Probabilistic Models for the Long Fatigue Crack Growth Rates of LZ50 Axle Steel
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摘要: 试验研究了随机疲劳长裂纹扩展率概率模型．首先发展了考虑平均应力影响和低应力强度因子范围趋于门槛值现象的扩展率方程．进而提出了同时考虑试验数据分散性规律与样本数量对概率评价影响的概率模型，模型参量由线性回归法结合极大似然统计分析原理测定．LZ50钢的试验数据分析，验证了方法的有效性与实用性．Abstract: Experimental study is performed on the probabilistic models for the long fatigue crack growth rates (da/dN) of LZ50 axle steel. An equation for crack growth rate was derived to consider the trend of stress intensity factor range going down to the threshold and the average stress effect. The probabilistic models were presented on the equation. They consist of the probabilistic da/dN- delta K relations, the confidence-based da/dN-delta K relations, and the probabilistic- and confidence-based da/dN-delta K relations. Efforts were made respectively to characterize the effects of probabilistic assessments due to the scattering regularity of test data, the number of sampling, and both of them. These relations can provide wide selections for practice. Analysis on the test data of LZ50 steel indicates that the present models are available and feasible.
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Key words:
- LZ50 steel /
- long fatigue crack /
- growth rate /
- average stress /
- threshold /
- probabilistic model
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