04.1 - Aerospace Grade Materials, Structural Analysis, Fatigue and Damage Tolerance
A DYNAMIC TEST METHODOLOGY FOR DETERMINING THE LONGITUDINAL COMPRESSIVE RESPONSE OF CARBON FIBER COMPOSITE TOWS
J. Gu¹, Y. Bai¹, Z. Zhao¹, C. Zhang¹; ¹Northwestern Polytechnical University, China
Textile composites have been applied widely in aircraft structure, such as fan blades and cases of aero-engine, since of their excellent impact resistance, great delamination resistance and high damage tolerance [1]. 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 [2]. However, determination of the Intrinsic properties of individual composite fiber tow mainly rely on theoretical and numerical predictions. Because of small size and challenges in effective loading of this unidirectional composites [3] in dynamic testing, it strain-rate effects still lacks direct test methodology and experimental results. In this study, a dynamic compression test method for composite fiber tows is proposed based on the Split Hopkinson compressive bar system combined with an ultra-high-speed camera. Firstly, the volume fraction, porosity content and fiber misalignment distribution of composite tows are evaluated characterized to compare the influence of different preparation methods. The comparison of several common specimen designs by quasi-static and dynamic compression test and finite element simulation shows that dumbbell design is a reasonable design. Then, the validity and applicability of the test methodology are verified systematically and comprehensively from stress distribution, data reduction method, dynamic stress balance and failure morphology. The preliminary test results show that the compressive properties of composite fiber tows are significantly dependent on the strain rate, and the compressive strength increases by more than 50% when the strain rate ranges from 0.01 s-1 to 400 s-1. This work will realize the direct and efficient test of composite tows and provide insightful inputs for multiscale analysis of textile composite.