| 张建宇*,李翠萍,郝雪萍.测定薄板疲劳裂纹扩展门槛值的升降法[J].实验力学,2008,23(2):175~179 |
| 测定薄板疲劳裂纹扩展门槛值的升降法 |
| On the Up-and-Down Threshold Measurement Method of Fatigue Crack Propagation in Sheet Metal |
| 投稿时间：2007-05-10 修订日期：2008-01-15 |
| DOI： |
| 中文关键词: 裂纹扩展 裂纹扩展门槛值 疲劳试验 可靠性 升降法 |
| 英文关键词:crack propagation threshold of crack propagation fatigue testing reliability up-and-down method |
| 基金项目: |
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| 中文摘要: |
| 测定疲劳裂纹扩展门槛值传统方法的整个过程只测出裂纹扩展门槛值的一个观测值，而由于材料不均匀等客观因素的限制，传统试验法的结果具有一定的随机性。本文利用升降法的原理，提出一种测定疲劳裂纹扩展门槛值的升降法：预制裂纹并逐级降载使裂纹扩展速率接近门槛值速率，设定应力强度因子的级差，按照设定级差逐级降载，直至裂纹扩展速率低于门槛值速率，然后开始升载，直至裂纹扩展速率高于门槛值速率，再开始降载，如此重复进行即可以在疲劳裂纹扩展门槛值附近测得多对相反的数据点。运用小子样升降法数据处理方法,就可得到疲劳裂纹扩展门槛值的均值和方差。最后通过某型铝合金薄板疲劳裂纹扩展门槛值的测定试验验证了此方法的可行性。 |
| 英文摘要: |
| Whole process of traditional threshold measurement method of fatigue crack propagation can only give one threshold. Due to the limit of material's heterogeneousness and other objective factors, the results of traditional threshold measurement method have randomicity. Up-and-down method is presented in this paper to measure the threshold of fatigue crack propagation, based the principle of up-and-down method. Firstly, lowing ΔK in the terms of the degree of the ΔK grads enacted above until the rate of fatigue crack propagation under 10 -7mm/cycle. Secondly, rising ΔK until the rate of fatigue crack propagation up 10 -7mm/cycle. Repeating this progress, many pairs of data points of crack propagation are gained round the threshold of fatigue crack propagation. Using data processing of up-and-down method gets mean and variance of the threshold of fatigue crack propagation. Finally, the feasibility of this method was validated by testing the threshold of fatigue crack propagation of one kind of Aluminum alloy. |
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