Abstract:
Based on the
principle of the stability of microstructure in metallic systems
and the cycle dependent property of materials, it is proposed
and verified that for cyclic hardening materials, in case of the
cycles of the first level of high stress are relatively small
under high-low two stress level test, the cumulative fatigue
damage ∑ni/Ni is inevitably greater than unity, and it's deduced
that such a conclusion should be also true under high-low
multi-stress level test. Whereas for cyclic softening materials
the cumulative damage is less than unity under high-low two
stress live test. Through a comprehensive analysis to the test
results, some suggestions on the calculation of cumulative
fatigue damage are proposed.
Key words:
Cumulative fatigue damage Cycle dependent property
Stability of microstructure Two stress level test
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