Multi-Physics of Elastomer Aging: Macrostructure Mechanical Properties based on Morphological Chemical Degenerations

弹性体老化的多物理场：基于形态化学退化的宏观结构力学性能

• 批准号: 1914565
• 负责人: Maryam Shakiba
• 金额: $ 36.15万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2023-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1914565&HistoricalAwards=false
• 关键词: Multi; Physics; Elastomer; Aging; Macrostructure

Elastomers, often commonly referred to as rubbers, have a wide range of applications as bearings, sealants, tires, and anti-vibration mountings. Under such operation, elastomers are exposed to oxygen and elevated temperature, in addition to cyclic mechanical loading. Oxygen and temperature heavily degrade the materials' properties. This degradation is known as aging and induces brittle, shrunken, and aggravated surfaces. The aging process, coupled with mechanical loading, intensifies crack propagation in elastomers and reduces their serviceability. Experimental testing of aging is, necessarily, a time-consuming process. Having a theoretical framework that can be used for simulations will tremendously speed up the development of new, exciting, and reliable materials with a broader range of applications. This work will elucidate how the mechanical response of elastomers changes over their lifetime under the coupled effects of mechanical loading and aging. This research will advance the scientific knowledge of degradation effects on durability of elastomers. The development cycle of the project consists of experimental work, followed by modeling, simulation, and back to experimental verification. This combined approach, which is an ideal illustration of the scientific method, will be used for outreach to K-12 and minority students through university programs. This research will also train a diverse group of undergraduate and graduate students in this interdisciplinary field, forming the next generation of scientists that the U.S. elastomer industry critically needs to compete globally. To characterize the evolution of the deformation response and failure mechanism of elastomers under thermo-chemo-mechanical aging processes, this project outlines a series of interconnected experimental, theoretical, and numerical studies of the chemical, morphological, and mechanical changes. In the first stage of work, the aggravation of macrostructural mechanical properties of elastomers will be experimentally linked to their morphological changes (such as cross-link breakage/formation, and transformation of linkages). The second stage of the project will develop a mathematically verifiable procedure for incorporating stored and dissipated energies - obtained in chemical experiments - into the thermodynamic formalism. In the third stage, the project seeks to understand the effects of heterogeneous aging degradation on the mechanical response of elastomers. Numerical simulations of the constitutive equations will be used to verify the model against further experimental studies. The to-be-obtained knowledge and to-be-developed theoretical framework will lead to highly coupled physics-based models which map the elastomers' macrostructural behavior and failure mechanisms.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.

通常称为橡胶的弹性体具有广泛的应用，作为轴承，密封剂，轮胎和防振动固定。在这种操作下，除了环状机械负荷外，弹性体还暴露于氧气和升高温度。氧气和温度大大降解了材料的特性。这种降解被称为衰老，并引起脆弱，缩小和加重的表面。结合机械负荷的老化过程加剧了弹性体中的裂纹繁殖并降低了它们的可维护性。衰老的实验测试必然是耗时的过程。拥有一个可用于模拟的理论框架将极大地加快具有更广泛应用的新，令人兴奋和可靠的材料的开发。这项工作将阐明在机械负荷和衰老的耦合作用下，弹性体的机械响应如何在其寿命中变化。这项研究将提高对降解对弹性体耐用性的影响的科学知识。该项目的开发周期包括实验性工作，然后进行建模，模拟和回到实验验证。这种合并的方法是科学方法的理想例证，将通过大学课程向K-12和少数族裔学生推广。这项研究还将培训这个跨学科领域的多样化的本科生和研究生，从而构成了下一代科学家，美国弹性体行业在全球范围内都需要竞争。为了表征在热化学机械老化过程下弹性体的变形响应和失效机理的演变，该项目概述了化学，形态和机械变化的一系列相互联系的实验，理论和数值研究。在工作的第一阶段，弹性体的宏观结构机械性能的加剧将与它们的形态变化（例如交联的断裂/形成以及链接的转换）进行实验联系。该项目的第二阶段将开发出数学上可验证的程序，用于将储存和消散的能量（在化学实验中获得）纳入热力学形式主义。在第三阶段，该项目试图了解异质衰老降解对弹性体机械反应的影响。本构方程的数值模拟将用于针对进一步的实验研究验证模型。获得的知识和发展的理论框架将导致高度耦合的基于物理学的模型，这些模型绘制了弹性体的宏观结构行为和失败机制。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子的知识和广泛的影响来评估Criteria的智力功能和广泛影响。