超声振动红外热像法(VT)是红外热像无损检测的重要方法之一, 在裂纹等紧贴型缺陷检测中有特殊的应用优势。为了寻找适宜的振动激励条件, 用解析法分析了材料热特性(热导率和热扩散系数)和缺陷深度对温升的影响, 分析了试件支撑条件和几何尺寸对共振频率的影响。结果表明, 复合材料较金属材料容易实现VT检测。对金属件宜用短时超声激励, 而对复合材料件宜用较长时间的超声激励。从共振角度看, 采用简支方式和超声激励相组合是比较好的选择。

Vibrothermography is one of the most important techniques in infrared thermographic NDT, and it has a special advantage in close crack-type defect detection. In order to find the suitable vibration excitation conditions, the influence of material thermal properties(conductivity and diffusivity) and defect depth on the surface temperature rise was solved with analytical method, and the influence of the support condition and geometric dimension of a specimen on its resonance frequencies was also studied. The results show that composite materials are easier to be detected than metals. A short duration excitation is appropriate for metal specimens, while a long duration excitation is preferred for composite parts. From the resonance point of view, the combination of simple support and ultrasonic excitation is a better choice.