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Influence of fiber volume fraction on Microstructure and Mechanical Properties of C/C Composites

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Influence of Fiber Volume Fraction on Microstructure and Mec...

Resin Matrix Shear Band and Its Special Effect on Stress Concentration of fiber Composites

加速功能材料自主创新，促进西部战略性新兴产业发展——2011中国功能材料科技与产业高层论坛

作者： Xingdong QIN,Ruiying LUO School of Physics and Nuclear Energy Engineering,Beijing University of Aeronautics and Astronautics,Beijing,China,100191

C/C composites,densified through chemical vapor infiltration(CVI) ,were prepared by needled felt with fiber volume fraction of 17.6%,25.6% and 35.8%. In order to study the relationship among fiber volume fraction,microstructure and mechanical properties,the textural of pyrocarbon was observed by polarized light microscopy and a flexure test was applied to C/C composites. The results show that fiber volume fraction influence the matrix and flexural properties of composite distinctly. Composite with fiber volume fraction 25.6% has more higher-textured pyrocarbon,the highest density,flexural strength and modulus,while composites with fiber volume fraction 17.6% and 35.8% has the lower flexural strength and modulus due to its more lower-texture pyrocarbon,unsuitable interfacial bonding strength and lower density.

关键词： fiber volume fraction C/C composites microstructure mechanical behavior

来源： cnki会议评论

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Chinese Journal of Polymer Science 2014年第6期32卷 703-710页

作者： Guo-wei Zhu Feng-de Ma 贾玉玺 Peng Qu Yun-li Guo Xiao-chen Sun Key Laboratory for Liquid-Solid Structural Evolution & Processing of Materials (Ministry of Education) Shandong University

A constitutive model is constructed to consider the resin matrix post-yield softening and progressive hardening behaviors. A user-defined material mechanical behavior （UMAT） subroutine is created, then the non-linear three-dimensional finite element analysis on the tensile processes of multi-fiber composites is conducted. The approximate 45° shear bands emanating from the matrix crack tip are found, being coincided with the experimental observations. The shear stress on the adjacent intact fiber/matrix interface is strongly influenced by the shear band and thus the stress concentration factor （SCF） changes obviously in the adjacent fibers. The distinct stress redistribution in the adjacent intact fibers implies the significant effect of the shear bands on the progressive fiber fracture initiation. As the inter-fiber spacing increases, the peak value of the SCF in the adjacent intact fiber decreases, whereas the overload zone becomes wider. The research has provided a helpful tool to evaluate the failure of fiber composites and optimize the composite performance through the proper selection of resin matrix properties and fiber volume fraction.

关键词： fiber composite Stress concentration Shear band fiber volume fraction Theory and modeling.

Yarn Architecture Analysis of Two-step 3D Braided Composites

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Journal of Donghua University(English Edition) 2005年第3期22卷 126-132页

作者：孙颖亢一澜李嘉禄 Depart ment of Mechanics Tianjin UniversityTianjin 300072 Institute oftextile composites Tianjin Polytechnics University Tianjin 300160

A comprehensive study of yarn architecture of two-step rectangle 3D braided composites is presented. Firstly, the braided surface, the shapes of yarns and the intertwining between braider yams and axial yams are analyzed from experimentation. With the microstructure being defined, three levels of unit cell structure are identified, i.e. large unit cell, second unit cell and minimal unit cell. Secondly, based on the minimal unit cell in the interior and on the boundary of the entire cross-section, the deformations of axial yams squashed by braider yams contribute to the increase of the fiber packing factors of axial yams. Finally, the predicted fiber volume fraction of the composites decreases with the increase of linear density of the braider yam and the pitch length. Favorable correlations between the predicted and the experimental results arc found for six groups of the composites.

关键词： composites mo -step 3D braided yarn geometry fiber volume fraction deformation

Compression Responses of Preform in Vacuum Infusion Process

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Chinese Journal of Aeronautics 2008年第4期21卷 370-377页

作者：段跃新谭朝元肇研孙静北京航空航天大学材料科学与工程学院北京100083

The final thickness of a product after the vacuum infusion process （VIP）, which is equal to the fiber volume fraction, depends in part on the compression responses of the preform because one of the mold faces is flexible in VIE This study aims at investigating the compression responses of different fabrics under dry or wet conditions. The main factors affecting the compression response under investigation include, the vacuum pressure, the loading and unloading repeatability on the preform, the layup design, the kinds of fabrics, and the resin viscosity. Besides, the effects of some internal factors such as nesting and elastic recovery of fibers, lubrication of resin, friction between fibers, and so on, are also studied. In the end, this article expatiates the meaning of the matching requirements of the permeability of the preform and that of the distribution medium.

关键词： vacuum infusion process compression response fiber volume fraction

Preparation and Mechanical Properties of UV⁃Assisted Filament Winding Glass fiber Reinforced Polymer⁃Matrix Composite

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Transactions of Nanjing University of Aeronautics and Astronautics 2020年第3期37卷 467-480页

作者： CHEN Xiaodong LI Yong HUAN Dajun WANG Wuqiang LIU Li College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106P.R.China National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

This paper studied the preparation and mechanical properties of glass fiber reinforced polymer-matrix composite rings prepared by filament winding assisted by ultraviolet(UV)curing.A ray-tracing method was used to calculate the penetration ability of UV light in the resin casting,and then a typical composite ring with dual⁃curing characteristics was prepared by UV-assisted *** effects of winding speed and thermal initiator concentration on the distribution of fiber fraction and mechanical properties were *** morphology was used for the observation of the differences in fiber volume *** properties tests and scanning electron micrographs were performed to investigate the failure and damage mechanisms of the composite ring *** ray tracing results indicate that the UV light can pass through a single yarn thickness and the energy transmitted is sufficient to cure the back side *** experimental results show that the mechanical properties of the composite ring prepared in this paper are comparable to those of the heat-cured samples,which is sufficient to meet the requirements of the flywheel.

关键词： glass fiber reinforced polymer(GFRP) ultraviolet(UV)curing dual-curable resin mechanical properties fiber volume fraction

Simulation on the Flow-Compaction Behavior of Thick Composite Laminate and the Effect of Interlaminar Permeability

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Simulation on the Flow-Compaction Behavior of Thick Composit...