AN EFFICIENT VARIABLE AMPLITUDE LOADING SCHEME FOR 3-DIMENSIONAL FATIGUE-CRACK

The finite element alternating method (FEAM) is an extremely useful an d efficient scheme for the accurate calculation of stress intensity fa ctors in complex three dimensional structures. This approach involves the combination of an analytical solution for a crack in an infinite b ody with a finite element solution for the uncracked component. Previo usly a three-dimensional fatigue crack growth algorithm has been incor porated into the alternating method for the case of constant amplitude loading. The major accomplishment outlined in this paper is the imple mentation of an additional numerical scheme for the more difficult cas e of variable amplitude loading. Test cases, with an emphasis on compo nents taken from the aerospace industry, are used to validate the revi sed alternating method computer program. Results reveal excellent leve ls of correlation with existing packages and highlight the suitability of the finite element alternating method for fatigue crack growth ana lyses in a wide variety of components such as aircraft components, pip elines, offshore structures, pressure vessels, ships, etc.