Experimental and Computational Investigation of Fracture Patterns in Thin Films and Multilayers

薄膜和多层膜中断裂模式的实验和计算研究本项目旨在通过实验和计算相结合的方式来研究薄膜和多层膜中的断裂模式。薄膜通常是预应力的，主要是由于薄膜和衬底的热膨胀系数不匹配。通过断裂可以及时消除残余应力。当残余应力水平较高，并且施加外部机械和/或热应力时，就会发生失效。虽然这些故障是非常常见的，但裂缝模式形成的基本原理尚不清楚。这一建议考虑了薄膜在拉伸和压缩两种情况下形成的断裂模式。建议研究压缩胶片中的正弦和螺旋拉伸裂纹的来源，以及“电话线”分层的形成。对断裂模式形成过程的基本了解将为薄膜和涂层的失效预防提供一个框架，这反映了这一建议的智慧价值。我们周围都是有薄膜的设备。防护涂层和薄膜广泛应用于许多行业，从微电子到汽车和航空航天。虽然它们有不同的用途，但根据应用情况，薄膜应该保持完好并附着在衬底上。要求具有良好的薄膜附着力和断裂性能。拟议研究对社会的更广泛影响立即从拟议研究中所获得的知识的应用中可见一斑，这将防止薄膜和涂层失效。其他更广泛的影响将包括研究生和本科生的研究和开发培训、课程丰富和广泛的跨学科出版物。

Experimental and Computational Investigation of Fracture Patterns in Thin Films and Multilayers.This project aims to investigate fracture patterns in thin films and multilayers in a combined experimental and computational effort. Thin films are normally pre-stressed, primarily due to the mismatch of the thermal expansion coefficients of the film and the substrate. The residual stress can be relieved in time by fracture. Failure occurs when the residual stress levels are high, and in addition an external mechanical and/or thermal stresses are applied. While these failures are very common, the fundamentals of fracture patterns formation are yet to be understood. This proposal considers fracture patterns formation in thin films both in tension and compression. It is proposed to study the origin of sinusoidal and spiral cracks in tension, as well as "telephone cord" delamination formation in compressed films. Fundamental understanding of the fracture patterns formation process will provide a framework of failure prevention in thin films and coatings, which reflects the intellectual merit of this proposal. We are surrounded by devices that have thin films in them. Protective coatings and thin films are widely used in many industries, from microelectronics, to automobile and aerospace. While they serve various purposes, depending on the application, the films should stay intact and attached to the substrate. Good thin film adhesion and fracture properties are required. The broader impact of the proposed research on the society is immediately evident from the applications of the knowledge gained in the proposed research, which will prevent thin films and coatings failures. Additional broader impacts will include research and development training of graduate and undergraduate students, course enrichment, and broad interdisciplinary publications.