钢桥疲劳裂缝的红外热成像无损检测

Nondestructive Inspection of Steel Bridge Based on Infrared Thermal Imaging

利用裂缝尖端应力集中的特点,提出一种钢桥疲劳裂缝无损检测方法.从理论上建立钢结构表面温度变化与其应力之间的本构关系模型,在实验中采用红外热成像法测试构件孔边畸变温度,计算构件相应点处的畸变应力,确定构件裂缝.以带孔平板为例,应用上述模型分析了周期荷载作用下圆孔周边点的应力和表面温度之间的关系.实验结果显示,当t=0.05 s时,圆孔左右节点温度降低达到最小值,上下节点温度升高达到最大值;当t=0.15 s时,左右节点温度升高达到最大值,上下节点温度降低达到最小值.实验结果符合理论模型,表明该检测方法可行.

A new inspection method is proposed to detect fatigue crack on steel bridges based on stress concentration features. The relationship between stress and temperature of the component is built theoretically. Fatigue cracks can be located by calculating distortion stress based on detection of temperature distortion of the component using an infrared thermal imager. As an example, consider a plate with a hole. Relationship between stress and temperature of the hole-edge spots is studied under cycle loads. The results show that the temperature of left/right spots decrease and top/bottom spots increase when t = 0.05 s, and the temperature of left/right spots increase and top/bottom spots decrease when t = 0.15 s. These agree with the theoretical result, and the mode test results show feasibility of the proposed method.