Random discontinuous long fiber (DLF) composites are increasingly finding utility in various aerospace secondary structural applications such as structural brackets, fittings, or frames/inter-costals. While these structures may undergo accidental impacts during operation and maintenance, identifying impact damage in DLF composite components is a desired capability before and during their application to aircrafts. Characterization of internal impact damage in DLF composites is difficult, especially in complex shaped composite structures. Geometric complexity and signal dispersion in DLF composites with many interfaces make impact damage inspection using conventional non-destructive inspection (NDI) methods such as ultrasonics, thermography, X-ray film, and digital radiography impractical. In this paper, evaluation of impact behaviors of DLF composites, compared to conventional continuous-fiber reinforced composites, is presented. 3-D computed tomography (CT) X-ray was employed to successfully characterize the impact damage in DLF and continuous-fiber reinforced composites. Impact behaviors of the two distinct materials are investigated by comparing their impact responses such as dent depth, energy absorption, damage extent and distribution, and residual strength after impact. DLF composite was found to offer much higher normalized residual strength after impact than continuous-fiber composite, while the two materials show similar impact responses.
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