Comparative Evaluation of a High Operating Temperature Midwave Infrared Detector for Automated Non-Destructive Inspection of Composite Damage

Abstract

Abstract. A new high operating temperature (HOT) midwave infrared (MWIR) imaging core is experimentally evaluated for use in automated inspection of composite impact damage by line scan thermography (LST). This evaluation is undertaken as part of a broader effort to develop an autonomous inspection capability for aerospace composite structures, deployable by ground and aerial robotic systems. The performance of the HOT MWIR core is assessed against a high-performance cooled photon-detector camera, an uncooled microbolometer core and an uncooled microbolometer camera, on two carbon epoxy laminate test specimens: one containing flat-bottom-hole synthetic defects and the other barely visible impact damage (BVID) introduced by controlled low-velocity impact. These test panels are scanned using a 3-axis robotic LST apparatus, at speeds of 25 and 100 mm/s. The HOT MWIR core is shown to match the detection performance of the cooled camera, and to significantly outperform both microbolometers. The high performance of this core combined with its relatively low mass, size and power consumption offers an encouraging basis for the development of a drone-deployable LST inspection capability.

The effect of positional instability on the detection of barely visible impact damage in composites using a mobile thermographic inspection robot

“…3 containing the 10 mm and 5 mm FBH was modelled with an additional material buffer of 50 mm in the y direction, to account for times where the detector field of view (FOV) travelled off the panel. Material properties used for this simulation can be found in previously reported work [16]. Fig.…”

“…Well-established NDI methods such as ultrasonic testing are relatively slow, especially when implemented manually, and because they typically require precise positioning and the use of an ultrasonic couplant, are not well suited to rapid wide-area inspection. Active thermography, a wide-area non-contact technique, provides a more encouraging basis for ground and aerial robotic deployment, as demonstrated in recent studies [6][7][8][9][10][11][12][13][14][15][16][17].…”

“…Several of these previous robotic implementations involve line-scan thermography (LST), e.g. [11][12][13][15][16][17]. LST utilises a focused light source to generate a line of heat which is moved at constant speed over the test area.…”

“…In DPPT, BVID and other near-surface defects produce a characteristic dipole-shaped signature in the phase spectrum [15]. Another key element of this inspection capability is a high operating temperature (HOT) infrared detector, which previous work [16] has shown can match the performance of a conventional cooled photondetector but with significantly reduced size, weight and power consumption, making it better suited to robotic applications [16].…”

Detection and Characterization of Artificial Porosity and Impact Damage in Aerospace Carbon Fiber Composites by Pulsed and Line Scan Thermography

“…This allows reconstruction of a pseudo-static sequence following the procedure described in previous works [21,22]. It is also possible to process the dynamic sequences by PPT as described in [9,23].…”