Fitting approach of the fatigue tensile response of textile composite materials

In this paper an approach to predict a complete fatigue life curve, from a reduced number of experimental data, is detailed for textile composites under tension-tension fatigue loading. The fatigue life curve (number of cycle to failure N vs. maximum stress in the loading cycle max) is predicted by a modified sigmoidal-like function. A modified Gauss-Newton technique is implemented to identify the five model coefficients. The robustness of the proposed approach and convergence of the identification process have been successfully validated with available experimental data of a single-ply non-crimp 3D orthogonal weave E-glass composite and a four plies plain weave E-glass laminate