共查询到16条相似文献，搜索用时 140 毫秒
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通过单一改变组分材料铝或者铅的密度,以及单一改变晶格常数的取值来调节一维铝/铅匀直杆状声子晶体的带隙分布情况。结果表明：该声子晶体中,当单一增大每种材料的密度时,散射体与基体材料的密度差值增大,其入射波散射就更为强烈,也就越容易产生低频带隙;当单一增大声子晶体的晶格常数,即增加复合结构的长度时,入射波散射得就越多,透射波就越来越少,该声子晶体带隙便呈现出向低频率区域靠近的特性。 相似文献
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本文用平面波方法，研究了Pb圆柱体在epoxy基体中按周期性排列时的弹性波带结构，研究发现弹性波在将质量密度较大的介质柱嵌入质量密度较小的基体构成的声子晶体中将有完全带隙出现。 相似文献
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邱学云 《蒙自师范高等专科学校学报》2011,(2):5-8
文章对声子晶体的概念、基本特征和分类进行简要概述.总结分析一维声子晶体的三种简化模型和一维声子晶体的计算方法及其带隙研究成果.展望一维声子晶体在低频振动、噪声控制、抗振防震方面的应用可能,为深入研究一维声子晶体提供依据. 相似文献
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邱学云 《楚雄师范学院学报》2014,29(6):12-16
选用非金属材料塑料和硅橡胶,组合成一维二元声子晶体匀直杆状结构。通过单一改变结构中非金属材料塑料的密度或者硅橡胶的密度,寻找单一材料密度变化与声子晶体杆禁带特性的关系。结果表明:当选取塑料密度为1190kg·m-3、硅橡胶密度为1300kg·m-3,晶格常数为0.3m,两种材料组份比相同时,一维二元非金属塑料/硅橡胶声子晶体存在低频禁带带隙,第1禁带起始频率为43.07Hz、禁带带宽为33.09Hz,第2禁带起始频率为99.84Hz,第2禁带带宽为52.49Hz;当单一改变塑料的密度,随着密度由小到大线性增加,结构第1带隙的起始频率由66.58Hz逐步减小到34.04Hz;第1带隙的截止频率为76.17Hz,保持不变,带隙宽度展宽;当单一改变材料硅橡胶的密度时,随着材料硅橡胶的密度由小到大线性增加,第1带隙的带宽由109.894HZ减小为18.3748Hz。对于一维二元非金属型声子晶体,选用密度更小的非金属材料与密度更大的非金属材料组合,更容易获得低频宽带带隙。另外,基于密度变化的同时还可以通过改变结构晶格常数的取值来获得更为理想的声子晶体禁带带隙。 相似文献
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研究了声波在二维声子带隙材料中的传输特性 ,把声子带隙材料作为一个散射体进行处理 .在远场近似下 (kr 1) ,计算了声波在有限范围内声子带隙材料中的传输系数 ,得到了与带结构符合很好的计算结果 相似文献
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应用平面波展开法对二维光子晶体分别在E偏振和H偏振下的带隙进行仿真计算,寻找到空气圆柱在背景基质硅中排列的四方和三角晶格光子晶体出现最大带隙时的孔隙率r/a=0.48,并算出它们的最大带隙宽度.对于四方晶格,最大完全带隙宽度ΔGmax=0.017（ωa/2πc）,归一化频率（ωa/2πc）范围在Δω=（0.448-0.456）,对于三角晶格,最大完全带隙宽度可达ΔGmax=0.076（ωa/2πc）,归一化频率（ωa/2πc）范围在Δω=（0.455-0.531）.研究结果对在实验上制作空气圆柱在背景基质硅中排列的四方和三角晶格光子晶体提供理论指导. 相似文献
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对二维光子晶体的电磁波理论及周期介质中的Bloch波解做了详细的推导；给出了光子晶体中禁带存在的理论依据；同时以三角格子晶格的二维光子晶体为例，验证了空气圆孔在电介质栅中的排列存在E偏振和H偏振的光子带隙重叠区绝对光子带隙． 相似文献
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The band structures of flexural waves in a phononic crystal thin plate with straight, bending or branching linear defects are theoretically investigated using the supercell technique based on the improved plane wave expansion method. We show the existence of an absolute band gap of the perfect phononic crystal and linear defect modes inside the gap caused by localization of flexural waves at or near the defects. The displacement distributions show that flexural waves can transmit well along the straight linear defect created by removing one row of cylinders from the perfect phononic crystals for almost all the frequencies falling in the band gap, which indicates that this structure can act as a high efficiency waveguide. However, for bending or branching linear defects, there exist both guided and localized modes, and therefore the phononic crystals could be served as waveguides or filters. 相似文献
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Phononic crystals that prevent the propagation of waves in a band gap have been widely applied in wave propagation control. In this paper, we propose the use of a metabarrier, based on a locally resonant phononic crystal mechanism, as a floating-slab track bearing to shield the infrastructure in a floating-slab track system from longitudinal waves from the slab, thereby improving mitigation of ground-borne vibrations. The locally resonant band gap properties of the metabarrier were studied based on the finite element method, and the shielding performance was verified by the transmission spectrum. Simplified models for band gap boundary frequencies were built according to the wave modes. Furthermore, a 3D half-track model was built to investigate the overall vibration mitigation performance of the floating-slab track with the metabarrier. An optimization mechanism for the band gap boundary frequencies is proposed. As the low-frequency ground-borne vibrations induced by subways carry the most energy, multi-objective genetic algorithm optimization was conducted to obtain a lower and wider band gap for a better shielding performance. The results show that the retained vibration isolation performance of the low natural frequency, the shielding performance of the band gap, and the controllability of band gap boundary frequencies all contribute to an improvement in overall vibration mitigation performance. The vertical static stiffness of the metabarrier was close to that of the existing bearing of the floating-slab track. An optimized locally resonant band gap from 50 to 113 Hz was generated using the optimization mechanism. 相似文献
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应用On-Shell方法研究带缺陷的正方二维园柱光子晶体，缺陷的引入使得原来不透电磁波的禁带中，出现了缺陷模，即某一波长的电磁波可以透过，计算结果表明缺陷模的频率与透射率随着缺陷的性质，即缺陷的大小和折射率及缺陷两边的层数而改变。 相似文献
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Yan-yan Ma 《浙江大学学报(A卷英文版)》2008,9(7):916-921
To take into account the couple stress effects, a modified Reynolds equation is derived for dynamically loaded journal beatings with the consideration of the elasticity of the liner. The numerical results show that the influence of couple stresses on the bearing characteristics is significant. Compared with Newtonian lubricants, lubricants with couple stresses increase the fluid film pressure, as a result enhance the load-carrying capacity and reduce the friction coefficient. However, since the elasticity of the liner weakens the couple stress effect, elastic liners yield a reduction in the load-carrying capacity and an increase in the friction coefficient. The elastic deformation of the bearing liner should be considered in an accurate performance evaluation of the journal bearing. 相似文献
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通常晶体熔化时弹性常数C44和(C11-C12)/2就将消失,由此提出晶体熔化的力学判据.本文采用第一性原理研究了高温下钼的弹性性质,并且得出结论:在计算温度范围内钼没有熔化并且弹性常数C11、C12、C44随着温度的升高逐渐减小.最后采用准谐德拜模型方法对钼的热力学性质进行了研究,得出了比较好的结论. 相似文献
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INTRODUCTION The elastic properties of coating layers in coating materials are very important in the design and evaluation for engineering purpose. They can serve as ground knowledge in the selection of surface coatings for particular applications, and can be used to monitor the quality of physical processes (Every, 2002). Therefore, estimation of the elastic properties of coating layers is of great practical value. Much effort has been put into measuring the material properties of coatin… 相似文献