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Abstract: It tends in the future to apply the knowledge of strain
dealing various failures of engineering structures. One of topical
problems is to develop strain-based fatigue reliability analysis to
consider the intrinsic scattering of fatigue damage. After a serious of
experimental and theoretical studies, a newly worthy note phenomenon,
the random cyclic stress-strain (CSS) responses of engineering material,
is revealed. An “effectively short fatigue crack criterion” is
introduced to facilitate an understanding of the mechanism of fatigue
damage. It is revealed that the difference and change of
micro-structural conditions in the initial zone and the zones ahead of
dominant effectively short fatigue crack are the intrinsic cause of the
scattering and involving CSS responses and other fatigue properties.
Statistical models for describing the responses are suggested by taking
into account the related random material constants in the Ramberg-Osgood
CSS equation and its modified form. A statistical model is given to
describe random of the cyclic strain-life relation, which treats the
material constants in the Coffin-Manson equation as related random
variables. A newly basic strain-based methodology is constructed by
considering interference of the random fatigue strain applied and
capacity histories. Two fundamental forward projects are suggested. One
is to establish the strain-based methods taking into account the
responses under non-symmetrical and multi-axial conditions. Another is
to construct the strain-based probabilistic methods for tolerate design
and safety assessment by short fatigue crack theory.
Key words: Fatigue Strain analysis Reliability Random cyclic
stress-strain responses
CLC No: TH114
O346.2 TB114.3
国家自然科学基金(50075073)、全国优秀博士学位论文作者专项资金(2002067)、四川省(杰出)青年科技基金(2000-14-458)和教育部优秀青年教师资助计划(2101)资助项目.
Received 20020830, received in revised form 20021010
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