Multiaxial fatigue analysis of a metal flexible pipe

In this paper, hydroformed metal corrugated tubes were subjected to a series of fatigue tests in which the amplitude of the mechanical fatigue load is constant, in addition to a constant inner pressure similar to the work conditions, which generate a three dimensional stress–strain states, then, the life of the structure was extracted in term of number of cycles at the crack initiation for different load configurations, further, a finite element model was created taking into account the residual stresses resulted from the hydroforming process, moreover, the numerical simulations were used to estimate and compare with the experiment the fatigue life by using different approaches: a stress–strain life approach which is widely used in commercial codes, a critical plane approach, an energy approach and a continuum damage based approach, then, it is shown that for these type of structures the critical plane model and the continuum damage model are more convenient to predict the fatigue life when the residual stresses are taken into account.