Comparative study of deterioration of composite due to ice formation using strain, electromechanical impedance and guided waves

Abstract

Glass fibre reinforced plastic (GFRP) composites are finding increasing application in aerospace structures. The monitoring of these structures is not only necessary but also mandatory by the safety codes. The present state of the art allows isolation of damage and the quantification of damage is the next challenge. The quantification may allow for better maintenance scheduling and as a result lower downtime for airplanes, which makes it significant in the aerospace discipline. It is known that the moisture absorption in the composites affects its mechanical properties. The moisture can interact with the composite sample in the gaseous, liquid or solid phase. The mechanism for deterioration of the composite due to the moisture depends on the phase in which the interaction occurs. The paper thus investigates the interaction of water absorbed by the sample in the solid phase. The GFRP sample is exposed to low temperatures after the ingress of the moisture. The sample is studied using three distinct damage detection methods namely, Electromechanical Impedance technique (EMI), Guided waves method (GW) and NA based technique based on measured strains. The aim of the research is to compare the performance of the three methods for the assessment of the deterioration of the composite samples due to ice. The EMI, GW and strain based method have been shown to be sensitive to moisture induced deterioration. In addition to the detection of deterioration, the use of measured strains provides an intuitive way for the quantification of the moisture induced deterioration in the sample.