CAREER: Integrated Research and Education on Bio-Inspired Burrowing

这项教师早期职业发展（Career）计划将促进对自然界中动物高效挖洞机制的科学理解。穴居生物可以居住在广泛的地下土壤类型中，并通过有节奏地改变其身体形状，采用多种挖洞策略，如压裂、挖掘、散装流化、局部流化、局部颗粒重排和压实。一些不同的物种，如蚯蚓和双壳类软体动物，与大多数人造穿透器相比，具有非凡的挖洞效率。为什么身体形状的动态变化能够促进颗粒土壤的渗透，这在很大程度上仍然是未知的。从地质力学的角度来看，该奖项支持发现和基本理解土壤和具有动态形状的生物启发穿透体之间的相互作用。该研究对下一代高效地下施工技术和多功能小型地下穿透仪的发展具有启发作用。这些技术的应用有助于减少能源消耗和提高生产力；而由生物启发的挖洞实现的地下传感网络可以帮助监测基础设施的安全。小型、敏捷的地下机器人也可用于正常的岩土工程现场表征，也可用于由于能源和环境限制通常难以到达的区域，例如火星或地球上由于自然灾害（如地震、滑坡、洪水等）而液化或损坏的地点的探测。此外，通过本研究获得的新知识和新技术可用于了解动物与沉积物之间的力学相互作用，以及阐明穴居生物的生态学和进化。这项研究将作为促进学习、教学和培训的平台：该研究的跨学科和生物启发性质是一个理想的推广主题，可以激发K-12学生和公众对STEM教育和研究的热情；将研究方法和成果整合到教学和指导中，将有助于改善岩土工程的形象，并激发学生对跨学科研究的兴趣。该项目的教育目标是利用这项生物启发的研究，通过两个主要途径向各种受众（包括K-12学生、本科生和研究生以及公众）宣传岩土工程的仿生学研究：(1)与专门从事仿生学创新和教育的组织GLBio合作，将研究成果传播给包括K-12学生和公众在内的更广泛的受众。与GLBio合作，将开发一个移动互动演示展台和一个关于挖洞机制的适应性讲座模块，以向观众介绍仿生学和跨学科研究。外展活动将通过GLBio的网络进行，该网络包括俄亥俄州东北部的学校、动物园和博物馆。(2)建立俄亥俄州东北部岩土工程教育区域联盟（NEOGeo），由公立和私立大学以及当地产业合作伙伴参与，整合教育资源，提高教育质量。为了促进多样性和平等，在招收研究项目学生时，将优先考虑来自历史上代表性不足的群体（女性和非洲裔美国人）的合格学生，以及来自低收入家庭和经济弱势地区的学生。项目的研究目标是通过实验和数值模型相结合的方法研究颗粒状材料与动态形状仿生穿透体之间的相互作用。掘进过程的复杂性在于颗粒物料与掘进物边界的时空变化，以及颗粒物料的固流过渡。实验数字图像相关（DIC）技术和数值离散元方法（DEM）是表征和建模颗粒动力学的理想方法，为充分理解这种动态结构-颗粒相互作用问题提供了关键的多尺度信息。在本研究中，(1)将设计一个简单的双组分装置，利用“人造肌肉”来模拟蛤蜊的挖洞运动学；人工蛤体的侵彻实验将提供基于DIC的土壤-穴居物相互作用的真实多尺度观测；(2)开发并验证基于DEM的虚拟标定室，用于研究多长度和时间尺度下更基本的掘进机制，并系统地研究土壤性质、土壤应力状态和掘进者运动学对掘进性能的影响。本研究将最终回答以下问题：1)给定特定类型的土壤，侵彻器形状的变化如何影响侵彻效率？2)给定穿透器的动力学和运动学，穿透效率（阻力）如何与土壤性质相关。

This Faculty Early Career Development (CAREER) Program grant will promote the scientific understanding of the highly efficient burrowing mechanisms of animals in the natural world. Burrowing organisms can inhabit a wide range of subsurface soil types, and adopt a variety of burrowing strategies such as fracturing, digging, bulk fluidization, localized fluidization, localized grain rearrangement and compaction, facilitated by rhythmically changing their body shape. Several different species such as earthworms and bivalve mollusks possess extraordinary burrowing efficiency compared to most man-made penetrometers. Why the dynamic change in body shape is able to facilitate penetration in particulate soil is still largely unknown. From a geomechanical perspective, this award supports the discovery and fundamental understanding of the interaction between soil and bio-inspired penetrators with dynamic shapes. This research has potential to inspire the development of next-generation, high-efficiency underground construction technologies and versatile small-scale underground penetrometers. Application of these technologies can help reduce energy consumption and improve productivity; and underground sensing networks enabled by bio-inspired burrowing can help monitor the safety of infrastructure. Small, agile underground robots can also be used for normal geotechnical engineering site characterization, and also regions that are normally difficult to reach due to energy and environmental restrictions, such as the exploration of Mars or sites on Earth that are liquefied or damaged due to natural hazards (e.g., earthquakes, landslides, flooding, etc.). In addition, the new knowledge and techniques obtained through this research can be used to develop an understanding of the mechanical interactions between animal and sediment as well as shed light on the ecology and evolution of burrowing organisms. This research will serve as a platform to promote learning, teaching and training: the interdisciplinary and bio-inspired nature of the research is an ideal outreach topic to generate enthusiasm in K-12 students and the public about STEM education and research; the integration of the research approaches and findings into teaching and mentoring will help improve the image of geotechnical engineering and invoke students' interests in interdisciplinary research. The education objective of this project is to utilize this bio-inspired research to educate various audiences, including K-12 students, undergraduate and graduate students, and the general public, on biomimicry research for geotechnical engineering via two major pathways: (1) Partnering with GLBio, a dedicated organization in biomimicry innovation and education, the research outcomes will be disseminated to a broader audience including K-12 students and the general public. In collaboration with GLBio, a mobile interactive demo booth and an adaptable lecture module on the burrowing mechanism will be developed to educate the audience about biomimicry and interdisciplinary research. Outreach activities will be performed through GLBio's network, which includes schools, zoos, and museums in northeast Ohio. (2) A regional alliance for geotechnical engineering education in northeast Ohio (NEOGeo), involving public and private universities as well as local industry partners, will be established to integrate the educational resources and to improve their educational quality. To promote diversity and equality, priority will be given to qualified students from historically underrepresented groups (females and African-Americans), as well as students from low-income families and economically disadvantaged regions when recruiting students for the research program.The research objective of project is to investigate the interaction between granular materials and bio-inspired penetrators with dynamic shape through integrated experimental and numerical models. The complexity of burrowing lies in the tempo-spatial change in the boundaries between granular materials and the burrower, as well as the solid-flow transition of the granular material. Experimental digital image correlation (DIC) techniques and the numerical discrete element method (DEM) are ideal for characterizing and modeling the granule dynamics, providing key multi-scale information to fully understand this dynamic structure-granule interaction problem. In this research, (1) a simple two-component apparatus utilizing an "artificial muscle" will be designed to mimic the burrowing kinematics of clams; penetration experiments with the artificial clam will provide ground truth multiscale observations of the soil-burrower interaction using DIC; (2) a virtual calibration chamber based on DEM will be developed and validated, and it will be used to investigate more fundamental mechanisms of burrowing at multiple length and time scales, as well as to systematically survey the effects of soil properties, soil stress states and burrower kinematics on burrowing performance. This research will ultimately answer the following questions: 1) Given a certain type of soil, how does the penetrator's changing shape affect the penetration efficiency? 2) Given the penetrator's dynamics and kinematics, how does the penetration efficiency (resistance) correlate to soil properties.