振动红外热像检测是一种发展迅速的红外热像无损检测技术, 可检测材料的内部缺陷, 在航空航天金属材料和复合材料的裂纹检测中有广阔的应用前景。为了揭示振动红外热像法的物理机制和影响因素, 为检测条件的设计提供理论指导, 用有限元单元法对振动热像检测的物理过程进行了数值模拟。以铝合金梁上的裂纹为检测对象, 用ANSYS有限单元法分析了裂纹的振动-热的转换机制, 并对瞬态温升与检测条件的关系进行了分析。通过分别改变试件厚度、裂纹开口宽度、预紧力、激振力等条件, 计算和考察了它们对裂纹缺陷区温升的影响。结果表明: 靠近裂纹尖端裂纹面处的温升会有明显的变化, 在时域上表现为波动式上升; 验证了摩擦和热弹效应是铝合金梁裂纹缺陷处温升的原因, 其中摩擦是主要原因。

Vibrothermography (VT) is a rapidly developing version of InfraRed (IR) thermographic Non-destructive Testing (NDT). VT can be applied to the detection of internal flaws in materials, and holds a great promise for detecting cracks in alloy material and composite structures used in aerospace industry. In order to reveal the physical mechanism and influence factors of VT, which provides theoretical guidance for the design of test conditions of VT, a numerical simulation of the process of VT is conducted by the ANSYS finite element method. Taking a crack in an aluminum alloy beam as the detected object, the vibration-heat transformation mechanism of the crack, and the relations between the transient temperature and testing conditions are analyzed. The effects of the thickness of the specimen, opening width of the crack, holding pressure and exciting force on the temperature increase at the crack are calculated and discussed respectively. The results show that the temperature increase at the crack faces closed to the crack tip has a significant change which is shown as a wave type rising in the time domain. It is proven that the friction and thermos-elastic effect are the reasons for the temperature rise of the crack defects of aluminum alloy beams. Friction is the main reason.