超声红外锁相热像技术是一种将调制激励和锁相技术应用于红外热像检测的新型无损检测技术。针对缺陷生热及传热研究中存在的摩擦生热过程难以有效模拟、缺陷内部生热机理不清等理论问题, 采用电-力类比方法, 建立了含疲劳裂纹金属平板与超声激励系统的有限元模型, 研究了调制超声激励下裂纹区域和裂纹面的生热特点, 结果表明: 在调制超声激励下, 裂纹区域生热呈现出周期性上升的特点, 因预紧力的作用, 靠近激励同侧的裂纹面区域生热更明显。基于仿真分析和Green函数, 建立了裂纹摩擦生热的传热理论模型, 进一步探究了裂纹区域温度分布规律; 最后利用被测平板上下表面温度比值(P值)对热源深度进行了估计, 证明了仿真结果与理论计算的一致性。研究成果将进一步丰富超声红外锁相热像技术的理论基础。

Ultrasonic infrared lock-in thermography is a novel nondestructive testing technology, which mainly combines the modulated excitation and lock-in technology to achieve infrared thermography test. With the lack of study on the frictional heating simulation and interior heating mechanism during the defect heating and diffusion, the electric-force analogy method was utilized to build the finite element model of the ultrasonic transducer and the metal plate with the fatigue crack. Simulation results show that the crack heating periodically increases with the modulated ultrasonic excitation, and the heating area of crack faces is closed to the excitation side by the influence of the engagement force. Based on the simulation results and the Green function, a theoretic model was introduced to describe the heat diffusion of the crack frictional heating and the heat distribution of the crack vicinity was demonstrated. Further, the depth of the heat source was estimated with the ratio between top and lower surface of the test plate(P-value), which shows consistency between simulation and theoretic results. This study aims to enrich the theoretic basis in ultrasonic infrared lock-in thermography.