LOCAL AND GLOBAL MEASUREMENTS OF DYNAMIC DAMAGE EVOLUTION IN WOVEN COMPOSITE SYSTEMS

摘要

In this study, measurements from low-impact velocity experiments including embedded and surface mounted optical fiber Bragg grating (FBG) sensors were used to obtain detailed information pertaining to damage progression in two-dimensional woven composites. The woven composites were subjected to multiple strikes at 2m/s until perforation occurred, and the impactor position and acceleration were monitored throughout. From these measurements, we obtained dissipated energies and contact forces. The FBG sensors were embedded and surface mounted at different locations near penetration damaged regions. These sensors were used to obtain residual strains and axial and transverse strains corresponding to matrix cracking and delamination. An analysis of the FBG spectra provided independent feedback on the integrity of the Bragg gratings. A comparison by number of strikes and dissipated energies corresponding to material perforation indicates embedding these sensors did not affect the integrity of the woven system, and that these measurements can provide accurate failure strains.