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This paper reports the large-scale finite element analysis (FEA) of a 3D angle-interlock layer-to-layer woven composite material undergoing low-cyclic three-point bending fatigue at microstructure level. A microstructure geometrical model of the 3D woven composite material was established to model the real structure of the woven composite. The fatigue behaviors of the 3D woven composite undergoing three-point bending with sinusoidal wave-form were investigated from experimental and FEA approaches. Based on displacement-controlled bending and inelastic hysteresis energy fatigue damage criterion, the interior deformation, energy absorption, and stress distribution characteristics during the fatigue process were analyzed. The different failure mechanisms and damage patterns of yarns and resin were discussed. The influence of the 3D woven structure on the fatigue behaviors was discussed. The fatigue damage morphologies and stiffness degradation were obtained to compare with the experimental results. The results show that the most of energy was absorbed by warp yarns. Stress concentration was emerged on the inclined part of warp yarns and the interface between yarns and resin. The damage morphologies from experimental and FEA results are in good agreement. The stiffness degradation curves also show the same tendency. 相似文献
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Application of textile waste for development of value added green composites has been carried out in this work. Textile fabric waste is collected from various sources. These waste materials are garneted, so as to produce loose fibrous material, subsequently this fibrous material was converted into twisted strand for manufacturing of 3D woven preforms for production of composites. Twisted strands are converted into orthogonal 3D woven structure. The fibers extracted from waste material are combined with polypropylene in 60/40 proportion. Composites of various specifications are developed to examine their end-use applications. These composite materials are characterized for their mechanical behavior to find out the response against tensile loading, flexural stress, and impact force. The effects of moisture absorption on mechanical properties of composites are investigated. 3D woven fabric reinforced composites produced by using waste fiber yarn and normal cotton OE yarn do not exhibit any significant difference in the mechanical behavior of composite. This result confirmed that waste material can be safely used as reinforcing structure in green composite manufacturing. 相似文献
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为解决层合间隔复合材料易开裂和整体性差的问题,采用绿色环保的玄武岩低捻长丝作为经、纬纱,合理设计经向截面图和组织图,并在普通织机上织造3种不同间隔高度的锯齿形三维机织间隔织物。以所织得的锯齿形三维机织间隔织物作为增强材料,环氧乙烯基树脂作为基体,利用真空辅助成型工艺,制备锯齿形三维机织间隔复合材料,同时对三维机织间隔复合材料进行三点弯曲性能测试,得到弯曲载荷-位移曲线、能量吸收图和破坏模式。结果表明:复合材料的纬向是主要承力方向;组织循环个数越多的材料表现出更好的弯曲性能;在一定间隔高度范围内,间隔高度越高的锯齿形三维机织间隔织物承受的弯曲载荷和吸收的能量也越高;锯齿形三维机织间隔复合材料的破坏模式是材料上表层受压,下表层受拉,而连接层受压;在作用力下材料只是出现明显的变形,但并未出现材料整体的破坏。 相似文献
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This paper presents the finite element simulation of stress distribution features of 3D layer-to-layer angle-interlock woven composite undergoing three-point bending cyclic loading. With the finite element analysis model, a microstructure shell element model of the woven composite at yarn level was established to calculate the fatigue behaviors and stress distribution during cyclic loading. The stress distributions in the warp, weft yarns, and the resin regions have been calculated to show the stress difference in the woven composite. It has been observed that the warp yarns share the most part of the stress or loading, i.e. the strength warp yarn is more important than that of the weft yarn for the fatigue design. In addition, the stress distributions at the locations where the weft yarns crossover the warp yarns have been investigated. The stress degradations of the top and bottom surface of the woven composite panels were also compared with those in experimental and good agreement was found. With the stress distribution in the woven composite, the method of improving the fatigue damage tolerance was expected to be developed. 相似文献
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The objective of this research is to develop the woven/knitted hybrid composites for improved in plane as well as out of plane mechanical properties. Two different type of structures and two different materials were used in this study. Firstly, the woven and knitted fabrics were developed with glass and Kevlar yarn. Secondly, the laminated composite samples were fabricated with different stacking sequence of fabric plies. The epoxy resin was used as matrix. The cured samples were characterized for impact, tensile and dynamic mechanical properties. The behavior of composite materials was then analyzed with percentages of different fiber and fabric types. The samples with higher percentages of knitted reinforcement gave better impact strength but failed to provide better tensile properties. Moreover, the samples with higher percentages of woven structure and glass materials gives better modulus values. 相似文献
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This paper reports the three-point bending fatigue behavior of three-dimensional (3D) orthogonal woven composite (3DOWC) in experimental and finite element analysis (FEA) approach. In experimental, the S–N curve was obtained to illustrate the relationship between applied stress levels and number of cycles to failure. The stiffness variation was recorded to present the degradation of mechanical properties of the 3DOWC during the process of fatigue loading. Furthermore, the fatigue damage morphologies of the tested 3DOWC coupons were given to indicate the damage modes of different parts (resin, yarns, and their interface) of the composite under the range of stress levels. In FEA approach, a user-defined material subroutine UMAT which characterizes the stiffness matrix and fatigue damage evolution of the 3DOWC was developed and incorporated with a finite element code ABAQUS/Standard to calculate the maximum deflection of the 3DOWC during each loading cycle. The bending deformation at different loading cycles was also calculated. From the comparisons between FEA and experimental approaches, it is indicated that the proposed model is reasonable for calculating the fatigue bending deformation. 相似文献
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二维与三维机织复合材料力学性能的实验研究 总被引:1,自引:0,他引:1
对超厚三维正交机织复合材料及二维要织层合板人别进行了拉伸和压缩实验,研究比较了两种复合材料刚度和强度特性的差异研究发现无论是三维机织材料的拉压还是二维层合板的拉压应力应变曲线都近似为直线,而且具有脆性破坏的特点;三维复合材料的拉压强度要高于二维层合板.这主要是由于材料不同的增强相结构及纤维含量造成;不同的破坏模式对材料强度影响很大. 相似文献
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为了研究正交机织物的实际结构,采用玻璃纤维在剑杆织机上织制了纬纱接结的6层经纱5层纬纱的正交机织物,然后利用VARI工艺与聚酯树脂复合,制成了复合材料板材试样,并在显微镜下观测纱线的形状。研究发现:三维正交机织物的经、纬纱基本呈直线状态,接结纬纱是曲线与直线组合的形状,且形状与在织物中的位置有关,越靠近织物中央,接结纬纱的直线部分越短;接结纬纱使其限定的经纱产生聚集现象,在复合材料中产生贫富树脂区,接结纬纱形状的变化也使织物的结构不均匀。对织造过程的分析表明,造成接结纬纱形状变化的原因是织物形成过程中接结纬纱的滑动,从织物边部到中央,接结纬纱的滑动阻力逐渐增大,接结纬纱的张力也逐渐增大。 相似文献
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为实现直升机板簧式起落架减重和提高层间剪切性能,采用碳纤维三维机织结构整体制备复合材料起落架。针对起落架的设计要求,通过受力分析和理论计算,建立了板簧式起落架的三维力学分析模型;通过材料实验和理论计算,获得了有限元计算所需的材料工程常数;结合最大应力-应变准则,采用有限元方法对板簧进行准静态加载模拟,确定了板簧的截面和轴线几何形状,以及变截面增厚部位的长度值与厚度值。结果表明:基于斜纹2.5维机织复合材料结构,截面宽度为120 mm,厚度为24 mm的弓式圆弧形、矩形截面板簧在满足挠度的同时其应变小于材料许用应变值;基于优选截面,增厚长度为760 mm,增厚厚度为36 mm时,复合材料起落架不仅能较好满足挠度、强度等设计要求,而且在同类型航空用4340钢制成的板簧结构件基础上质量减少约30%。 相似文献
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为满足市场对不同种类三维机织物的需要,提高多剑杆织机的产品适应性,在分析现有三维机织物造型工艺优缺点的基础上,提出了一种在多剑杆织机上织造三维机织物的新型造型工艺即织边造型工艺。结合新型工艺的需要,对现有多剑杆织机的织边系统和打纬机构的结构进行了改进设计,简单介绍了这种新型工艺的织造过程。通过在小样织机上试织,按照工艺织造出圆形横截面仿形织物。实验结果表明,织边造型工艺应用于复合材料预制件的织造会在一定程度上提高织机对更多织物产品种类的适应性,同时可解决织机因层数限制而不能织造壁厚较大的空心机织物的问题。 相似文献
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Conventional 3D woven T-shaped preforms were modified for improving joint/ peel off strength of associated T-shaped polymeric composites. Preforms were modified at weaving level by preferred yarns orientations for better performance in associated composites. Major modifications studied are; the addition of supporting layer, single or double-crossing in joint layers and crossing along with supporting layer (in a single sample). Novel derivatives were compared with conventionally used (on-loom and off-loom) T-shaped 3D woven composites. Microscopic analysis was also carried out to analyze the orientation of yarns and analysis of samples from failure point after testing. By combined variation of crossing and supporting layers improvement of 47.37% in peel off strength and 70.37% in impact strength was observed. Modified T shapes can serve to be a good replacement for conventional T-shaped stiffener (used to avoid folding under loads) and in joints. 相似文献
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为研究开孔尺寸对三维机织复合材料拉伸力学行为、破坏模式以及失效机制的影响规律,设计了3种不同孔径的三维机织复合材料试样,利用非接触全场应变测试系统和显微图像技术进行表征。结果表明:6、10、14 mm 的孔径对三维机织复合材料的拉伸模量几乎没有影响,开孔后全截面拉伸强度分别下降35.6%、44.5%和51.8%,但开孔后的净截面拉伸强度基本相同,与未开孔试样相比,平均拉伸强度下降约22.4%;未开孔试样的全场应变呈现均匀分布,而开孔试样在孔左右两侧呈现出应变集中;开孔试样的断口形貌相似,主要表现为经纱的断裂,并伴随有部分纱线的抽拔以及层间开裂。 相似文献
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为准确分析不同结构厚截面复合材料不同方向上的弯曲性能差异,通过设计织造三向正交、浅交直联、浅交弯联3种典型机织结构的厚截面碳纤维三维机织物,并采用真空辅助树脂成型工艺制备了近似纤维体积含量的碳纤维复合材料板,对其进行了XYZ方向的弯曲实验。结果表明:三向正交结构由于内部纤维束近似平直,碳纤维束自身性能得到最大利用,对应复合材料经向弯曲强度最好;浅交直联结构复合材料的Z经和Z纬弯曲强度累加值最大,其厚度截面上的综合弯曲性能最好,且其他各方向的弯曲强度较为均衡;浅交弯联结构内部纱线交织摩擦损伤严重,且经纱屈曲程度最大,对应复合材料经纬向弯曲性能均为最差。 相似文献
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Fracture toughness is a key factor to design impact behaviors of composite materials. This paper reports the influence of pre-crack length on Mode I fracture toughness of 3-D angle-interlock woven composites. Double cantilever beam specimens with different pre-crack lengths were tested to obtain load-displacement curves and strain energy release rates. A finite element analysis model at microstructure level was established to reveal the fracture damage development and stress distribution in the specimens. We found that the fracture toughness decreases with increase in pre-crack length. The higher pre-crack length resulted in increased stress concentration at crack tip position and the enhanced crack propagation. The higher strength through-thickness yarns are recommended for improving fracture toughness. 相似文献