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| Analytic model based on stress intensity factor for estimating the reliability of structural components under constant amplitude loading |
| Revised:September 09, 2003 |
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| DOI：10.7511/jslx20054091 |
| KeyWord:stress intensity factor,fracture toughness,fatigue reliability,logarithmic normal distribution |
| GUO Sheng-jie YAO Wei-xing~* |
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| Abstract: |
| This paper presents a reliability model of structural components under constant amplitude, which is based on the distribution of stress intensity factor (SIF). Considering the stochastic nature of the environmental influences and the geometrical and mechanical properties of structural materials, the fracture toughness and the instantaneous length of fatigue crack are random variables and assumed to follow logarithmic normal distribution approximately. Consequently, this paper deduces that the SIF of components under constant amplitude loading also follows logarithmic normal distribution and the distribution parameters can be obtained from the expectation and variance of fatigue crack length. We give the steps of parameter computation of the Paris-Erdogan's crack propagation equation, and based on that, present methods for calculating the expectation and variance of the crack length at a given time. Then, a SIF-based reliability model is set up and the experimental data of the center crack testpieces of 7075-T7351 aluminum alloy are employed to demonstrate it. The results show that this model is in a good agreement with the experimental results. |
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