Abstract InfraRed Thermography is an expeditiously growing non-destructive testing and evaluation technique widely used to estimate the subsurface defect details in fibre reinforced polymer materials due to its remote, fast, easy, safe and wide area monitoring abilities. In order to explore the details of subsurface anomalies in active infrared thermography, a modulated heat flux with a predefined intensity and bandwidth is employed to excite the test sample. Among various widely used active infrared thermographic techniques for non-destructive testing and evaluation applications, pulse based and modulated lock-in thermography are predominantly in use. However, these conventional techniques limits their applicability due to high peak power heat source requirements (pulse based techniques) and poor resolution (modulated lock-in thermography) for detecting the defects located at various depths of different lateral dimensions. The present paper highlights a pulse compression favourable frequency modulated thermal wave imaging which can be carried out with moderate peak power heat sources in a limited span of time with improved test resolution and sensitivity. Further the proposed experimentation is validated with the analytical as well as numerical simulations on glass fibre reinforced polymer samples having flat bottom hole defects.

中文翻译：

---

用于玻璃纤维增​​强聚合物定量表征的深度分辨脉冲压缩有利调频热波成像

摘要 红外热像仪是一种快速发展的无损检测和评估技术，由于其远程、快速、简便、安全和广域监测能力，被广泛用于估计纤维增强聚合物材料中的亚表面缺陷细节。为了探索主动红外热成像中地下异常的细节，采用具有预定义强度和带宽的调制热通量来激发测试样品。在用于无损测试和评估应用的各种广泛使用的主动红外热成像技术中，主要使用基于脉冲和调制锁定热成像技术。然而，由于需要高峰值功率热源（基于脉冲的技术）和用于检测位于不同横向尺寸的不同深度的缺陷的低分辨率（调制锁定热成像），这些传统技术限制了它们的适用性。本文重点介绍了一种脉冲压缩有利的调频热波成像，它可以在有限的时间跨度内使用中等峰值功率热源进行，并提高了测试分辨率和灵敏度。此外，建议的实验通过对具有平底孔缺陷的玻璃纤维增​​强聚合物样品的分析和数值模拟得到验证。本文重点介绍了一种脉冲压缩有利的调频热波成像，它可以在有限的时间跨度内使用中等峰值功率热源进行，并提高了测试分辨率和灵敏度。此外，建议的实验通过对具有平底孔缺陷的玻璃纤维增​​强聚合物样品的分析和数值模拟得到验证。本文重点介绍了一种脉冲压缩有利的调频热波成像，它可以在有限的时间内用中等峰值功率热源进行，并提高了测试分辨率和灵敏度。此外，建议的实验通过对具有平底孔缺陷的玻璃纤维增​​强聚合物样品的分析和数值模拟得到验证。