Fast fatigue limit estimation of woven composite materials by self-heating analysis

The fatigue limit of materials is usually difficult to estimate, and requires an expensive experimental campaign to test every sample under a large number of cycles in order to determine the asymptote of the S-N curve. An experimental study is here reported with the purpose to show an efficient and fast way to estimate the fatigue limit of a woven composite using only one sample. The studied material is subjected to stepped fatigue cycles, for increasing values of stress, with a fixed frequency and a constant stress ratio. The surface temperature variation and its heating rate are analyzed. Nomenclature Sample heating K f Excitation frequency Hz Sample temperature K R Stress ratio Upper clamp temperature K t Time s Lower clamp temperature K  Density kg/m 3 Stabilised heating K  Specific heat J/kg/K Initial heating rate mK/s  Mechanical dissipation J/m 3