Design of 3D composites and their structural health monitoring system

This book is divided into two parts. The first part deals with the design of 3D woven structures on modified looms and their geometrical and mechanical characterization. The second part treats the complete design and development issues related to SHM system using flexible sensors. Manufacturing and testing of an intelligent carbon fiber composite based on 3D woven reinforcement has been described in detail. Piezoresistive fibrous sensors have been developed, optimized and inserted in the carbon fiber reinforcement in the weft direction on a modified loom. These sensors were integrated in the middle layer. Afterwards the reinforcement with embedded sensors was impregnated in epoxy resin using VARTM technology. The composite specimens thus obtained were tested for tensile loading. The results obtained show that the sensors allow mapping of traction in the composite specimen. This is due to the fact that, unlike traditional strain gauges, the inserted sensors become integral part of the reinforcement and follow the deformation pattern of the composite. This allows on-line monitoring of strain and propagation of cracks in the composites.