Initiation Mechanics: The Prediction of Metal Fatigue Damage

Abstract

Initiation mechanics is a term that we at my laboratory has given to a new materials science discipline whose goal is the quantitative prediction of the mechanical reliability of structures. Traditional engineering approaches cannot provide with assurance the high levels of reliability (1 in 1000 to 1 in 100,000) now sought in complex aerospace and energy systems. Although overdesign can make systems more reliable, traditional approaches cannot tell you how much more or whether the often huge expense is warranted. Changing a chemical environment or a load sequence affects many aspects of reliability, frequently in different directions. Direct engineering measurements for all possibilities, or even for a few, are extraordinarily expensive even for a reliability of 99% and cannot hope to achieve the levels needed.