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AISI 304 stainless steel pipe has been widely used in It is
well known that practical engineering components and
structures often suffer variable amplitude loading in our
daily life. If cracks in components are made during
manufacture or setup, they will propagate under sustaining
loading. Finally, structure will be destoried. Consequently,
it is important to consider the structure of frature caused
by crack propagation when designed and built. An overwhelming
amount of fatigue test have been carried out under constant
amplitude loading. In order to ensure the continued safe
operation of structure it is necessary to improve further
our predictive models of crack propagation behaviour under
complex loading conditions. In this research we take 7075-T651
aluminum to investigate fatigue crack closure and crack
propagation behavior, and apply the meterial constant
obtained by constant amplitude testing to predict fatigue
life of the specimen under variable amplitude loading.
A numerical method is also attempted. The very important
parameter "opening load" in fatigue behavior will be
calculated by the model. Finally, the model is
investigated to predict fatigue life under various load
condition.
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