基于红外热像的网架焊接空心球节点疲劳试验研究

焊接空心球网架结构被广泛使用在带悬挂吊车的工业厂房中。悬挂吊车带来的往复交变荷载会造成网架焊接节点的疲劳破坏。在焊接空心球节点的疲劳试验过程中，借助红外热像仪记录试件表面的温度，得到了试件表面的温升分布，温升高区位于钢管与焊接球的焊接连接球面焊趾处，此区域对应节点最后的疲劳破坏位置。在疲劳试验过程中，焊趾处的温升高区位置几乎不变，当疲劳裂纹穿透球壁厚时，温升高区的位置发生变化。试验表明:红外热像仪可以实时记录焊接空心球节点试件在疲劳试验过程中表面的温度，通过分析温升高区在没有可见裂纹的情况下就可预测疲劳破坏发生的位置，温升高区位置的变化对应裂纹贯穿球壁时节点试件的疲劳寿命。

Research on fatigue test of welded hollow spherical joints in grid structure based on infrared thermography

The grid structure with welded hollow spherical joints has been widely used in industrial buildings with suspending cranes. The alternating and reciprocating action of the suspending crane causes fatigue failure to welded hollow spherical joints. During the fatigue test, temperature of the surface of welded hollow spherical joint was detected by infrared thermal imager. The higher temperature rise area was located at the weld toe of the sphere in the welded parts. This area corresponded to the final fatigue failure position. During the test, the location of the temperature rise area at the weld toe was almost constant. When the fatigue crack penetrated the wall thickness of the sphere, the position of the temperature rise area changed. The experimental results show that the temperature rise of the surface of the joint can be recorded in real time by infrared thermal imager. By analyzing the temperature rise in those area, the location of fatigue fracture can be predicted without any visible cracks. The fatigue life of the joints when the crack penetrates the wall of the sphere corresponds to the change of the position of the temperature rise area at weld toe.