Intelligent carbon fibre composite based on 3D-interlock woven reinforcement

In this paper we describe the manufacturing and testing of an intelligent carbon fibre composite based on 3D-woven reinforcement. Piezoresistive fibrous sensors developed and optimized previously have been inserted into the carbon fibre reinforcement in the weft direction on a modified loom. These sensors were integrated at the top and bottom faces. Afterwards the reinforcement with embedded sensors was impregnated in epoxy resin using VARTM technology. The composite specimens thus obtained were tested for bending using the three-point bending test method. The results obtained show that the sensors allow simultaneous mapping of compression and traction at the top and bottom of the reinforcement when it undergoes bending. This is due to the fact that, unlike traditional strain gages, our sensors become integral part of the reinforcement and follow the tow architecture as dictated by the weaving process and interlacement pattern. Moreover, these sensors are compatible with the weaving process as they are flexible and sensitive enough to follow the deformation pattern of the reinforcement. Such sensors can be inserted inside various types of reinforcements during weaving in both warp and weft directions. Their location can be strategically chosen so as to form a network of sensors inside the reinforcement capable of following the deformation patterns of the reinforcement and mapping its stress–strain history.