含过渡膜软基微纳米膜结构应力传递和界面损伤行为研究

As the interlayer structure can effectively improve the interfacial properties of the micro-nano film and the substrate, the stress transmission, damage and evolution of the interface has been a frontier topics of mechanics, materials and other fields ..In this program, to the deformation and damage behavior of micro-nano structures with Nb and Cu etc. interlayer on polyimide or PMMA substrate, we intend to research and manufacture situ biaxial and shear loading system, matching with microscope with the characteristic of small loading and high precision. By the means of confocal microscopy and high-speed camera systems, we will study the damage behavior and evolution of the interface between the thin film and the soft substrate with the interlayer, like buckling, fracture and delamination by experiments. Meanwhile, by mechanics theory and numerical simulation methods, we will characterize the intrinsic differences, similarities as well as the critical parameters of damage between the interlayer structure and the monolayer structure, and obtain the intrinsic relationship between the thickness, stiffness, strength, and bonding strength of the structure. And then, we will study the stress transmission and damage evolution of the interlayer structure, which has the straight edge, circular defects and simulative residual stress. By numerical simulation and inversion method, we also quantitatively analysis the damage evolution of various interlayer structure..Additionally, we will combine with the elastic-plastic theory to establish the model of deformation transmission, damage and evolution in micro-nano interlayer structure under biaxial stress. The study not only has important academic value, but also helps to enhance the design and development of the interlayer components.

过渡膜结构因能有效地提高微纳米膜基构件的界面特性，膜基界面的应力传递、损伤、演化逐渐成为力学、材料等领域的前沿课题。项目拟针对聚酰亚胺、有机玻璃等软基上制作的含镍铜等微纳米过渡膜基结构的变形和损伤行为，研制与显微镜匹配的小载荷高精度原位双向加载和剪切加载系统，借助共聚焦显微镜和高速摄像系统等手段实验研究含过渡膜/软基结构界面的屈曲、断裂和分层等损伤行为和演化规律；结合力学理论和数值仿真方法表征其和单层膜基结构的本征异同及损伤临界参数与膜层基层厚度、刚度、强度、结合能间及载荷比例的内在关系；研究过渡膜结构存在界面直边、圆形缺陷和模拟残余应力下过渡膜结构应力传递和损伤发展行为；利用数值仿真方法定量反演分析不同过渡膜基结构的损伤演化行为。结合弹塑性力学理论建立微纳米过渡膜基结构在双向应力下的变形传递模型及损伤和演化分析模型;项目研究有重要的学术价值，也有助于提升过渡膜元器件的设计与开发水平。

基于双向拉伸十字形试件中心区域应变的均匀性优化设计了实验试件，并给出了不同加载比下，中心均匀应变区域的尺寸。同时自主研发了适用于柔性基底成型的模具可实现柔性基底材料的快速批量生产研发了一套双向拉伸加载系统，该系统具有大量程、小增量、高精度、成本低、可调加载比和对中加载等特点，并可以配合高倍光学显微镜实现微纳米尺度薄膜原位实时测量。.以共聚焦显微镜为基础，设计开发了另一一台应用于软基薄膜材料原位观测的微型双轴拉伸设备。此设备采用了新型的转动加载与转动夹持的结构。有限元分析了不同加载比和中间层泊松比对各层双向应力比及其传递的影响。研究了双向拉伸载荷下裂纹形貌的特点。并针对不同位移加载比例和不同薄膜结构影响下的裂纹形貌进行了分析。通过最小应变能密度因子理论分析了二级裂纹开裂角度。.建立了一套求解膜基结构应力传递的解析解法。给出了单层以及多层膜基结构在拉伸载荷下的完整的应力场，应变场以及位移场的表达式。观察含过渡层软基薄膜在双轴拉伸载荷下的裂纹演化行为，研究了不同厚度以及不同材料过渡层对上层薄膜的裂纹形貌以及裂纹演化的影响。采用裂纹密度表征软基薄膜结构拉伸断裂过程的损伤演化，提出了双轴载荷下薄膜裂纹密度的两种定义方法。推导了双轴拉伸时的薄膜应力分布，依据断裂强度准则和能量准则，得到了单轴和双轴载荷下薄膜裂纹密度与应变的关系。依据薄膜裂纹形貌提出两种裂纹密度的测量方法，并编写程序实现高通量裂纹密度测量。设计了基于MATLAB的图形用户界面，将所有的数据处理程序整合为一个整体，实现了快速高效的数据处理过程。.进行了软基薄膜结构的双轴拉伸损伤实验，研究不同加载比对裂纹萌生和演化行为的影响。究预制裂纹和双轴加载比对薄膜新生裂纹的调制作用。提出了分析加载比和预制裂纹对新生裂纹角度影响的理论模型，预测了新生裂纹的角度。设计六臂预制裂纹试件。 .发表论文6篇，申请专利3项，培养研究生硕士生、博士生8人。