A comprehensive evaluation of the low-velocity impact behaviour of intraply hybrid flax/basalt composites using infrared thermography and terahertz time-domain spectroscopy techniques

Low-velocity impacts severely jeopardize the structural reliability of polymer composites. In view of this, a thorough evaluation of the impact damage of the polypropylene (PP) composites reinforced with an ecofriendly intraply flax/basalt hybrid fabric was performed based on infrared thermography (including pulsed thermography, linear scanning thermography) and terahertz time-domain spectroscopy (THz-TDS) techniques. However, the main problem is the lack of multi-source fusion technique regarding more than two sensors, and the discussions regarding homologous fusion (pulsed thermography and linear scanning thermography), and non-homologous fusion (infrared thermography and THz-TDS). In this work, a comprehensive evaluation for the impact resistance of hybrid polymer composites was conducted, including detecting the uneven resin distribution and exploring new multi-sources fusion strategy. The experimental results demonstrate the superior capability of multi-source fusion techniques. • An improved pulsed phase thermography method is discussed to reduce noise caused by the fibre weaving patterns. This novel technique can increase at least 1/6-fold over the original version. • A new multi-fusion strategy based on Dempster-Shafer theory and unsupervised network U2Fusion is proposed. • A normalized time-domain integration (NTDI) method is presented to efficiently and accurately identify the uneven resin distribution.