Spectrum truncation

Most applications have a variable fatigue loading typically known as a spectrum, particularly in the aerospace industry. Spectrum truncation considers only the high fatigue threshold behaviour to reduce fatigue test time. Advantage is taken of composites relatively insensitivity to low load cycles. The fatigue life is dominated by the higher fatigue stresses. The spectrum truncation fatigue approach assumes that the composite material is brittle and there are no fatigue load sequence effects. Therefore, removing the low load cycles will not affect the fatigue life nor the damage initiation and growth processes. The fatigue threshold of the material is generally used to identify the loading cycles that can be truncated.