碳纤维增强复合材料板补强平面外纵向焊接接头疲劳性能试验研究

Experimental study on fatigue behavior of out-of-plane gusset welded joints strengthened by CFRP

以碳纤维增强复合材料(CFRP)补强的平面外纵向焊接接头为研究对象,对其进行疲劳性能试验。为了模拟初始损伤,在节点板两端焊趾处引入人工预制初始缺陷。分析了应力幅、单/双面粘贴和CFRP板弹性模量对试件疲劳性能的影响。试验过程中采用沙滩纹加载方式,得到了疲劳裂纹随着荷载循环次数的扩展情况。试验结果表明:试件沿着其中一条预制裂纹发生断裂破坏,另一条预制裂纹也有不同程度的扩展;普通弹性模量CFRP板补强试件发生黏结层内破坏,高弹性模量CFRP板补强试件发生CFRP板断裂破坏;采用粘贴CFRP补强方法能够有效提高焊接接头疲劳性能,其疲劳寿命延长至未补强的1.28~8.17倍;裂纹扩展速率明显减慢,在CFRP材料覆盖区域尤为明显。采用双面粘贴和高弹性模量CFRP材料可以取得更好的补强效果,试件疲劳寿命延长程度分别约为单面粘贴和普通弹性模量CFRP板补强试件的2倍和3倍。

An experimental study on the fatigue behavior of out-of-plane gusset welded joints strengthened with CFRP laminates was presented. Artificial slots were cut at weld toes to simulate the initial damage and to guide the crack growth. Effects of stress range, single-or double-sided strengthening and modulus of CFRP laminates were investigated. The beach marking technique was adopted to record fatigue crack propagation during the test. The test results show that all the specimens fractured along one predefined slot while the other one grew to different lengths. Cohesion failure and CFRP fracture were observed for specimens repaired by CFRP laminates with normal modulus and ultra-high modulus, respectively. It is found that the fatigue life of welded joints after strengthening is significantly prolonged from 1.28 to 8.17 times in comparison with plain specimens. The crack propagation rate is considerably delayed especially in the area of CFRP overlay. Double-sided bonding and high modulus CFRP materials could lead to a better strengthening effect. The corresponding fatigue life extension ratios are about two times and three times that with single-sided bonding and normal modulus CFRP materials, respectively. © 2016, Editorial Office of Journal of Building Structures. All right reserved.