Before revision: Some structures operate under the safe-life design principle, where an extremely low level of risk is accepted through a combination of testing and analysis that the part will ever form a detectable crack due to fatigue during the service life of the part.
After revision: Some structures operate under the safe-life design principle, where an extremely low level of risk is accepted through a combination of testing and analysis that the part will never form a detectable crack due to fatigue during the service life of the part.