The main purpose of structural health monitoring (SHM) is to detect damage at its earliest possible stage to prevent severe deterioration and reduce subsequent repair costs. Carbon nanotubes (CNTs) buckypaper (BP) was embedded into different cross-ply glass fibre composites to monitor the curing process and impact damage as an in situ sensor in this research. BP sensor can capture the four stages of the curing process, the gel point of the resin and residual stresses of the composite structure can be achieved by analysing the change of the resistance curve. Numerical and experimental analyses were performed to predict the damage in composite structures subjected to low-velocity impact. BP sensors’ electrical resistance increases with repeated impact loading; composite structure elastic deformation and damage evolution can be identified from resistance change. Experiment results show that structure monitoring based on the BP sensors cannot only detect small, barely visible impact damage flaws and the damage evaluation of composite structures subjected to impact, but also provide a new method to monitor the curing process through the analysis of results. This work makes some constructive contributions to monitoring the manufacturing process of composites and long-term SHM to evaluate impact resistance and damage prediction of composite structures.

Adding heterogeneous fillers with high thermal conductivity (TC) to polymer has been recognized as an effective way to increase the effective thermal conductivity (ETC) of polymer composites. Extensive researches have been conducted on the ETC of composites with heterogeneous fillers. However, the heat transfer enhancement mechanism of heterogeneous fillers remains unknown, and the combined effects of filler size, filler contact, interface thermal resistance (R_c) and other parameters on the ETC have not been explored. In this study, above combined effects are investigated. The results show that the filler contact and R_c are the key factors determining the ETC. The ETC of composite with filler contacts reaches 2.35 at filler content of 25%, which is 11.9% higher than that without filler contacts. The ETC also strongly depends on the R^*_c (dimensionless form of R_c) ratio (R^*_c1/R^*_c2) between two fillers, with it becoming asymmetrical when the amount of R^*_c(R^*_c1 + R^*_c2) is larger. The ETCs decrease with the increase of R^*_c1/R^*_c2 when the R^*_c1/R^*_c2<1, while they increase with R^*_c1/R^*_c2 when the R^*_c1/R^*_c2>1. When R^*_c1 + R^*_c2 is a constant, the ETC increases with the competing effects of R^*_c. The models with filler contacts exhibit higher accuracy than other classical models in calculating the ETC across the entire range of filler content.