非局部应变梯度理论对充流单壁碳纳米管波动影响的研究

发布时间：2018-05-21 02:10

本文选题：充流碳纳米管 + 非局部应力/应变梯度耦合　；参考：《昆明理工大学》2017年硕士论文

【摘要】：碳纳米管的力学性能分析,随着纳米科学和工程的发展,逐步成为研究热点。研究碳纳米管力学特性的跨尺度连续介质弹性模型,主要以非局部应力模型和应变梯度模型为主。这两种模型在分析碳纳米管各项力学性能时,展现出不同的特点,也都存在不足。本文应用Lim提出的非局部应力/应变梯度耦合理论,讨论分析充流碳纳米管系统的各项动力学特性。首先,本文结合学科和工程技术领域的发展,讨论了碳纳米管的研究背景、结构特点、力学特性和应用前景。接下来总结了当前碳纳米管力学特性的研究方法。然后本文在非局部应力/应变梯度耦合理论的基础上,结合流体滑移边界理论,分别根据经典欧拉梁模型和铁木辛柯梁理论,建立了两种考虑流体和固体小尺度效应的充流单壁碳纳米管流固耦合动力学模型。以非局部应力效应、应变梯度效应和流体滑移边界效应模拟碳纳米管(固体部分)和管腔内流体(流体部分)微观小尺度效应对系统的影响,推导得出充流单壁碳纳米管欧拉梁和铁木辛柯梁模型的波动控制方程。通过对控制方程的求解,分析材料不同类型尺度效应对充流碳纳米管的振动和波动特性影响规律。基于欧拉梁模型的充流单壁碳纳米管波动分析结果显示:应变梯度效应和流体边界效应对低频波动起促进作用,对高频波动起阻尼作用,应力非局部效应则对波动始终产生阻尼作用。三种尺度效应对低流速系统的振动有促进作用,而对高流速系统产生阻尼作用。而基于铁木辛柯梁模型的波动分析结果显示:应力非局部效应和流体的滑移边界效应对振动会产生阻尼作用;而应变梯度效应会促进系统的振动和波动。
[Abstract]:With the development of nanoscience and engineering, the mechanical properties analysis of carbon nanotubes has gradually become a hotspot. The non-local stress model and strain gradient model are the main models for studying the mechanical properties of carbon nanotubes in cross-scale continuum media. When analyzing the mechanical properties of carbon nanotubes, the two models show different characteristics and shortcomings. In this paper, the nonlocal stress-strain gradient coupling theory proposed by Lim is applied to discuss and analyze the dynamic characteristics of the flow filled carbon nanotubes (CNTs) system. Firstly, the research background, structural characteristics, mechanical properties and application prospect of carbon nanotubes are discussed in this paper. Then the research methods of mechanical properties of carbon nanotubes are summarized. Then, based on the non-local stress / strain gradient coupling theory and the fluid slip boundary theory, the classical Euler beam model and the Temocco beam theory are used, respectively. Two kinds of fluid-solid coupling kinetic models for single-walled carbon nanotubes filled with fluid and solid were established. The effects of micro-scale effects of carbon nanotubes (solid parts) and in-tube fluids (fluid parts) on the system were simulated by non-local stress effect, strain gradient effect and fluid slip boundary effect. The wave governing equations of Euler beam and Temocco beam are derived. By solving the governing equation, the effects of different types of scale effects on the vibration and wave characteristics of filled carbon nanotubes are analyzed. The wave analysis of single-walled carbon nanotubes filled with Eulerian beam model shows that the strain gradient effect and the fluid boundary effect promote the low frequency wave and damp the high frequency wave. The stress nonlocal effect always has damping effect on the wave. The three scale effects can promote the vibration of the low velocity system and have damping effect on the high velocity system. The results of wave analysis based on the Temuxinko beam model show that the non-local stress effect and the slip boundary effect of fluid will have damping effect on the vibration, while the strain gradient effect will promote the vibration and wave of the system.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TB383.1

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