兰州大学机构库 >土木工程与力学学院
薄膜基底结构的振动理论与实验研究
Alternative TitleResearches on vibration theory and experiment of thin film/substrate structure
刘苗
Thesis Advisor张兴义
2017-05-01
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword薄膜基底结构 CGS光测实验技术 动力学 自由振动 理论研究
Abstract

现代科学技术的迅猛发展,促使各类高度集成、多功能化的器件层出不穷。薄膜基底结构因具有这类特征日渐成为研究的热点之一,在微电子、光学、物理学和材料学研究领域得到了越来越广泛的应用,在集成电路、微机电系统(MEMS)等微器件方面的应用有力的促进了人类的生产生活。对于薄膜基底材料而言,通常由纳米尺度的薄膜和微米尺度的基底组合而成,其结构相对比较简单。由薄膜基底材料之间晶格常数不匹配产生的错配应变及外界非均温度分布引起的薄膜变形研究成为力学学科重要的研究方向之一。早在1909年,Stoney建立了薄膜应力与曲率之间的关系式,从而奠定了薄膜应力研究的基本框架,即通过薄膜曲率的测量来计算其全场应力分布。后来,大量学者通过放松Stoney基本假设实现了对Stoney公式的扩展,但是截至目前这些研究均主要考虑薄膜在准静态情形下的力学行为,而对于薄膜基底结构的振动特性研究鲜有涉及,成为薄膜基底结构器件安全设计所面临的困难。为此,本文建立了薄膜基底结构在轴对称和非轴对称情形下的自由振动方程,得到了薄膜应力关于曲率的解析表达式。随后,以高温超导薄膜为例,采用低温环境下激光剪切干涉(CGS)技术和本文所建立的薄膜应力与曲率之间的理论关系,首次获得了脉冲磁场作用后超导薄膜全场应力随时间的演化特征,为后期深入研究超导薄膜在电磁场中的力学响应提供了基础。

本论文的主要工作如下:(1).通过考虑界面切应力,建立了薄膜基底结构在轴对称情形下自由振动方程,求得了薄膜应力关于曲率的解析表达式,并且针对振动方程,讨论了其挠度振型解以及相应固有频率。(2).通过考虑界面切应力,建立了薄膜基底结构在非轴对称情形下的自由振动方程,求得了薄膜位移表达式,应力表达式,界面切应力表达式,并且求给出了薄膜应力关于曲率的理论关系式。(3).利用低温下激光剪切干涉技术,实时测量了超导薄膜在受到电磁脉冲作用后的全场曲率变化,采用本文推导所得的薄膜曲率理论关系式,首次获得了超导薄膜全场应力随时间变化情况,并且针对测量结果做了相关分析以及讨论。

Other Abstract

With the rapid development of modern science and technology,all kinds of highly integrated and multi-functional industrial products have been manufactured. The thin film/substrate structure as the key component of the above application, it has become one of the research hotspots and it has been widely used in the fields of microelectronics, optics, physics and materials science. Specially, the thin film/substrate structure in the integrated circuit, micro-electromechanical systems (MEMS) and other micro-device applications greatly promote the development of human society. The thin film substrate materials are usually composed of nano scale thin-films and micron scale substrates and the overall structure is quite simple. However, strain mismatch between the film and the substrate due to interfacial misfit strain and the deformation of thin films caused by the non uniform temperature distribution, both of them had become the important research directions in field of mechanics. As early as 1909, Stoney established the relationship between the stress and curvature of the film, thus laid the basic framework of thin film stress research, that is, by measuring the curvature of the film to calculate stress distribution of the whole field. Later, a large number of scholars through the relaxation of Stoney basic assumptions to achieve the expansion of the Stoney formula, but as of now these studies are mainly considering the film in the quasi-static state of the mechanical behavior, while the vibration characteristics of thin film/substrate structure rarely involved that it has been become a difficult problem for the safety design of the thin film/substrate. To solve this problem, in this thesis, the free vibration equations of the thin film/substrate structure under axisymmetric and non axisymmetric conditions are established and the analytical expression of the film stress on the curvature is obtained. Then, taking the high temperature superconducting thin film as an example, the temporal evolution of the full field stress of superconducting thin films was abtained for the first time, which by using the Coherent Gradient Sensing (CGS) technique in the low temperature environment and then according to the theory of film stress-curvature that deriving from this thesis, and it provides a basis for further study of the mechanical response of superconducting films in electromagnetic fields.

The works of this paper are listed as follows: (1). By analyzing the film substrate interface shear stress, the free vibration equation of the thin film/substrate structure under the axisymmetric condition is established. The analytic expression of the film stress-curvature is obtained. We also discussed the deflection mode shapes and corresponding solutions of natural frequencies. (2).By considering the film substrate interface shear stress, free vibration equation is established at the film substrate structure axisymmetric case. In this thesis, the expression of thin film displacement, stress and interface shear stress are obtained, meanwhile, the theoretical relationship between of film stress and curvature is given. (3). Using the Coherent Gradient Sensing technique at low temperature, the full-field curvature change of the superconducting thin films caused by the electromagnetic pulse was measured . Using the theoretical relationship of the thin film and the curvature derived from this thesis, we first obtained the full-field stress varied with time about the superconducting thin films. At the same time, this thesis makes a correlation analysis and discussion on the measurement results.

URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226716
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
刘苗. 薄膜基底结构的振动理论与实验研究[D]. 兰州. 兰州大学,2017.
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