Characteristic analysis of carbon nanotube thread embedded into three-dimensional braided composite under bending load

In this paper, we introduce an embedded method of carbon nanotube threads (CNTs) in three-dimensional (3-D) braided composite material preform. We investigate the strain sensing properties of CNTs embedded into 3-D braided composites using three-point bend test under different loads. The resistance change rate properties of CNTs in composites under tensile and compressive loading are analyzed in detail. Experimental results show that in the three-point bending process, the resistance of CNTs exponentially increases with the increase of strain until the specimen loading to fracture. Moreover, the residual resistance of CNTs has been observed after unloading. Our experiments have shown that structure health status of 3-D braided composites can be sensed and monitored in real-time using CNTs sensor under bending load. This study provides an experimental basis to lay the foundation for the structural health monitoring system construction of 3-D braided composites.