LAUSR

Abstract An investigation of the feasibility of inspecting impact damage in polymer composite aircraft components using remote line scan thermography (LST) is presented. A numerical study is undertaken to determine the minimum heat-source beam width required to detect barely visible impact damage (BVID) above a threshold size. It is shown that the beam width requirement can be met with a non-laser-based heating source. A light-weight incandescent focusing-optic luminaire meeting this requirement is designed, developed and experimentally validated. A new image processing strategy for line-scan thermography is introduced. This method, called Dynamic Pulse Phase Thermography (DPPT), does not require static reconstruction of LST data streams and therefore is less restrictive than established processing methods for real-time applications. Experiments on carbon epoxy laminates, one containing flat-bottom-hole defects and another BVID, are used to demonstrate the performance of DPPT compared to Static Pulse Phase Thermography. It is shown that an LST inspection system comprising a light-weight luminaire and a relatively compact low-cost microbolometer, in conjunction with DPPT processing, is able to detect BVID in an aerospace grade carbon-epoxy laminate, at a scan rate of 50 mm/s and a stand-off distance of 500 mm. The significance of this finding for remote LST inspection via an unmanned aerial vehicle is discussed.