ABSTRACT

Ultrasound excited vibro-thermography is based on the local heat generation due to the friction between the opposite surfaces of the defect, the plastic deformation around the defect, and/or the viscoelastic loss. This paper presents vibro-thermography applied to hybrid plates containing viscoelastic material when the viscoelastic heat generation mechanism alone is considered. The debonding-like calibrated defects without friction surfaces in the hybrid plate are detected. The dynamic temperature field is obtained by both experiment and numerical simulation. The influence of excitation frequency on the temperature increase over the defects is analysed by modelling the thermo-mechanical coupled field. The results show that the viscoelastic loss of the non-metal material is the leading factor of the local temperature increase over defects; an excitation frequency has its selective heating character to defects; a defect has a so-called defect characteristic frequency which can act as the optimal excitation frequency for this defect to be detected; the defect characteristic frequency is between the two local defect resonance frequencies corresponding to the simply supported boundary and the clamped boundary, respectively.

摘要

超声激发振动热成像基于由于缺陷相对表面之间的摩擦、缺陷周围的塑性变形和/或粘弹性损失而产生的局部热量。本文介绍了当单独考虑粘弹性发热机制时，振动热成像应用于含有粘弹性材料的混合板。检测混合板中没有摩擦表面的剥离状校准缺陷。动态温度场是通过实验和数值模拟获得的。通过对热-机械耦合场建模，分析了激发频率对缺陷温度升高的影响。结果表明，非金属材料的粘弹性损失是缺陷局部温度升高的主导因素；激发频率对缺陷具有选择性加热特性；缺陷具有所谓的缺陷特征频率，可以作为该缺陷被检测的最佳激励频率；缺陷特征频率介于简支边界和夹持边界对应的两个局部缺陷共振频率之间。