Papers by Author: Ying Sun

Abstract: Silica（SiO2）matrix composite materials toughened by continuous fiber and fabric are the ideal materials for radomes, possessing many outstanding properties, for instance, high strength, excellent toughness and low density and so on. A comprehensive introduction is provided to the research and application of continuous fiber toughened SiO2 matrix composites, and some three dimensional configurations suitable for SiO2 matrix composites are mainly introduced. Combining with the future of the radome materials for missile, it is pointed out that SiO2 matrix composite materials toughed by continuous fiber or its three-dimensional fabric are the focus and development direction.

Abstract: The low-velocity impact response of Ultra-High Molecular Weight Polyethylene (UHMWPE) laminated composites were studied by drop-weight experiments. Laminated composites were fabricated with unidirectional UHMWPE prepreg using hot-pressing process. Laminated composites of size 150mm×100mm were subjected to low-velocity impact loading at three energy levels of 15J, 25J and 35J. It is found that the slops of load-time and energy-time curves increase with increase in the impact energy. However, load-time curve shows that there are some fluctuations before the peak load was reached. Peak load and absorbed energy increase with increasing impact energy. However, time to peak load decreases linearly with increasing impact energy.

Abstract: Based on the principle and fabricating process of Quasi-Isotropic braided composites, the regular pattern of movement of each yarn is analyzed and the inner unit cell model is established in this paper. The real Quasi-Isotropic braiding structure is built using 3D paint software named UG NX4.0. Compressive mechanical properties of 3D Quasi-Isotropic braided composites are also discussed. It is found that the load–deflection curve of the Quasi-isotropic braided composites displays a relatively linear behavior, behaving mostly as the characteristics of shear.

Abstract: The effects of machining methods such as high pressure water jet cutting, laser cutting, mechanical cutting on the geometry accuracy,macro aspect of UHMWPE fiber reinforced epoxy composite laminates are studied.Compare the property of geometry accuracy, macro aspect after the UHMWPE fiber reinforce composites laminates, find the processing method and the optimal parameters to provide the best choice for the machining of UHMWPE reinforce composites laminates and further speed up the study of composite dynamic property.

Abstract: Based on the photographic observation and analysis of different cross section of the materials, it is found that both the section of normal and warp yarns are rectangular in shape, the sections of weft yarns are the convex lens in shape, the weft and normal yarns are kept straight along their directions, the warp yarns are wavy. 3D images and geometry model of normal yarns reinforced 2.5D woven materials are established. This model can be used to calculate the fiber volume fraction of each yarn system. Compared with the experimental data, the computational results show excellent agreement. The work will lay the foundation for prediction of mechanical properties.

Abstract: As a universal finite element method commercial software, ABAQUS has been widely used in scientific research and engineering applications. However, convergence difficulties are familiar issues while carrying out damage and fracture analysis. Several methods, which are helpful to avoid these convergence problems, are presented in this paper. Baseline simulations about damage initiation and propagation in composites indicate that a larger value of viscous regularization causes the peak of the reaction force to be higher. A smaller viscosity parameter is better than bigger one. Other advanced techniques, include using automatic stabilization and customized general solution controls, are adoptable to improve convergence in ABAQUS/Standard analysis. The results of the paper are expected to provide guidance for the new user of ABAQUS.

Abstract: Some dynamic compressive tests about Ultra-High Molecular Weight Polyethylene Fiber-reinforced laminated Composites have been done using SHPB experimental system．The stress-strain curves of UHMWPE Fiber-reinforced Composites of three different laminated angles (0/90°, 0/90/45/-45°, 0/90/30/-60/60/-30°) are obtained at higher strain rates and their dynamic mechanical properties are also investigated at the same time．Based on all the stress-strain curves obtained, the characteristics of energy absorption of UHMWPE fiber angle-plied composites are analyzed and discussed．It is found that laminated angle has made little effect on the dynamic energy absorption of composites at higher strain rates．In addition，delamination and compaction in the thickness direction constitute the main dynamic failure mechanisms, which are studied by means of image analyses for the specimens after compression.

Abstract: The high strain rate compressive properties of UHMWPE/ vinyl ester 3D orthogonal woven composites are investigated experimentally. The composites are made from UHMWPE fiber 3D orthogonal woven preforms impregnated with vinyl ester resin by resin transfer molding. The samples are subjected to dynamic loading through the thickness direction using the Split Hopkinson Pressure Bar at three kinds of strain rate. The testing results are compared with the results of quasi-static tests on specimens with the same fiber volume fraction. The stress-strain relationships of UHMWPE/vinyl ester 3D orthogonal woven composites are rate dependent. It is found that the yield stress, strain at yield stress and modulus increased with the increased the strain rates. Additionally, the predominant failure mode of the composites under dynamic loading shear fracture from the optical microscopic images of fracture surfaces.

Abstract: This paper investigated the mechanical properties and the relationships between fiber architecture and the composites properties of three-dimensional multidirectional braided composites made of Toray@T700 carbon fiber impregnated with TDE 86# epoxy resin using RTM. The strength and stiffness properties measured here include tension, compression, flexure and short beam shear, all of these in both the longitudinal and transverse directions. It is found that the 3D six-directional braided composites with 55 % fiber volume fraction and 25°surface braiding angle represent quasi-isotropic in-plane elastic behaviors due to their symmetric, intertwined architecture and unidirectional reinforcements in both the longitudinal and transverse directions. Compared with the tension strength and modulus, those for compressions in the same directions descend near 40% and 10% respectively. The cut-edge on the width destroys the integrity of microstructure and inevitably cuts down the carrying capacity of composites under the longitudinal tension.