- A Notable Example of Fatigue Failure in the Aerospace Industry. -- Before segueing into a discussion of fatigue failure, a good exercise would be to consider the repercussions of mechanical failure. A notable real-world example to aid this is the 1954 crash of the De Havilland Comet. As the world’s first commercial jetliner, the Comet was the crown jewel of Britain’s aerospace industry, representing a symbol of British aviation prowess…until a string of accidents changed its course. Starting with BOAC Flight 781, two fatal Comet aircraft disasters were the subject of a multi-year investigation, with authorities concluding that metal fatigue due to design defects led to explosive cabin decompression mid-flight. In particular, the square design of forward-facing windows created opportunities for stress accumulation at the corners, the effect of which was exacerbated by riveted window supports (instead of glued). Together, these design decisions triggered fatigue cracks following cyclic cabin pressurization, eventually leading to propagation of cracks and subsequent violent decompression of the aircraft.