Papers by Author: Hui Juan Li

Abstract: To reduce weight and improve strength in the aerospace industry, composite structure connected by glue has gained popularity as a replacement for conventional materials and structures. However, the adhesive bonding process is more susceptible to quality variations during manufacturing than traditional joining methods. The integrality, strength and rigidity of product would be broken by disbonding. Investigate the sensitivity and accuracy of the testing method was more impotent to ensure the product quality and testing efficiency. This paper presents a study of detecting sensitivity of sheargoraphy methods when it is used for inspecting disbondinging on honeycomb structures. The potential of shearography method is also outlined.

Abstract: Lock-in thermography (LT), that is active infrared testing technology, mainly includes optical lock-in thermography (OLT) and ultrasound lock-in thermography (ULT). LT can be used to detect unbonds between honeycomb core and face sheet of sandwich structures. However, modulation frequency is an important influencing factor. In this paper, the principles of LT are represented, in experimental detections of simulated unbonds in honeycomb sandwich structures with Al-face sheet and CFRP-face sheet using OLT and ULT, detectability of OLT and ULT is compared and analyzed, effect of modulation frequency is researched and the optimal frequencies are obtained.