07/28/2010

Leibniz-Institut für Polymerforschung Dresden e.V.

Health monitoring in composite materials: Interphase sensor

Scheme of the function of the interphase sensor
Scientists of the Leibniz Institute of Polymer Research Dresden (IPF) present at the K 2010 (hall 10, G33) a novel innovative approach for structural health monitoring in continuous glass-fibre reinforced composites.
Application of electrically conductive carbon nanotubes (CNT) in a coating system induces electrical conductivity on the glass fibre surfaces and in the composites’ interphases that have not been conductive before. If the composite is subjected to mechanical loading, the CNT network is deformed, and this deformation can be measured as a change in electrical resistance. Consequently, irreversible damages of the composite material due to defects in the interphase or the failure of the reinforcing fibres may be detected by observing changes in electrical resistance.
During application in service life, structural components made of fibre-reinforced composites are locally differently loaded and strained, due to their textile architecture and the dimensions of the components. The application of CNT-based interfacial sensors in continuous glass-fibre reinforced composites offers a new alternative approach allowing to monitor interphase related damage of the composite structure. Thus, defects can be identified at an early stage of damage providing valuable information for the further damage assessment of the composite structure. The single fibres, yarns, or semi-finished products with sensor properties may be introduced into the preform in different local arrangements, according to the expected load distribution in the component. As compatibility of the coating with the matrix is provided, no additional interfaces are created which could be a potential flaw in the composite material.