Hybrid Sensors for Impact-induced Strain in Smart Composite Plates

An experimental study if conducted to evaluate the performance of different types of strain gauges for impact detection in eight layer symmetric cross-ply Graphite/Epoxy composite plates. The plates were impacted with rigid spheres using the drop-weight technique. The impacts did not produce apparent damage in the composite plate. The responses of calibrated surface-mounted extrinsic Fabry-Perot fiber optical sensors, a metalized polyvinylidene fluoride foil sensor, and a conventional electrical resistance rosette are compared. Characteristics of signal signatures from each sensor are demonstrated. Advantages and disadvantages of utilizing each type of strain sensor in the composite structure are discussed. The experimental strain responses are presented for various impact energies. The significant features of the strain response are contact duration, peak strain, strain rise time, and full width at half maximum. All of the sensors exhibited reproducible and similar results. The extrinsic Fabry-Perot fiber optical sensor performed superior with respect to sensitivity and accuracy of point measurement