Mechanical Behaviour of 3D Multi-layer Braided Composites: Experimental, Numerical and Theoretical Study
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Mechanical Behaviour of 3D Multi-layer Braided Composites: Experimental, Numerical and Theoretical Study Jian Deng1 · Guangming Zhou1 Xiaopei Wang1
· Le Ji2 ·
Received: 19 February 2017 / Accepted: 14 March 2017 © Springer Science+Business Media Dordrecht 2017
Abstract Mechanical properties and failure mechanisms of a newly designed 3D multilayer braided composites are evaluated by experimental, numerical and theoretical studies. The microstructure of the composites is introduced. The unit cell technique is employed to address the periodic arrangement of the structure. The volume averaging method is used in theoretical solutions while FEM with reasonable periodic boundary conditions and meshing technique in numerical simulations. Experimental studies are also conducted to verify the feasibility of the proposed models. Predicted elastic properties agree well with the experimental data, indicating the feasibility of the proposed models. Numerical evaluation is more accurate than theoretical assessment. Deformations and stress distributions of the unit cell under tension shows displacement and traction continuity, guaranteeing the rationality of the applied periodic boundary conditions. Although compression and tension modulus are close, the compressive strength only reaches 70% of the tension strength. This indicates that the composites can be weakened in compressive loading. Additionally, by analysing the micrograph of fracture faces and strain-stress curves, a brittle failure mechanism is observed both in composites under tension and compression. Keywords Braided composites · Unit cell · Fnite element method · Mechanical behaviour
Guangming Zhou
[email protected] 1
State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, No. 29 Yudao Street, Nanjing 210016, China
2
Sinoma Wind Power Blade Co., Ltd, Zhongguancun Dongsheng Technology Park, No. 66 Xixiaokou St, Haidian District, Bejing 100192, China
Appl Compos Mater
1 Introduction For the sake of weight reduction and high performance, various fibre-reinforced composite materials are developed and widely applied in industries (e.g. aerospace, transportation and marine) in recent years, as a supplement of metallic alloys. Conventional laminated composite materials have accounted for major appliance in structural design due to the traits in specific stiffness, strength and fatigue performance. However, the fibrous discontinuity through thickness orientation reduces damage tolerance, which partially restrict its industrial appliance for some specific purposes. This stimulates the development of three-dimensional (3D) braided composites that can be manufactured economically and productively with well-designed textile procedures [1]. Due to the fibre distribution in thickness direction, inter-laminar failure(e.g. delamination), is dramatically eliminated [2–5]. This reinforcement usually contributes to an improvement of damage tolerance and impact resistance. However, the study on mechanical p
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