双轴向经编针织复合材料的弹道侵彻破坏

通过真空辅助树脂传递模压法（VARTM）制造双轴向经编针织复合材料。在350～750m/s冲击速度范围内对复合材料作弹道冲击测试,得到弹体的入射速度、剩余速度及动能损失,弹体的剩余速度与入射速发近似满足线性关系,动能损失随弹速的增加呈现先上升后下降的状态。考察复合材料靶体的弹道侵彻破坏损伤形态,发现复合材料受弹面的破坏区域较子弹出射面的破坏区域小且破坏形态不同,由此揭示双轴向经编针织复合材料的弹道侵彻破坏模式与机理。     

不同结构纺织复合材料准静态侵彻实验分析及有限元模拟

本文研究了两种不同结构三维结构纺织复合材料——三维正交机织玻璃纤维,不饱和树脂复合材料和双轴向纬编针织玻璃纤维／不饱和树脂复合材料在MTS材料试验机上的准静态侵彻测试。以纯铝MTS实验数据为标定,分析了准静态侵彻载荷一位移曲线及其破坏机理,比较了不同结构纺织复合材料以及纯铝的位移一载荷曲线,由此计算得到位移与吸能关系曲线。同时根据复合材料各自织物中纤维束排列及织物成型特点,分别建立了复合材料的细观结构模型和单胞模型。编写用户子程序（VUMAT）,用ABAQUS软件进行了有限元模拟。结果表明：三维纺织复合材料各自损伤结果和载荷-位移曲线与实验结果吻合较好,证明有限元的有效性。三维正交结构复合材料抗侵彻能力优于双轴向纬编针织复合材料,但是破坏过程中其抗侵彻能力幅值变化差异大,没有针织复合材料抗侵彻能力稳定。     

三维正交机织复合材料弹道冲击实验及破坏模式

本文用钢芯弹对三维机织复合材料作弹道冲击测试。得到了弹体的入射速度和剩余速度,比较了常见几种材料的弹道性能评价参数的差异,并考察侵彻破坏模式和靶体最后的损伤破坏形态。在300-800m/s冲击速度范围下观测了材料的冲击破坏形态,发现机织复合材料受弹面和子弹出射面破坏形态不一样,受弹面主要是以纤维的压缩、剪切破坏以及基体开裂为主,出射面以纤维的拉伸、厚度方向的纱线断裂为主要破坏模式。通过对破坏模式和形态的分析,可以帮助建立更加准确的破坏准则,从而在设计抗弹材料时起到一定的作用。     

三维正交机织复合材料准静态侵彻实验和有限元模拟

用钢制侵彻体对三维正交机织复合材料在MTS材料试验机上作准静态侵彻测试，得到的准静态侵彻位移一载荷曲线用来研究材料的能量吸收和破坏模式。根据三维机织复合材料的细观结构建立单胞模型，结合应力更新原理编写用户子程序（VUMAT）。利用ABAQUS有限元软件及用户子程序模拟实验过程，得到的位移一载荷曲线与实验对比，可以看出有限元计算得到的结果与真实实验比较吻合，表明单胞的建立和用户子程序的编写是正确的。     

三维角链锁机织物弹道侵彻性能实验研究

选用一种三维角链锁组织结构进行实弹侵彻测试,研究三维角链锁机织物的弹道侵彻性能。实弹测试时,由靶道两侧两对发光二极管测试弹体入射速度与剩余速度,并结合弹体和织物靶体几何结构参数计算三维角链锁机织物的弹道侵彻性能指标,从而预测三维角链锁机织物的弹道侵彻性能。实弹测试后采用微距相机观察织物靶体实弹侵彻后的变形与破坏,从而揭示三维角链锁机织物的能量吸收机理。     

动力有限元在三维编织复合材料弹道冲击性能研究中的应用

三维编织复合材料具有高的层间剪切强度,高的损伤容限和显著的抵抗裂纹扩展的能力。三维编织复合材料弹道性能的研究一般局限于实验观察阶段。本文运用数值计算方法对三维编织复合材料细观结构有限元模型进行弹道冲击性能研究,得出了合理的结果,说明了这种方法的有效性。     

高强玻璃纤维板抗高速破片侵彻性能试验

为了研究高强玻璃纤维板抗高速破片侵彻性能,开展了弹道试验,探讨了破片入射速度、靶板厚度对高强玻璃纤维板抗侵彻性能的影响,通过对弹道试验结果分析,指出了高强玻璃纤维板的变形失效模式、吸能特性和抗侵彻机理。结果表明:破片在侵彻高强玻璃纤维板过程中可视为刚体,高强玻璃纤维板迎弹面破坏模式为纤维剪切破坏并伴随纤维反向喷出,迎弹面弹孔附近区域出现基体碎裂、纤维脱粘;背弹面破坏模式为纤维拉伸断裂,背弹面损伤区域远大于迎弹面损伤区域;高强玻璃纤维板单位面密度吸能随着破片侵彻速度增加呈线性增加,在试验速度范围内,得出了立方体破片侵彻不同厚度靶板入射速度与剩余速度、入射速度与靶板单位面密度吸能关系。     

织物及其复合材料的弹道冲击性能研究进展

本文总结了近年来织物及其复合材料弹道冲击性能研究的进展以及发展现状,详细分析了不同纺织结构的织物及其复合材料对弹道冲击损伤机理以及吸收能量机制的影响,阐述了目前弹道侵彻分析模型以及数值模拟计算的现状,对优化弹道防护材料设计进行了探索,对弹道防护材料的开发进行了展望。     

含z向纤维增强的连续纤维增强树脂基复合材料冲击性能研究进展

层合复合材料受到冲击载荷时会产生严重分层破坏,z向增强纤维的引入可明显改善层间韧性,提高复合材料的抗冲击性能.本文首先对纤维增强复合材料的冲击过程进行了阐述,并综述了近年来z向纤维增强复合材料冲击研究成果,包括缝合结构、z-pin结构和三维纺织结构.从实验方法和数值模拟两方面进行总结,介绍了低速、高速冲击的破坏模式、损...     

三维角联锁机织复合材料三点弯曲疲劳的细观结构效应

依据层层接结三维角联锁机织复合材料的结构特点,建立能真实反映细观结构特征的大型精细实体几何结构模型;基于非弹性滞后能疲劳破坏准则,用有限元法计算三维角联锁机织复合材料在三点弯曲低周交变循环载荷下的变形和刚度降解,揭示疲劳过程中三维角联锁机织复合材料内部应力分布特征和变形特征,分析纱线与树脂的破坏机理,阐述该复合材料在循环载荷下发生疲劳破坏的结构效应。结果表明,经纱在疲劳过程中承担大部分的载荷,且不同的组分呈现不同的破坏扩展过程。本文研究结果和研究方法将可进一步扩展至三维机织复合材料工程结构设计。     

Micromechanical model of time-dependent damage and deformation behavior for an orthogonal 3D-woven SiC/SiC composite at elevated temperature in vacuum

This paper presents a micromechanical model to predict the time-dependent damage and deformation behavior of an orthogonal 3-D woven SiC fiber/BN interface/SiC matrix composite under constant tensile loading at elevated temperature in vacuum. In-situ observation under monotonic tensile loading at room temperature, load–unload tensile testing at 1200 °C in argon, and constant load tensile testing at 1200 °C in vacuum were conducted to investigate the effects of microscopic damage on deformation behavior. The experimentally obtained results led to production of a time-dependent nonlinear stress–strain response model for the orthogonal 3-D woven SiC/SiC. It was established using the linear viscoelastic model, micro-damage propagation model, and a shear-lag model. The predicted creep deformation was found to agree well with the experimentally obtained results.     

三维正交机织物组织结构的几何表征和数学表征

切取三维正交机织物沿经向和纬向的连续横截面,在三维视频显微镜下拍摄和分析织物横截面中经纱、纬纱和Z纱的横截面形态、纱线空间构型,用参数方程表征理想状态下织物中经纱、纬纱和Z纱截面尺寸及屈曲形态。基于三维绘图软件Pro/E,重构三维正交机织物单胞模型及大尺寸织物模型,使其能更准确、更真实地反映三维正交机织物真实细观结构。     

Multiple Cracking and Tensile Behavior for an Orthogonal 3-D Woven Si-Ti-C-O Fiber/Si-Ti-C-O Matrix Composite

This paper presents experimental results for the multiple microcracking and tensile behavior of an orthogonal 3-D woven Si-Ti-C-O fiber (Tyranno™ Lox-M)/Si-Ti-C-O matrix composite with a nanoscale carbon fiber/matrix interphase and processed using a polymer impregnation and pyrolysis route. Based on microscopic observations and unidirectional tensile tests, it is revealed that the inelastic tensile stress/strain behavior is governed by matrix cracking in transverse (90°) fiber bundles between 65 and 180 MPa, matrix cracking in longitudinal (0°) fiber bundles between 180 and 300 MPa, and fiber fragmentation above 300 MPa. A methodology for estimation of unidirectional tensile behavior in orthogonal 3-D composites has been established by the use and modification of existing theory. A good correlation was obtained between the predicted and measured composite strain using this procedure.     

Relationship between tensile properties and ballistic performance of poly(ethylene naphthalate) woven and nonwoven fabrics

In this study, we investigated the effect of tensile properties of poly(ethylene naphthalate) (PEN) yarns on the ballistic performance of woven and nonwoven soft and composite armors. The results of ballistic tests of PEN armors were compared with Kevlar 49 armors as a reference. Based on these results, the Cunniff's equation was revised by removing the fiber elongation at break to predict the relationship between tensile properties and ballistic performances of PEN fibers. The calculations showed that by increasing tenacity of PEN fibers from 8.5 g/den (commercial product) to 12.5 g/den (strongest up to date PEN fibers produced by a novel melt spinning process discovered by our research group), the weight ratio of PEN to Kevlar 49 decreased from 1.8 to 1.35 with the same ballistic performance. Contrary to the results of the soft armors, composite armors made of high modulus PEN woven fabric showed a 17% lower ballistic resistance compared to the composite armor made of low modulus PEN woven fabric. The results of ballistic tests indicated that high tenacity PEN fibers produced in this research could have potential in soft and composite armors, and high velocity impact applications or improve performance of PEN in its current applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

芳纶复合材料抗弹性能研究

通过研究芳纶复合材料不同纤维类型，不同纤维编织方式和不同纤维体积含量对抗弹性能的影响关系以及芳纶复合材料与陶瓷复合结构的抗弹性能，为提高芳纶复合材料结构单元的综合抗弹性能找到了一条重要途径。     

Energy absorptions and failure modes of 3D orthogonal hybrid woven composite struck by flat‐ended rod

Three‐dimensional (3D) orthogonal woven composite has high stiffness, strength, and energy absorption capacity along X, Y, and Z directions because there are no crimps in yarn. This paper presents mechanical behaviors and energy absorptions of the 3D orthogonal hybrid woven composite under transverse impact and quasi‐static loading by flat‐ended rod. The failure load and energy absorption of the composite increase with the increase in loading rate. The damage morphology of the composite coupon manifests the compression failure in the front side and tension failure in rear side. There are no delaminations in the composite coupons for both quasi‐static and impact loading for the existence of Z‐yarn in fabric structure. This phenomenon manifests the potential application of the 3D orthogonal woven composite to impact resistance areas. POLYM. COMPOS., 27: 410–416, 2006. © 2006 Society of Plastics Engineers     

Comparison of mechanical and ballistic performance of composite laminates produced from single‐layer and double‐layer interlocked woven structures

Textile structures have become quite popular as reinforcement materials in composite laminates due to their high impact‐damage tolerance and energy absorption ability. The impact performance of textile composites is not only affected by the type of fiber/matrix but also by the fabric structure used as reinforcement. The aim of this study was to compare the mechanical and ballistic performance of composite laminates reinforced with single‐layer and double‐layer interlocked woven fabrics. Kevlar^®−29 multifilament yarn was used for preparation of all the fabric structures and epoxy resin was used as the matrix system. The composites were produced using a hand lay‐up method, followed by compression molding. The mechanical and ballistic performance of composites reinforced with single‐layer and double‐layer interlocked woven fabrics was investigated in this study. The energy absorption and mechanical failure behavior of composites during the impact event were found to be strongly affected by the weave design of the reinforcement. The composites reinforced with double‐layer interlocked woven fabrics were found to perform better than those comprising single‐layer fabrics in terms of impact energy absorption and mechanical failure. POLYM. COMPOS., 35:1583–1591, 2014. © 2013 Society of Plastics Engineers