Li Anbang, Wang Lu, Xu Shanhua
School of Civil Engineering, Xi'an University of Architecture & Technology, Xi'an 710055, China.
State Key Laboratory of Green Building in Western China, Xi'an University of Architecture & Technology, Xi'an 710055, China.
Polymers (Basel). 2022 Nov 4;14(21):4738. doi: 10.3390/polym14214738.
The purpose of this study is to investigate the mechanism of improving fatigue performance and the estimation model of fatigue life for corroded steel plate strengthened with CFRP plates. A new two-stage fatigue crack propagation prediction model for the corroded steel plate strengthened with CFRP plates was proposed; moreover, the identification of critical rust pits and the equivalent method of initial cracks, and the calculation method of stress intensity factor (SIF) values at the crack tip were established. The accuracy of the proposed model was verified by comparing the predicted and tested fatigue life of the corroded steel plate strengthened with CFRP plates. Finally, the proposed two-stage crack propagation model was applied to carry out a parameter analysis to investigate the effect of weight loss rate, equivalent initial crack size, adhesive thickness, CFRP stiffness and CFRP prestress level on the fatigue crack propagation of the corroded steel plate strengthened with CFRP plates. Results showed that the maximum depth and the average width of the rust pits were suggested to be taken as the equivalent dimensions of the initial semi-elliptical surface crack for the fatigue crack propagation prediction of corroded steel plate strengthened with CFRP plates. Increasing the weight loss rate of the corroded steel plate, the initial crack size or the adhesive thickness would accelerate the crack growth and reduce the fatigue life, whereas increasing the stiffness or prestress level of the CFRP plate would significantly reduce the crack growth rate and increase the fatigue life. The smaller the initial crack size, the more sensitive the crack propagation life was to the variation of equivalent initial crack size. The influence of adhesive thickness on the fatigue life was limited and convergent, and the application of prestressing could significantly improve the utilization rate of CFRP materials and the fatigue strengthening effect of the corroded steel plate.
本研究旨在探讨碳纤维增强复合材料（CFRP）板加固锈蚀钢板疲劳性能改善机理及疲劳寿命估算模型。提出了一种新的CFRP板加固锈蚀钢板两阶段疲劳裂纹扩展预测模型；此外，建立了关键锈坑的识别方法、初始裂纹的等效方法以及裂纹尖端应力强度因子（SIF）值的计算方法。通过对比CFRP板加固锈蚀钢板的预测疲劳寿命和试验疲劳寿命，验证了所提模型的准确性。最后，应用所提两阶段裂纹扩展模型进行参数分析，研究失重率、等效初始裂纹尺寸、粘结层厚度、CFRP刚度和CFRP预应力水平对CFRP板加固锈蚀钢板疲劳裂纹扩展的影响。结果表明，对于CFRP板加固锈蚀钢板的疲劳裂纹扩展预测，建议将锈坑的最大深度和平均宽度作为初始半椭圆形表面裂纹的等效尺寸。锈蚀钢板失重率、初始裂纹尺寸或粘结层厚度的增加会加速裂纹扩展并降低疲劳寿命，而CFRP板刚度或预应力水平的增加会显著降低裂纹扩展速率并提高疲劳寿命。初始裂纹尺寸越小，裂纹扩展寿命对等效初始裂纹尺寸变化越敏感。粘结层厚度对疲劳寿命的影响有限且趋于收敛，施加预应力可显著提高CFRP材料的利用率和锈蚀钢板的疲劳加固效果。
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