D'Accardi Ester, Palumbo Davide, Galietti Umberto
Politecnico di Bari, Department of Mechanics, Mathematics & Management, Via Orabona 4, 70125 Bari, Italy.
Materials (Basel). 2021 May 12;14(10):2525. doi: 10.3390/ma14102525.
The main goal of non-destructive testing is the detection of defects early enough to avoid catastrophic failure with particular interest for the inspection of aerospace structures; under this aspect, all methods for fast and reliable inspection deserve special attention. In this sense, active thermography for non-destructive testing enables contactless, fast, remote, and not expensive control of materials and structures. Furthermore, different works have confirmed the potentials of lock-in thermography as a flexible technique for its peculiarity to be performed by means of a low-cost set-up. In this work, a new approach called the multi-frequency via software approach (MFS), based on the superimposition via software of two square waves with two different main excitation frequencies, has been used to inspect a sample in carbon fiber reinforced polymers (CFRP) material with imposed defects of different materials, sizes and depths, by means of lock-in thermography. The advantages and disadvantages of the multi-frequency approach have been highlighted by comparing quantitatively the MFS with the traditional excitation methods (sine and square waves).
无损检测的主要目标是尽早检测出缺陷，以避免灾难性故障，这对于航空航天结构的检测尤为重要；从这方面来看，所有快速可靠的检测方法都值得特别关注。从这个意义上说，用于无损检测的主动热成像技术能够对材料和结构进行非接触、快速、远程且低成本的检测。此外，不同的研究已经证实了锁相热成像技术作为一种灵活技术的潜力，因为它可以通过低成本的装置来实现。在这项工作中，一种名为多频率软件叠加法（MFS）的新方法被用于通过锁相热成像技术检测碳纤维增强聚合物（CFRP）材料中的样品，该方法基于通过软件叠加两个具有不同主要激励频率的方波，样品中存在不同材料、尺寸和深度的人为缺陷。通过将MFS与传统激励方法（正弦波和方波）进行定量比较，突出了多频率方法的优缺点。
