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短玻璃纤维增强聚合物注塑充填过程及纤维取向数值模拟 总被引:1,自引:0,他引:1
基于Hele-Shaw理论及广义非牛顿流体本构方程,建立了纤维增强聚合物三维薄壁注塑成型充填阶段数学模型,根据Folgar-Tucker取向模型,建立了纤维取向张量模型。采用Moldflow对拉伸试样的注塑流动过程进行模拟,研究纤维含量f和纤维间相互作用系数Ci对纤维取向的影响。结果表明,随着Ci增大,平均纤维的取向性呈减小的趋势;试样不同部位的纤维取向不同;f对纤维取向性影响较小,且存在一个最佳含量百分比数值。 相似文献
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基于广义牛顿流体本构方程,采用ARD-RSC纤维取向模型,考虑纤维间相互作用,仿真预测长玻纤增强复合材料注塑构件的纤维取向分布;应用复合材料细观力学Eshelby夹杂理论和Mean Field均匀化方法,建立长玻纤增强复合材料均质化RVE模型;综合运用复合材料细观建模、离散RVE模型场、注塑成型和结构有限元分析技术,提出了长玻纤增强复合材料注塑构件强度分析方法。对推力杆注塑构件进行强度分析,显示仿真危险位置与实际破坏位置较为吻合。在此基础上对推力杆进行结构改进,结果表明杆体中间部分在拉伸载荷下的最大主应力降低了57.18%,在压缩载荷下的最大主应力降低了71.25%。 相似文献
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纤维增强聚合物熔体的纤维取向和流场应力分析 总被引:1,自引:0,他引:1
针对纤维增强聚合物基复合材料的成型流动过程, 基于宏观流场、 介观纤维取向和微观聚合物大分子链三尺度信息耦合的多尺度模型, 使用有限体积法和有限差分法相结合的数值算法, 分析了纤维增强聚合物熔体在收缩流腔中的流动行为, 得到了其纤维取向和应力分布, 并讨论了纤维存在对聚合物熔体流场应力的影响。结果表明: 当剪切运动占优时, 纤维呈现周期旋转取向; 而拉伸运动占优时, 纤维沿单轴拉伸取向。同时, 由于纤维的周期旋转, 纤维增强聚合物熔体法向应力差的空间分布呈现出随时间逐步发展的拟序涡结构。 相似文献
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利用自行研制的活塞式挤压流变仪研究了掺加聚乙烯醇(PVA)短纤维和粉煤灰的地聚合物浆体在挤压过程中的流变学特性,在此基础上通过单轴挤压机成功制备出宽厚比=12.5∶1.0的短纤维增强地聚合物基复合材料。利用MTS电液侍服机系统研究了各种纤维和粉煤灰掺量的地聚合物基复合材料的弯曲行为。采用扫描电镜(SEM)研究了地聚合物基复合材料中纤维的分布、取向、纤维-基体间界面,以及弯曲实验后试样断裂面上的纤维伸出长度、纤维尖端断裂形貌和纤维表面组织,从细观和微观角度探讨各种地聚合物基复合材料微观结构和弯曲破坏机制。结果表明:PVA短纤维的加入改变了地聚合物浆体的破坏模式,由脆性破坏变为延性破坏;对于不掺或掺加少量粉煤灰(≤10%)的地聚合物基复合材料弯曲强度高,但延性小,当粉煤灰的掺加量≥30%时,地聚合物基复合材料的弯曲强度显著下降,但延性增大。 相似文献
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发展了一种细观力学有限元分析方法——拟真实的参数化双随机分布模型, 该模型综合考虑了纤维增强树脂基复合材料的真实微结构特点和纤维单丝综合力学性能测试结果的离散性特征, 模拟了复合材料中纤维排列和强度分布的随机性。借助移动窗口法研究了该参数化双随机分布模型的可靠性, 确定了其代表性体积单元的尺寸。基于能量法原理推导了单向复合材料的弹性模量预测公式, 结合能量法和渐进失效分析方法, 利用该细观力学有限元方法分别预测了单向纤维增强树脂基复合材料T300/5228的弹性模量和强度性能。数值模拟结果和大部分试验结果吻合良好, 表明发展的细观力学有限元方法能够较好地预测复合材料的力学性能。 相似文献
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Short fiber reinforced composites inherently have fiber length distribution (FLD) and fiber orientation distribution (FOD), which are important factors in determining mechanical properties of the composites. Since the internal structure has a direct effect on the mechanical properties of the composites, a Micro-CT was used to observe the three dimensional structure of fibers in the composites and to acquire FLD and FOD. It was successful to investigate FLD, FOD, and fiber orientation states and to predict the elastic modulus of the hybrid system. Since hybrid composites used in this study consist of three phases of particles, glass fibers, and matrix, theoretical hybrid modeling is required to consider reinforcing effects of both particles and glass fibers. Interaction between the particles and matrix was considered by using a perturbed stress–strain theory, the Tandon–Weng model. In addition, the laminating analogy approach (LAA) was used to predict the overall elastic modulus of the composite. Theoretical prediction of hybrid moduli indicated that there was a possibility of poor adhesion between glass fibers and matrix. The poor interfacial adhesion was confirmed by morphological experiments. This theoretical and experimental platform is expected to provide more insightful understanding on any kinds of multiphased hybrid composites. 相似文献
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利用压制成型工艺制备了洋麻纤维增强全降解复合材料, 分析了纤维体积分数、长度以及取向分布对材料弯曲模量的影响, 并根据COX 剪滞法和洋麻纤维在成型后被压缩的结构特点, 探讨了一种修正COX 剪滞模型对弯曲模量的预测。实验表明, 随着纤维体积分数、长度和取向因子的增加, 材料的弯曲模量增加。扫描电镜的观察显示洋麻纤维的横断面呈现多孔状结构, 成型后受到压缩而变得致密, 增加了材料的弯曲模量。预测结果表明, 结合了纤维压缩率的修正模型的预测计算值与实验值取得较好的一致。 相似文献
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界面对复合材料蠕变性能的影响很大。在试验分析的基础上建立了硅酸铝短纤维增强AZ91D镁基复合材料理论分析模型,利用三维有限元分析方法,系统研究了界面特性、界面上应力应变分布和短纤维位向变化对硅酸铝短纤维增强AZ91D镁基复合材料蠕变性能的影响。研究表明:界面特性,如厚度、模量,均对纤维最大轴应力和稳态蠕变速率有影响,当界面厚度增加,纤维最大轴应力减小而稳态蠕变速率增大;当界面模量增大,纤维最大轴应力增大而稳态蠕变速率减小,但当界面模量高于基体模量时,纤维最大轴应力和稳态蠕变速率均保持不变;纤维位向也影响轴应力分布和稳态蠕变速率,纤维在其末端界面上存在较大的应力和应变,此处容易产生微裂纹而使材料抗蠕变能力下降;界面对硅酸铝短纤维增强AZ91D镁基复合材料的蠕变曲线和蠕变断裂机制也有影响,其影响程度还与纤维位向有关。 相似文献
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基于均匀化方法,根据长玻纤增强聚丙烯(LGFR-PP)的微观特征,建立了非连续长玻纤增强复合材料的代表性体积单元(RVE),通过有限元方法模拟预测了复合材料的宏观等效弹性力学参数,与注塑样条拉伸性能测试结果进行了比较。研究表明,通过在玻纤两侧增加聚丙烯(PP)分布,所采用的RVE较传统连续纤维的有限元模型更为合理;当玻纤成单一取向时,玻纤增强聚丙烯为一种横观各向同性材料;改变玻纤取向与拉伸方向之间的角度,拉伸方向的等效模量先微幅减小,再迅速降低,而后趋于稳定。利用均匀化方法预测非连续长玻纤增强注塑件的等效弹性力学性能具有较高的工程可行性,能进一步为玻纤增强注塑件的结构服役性能分析提供科学依据。 相似文献
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Young’s modulus of unidirectional glass fiber reinforced polymer (GFRP) composites for wind energy applications were studied using analytical, numerical and experimental methods. In order to explore the effect of fiber orientation angle on the Young’s modulus of composites, from the basic theory of elastic mechanics, a procedure which can be applied to evaluate the elastic stiffness matrix of GFRP composite as an analytical function of fiber orientation angle (from 0° to 90°), was developed. At the same time, different finite element models with inclined glass fiber were developed via the ABAQUS Scripting Interface. Results indicate that Young’s modulus of the composites strongly depends on the fiber orientation angles. A U-shaped dependency of the Young’s modulus of composites on the inclined angle of fiber is found, which agree well with the experimental results. The shear modulus is found to have significant effect on the composites’ Young’s modulus, too. The effect of volume content of glass fiber on the Young’s modulus of composites was investigated. Results indicate the relation between them is nearly linear. The results of the investigation are expected to provide some design guideline for the microstructural optimization of the glass fiber reinforced composites. 相似文献
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为了实现高硬度和高耐磨模具自由曲面的高效光整加工,提出了一种以Lyocell短纤维增强气压砂轮基体的新方法,分析了Lyocell短纤维增强橡胶基复合材料的理论模型及气压砂轮结构模型。利用Instron试验机对复合材料试样进行了拉伸试验,并通过误差分析研究了其强度极限。对比分析了弹性模量的试验数值与理论数值,证明了剪滞模型预测气压砂轮基体弹性模量的准确性。对不同短纤维体积分数的气压砂轮光整加工时的压力变化与形变范围进行了仿真分析,验证了短纤维增强气压砂轮基体的可行性。分析了凸曲面与气压砂轮呈不同角度接触时的受力大小及加工面积,获得了理想的接触角度。通过对高硬度凸曲面的材料去除试验,证明了短纤维增强气压砂轮基体这一设想以及气压砂轮仿真试验的可行性。 相似文献
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An experimental study was conducted to investigate anisotropy effects on tensile properties of two short glass fiber reinforced thermoplastics. Tensile tests were performed in various mold flow directions and with two thicknesses. A shell–core morphology resulting from orientation distribution of fibers influenced the degree of anisotropy. Tensile strength and elastic modulus nonlinearly decreased with specimen angle and Tsai–Hill criterion was found to correlate variation of these properties with the fiber orientation. Variation of tensile toughness with fiber orientation and strain rate was evaluated and mechanisms of failure were identified based on fracture surface microscopic analysis and crack propagation paths. Fiber length, diameter, and orientation distribution mathematical models were also used along with analytical approaches to predict tensile strength and elastic modulus form tensile properties of constituent materials. Laminate analogy and modified Tsai–Hill criteria provided satisfactory predictions of elastic modulus and tensile strength, respectively. 相似文献