CAREER: Nonlinear Dynamics of Shear Wave Propagation and Shock Formation in Soft and Biological Materials

这个教师早期职业发展（CAREER）补助金将集中在剪切冲击的形成和软材料的传播。 近年来，制造技术的进步促使高度可变形材料在无数工程应用中的使用迅速增加，例如可穿戴电子产品和软机器人，头盔和抗震轴承。这种软结构的动态加载会导致各种材料现象，从而产生显著的损伤。因此，防护装备应能够吸收冲击和爆炸等动态载荷，现在人们越来越认识到，冲击和爆炸在体育等普通场合以及在暴露于简易爆炸物等更极端的事件中也是对平民生命的重大威胁。在这些情况下，保护材料和软生物组织都可能受到极端压力梯度和冲击。然而，人们对损伤和能量吸收的基本机制仍然知之甚少，从而阻碍了能够减轻极端环境中损伤的新保护技术的成熟。 综合研究和教育计划将解决有关剪切冲击形成标准和能量耗散水平的深层力学问题，并努力扩大对工程领域的参与。最近的实验观察表明，普通剪切波到剪切冲击的非线性演化可以在软材料和生物材料中产生损伤方面发挥重要作用。然而，尽管现有的大量关于冲击波在固体中传播的实验和理论研究都围绕着纵向冲击机制，但从大变形固体力学的角度来看，剪切冲击形成和传播的研究还处于新生状态，这些冲击过程的基本性质、形成它们所需的条件、所产生的损伤以及能量耗散的水平，仍然难以捉摸因此，对报告的观察结果的解释是有限的。该CAREER奖旨在通过采用理论研究和高精度实验的互补组合来填补这一空白，通过该组合，它将阐明剪切冲击过程的本构敏感性和由此产生的损伤机制。这种基本认识将指导更具弹性的材料系统的设计，并可以解释特定生物器官的脆弱性。该奖项反映了NSF的法定使命，并且通过使用基金会的知识价值和更广泛的影响进行评估，被认为值得支持审查标准。

This Faculty Early Career Development (CAREER) grant will focus on shear shock formation and propagation in soft materials. The advancement of fabrication techniques in recent years has spurred a rapid increase in the use of highly deformable materials in a myriad of engineering applications with examples ranging from wearable electronics, and soft robotics, to helmets, and seismic bearings. Dynamic loading of such soft structures can lead to a variety of material phenomena, which can generate significant damage. Protective gear should thus be capable of absorbing dynamic loads, such as impacts and blasts, which are now becoming appreciated as a major threat also to civilian lives in both mundane settings, such as sports, and as a result of more extreme events, such as exposure to improvised explosives. In these situations, both the protective material and the soft biological tissue may be subjected to extreme pressure gradients and impact. However, the basic mechanisms of damage and energy absorption are still poorly understood, thus hindering the maturation of new protective technologies that can mitigate damage in extreme environments. The integrated research and education plan will resolve deep mechanics questions regarding the shear shock formation criteria and level of energy dissipation and work to broaden participation in the engineering field. Recent experimental observations have suggested that the nonlinear evolution of ordinary shear waves into shear shocks could play a significant role in generating damage in soft and biological materials. However, while the vast amount of existing experimental and theoretical research on shock wave propagation in solids revolves around longitudinal shock mechanisms, the study of shear shock formation and propagation, from the point of view of large deformation solid mechanics is in nascent state, and the fundamental nature of these shock processes, the conditions required to form them, the resulting damage, and the level of energy dissipation, remain elusive. Hence, the interpretation of the reported observations is limited. This CAREER award aims to fill this void by employing a complementary combination of theoretical investigation and high-precision experimentation, through which it will illuminate the constitutive sensitivities of shear shock processes and the resulting mechanisms of damage. This fundamental understanding will then guide the design of more resilient material systems and can explain the vulnerability of specific biological organs.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.