CAREER: Nonlinear Resonances of Highly Damped, Soft Materials

这项学院早期职业发展计划(Career)赠款通过研究促进科学进步和促进国民健康，使人们能够更好地了解高度受潮的软材料(例如人脑组织)中因冲击和振动而造成的损害，从而为改进病理诊断和保护装置的设计铺平道路。软材料存在于各种工程领域，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共同作用，传统的表征材料结构对动态载荷响应的方法对于软材料是不适用的。相反，在这个项目中开发的实验和理论框架将精确地专注于产生显著材料变形并激活最强耗散和非线性作用力的共振条件。这一框架将对软材料中局部损伤的发生产生新的见解，例如在突然撞击等瞬时加载事件期间。这些见解将对软结构的结构健康监测特别具有变革性，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。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来激发学生对STEM的参与。LGBTQ社区目前存在STEM可见性和代表性不足的问题，为了增加LGBTQ社区的参与，一项专门的努力包括年度活动、研讨会和指导网络。这项研究旨在为描述高阻尼软材料在稳态和瞬时载荷下的变形响应，特别是非均匀膜材料系统中的变形局部化和损伤的建模和系统辨识框架做出基本贡献。它通过分析具有复杂分布内力的高阻尼软材料系统模型中的振幅共振骨干，研究这种振幅共振与瞬时冲击响应之间的对应关系，并使用代表生物组织的硅胶模体的磁共振成像来验证这些预测，从而实现了这一目标。将开发一种有效的计算框架，以使用谐波平衡方法、有限元模拟和基于贝叶斯傅里叶神经算子的新型机器学习技术的创新组合，实现大规模模型的幅度共振主干的参数连续。将使用真实世界头部撞击的计算模型来确定振幅共振骨干与人脑中撞击引起的应变局部化模式之间的关系。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.