EAGER: Investigating the Use of Spiral Cracking Pattern in Fracture Characterization of Soft Adhesive Materials

这个早期概念探索性研究（EAGER）项目将研究一种新的断裂表征方法，通过将这些材料附着在坚硬的基材上时形成的螺旋裂纹模式来表征软粘接材料的断裂。传统的断裂测试方法在软质材料断裂评估中的应用具有很大的挑战性，因为其重复性差，而且在测试过程中会发生较大的蠕变变形。该项目的研究成果可以使软粘接材料断裂行为表征的范式转变。此外，该研究将提供对薄膜/基材系统开裂的理解，这对设计抗开裂涂层至关重要。通过这项研究创造的知识将使研究人员能够精确地解释重要应用领域的裂纹模式，例如热障涂层、光学应用中的反射涂层、现代高性能陶瓷（例如喷气发动机中的涡轮叶片）、微机电系统（MEMS）和医学。对美国经济和社会的其他潜在好处包括制造耐用和高性能抗断裂材料，如油漆、环氧树脂和碳氢化合物聚合物。本EAGER项目的主要目标是有效地利用螺旋裂纹模式作为一种强大的诊断工具，以获得有关软粘接材料的成分和断裂行为的有价值的信息。将探索一种将声发射（AE）技术与数字图像分析（DIA）相结合的创新集成方法：(1)确定螺旋裂纹的精确三维几何形状；(2)寻找最佳的数学模型来表示裂缝模式；(3)测量材料的ae基断裂能。采用多传感器声发射源定位方法，沿螺旋裂纹路径提供断裂过程区三维几何形状的实时精确可视化。最后，将探讨泥浆（通道）裂缝模式的定量评估，裂缝的形态，以及破碎形状和大小的统计分析。本文将深入研究螺旋破裂能与泥浆破裂能之间的关系，利用材料的螺旋破裂能来预测薄膜中泥浆的破裂模式。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This EArly-concept Grant for Exploratory Research (EAGER) project will investigate a novel method of fracture characterization of soft adhesive materials through spiral cracking patterns that can form on these materials when they are attached to a stiff substrate. Application of traditional fracture testing methods in fracture assessment of soft materials is quite challenging due to poor repeatability as well as large creep deformations that occurs during the test. The research outcome of this project could enable a paradigm shift in fracture behavior characterization of soft adhesive materials. Moreover, the research will provide understanding of cracking in film/substrate systems, which is essential in designing crack-resistant coatings. Knowledge created through this research will empower researchers to precisely interpret cracking patterns in important applications areas, such as thermal barrier coatings, reflective coatings in optical applications, modern high-performance ceramics (e.g. turbine blades in jet engines), micro-electro-mechanical systems (MEMS), and medicine. Other potential benefits to the US economy and society include manufacturing of durable and high-performance fracture resistant materials, such as paint, epoxies, and hydrocarbon polymers. The primary objective of this EAGER project is to effectively utilize spiral cracking pattern as a powerful diagnostic tool to obtain valuable information about the composition and fracture behavior of soft adhesive materials. An innovative integrated approach coupling acoustic emissions (AE) technique with Digital Image Analysis (DIA) will be explored: (1) to determine the precise 3D geometry of spiral cracks; (2) to find the best mathematical model to represent the cracking patterns; and (3) to measure the AE-based fracture energy of the material. Multi-sensor AE source-location approach will be used to provide real-time accurate visualization of the 3D geometry of fracture process zone along the spiral crack path. Finally, quantitative assessment of mud (channeling) cracking patterns, morphology of cracks, and statistical analysis of shape and size of fragmentation will be explored. The relationship between fracture energies from spiral and mud crackings will be thoroughly investigated to predict the mud cracking patterns in thin films using the spiral cracking-based fracture energy of the material.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.