Supersonic impact, shock and frictional processes in planetary materials

该提案寻求资助，以研究行星材料中的高应变率现象。许多地质过程需要数百年、数千年甚至数百万年才能完成。相比之下，与小行星撞击相关的动态事件通常发生在不到一秒的时间内（冲击波通过），整个事件持续几分钟（主要是重力驱动的调整）。同震滑动在大地震中通常持续几秒钟。我们对“快速”变形的集体知识是有限的，特别是在天然陶瓷（即大多数行星材料）的响应方面。我将研究动力学行为的两个主要领域：(1)超高速撞击，以及相关的冲击波-物质相互作用，(2)通过基于实验室的模拟和现场研究的发震断裂。冲击研究将包括冲击波的产生和固体状态下材料的转变（例如，创造新的高压和高温矿物状态），以及它们转化为熔体和蒸汽。硕士和博士研究生的相关培训将侧重于地球撞击坑（例如，Manicouagan），月球，火星和小行星材料，以及冲击和摩擦过程。重点将放在理解冲击和相关的冲击聚焦机制，后者导致冲击能量大于整体冲击。发震断裂研究将从断层润滑和地震震级两个方面把滑动界面的力学与地震危险性联系起来。随着最先进的实验室摩擦装置用于模拟地震，我最近建立的高速冲击实验室为直接研究冲击波-材料相互作用提供了研究基础。所提出的活动将进一步加深我们对极端条件下材料行为的理解。这与(a)将撞击和冲击理解为基本的行星建设和行星改造过程，以及(b)为我们的社会开发防护材料（例如，天基基础设施的撞击屏蔽）有关。增强的地震力学知识将有助于描述危险断层系统，以开发新的预测工具为目标。

This proposal seeks funding to investigate high strain-rate phenomena in planetary materials. Many geological processes take hundreds, thousands or millions of years to complete. In contrast, dynamic events associated with asteroid impact typically occur in less than a second (shock wave passage), with a total event lasting minutes (dominated by gravity-driven readjustments). Coseismic slip is typically several seconds duration for a large earthquake. Our collective knowledge of "fast" deformation is limited, especially in terms of the response of natural ceramics (i.e., most planetary materials). I will investigate two main areas of dynamic behaviour: (1) hypervelocity impact, and associated shock wave-materials interactions, and (2) seismogenic faulting via laboratory-based simulations and field studies. The impact research will embrace shock wave generation and the transformation of materials in the solid state (e.g., the creation of new high-pressure and high-temperature mineral states), as well as their conversion into melt and vapour. Associated graduate student training at the Master's and PhD levels will focus on terrestrial impact craters (e.g., Manicouagan), lunar, martian and asteroid materials, and shock and frictional processes. Emphasis will be placed on understanding shock and associated shock focussing mechanisms, the latter resulting in shock energies greater than the bulk shock. Seismogenic faulting research will relate the mechanics of the sliding interface to seismic hazard in terms of fault lubrication and earthquake magnitude. Along with a state-of-the-art laboratory-based friction apparatus used to simulate earthquakes, my recently established high-speed impact laboratory provides the research foundation for directly investigating shock wave-materials interactions. The proposed activities will further our understanding of materials behaviour under extreme conditions. This is relevant to (a) understanding impact and shock as fundamental planet-building and planet-modifying processes, and (b) developing protective materials for our society (e.g., impact shielding for space-based infrastructure). An enhanced knowledge of earthquake mechanics will help characterize hazardous fault systems, with the goal of developing new predictive tools.