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1.
作为对平面编织复合材料弹性质预测的单向直波纹模型的改进,本文提出一个双向的,在经线和纬线方向上均衡的直波纹模型,它更为符合编织复合材料微结构特点。采用这个新模型和经典层板理论,通过对模型上,下表面的两种极限约束条件,予测了平面编织复合材料层板弹性常数的界限。结果表明,这个模型所予测的值更为准确,合理。  相似文献   

2.
柔性复合材料及其应用   总被引:9,自引:0,他引:9  
姚立宁 《力学进展》1993,23(3):386-397
本文综述了目前柔性复合材料的研究。柔性复合材料具有大变形和非线性弹性的特点,基本分析建立在经典的层合理论和非线性弹性力学的基础上。这种材料的应用实例有帘子线/橡胶复合材料,涂层纤维织物,以及含波纹纤维的复合材料等。  相似文献   

3.
利用有限元方法求取单向纤维增强复合材料的横向弹性性能参数的计算模型包括三维模型、两维平面应变模型、单胞模型等等.由于单胞模型仅仅适用于纤维规则排列情况.在纤维随机分布且纤维大小亦为随机时,单向纤维增强复合材料横向弹性性能参数必须通过对于复合材料块体的计算才能获得.同时在随机分布纤维的数量增大时,三维模型和二维平面应变模型的计算量急剧增加,模型的处理能力不强.该文提出一种利用内嵌区域模型来计算含大量随机大小、随机分布细小纤维的单向纤维增强复合材料块体的横向弹性性能参数的方法,有效降低了计算量.在较低的计算费用下,能够快速获得单向纤维增强复合材料的横向弹性性能参数.  相似文献   

4.
三维机织复合材料的弹性性能预报模型   总被引:9,自引:0,他引:9  
易洪雷  丁辛 《力学学报》2003,35(5):569-577
建立了基于等效响应比拟技术的三维机织复合材料弹性性能预报模型.首先将三维机织物的结构单元分解为4个子元(经纱、纬纱、填充纱和接结纱),用几何模型去估算这些子元的体积分数.然后依据不同的外载形式,将复合材料的应力-应变关系等效地表达为3组诸子元所组成的三维弹簧网络.根据刚度系数的物理意义,采用不同的弹簧网络连接形式,并按体积平均化方法获得材料总体刚度矩阵中相应的刚度系数,进而计算得到三维机织复合材料的9个弹性系数.该模型考虑了层内交织经纱、层间交织接结纱的弯曲以及材料内部纯树脂区对三维机织复合材料弹性性能的影响.试验结果与模型的理论预测值进行比较,表明这个模型是有效的。  相似文献   

5.
根据纤维增强复合材料宏细观结构特征,基于ABAQUS软件平台,建立了层合板高速冲击损伤三维有限元分析模型。该模型在复合材料层间引入界面单元模拟层间分层,采用三维粘弹性本构,结合Hashin失效准则模拟单层板面内损伤.利用该模型,深入研究了复合材料层板的抗弹性能和损伤特性,数值分析结果与实验结果吻合良好,证明了该方法的合理有效性。通过数值分析,详细探讨了材料强度参数对层板抗弹性能和损伤特性的影响规律,获得了一些有价值的结论。  相似文献   

6.
王玮  杜星文 《力学进展》2007,37(2):205-213
织物复合材料具有高的抗损伤性, 各方向的性能优于层合复合材料, 因而引起人们的重视. 织物增强复合材料由于其高比强度、易于制造和充分发展的织物技术等优点使其已经广泛用 于航空、汽车和运动产品. 由于使用这些材料越来越普遍, 自动化生产替代了手工生产, 用 精确的方法模拟材料的变形是必不可少的. 为了精确的反映材料的行为, 那么就需要描述材 料力学性质的本构方程,而作为验证本构模型的试验是伴随着本构模型的发展而发展的. 本文首先综述了织物及织物复合材料的发展和现状, 接着重点介绍了织物及织物复合材料的本构理论的研究发展, 并对织物及织物复合材料的斜拉伸试验、像框试 验等内容进行了介绍. 最后根据织物复合材料的最新进展对其未来的发展趋势进行了展望.  相似文献   

7.
三维编织复合材料几何建模及数值分析   总被引:3,自引:0,他引:3  
论文根据三维编织复合材料的结构特点,把整体结构分为内部单胞、表面单胞和角单胞三种类型的子单胞,考虑空间纤维束的相互扭结和挤压所造成的纤维束的弯曲和截面变形,针对每种类型的子单胞,建立了相应的几何分析模型.引入周期性位移边界条件,建立了材料的弹性性能预报模型,得到了三维编织复合材料的工程弹性常数.通过数值比较可以看出,论文所给出的数值计算结果与实验结果吻合较好,从而验证了本文模型的有效性.  相似文献   

8.
编织复合材料弹性性能的细观力学模型   总被引:7,自引:0,他引:7  
燕瑛 《力学学报》1997,29(4):429-438
提出了编织复合材料弹性性能分析的细观力学模型,这个力学模型考虑了实际编织结构中的纬向和经向纤维束的曲屈,相邻纤维束之间的间隙和纤维束的横截面尺寸对编织复合材料弹性性能的影响,并探讨了在纤维束间纯树脂区内孔隙的含量和两种叠层结构对材料弹性性能的影响.理论计算结果与实测值的比较,表明所提出的细观力学模型是合理的.根据理论分析的结果,提出了优化单层和叠层编织结构的结构参数选择方法  相似文献   

9.
本文对单向纤维增强复合材料裂纹扩展统计理论的两个主要论据进行了研究.1.由于纤维断裂引起的应力重分布的计算:文中采用通常的剪滞模型,进行了弹塑性形变理论分析和弹性分析,弹性分析的结果与已有的J.M.Hedgepeth 的结果相符.2.裂纹扩展模型的探索:这里舍弃沿用Gücer-Gurland.Rosen 链式模型,提出了逐渐扩大断裂层的模型,参照A.S.Argon 等人的方法进行了统计分析,得到了单向纤维增强复合材料拉伸强度的计算公式.  相似文献   

10.
随着复合材料日益广泛的应用,其断裂问题的研究亦受到重视,本文将复合材料视为均匀各向异性材料,从而采用各向异性平面弹性理论来处理复合材料的二维断裂问题.1.带单边裂纹的各向异性板的应力和位移分布根据各向异性平面弹性理论,当复参数(其大小将表征物体偏离各向同性的程度)为  相似文献   

11.
热环境中旋转运动功能梯度圆板的强非线性固有振动   总被引:2,自引:0,他引:2  
研究热环境中旋转运动功能梯度圆板的非线性固有振动问题.针对金属-陶瓷功能梯度圆板,考虑几何非线性、材料物理属性参数随温度变化以及材料组分沿厚度方向按幂律分布的情况,应用哈密顿原理推得热环境中旋转运动功能梯度圆板的非线性振动微分方程.考虑周边夹支边界条件,利用伽辽金法得到了横向非线性固有振动方程,并确定了静载荷引起的静挠度.用改进的多尺度法求解强非线性方程,得出非线性固有频率表达式.通过算例,分析了旋转运动功能梯度圆板固有频率随转速、温度等参量的变化情况.结果表明,非线性固有频率随金属含量的增加而降低;随转速和圆板厚度的增大而升高;随功能梯度圆板表面温度的升高而降低.  相似文献   

12.
对二维编织陶瓷基复合材料拉伸应力-应变行为进行了试验研究和理论模拟. 将二维 编织结构简化为:正交铺层结构和纤维束波动结构. 基于基体随机开裂、纤维随机断裂分布 理论,得到正交铺层结构的应力-应变关系;基于体积平均方法,将纤维束波动部分进行分割, 引入强度分析模型,得到纤维束波动部分的应力-应变关系. 结合正交铺层部分和纤维束波动 部分的应力-应变关系,得到二维编织结构的应力-应变行为,理论与试验吻合较好.  相似文献   

13.
A model to predict the effective stiffness of woven fabric composite materials is presented. Taking advantage of the inherent periodicity of woven fabric architecture, periodic microstructure theory is used at the mesoscale for the case of a two-phase heterogeneous material with multiple periodic inclusions. For plain weave fabrics, the representative volume element (RVE) is discretized into fiber/matrix bundles and the pure matrix regions that surround them. The surfaces of the fiber/matrix bundles are fit with sinusoidal equations using two approaches. The first is based on measurements taken from photomicrographs of composite specimens and the second is based on an idealized representation of the plain weave structure. Three-dimensional sinusoidal surfaces are generated from the face equations and weave shape for the real and idealized cases in order to mathematically describe the fiber/matrix bundle regions, which are treated as unidirectional composites. Model results from the idealized geometry are compared to experimental data from the literature and show good agreement, including interlaminar material properties. From a comparison of the real and idealized geometry results for similar material RVE dimensions, it is seen that the model is capable of predicting significant changes in the in-plane material properties from slight mismatch in the fiber/matrix bundle shape and crimp, which can be captured using the geometric surfaces generated from photomicrograph measurements.  相似文献   

14.
The losipescu shear test method was used to determine the in-plane shear response of AS4 and Celion carbon fiber/epoxy fabric composite materials. Several weave architectures were studied: AS4 uniweave, AS4 and Celion plain weaves, Celion 5-harness and 8-harness satin weaves. Specimens were tested using traditional strain gage techniques and full-field moiré interferometry. A full-node localized hybrid analysis is introduced to perform efficient reduction of moiré data, producing whole-field strain distributions in the specimen test section. It was found that the fabric yarn size greatly influenced the uniformity of the shear field in the specimen test section. However, consistent shear moduli still can be obtained using the modified losipescu specimen and Wyoming fixture except for fabrics with large fiber yarns.  相似文献   

15.
We propose a new approach for developing continuum models for the mechanical behavior of woven fabrics in planar deformation. We generate a physically motivated continuum model that can both simulate existing fabrics and predict the behavior of novel fabrics based on the properties of the yarns and the weave. The approach relies on the selection of a geometric model for the fabric weave, coupled with constitutive models for the yarn behaviors. The fabric structural configuration is related to the macroscopic deformation through an energy minimization method, and is used to calculate the internal forces carried by the yarn families. The macroscopic stresses are determined from the internal forces using equilibrium arguments. Using this approach, we develop a model for plain weave ballistic fabrics, such as Kevlar®, based on a pin-joined beam geometry. We implement this model into the finite element code ABAQUS and simulate fabrics under different modes of deformation. We present comparisons between model predictions and experimental findings for quasi-static modes of in-plane loading.  相似文献   

16.
将材料细观结构优化和宏观结构优化结合起来,从结构与材料两个尺度出发,发展复合材料导向叶片的结构与材料一体化优化设计方法.在建立平纹编织复合材料细观结构分析模型的基础上,采用细观力学有限元法进行材料刚度性能预测,热-固耦合分析方法进行涡轮导向叶片结构分析.同时以细观结构参数和宏观结构参数为设计变量,以叶片质量最小为优化目...  相似文献   

17.
A general and systematic approach for the development of mesostructurally-based continuum model of woven fabrics has been elaborated, relating the fabric behavior at the macroscopic continuum scale to the response and geometry of the fabric’s mesostructure (geometrical configuration of the weave and the yarn properties). Mesoscopic discrete models of dry fabric have been developed based on a discretization of the yarn geometry, accounting for the yarn–yarn interactions at the yarns crossing points. The yarns are modeled within a unit cell consisting of the repetitive fabric pattern as curved planar beams submitted to the reaction forces of the transverse yarns at discrete crossover points. Those reaction forces are expressed in semi-analytical form versus the yarn geometry and mechanical properties for general armour from beam theory. The equilibrium shape of the woven fabric is obtained by minimizing its total potential energy, accounting for the work of the reaction forces due to the transverse yarns. The absolute minimum of the structure’s total potential energy is achieved by a classical genetic algorithm. Simulation results show that plain weave presents a nonlinear response in the early deformation stage due to the crimp change, whereas twill shows a quasi linear response due to yarn extension being the dominant deformation mechanism. Plain weave fabric overall exhibits an orthotropic constitutive law, as biaxial simulations show. The transverse behavior of plain weave fabric is presently evaluated in terms of Poisson’s ratio, based on virtual simulations at the mesoscopic scale of analysis. Simulation results show that Poisson’s ratio first increases towards a maximum due to the rapid shrinkage of the sample in the transverse direction, and decreases thereafter when the crimp changes become limited by the reaction forces of the transverse yarns. The influence of the mechanical properties of both warp and weft on Poisson’s coefficient is assessed. The predictions of the mesoscopic models regarding the impact of yarn geometry and mechanical properties on the overall behavior provide a guideline for the design of woven fabrics.  相似文献   

18.
The market demand for thicker complex shaped structural composite parts is increasing. Processes of the Liquid Composite Moulding (LCM) family, such as Resin Transfer Moulding (RTM) are considered to manufacture such parts. The first stage of the RTM process consists in the preforming of the part. During the pre-forming of multilayered reinforcements, frictions between the plies occur and need to be taken into account for the forming simulation. An experimental device designed to analyse the ply/ply and ply/tool frictions has been set up. The different set up steps of the device are described. First results are presented, which show the ply/ply friction behaviour for a glass plain weave fabric. A specific contact behaviour has been observed for dry reinforcement fabric in comparison to non-technical textiles. A honing effect classically observed in dry fabric testing has also been pointed out through cyclic experiments. It can be attributed to both fibre material abrasion and fibre reorganisation inside the yarn.  相似文献   

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