6. Conclusion
In this study, a low-velocity impact test for a composite plate was performed to investigate the effect of the sensing distance of three multiplexed Al-coated FBG sensors. The results obtained from the FEA based on CDM approach were compared to that of the experimental tests to validate the impact behaviors of the plate. All the results from the experimental tests and the simulation were consistent with each another. The permanently induced residual strains of the three multiplexed Al-coated FBG sensors were linearly related to the sensing distance from the impact point despite the sensors experiencing severe vibrations after the impact. This mean that some residual strain linearly increased as the impact point was approached. The results indicated that the linear relationship between the residual strain values and sensing distance was closely related to the linear correlation between the sensing position and the maximum strains experienced by the composite plate. This suggested that the impact information experienced by the composite structure could be quantitatively evaluated if the correlations between the structural deformation and residual strains with respect to the sensing distance were constructed in advance. Therefore, the correlation between the residual strains and the sensing distance of three multiplexed Alcoated FBG sensors examined in this study could improve the integrity of the proposed damage evaluation methodology. Furthermore, the results of this study could be utilized as guidelines for designing MCOFS based damage evaluation systems for actual applications.
