CAREER: Nonlinear Resonances of Highly Damped, Soft Materials

该学院早期职业发展计划（CAREER）资助促进科学进步，并通过研究促进国民健康，从而能够更好地了解高度阻尼的软材料（例如人脑组织）中的冲击和振动引起的损伤，从而为改善病理学诊断和保护装置设计铺平道路。软材料在各种工程领域都有应用，从航空航天应用中的弹性阻尼器到为耐磨性设计的顺应性机器人设备。由于大变形和复杂材料行为的综合影响，用于表征材料结构对动态载荷的响应的传统技术在软材料中失效。相比之下，本项目中开发的实验和理论框架将精确地关注产生显著材料变形并激活最强耗散和非线性力的共振条件。这个框架将产生新的见解发生在软材料的局部损伤，例如在瞬态加载事件，如突然冲击。这些见解对于软结构的结构健康监测尤其具有变革性，包括人体器官等生物系统。项目成果有可能为创伤性脑损伤的生物力学研究提供信息，创伤性脑损伤是美国儿童和青少年死亡和残疾的主要原因之一。一个紧密结合的研究和教育计划将通过课程开发、头盔设计外展研讨会和数字艺术展览激发学生对STEM的参与。一个专门的努力，以增加从LGBTQ+社区的参与，其中一个干的知名度和代表性不足的问题，目前存在，包括年度活动，研讨会和辅导网络。本研究旨在为表征高阻尼软材料对稳态和瞬态载荷的变形响应的建模和系统识别框架做出基本贡献，特别强调非均匀膜材料系统中的变形局部化和损伤。它实现了这一目标，通过分析振幅共振骨干模型的高阻尼，软材料系统与复杂的，分布的内力，研究这种振幅共振和瞬态冲击响应之间的对应关系，并验证这些预测使用磁共振成像的硅胶幻影代表生物组织。将开发一个有效的计算框架，使参数连续的振幅共振骨干的大规模模型，使用谐波平衡，有限元模拟的方法，和一种新的贝叶斯傅立叶神经运算器为基础的机器学习技术的创新组合。真实世界头部撞击的计算建模将用于确定振幅共振骨干和人类大脑中撞击引起的应变定位模式之间的关系。该奖项反映了NSF的法定使命，并通过使用基金会的智力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 Faculty Early Career Development Program (CAREER) grant promotes the progress of science and advances the national health through research that enables an improved understanding of impact and vibration-induced damage in highly damped, soft materials, for example, human brain tissue, thereby paving the way for improved diagnosis of pathologies and design of protective devices. Soft materials are found across a variety of engineering domains, ranging from elastomeric dampers in aerospace applications to compliant robotic devices designed for wearability. Traditional techniques for characterizing the response of material structures to dynamic loading fail for soft materials due to the combined effects of large deformations and complex material behaviors. In contrast, the experimental and theoretical framework developed in this project will focus precisely on resonant conditions that produce significant material deformations and activate the strongest dissipative and nonlinear forces. This framework will generate new insights into the occurrence of localized damage in soft materials, for example during transient loading events such as sudden impacts. These insights will be particularly transformative for structural health monitoring of soft structures, including biological systems such as human organs. Project outcomes have the potential to inform research in the biomechanics of traumatic brain injury, one of the leading causes of death and disability among children and adolescents in the US. A closely integrated research and education plan will excite student engagement in STEM through curriculum development, outreach workshops on helmet design, and digital arts exhibits. A dedicated effort to increase participation from the LGBTQ+ community, where a STEM visibility and underrepresentation problem currently exists, includes annual events, workshops, and mentoring networks. This research aims to make fundamental contributions to a modeling and system identification framework for characterizing the deformation response of highly damped, soft materials to steady-state and transient loading, with particular emphasis on deformation localization and damage in heterogeneous, membranous material systems. It achieves this aim by analyzing amplitude resonance backbones in models of highly damped, soft material systems with complex, distributed internal forces, studying the correspondence between such amplitude resonances and the transient impact response, and validating these predictions using magnetic resonance imaging of silicone phantoms representing biological tissue. An efficient computational framework will be developed to enable parameter continuation of amplitude resonance backbones for large-scale models using an innovative combination of the method of harmonic balance, finite-element simulations, and a novel Bayesian Fourier Neural Operator-based machine learning technique. Computational modeling of real-world head impacts will be used to determine the relationship between amplitude resonance backbones and impact-induced strain localization patterns in the human brain.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.