The crack growth monitoring is an important task for the maintenance policies of steel structures subjected to cyclic loading, such as bridges, cranes, off shore facilities and wind energy towers. A reliable crack detection method allows to survey properly the crack initiation and growth in responsive details of these structures, so that, they can be repaired or restored in time in order to avoid services interruption, accidents or structural collapses. In this paper, a crack detection system, which is based on inductive thermography is applied to survey the crack growth on a SM490 steel welded specimen subjected to cyclic loading. The required thermal excitation of this system is based on the generation of eddy currents, which cause a temperature increase on the crack tips. This temperature rise can be observed and recorded by using an infrared camera. Afterwards, the crack tip and growth are established by analysing the infrared (IR) images. The mentioned system allows to detect cracks on steel structures in real time and in situ, characteristics that represent the efficiency and the potential of this method in the field of NDT.

中文翻译：

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通过应用方波感应热成像监测焊接试样上的裂纹长度增长


裂纹扩展监测是桥梁、起重机、海上设施和风能塔等承受循环载荷的钢结构维护政策的一项重要任务。可靠的裂缝探测方法可以正确调查这些结构的裂纹萌生和响应细节的增长，以便及时修复或恢复它们，以避免服务中断、事故或结构倒塌。在本文中，应用基于感应热成像的裂纹探测系统来调查承受循环载荷的 SM490 钢焊接试样的裂纹扩展。该系统所需的热激励基于涡流的产生，涡流会导致裂纹尖端的温度升高。可以使用红外相机观察和记录这种温升。然后，通过分析红外 （IR） 图像来确定裂纹尖端和生长。上述系统允许实时和原位检测钢结构上的裂缝，这些特性代表了该方法在无损检测领域的效率和潜力。