Global measurements from low-velocity impact experiments and local strain measurements from embedded and surface mounted optical fiber Bragg grating (FBG) sensors were used to obtain failure maps for two- and three dimensional woven composites. These maps delineated five distinct regimes spanning behavior from initial impact to complete penetration. Sensor and host damage were separated by signal intensity and the evolution of Bragg peaks due to repeated impact loads. The results indicate that a local-global framework can be used to monitor damage progression in different host materials, and hence it can be potentially used to mitigate damage.

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An exact solution is obtained for the diffraction of a plane harmonic electromagnetic wave incident on a semi-infinite open-ended perfectly conducting circular wave guide.

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An investigation of the low velocity impact and quasi‐static failure of polymethylmethacrylate (PMMA) based on global and local strain measurements was conducted. Local strains were obtained from surface‐mounted fiber Bragg grating (FBG) sensors, and they were combined with global measurements from quasi‐static indentation and low‐velocity impact experiments to obtain detailed maps of how failure evolves. For both loading regimes, the interactions between the host PMMA specimens and the sensors played a crucial role in the evolution of residual strains. A mapping of the strains clearly shows that strains decrease radially, from high values near the point of impact to far‐field values. Sensors located in critical locations had the highest residual strains prior to PMMA fracture. Furthermore, it was determined that strain transfer to the sensor is strongly influenced by the bonding conditions at the specimen's surface. Because of the debonding of the sensor and the frictional effects associated with the bonding agent, compressive residual strains occurred on the rear‐surface. Hence, a detailed understanding of how strain evolves due to sensor–host interactions and catastrophic fracture can be obtained, which can potentially be used to mitigate damage in PMMA for a range of strain rates. POLYM. COMPOS., 28:381–391, 2007. © 2007 Society of Plastics Engineers