A dynamic test methodology for determining the longitudinal compressive response of carbon fiber composite tows

Textile composites have been applied widely in aircraft structures, such as fan blades and cases of aero-engine, because of their excellent impact resistance, great delamination resistance and high damage tolerance. Composite fiber tows, as the main load-bearing component, have a critical influence on the dynamic performance of textile composites and even the whole composite structures. However, the determination of the intrinsic properties of individual composite tow mainly relies on theoretical and numerical predictions. In this study, a dynamic compression test method for composite fiber tows is proposed based on the Split Hopkinson pressure bar system combined with an ultra-high-speed camera. Firstly, the porosity contents of composite tows are evaluated and characterized to compare the influence of different preparation methods. A reasonable dumbbell-shaped configuration for the compressive specimen is then proposed, based on the results of both simulated and experimental validation on the stress distribution, the data reduction method, dynamic stress balance, and failure morphology. The preliminary test results show that the compressive properties of composite tows are significantly dependent on the strain rates, and the compressive strength increases by nearly 90% when the strain rate ranges from 0.01 s-1 to 400 s-1. This work will realize the direct and efficient test methodology for determining the dynamic longitudinal compressive performance of composite tows and provide insightful inputs for multiscale analysis of textile composite.