Dr. Kara Peters

Embedded sensors provide a high sensitivity to sub-surface damage due to their proximity to the damage features. In particular, fibre Bragg gratings (FBG) are easily embedded into laminates with a minimum of perturbation to the surrounding material microstructure. In this paper we summarize some recent advances derived from full-spectral interrogation of FBG sensors for structural health monitoring and damage identification in composites. In particular we will present signals from the FBG reflected spectra that have been correlated to stress concentrations near crack tips, curing conditions during processing of composite laminates and the progression of delamination due to multiple low-velocity impacts in woven composite laminates and foam-core sandwich composites. We also discuss recent advances in interrogation systems for these sensors which have permitted dynamic evaluation of these parameters. Finally, spectral distortion can lead to errors in the interpretation of strain values from the peak wavelength measurement when peak waveforms are assumed. This distortion is highly dependent upon the local microstructure surrounding the sensor and therefore cannot be compensated a-priori through a calibration factor. We demonstrate that full-spectral interrogation can provide sensor specific error compensation for these measurements. These results demonstrate the richness of information that can be obtained from full-spectral interrogation of FBG sensors in a complex, multiple stress component environments.

BIOGRAPHY: Dr. Kara Peters is an Associate Professor in the Department of Mechanical and Aerospace Engineering at North Carolina State University. She received her PhD in Aerospace Engineering from the University of Michigan in 1996. For her dissertation work, she received the Ivor K. McIvor Award for Applied Mechanics at the University of Michigan. Following her PhD, Dr. Peters worked as Post-Doctoral Researcher in the Laboratory of Applied Mechanics at the Ecole Polytechnique Fédérale de Lausanne (Swiss Institute of Technology at Lausanne). She joined North Carolina State University in 2000. Dr. Peters is a member of the ASME Adaptive Structures and Material Systems Technical Committee and was the chair of the SPIE Smart Structures and Materials Symposium in 2010 and 2011. She has also been a visiting researcher at NASA Langley. Dr. Peters’ research focus on the development, modeling and integration of optical fiber based sensors for structural health monitoring of composite structures.  She is an Associate Editor of the journal Smart Materials and Structures.