考虑累积塑性的船体裂纹板变幅低周疲劳裂纹扩展行为研究

船舶结构的扩展断裂失效往往是低周疲劳破坏和累积递增塑性耦合作用的结果,疲劳裂纹的扩展就是裂纹尖端前缘材料刚度不断降低、延展性不断耗失而逐渐分离的过程。基于弹塑性断裂力学理论,文章在作者对常幅载荷下提出的考虑累积塑性损伤的低周疲劳裂纹扩展速率预测模型的基础上对具有单个过载峰的拉伸/压缩过载下的扩展行为进行了研究。通过低周疲劳裂纹扩展试验进一步验证了该预测模型能合理评估具有单个过载峰的拉伸/压缩过载下的低周疲劳裂纹扩展行为。

Low-Cycle Fatigue Crack-Propagation Behavior of Ship Cracked Plate Considering the Accumulative Plasticity under Variable Amplitude Loading

The fracture failure of ship structure is often the coupling result of low-cycle fatigue dam-age and accumulative plasticity. Based on the prediction model proposed in author's previous study about the low-cycle fatigue crack growth considering accumulative plasticity under constant ampli-tude loading, the low-cycle fatigue crack propagation behavior under the tensile/compressive over-load with a single overload peak is investigated. In order to validate the proposed model whether can precisely evaluate the low-cycle fatigue crack propagation under the single peak tensile/compressive overload,the low-cycle fatigue crack propagation experiment was carried out for cracked plate speci-men with Q235 steel. The effects of stress ratios, mean stresses and overload ratios on low-cycle fa-tigue crack propagation were investigated by the low-cycle fatigue crack propagation tests of cracked component. A good comparison was found between predictions and experimental results, which show that the low-cycle fatigue crack growth behavior under the tensile/compressive overload with a sin-gle peak can be reasonably evaluated by the proposed prediction model.