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变蒙皮厚度的钛合金蜂窝在航空航天领域有着广泛的应用,蒙皮脱焊是钛合金蜂窝结构最常见的缺陷类型之一。传统锁相红外检测由于调制频率单一,不能对变蒙皮厚度的蒙皮脱焊实现一次性检测,检测效率低。针对这一问题,研究了线性调频激励红外检测以及激励参数选择方法。使用ANSYS建立了钛合金蜂窝有限元仿真模型,通过相关算法计算了对应脱焊区域和正常区域的相位差,分析了频带范围、啁啾时间对相位差绝对值最大值的影响以及蒙皮厚度与相位差绝对值最大值所在频率成分的关系。利用线性调频激励对预制脱焊缺陷的蜂窝试样进行了实验研究,获得了不同频带范围和不同啁啾时间下的相位图。实验结果表明,采用频带范围为0.01~0.21 Hz,啁啾时间为22 s的线性调频信号可以对蒙皮厚度为0.6~1.2 mm的钛合金蜂窝实现一次性检测,为钛合金蜂窝结构的实际检测提供了工艺指导。
Titanium alloy honeycomb with variable skin thickness has been widely used in the aerospace field. Skinning is one of the most common types of defects in titanium alloy honeycomb structure. Traditional phase-locked infrared detection due to a single modulation frequency, can not change the thickness of the skin skinning off a one-time test, detection efficiency is low. In response to this problem, the chirp excitation of infrared detection and excitation parameter selection method is studied. The finite element simulation model of titanium alloy honeycomb was established by using ANSYS. The phase difference between the soldering area and the normal area was calculated by the correlation algorithm. The influence of frequency range and chirp time on the absolute value of the phase difference was analyzed. The relationship between the frequency components where the absolute value of the phase difference is maximum. The linear frequency modulation excitation was used to study the honeycomb samples of prefabricated desoldering defects, and the phase diagrams of different frequency bands and different chirp time were obtained. The experimental results show that using a chirp time of 22 s in the frequency range of 0.01 ~ 0.21 Hz can achieve a one-time inspection of titanium alloy honeycomb with a skin thickness of 0.6 ~ 1.2 mm, which is the practical test for the titanium alloy honeycomb structure Process instruction is provided.