共查询到19条相似文献,搜索用时 78 毫秒
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介绍了近年来建立粘弹性材料本构模型的方法。目前主要有两种方法:利用现有本构模型;对粘弹性材料进行试验研究,拟合实验曲线。 相似文献
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高性能PVA 纤维增强水泥基复合材料常规三轴受压本构模型 总被引:2,自引:0,他引:2
对PVA 纤维体积率从0%~2%的高性能水泥基复合材料(HPFRCC)圆柱体试件进行了6 种不同围压下的常规三轴受压试验,研究其三轴受压性能,测得了极限抗压强度、峰值应变、极限应变以及应力-应变曲线。根据试验结果得出HPFRCC 的极限抗压强度、峰值应变以及极限应变与侧向围压之间的关系。基于实测圆柱体应力-应变曲线的特点,提出了HPFRCC材料常规三轴受压本构模型。计算结果与试验数据的对比表明,根据该文模型所得的计算曲线与试验曲线吻合较好,研究成果可为HPFRCC结构非线性有限元分析提供依据。 相似文献
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利用细观力学的Eshelby和Mori-Tanaka理论,考虑纤维和筒 裂纹之间的相互作用,研究了材料内部微裂纹的损伤演化规律及其材料力学性能的影响,导出了基本体开裂的 条件及多向复合材料的细观本构关系。 相似文献
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验证已建立的刚性颗粒增强复合材料刚塑性细观损伤本构理论的合理性和可靠性。将上述本构理论的数值计算结果与SiC颗粒增强的铝基复合材料单轴拉伸实验结果进行比较。结果表明:由此本构模型得到的应力-应变理论曲线与拉伸实验所得的应力-应变曲线基本吻合,从而验证了该本构模型的合理性和可靠性。因此已建立的刚塑性细观损伤本构模型可用于数值计算,在一定程度上可预测颗粒增强复合材料的力学特性。在此基础上对大、小颗粒增强复合材料的延展性、空洞和颗粒体积分数演化规律等作了讨论。 相似文献
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介绍了Leonov粘弹本构模型以及它在简单剪切流中的应用,它对于不同的流动问题具有较好的描述能力,能用来描述剪切流动、振荡流动及瞬态剪切流动等。并且基于高聚物材料的动态实验,采用非线性回归方法拟合出了Leonov模型中的物性参数,并用拟合的数据与材料的简单剪切行为进行了比较。 相似文献
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钢纤维与聚乙烯醇纤维混杂增强应变硬化水泥基复合材料(SF-PVA/SHCC)的力学性能研究是近年来的热点问题之一,但目前依然欠缺能够完整描述SF-PVA/SHCC拉伸本构关系的理论模型。本文基于混凝土断裂力学和细观力学理论,通过考虑拉伸应力-应变曲线软化段及SF-PVA混杂纤维对SHCC拉伸性能的影响,提出一种新的可适用于SF-PVA/SHCC材料的单轴拉伸本构模型。为了验证模型的有效性,开展了SF-PVA/SHCC单轴拉伸性能试验,分析了纤维种类和掺量对SHCC拉伸强度、拉伸应变及拉伸韧性的影响。通过与试验数据对比发现,本文所提出的拉伸本构模型可以较好地预测SF-PVA/SHCC的拉伸应力-应变关系。 相似文献
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混杂纤维增强应变硬化水泥基复合材料(HyF/SHCC)的力学性能是近年来的研究热点问题之一,但是目前依然欠缺HyF/SHCC压缩本构关系的深入探讨。本文研究了钢纤维(SF)-聚乙烯醇(PVA)纤维增强SHCC (SF-PVA/SHCC)的压缩应力-应变全曲线,分析了纤维对HyF/SHCC抗压强度、压缩应变以及压缩韧性的影响。研究发现,在本文研究工况下混杂纤维的引入对材料的抗压强度无明显影响,但是提高了压缩峰值应变。钢纤维对HyF/SHCC压缩韧性的影响较为显著,且随着钢纤维掺量的增大,HyF/SHCC的压缩韧性逐渐提高。基于损伤力学理论,从能量的角度提出了一种新的单轴压缩本构模型,通过与试验曲线的对比,发现该模型可以较好地预测SF-PVA/SHCC的压缩应力-应变关系。 相似文献
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碳化硅纤维增强碳化硅(SiCf/SiC)复合材料具有低中子毒性、耐中子辐照和耐高温氧化等特性, 成为先进核能系统重要的候选结构材料。近年来, 国内外学术界和工业界针对核用SiCf/SiC复合材料开展了大量研究工作, 取得了一系列重要的研究进展。针对SiCf/SiC复合材料面向核用所关注的重点方向, 如核用SiC纤维、纤维/基体界面相、复合材料制备工艺、数值仿真、腐蚀行为和表面防护、连接技术以及辐照损伤等方面, 本文进行了综述和讨论, 并针对核用要求指出了SiCf/SiC复合材料存在的主要问题和可能的解决思路, 希望对该材料的进一步研发和最终应用有所裨益。 相似文献
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Two continuous field variables, called as continuity tensor and damage variable tensor, are used to describe the anisotropic responses of an elastic-brittle material under transverse impact load. Based on the continuum damage mechanics, anisotropic damage constitutive equations in both full and incremental forms are proposed here. The expressions of effective elastic module tensor, damage variable tensor and damage propagation force tensor are further derived, and the methods for determining the tensors are explained in detail. An example of strain and damage response of a fiber reinforced composite laminated plate under transverse impact load is employed to demonstrate the application of this theory. In the example, the damage variable coupled with geometric large deformation of laminated plate is also considered. The calculating results illustrate the influence of damage on strain field in the impacted laminated plate. 相似文献
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Homogenized Constitutive Equations for Linear Viscoelastic Unidirectional Composites with Growing Transverse Cracks 总被引:4,自引:0,他引:4
Three-dimensional, thermomechanical constitutive equations and an associated correspondence principle are developed for a linear viscoelastic, unidirectional composite with growing damage. The type of damage modeled is transverse cracking, which is commonly observed in laminates consisting of unidirectional fiber layers. The equations allow for aging. First, the constitutive equations without damage are summarized. They are then modified to allow for time-dependent damage by means of a correspondence principle. This principle relates elastic and viscoelastic solutions in the time-plane; the familiar correspondence principle based on the Laplace transform is not applicable because of the aging and crack growth. Some existing, simplified micromechanical models for elastic media are extended to viscoelasticity and then used to demonstrate that the requirements of the correspondence principle are quite-well satisfied for realistic material behavior. The correspondence principle is developed in the Appendix. It generalizes a previously-developed principle for plane stress in fiber-composites to three-dimensional conditions, and is not limited to the specific type of damage covered in the body of the paper. 相似文献
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This study examines the development of damage in randomly reinforced polymeric composite materials. The material under consideration
was made in a structural reaction injection molding process (SRIM) involving a continuous strand swirl mat of E-glass fibers
and a urethane matrix. Theobjective of this work is to establish a predictive deformation model based on principles of viscoelasticity,
damage mechanics and plasticity which maybe experimentally verified. Tests involving creep above a threshold stress level
and recovery after load removal showed evidence of damage that was uniformly distributed throughout the coupon in the form
of multitudes of matrix micro-cracks. Previous studies have shown that the material possesses a void content of about 5% and
exhibits material property scatter of about 20%. The effects of damage could be assessed only when the scatter was separated
by normalizing the data with individual coupon stiffness. Damage was measured through an increase in compliance and resulted
in a permanent strain after load removel. The current study involves repeated loading. Compliance has been observed to increase
with load cycle, while the permanent strain remains small and is neglected.Damage, as a function of load cycle, is incorporated
into the non-linear viscoelastic model developed previously for creep/recovery response.Comparisons of the predictive model
with experimental data are presented and show good agreement.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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植物纤维增强LDPE复合材料的性能研究 总被引:1,自引:1,他引:0
以纸纤维和低密度聚乙烯(LDPE)为原料,经配方改性后,利用双螺杆挤出机共混挤出造粒,最后注塑成型复合材料试样。研究了纸纤维的用量、相容剂LDPE-g-MAH的用量及发泡剂AC的用量对该复合材料力学性能的影响。结果表明:纸纤维添加质量分数为40%~50%时,复合材料的拉伸性能最佳,弯曲强度较好;LDPE-g-MAH的加入提高了复合材料的力学性能,且当LDPE-g-MAH添加质量分数为5%时,复合材料的综合性能较好;发泡后复合材料的密度下降,但冲击强度、拉伸强度、弯曲强度都有不同程度的提高,当AC添加质量分数为3%时,复合材料的综合性能较佳。 相似文献