Non-destructive evaluation of laminated composite plates using dielectrometrysensors

Abstract

The use of composite materials in marine, aerospace and automotive applications isincreasing; however, several kinds of damages of composite materials may influence itsdurability and future applications. In this paper, a methodology was presented for damagedetection of laminated composite plates using dielectrometry sensors. The presence ofdamage in the laminated composite plate leads to changes in its dielectric characteristics,causing variation in the measured capacitance by the sensors. An analytical model wasused to analyse the influence of different sensor parameters on the output signalsand to optimize sensor design. Two-dimensional finite element (FE) simulationswere performed to assess the validity of the analytical results and to evaluateother sensor design-related parameters. To experimentally verify the model, thedielectric permittivity of the composite plate was measured. In addition, a glassfibre reinforced polymer (GFRP) laminated plate containing pre-fabricated slotsthrough its thickness to simulate delamination and water intrusion defects wasinspected in a laboratory setting. Excellent agreements were found between theexperimental capacitance response signals and those predicated from the FE simulations.This cost-effective technique can be used for rapid damage screening, regularscheduled inspection, or as a permanent sensor network within the compositesystem.