共查询到19条相似文献,搜索用时 93 毫秒
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采用分子动力学模拟技术,从分子水平研究碳纳米管(CNTs)增强丁腈橡胶(NBR)复合材料的力学性能及摩擦学性能。运用恒应变法计算材料的力学性能,分别建立纯NBR和CNTs/NBR复合材料的3层模型,并对顶层和底层的铁摩擦副施加剪切载荷,研究材料的摩擦学性能。研究结果表明:在摩擦过程中,由于CNTs表面存在很强的吸附力,抑制了NBR分子链的迁移率,使得CNTs和聚合物分子链间的相互作用增强;CNTs/NBR复合材料具有更高的致密性以及更强的结构,从而表现出了比纯NBR更加优异的力学和摩擦学性能。 相似文献
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采用分子动力学模拟方法研究了常温300 K时,公度、不公度情况下,单壁碳纳米管CNT(10,10)在石墨基底上的运动、摩擦行为。计算中首先使碳纳米管在基底上弛豫平衡,而后施加持续时间500 fs的固定外力,撤去外力后碳纳米管在基底上减速至相对基底静止。结果表明,碳纳米管在石墨基底上不同的放置位置决定了它与基底接触面的微观构型,从而决定了碳纳米管的运动、摩擦规律。公度时,碳纳米管先在基底上滑动,摩擦力、平动能均呈现周期性起伏,之后碳纳米管在基底上滚动、滑动、翻转,滑动、转动之间运动形式的转变提高了能量耗散,增大了摩擦力,非公度时摩擦力约为公度时的70%。非公度时碳纳米管一直在基底上滑动,平动能和摩擦力不具有周期性。 相似文献
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采用分子动力学模拟的方法,分别建立手性指数为(5,5)、(6,4)、(9,0)的3种碳纳米管/丁腈橡胶(CNTs/NBR)复合材料模型,通过恒应力法和剪切行为模拟方法,研究了CNTs手性指数对NBR基体力学性能和摩擦学性能的影响。研究结果表明:手性指数为(6,4)的螺旋型CNTs/NBR复合材料具有更高的弹性模量和拉伸强度,更低的磨损量、摩擦因数、界面摩擦温度,抵抗弹性变形能力和耐磨性能更佳。 相似文献
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微型机械力学行为的分子动力学模拟研究进展 总被引:2,自引:0,他引:2
介绍了国外分子动力学模拟在微型机械力学行为分析中的研究进展;阐述了分子动力学模拟的基本方程,分子动力学的算法以及应用于微型机械力学徒为分析中的势函数等。最后介绍了几个在微型机械力学行为分析中的应用动力学模拟的例子。 相似文献
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介绍了国外分子动力学模拟在微型机械力学行为分析中的研究进展;阐述了分子动力学模拟的基本方程、分子动力学的算法以及应用于微型机械力学行为分析中的势函数等.最后介绍了几个在微型机械力学行为分析中应用分子动力学模拟的例子. 相似文献
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连续介质理论在研究碳纳米管力学性能中的应用进展 总被引:6,自引:2,他引:4
综述连续介质理论在微尺度力学,尤其是在碳纳米管力学性质研究中的应用及进展。介绍近期发展的用于模拟碳纳米管力学行为的各种连续介质模型的理论框架与典型算例。重点阐明各连续介质模型实现宏微观关联的基本思想,详述碳纳米管的桁架模型、Yakobson和Ru等人的壳模型(shell model)、Arroyo和Belytschko的薄膜模型(membrane model)以及Tadmor、Ortiz和Phillips的准连续介质理论;归纳、总结这些理论模型的基本假设、主要结论及其局限性;分析指出它们所涉及的理论推导与数值算法中的一些关键因素;简要介绍这些理论在微尺度力学中的应用。最后,预测连续介质理论应用于微尺度现象分析的发展趋势,指出今后的研究方向。 相似文献
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中碳钢在低应力超长寿命范围内的疲劳性能 总被引:5,自引:2,他引:5
用20kHz超声疲劳试验技术测试40Cr钢、50车轴钢在105~1010周次范围内的疲劳性能.结果表明,两种钢并不存在传统意义上的所谓"疲劳极限".在超过107周次,甚至109周次的超长寿命范围内仍发生低应力疲劳断裂,其中40Cr钢的S-N曲线呈现"连续下降型"特征;50车轴钢呈现"阶梯下降型"特征.对两种钢缺口试样的疲劳性能测试表明,缺口应力集中对疲劳性能的影响呈现"阶段性特征",在106~107周次内存在一个临界疲劳断裂循环周次Nc当疲劳断裂循环数Nf<Nc随Nf的增加,缺口应力集中对疲劳性能的影响程度呈上升趋势;当疲劳断裂循环数Nf>Nc,随Nf的增加,缺口应力集中对疲劳性能的影响程度呈逐渐下降的趋势. 相似文献
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ZHAO Yinghong LEI Liping ZENG Pan Key Laboratory for Advanced Materials Processing Technology of Ministry of Education Beijing China Department of Mechanical Engineering Tsinghua University Beijing China 《机械工程学报(英文版)》2007,20(3):59-61
An equivalent continuum method and a deformable discrete method to describe the mechanical behaviors of superconducting powder BSCCO (BiSrCaCuO) aggregate are studied syste-matically. The equivalent continuum model idealizes the aggregation of the powder as an equivalent continuum material. The powder aggregate yielding is caused by not only the deviatoric stress but also the hydrostatic stress and the modified Drucker-Prager/Cap model is adopted to describe the mechanical behaviors of BSCCO powder aggregate in continuum method. The deformable discrete model is known as a direct model, which considers the discrete nature of the powder particles. Its framework encompasses the local behaviors between the particles, such as particles contact, sliding and rolling. Based on commercial finite element software ABAQUS, the equivalent continuum model and the deformable discrete model are used to simulate the confined compression of superconducting powder BSCCO, and the numerical results show agreement with experimental results, which verify the correctness of these built models. Compared with the equivalent continuum model based on macroscopic statistics method, the deformable discrete model can present the microscopic information during processing and can describe the nature of mechanical behaviors of superconducting powder BSCCO. But from an industrial viewpoint, the equivalent continuum model has a definitive edge over the microscopic models in that the gross behavior of the powder mass can be modeled and simulated on an industrial scale. 相似文献
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Ruqin Zhang Xiaoping Wang Pranav Shrotriya Rana Biswas Ashraf Bastawros Abhijit Chandra 《Machining Science and Technology》2007,11(4):515-530
Mechanistic numerical analysis and molecular dynamics (MD) simulation are employed to understand the material detachment mechanism associated with chemical mechanical polishing. We investigate the mechanics of scratch intersection mechanism to obtain a characteristic length scale and compare the theoretical predictions with previous experimental observations on ductile copper discs at the micro-scale. First, an analytical model is developed based on mechanics of materials approach. The analytical model includes the effects of strain hardening during material removal as well as the geometry of indenter tip. In the next step, molecular simulations of the scratch intersection are performed at the atomistic scale. The embedded atom method (EAM) is utilized as the force field for workpiece material and a simplified tool-workpiece interaction is assumed to simulate material removal through scratch intersection mechanism. Both models are utilized to predict a characteristic length of material detachment related to material removal during scratch intersection. The predictions from two approaches are compared with experimental observations in order to draw correlations between experiment and simulation. The insights obtained from this work may assist in understanding the mechanism for chemical mechanical planarization (CMP), and even be applied to other different machining and polishing events. 相似文献
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Ruqin Zhang Xiaoping Wang Pranav Shrotriya Rana Biswas Ashraf Bastawros 《Machining Science and Technology》2013,17(4):515-530
Mechanistic numerical analysis and molecular dynamics (MD) simulation are employed to understand the material detachment mechanism associated with chemical mechanical polishing. We investigate the mechanics of scratch intersection mechanism to obtain a characteristic length scale and compare the theoretical predictions with previous experimental observations on ductile copper discs at the micro-scale. First, an analytical model is developed based on mechanics of materials approach. The analytical model includes the effects of strain hardening during material removal as well as the geometry of indenter tip. In the next step, molecular simulations of the scratch intersection are performed at the atomistic scale. The embedded atom method (EAM) is utilized as the force field for workpiece material and a simplified tool-workpiece interaction is assumed to simulate material removal through scratch intersection mechanism. Both models are utilized to predict a characteristic length of material detachment related to material removal during scratch intersection. The predictions from two approaches are compared with experimental observations in order to draw correlations between experiment and simulation. The insights obtained from this work may assist in understanding the mechanism for chemical mechanical planarization (CMP), and even be applied to other different machining and polishing events. 相似文献
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HUANG Zhigang GUO Zhongning CHENG Xing Faculty of Electromechanical Engineering Guangdong University of Technology Guangzhou China YU Daming DU Xue LI Rongbing Faculty of Engineering The Hong Kong Polytechnic University Hong Kong China 《机械工程学报(英文版)》2006,19(1):19-24
Molecular dynamics method is applied to study the machining mechanisms of polishing based on coupling vibrations of liquid. The physical phenomena of abrasive particles bombarding on silicon monocrystal surface are simulated using Tersoff potentials. The effects of vibration parameters, particle size, incident angle and panicle material are analyzed and discussed. Material removal mechanisms are studied. Deformation and embedment phenomena are found in the simulations. Bombardment will destroy the crystal structures near the impact point, and adhesion effect is responsible for final removal of material. 相似文献