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Nanoimprint lithography is an economical and convenient method for manufacturing nanostructures, which has developed very quickly and has been widely used in the nanoindustry. However, during the process of nanoimprinting, mechanical instabilities of soft nanostructures could lead to buckling. In order to study the mechanism of this problem, we analyze the buckling of one vertical elastic column under its own weight. Based on the comparison between two critical heights of different substrates (rigid and elastic), we conclude that the approximation of considering the substrate as rigid is acceptable. Furthermore the interaction between columns with the deformation of a substrate could lead to collective buckling. Our theoretical
calculations show that whether the columns are elastic or rigid makes little difference for the buckling modes. 相似文献
calculations show that whether the columns are elastic or rigid makes little difference for the buckling modes. 相似文献
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本文发展了一种基于振动的复合材料板的损伤检测方法,将原有的一维间隔平滑法(1D GSM,one dimensional gapped smoothing method)发展至二维(2D GSM),并进一步提出二维间隔平滑法的标准化损伤指标.与其他多数基于振动分析的损伤检测方法不同,该方法只需分析含有损伤结构的检测数据,无需结构健康时的数据或理论、计算结果作为对比信号,即可判定缺陷的存在,并能准确定位.针对由冲击造成的准各向同性碳纤维增强复合材料板中的层裂损伤,本文采用压电片阵列组合激励的方式,得到了复合材料板多频率扭转振型的同时激励,可实现快速、高效的损伤检测.通过扫描式激光测振仪测得结构在不同固定频率下的结构响应ODS(operational deflection shapes),利用提出的二维间隔平滑法,分析得出损伤指标.实验结果表明,二维间隔平滑法可以准确地检测碳纤维增强复合材料板的冲击损伤,并具有较好的精度. 相似文献
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以浅桁架为例, 介绍了弹性结构两类不同的失稳形态: 分岔点失稳和极值点失稳. 浅桁架失稳形态与斜杆的柔度λ和倾角α0 有关. 当α0λ < 33/4π 时为极值点失稳, 发生突跳; 否则为分岔点型失稳. 相似文献
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A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method (SSEM),
and its applicability condition is introduced. For a beam with the continuously varying flexural stiffness and an edge crack,
the SSEM is used to detect the crack location effectively by numerical modal shapes. As a complicated beam, the glass fiber-reinforced
composite model of a wind turbine blade is studied based on an experimental modal analysis. The SSEM is used to calculate
the damage index from the measured modal parameters and locate the damage position in the blade model successfully. The results
indicate that the SSEM based on the modal shapes can be used to detect the damages in complicated beams or beam-like structures
for engineering applications. 相似文献
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界面强度对玻璃微珠填充聚丙烯力学性能的影响 总被引:2,自引:0,他引:2
本文针对玻璃微珠填充聚丙烯这一刚性粒子填充聚合物复合体系进行了实验研究。通过偶联剂改性对比,研究了该聚合物复合材料在不同界面粘结状态下的宏观拉伸、冲击力学性能。此外,根据冲击破坏断面的电镜观测结果,发现复合体系的断裂和增韧机制随界面粘结强度不同而发生改变,界面改性使得材料抗冲击破坏能力得到增强。本文还采用在位拉伸过程中的细观观测方法,观测到材料在一维应力作用下,刚性粒子和基体界面的脱粘、开裂过程,分析了该复合体系细观结构和宏观力学性能之间的关系,发现界面改性对于材料细观结构的界面脱粘和宏观屈服现象的重要影响,为发展新型复合材料提供了实验依据。 相似文献
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正交异性动态光弹性方法的几个基本问题的研究 总被引:2,自引:0,他引:2
文章对适用于动态研究的正交异性光弹性复合材料进行了分析,详细说明了光弹性复合材料中残余双折射的确定方法;基于静态下Hyer和Liu应力-光性定律,提出了正交异性动态应力-光性定律,并对正交异性材料的动态力学参数及动态光弹性常数给出了实用的标定方法;最后,利用三个单轴压缩试件(0°,90°及45°),采用动态应变测量方法,证实了单轴应力状态下正交异性动态应力-光性定律的正确性。 相似文献
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