Collaborative Research: Revealing Strengthening and Toughening Mechanisms in Coconut Endocarp through Integrated Multiscale Modeling and Characterization

合作研究：通过综合多尺度建模和表征揭示椰子内果皮的强化和增韧机制

• 批准号: 2316676
• 负责人: Ning Zhang
• 金额: $ 26万
• 依托单位: Baylor University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2316676&HistoricalAwards=false
• 关键词: Collaborative; Research; Revealing; Strengthening; Toughening

Non-Technical Summary:The hard shell of the coconut, called endocarp, is a lightweight material with impressive strength, toughness, and hardness. As with many biological materials, this outstanding behavior is due to a highly complex structure. When studied at increasing magnifications, the endocarp reveals different structures at each magnification level. At the largest level, a porous network can be seen, consisting of bundles of hollow channels. Larger magnifications reveal a graded cellular structure, where larger cells are found toward the inside of the coconut, and smaller cells toward the outside. The cells themselves feature walls consisting of many layers, and each of these layers consists of tiny fibrils. Understanding comprehensively how all of these elements work together to make the coconut so strong and tough is a significant challenge, especially because of their disparity in size. This project will develop novel computer simulation techniques with the capability of treating these different elements simultaneously at the relevant sizes. This project will also develop new experimental techniques to measure and visualize directly how the different elements inside the coconut endocarp interact, to test and calibrate the computer models. This integrated computational and experimental approach will provide unprecedented insights into how the coconut’s structure gives rise to its outstanding performance. These insights and methods can then be used to engineer coconut-inspired lightweight applications that are strong and tough, for instance to improve helmets. This project will provide research opportunities to undergraduate students. For instance, computational and experimental training series will be offered to undergraduate students during the summer. Underrepresented students including female and minority students will participate in this research project. This project will also provide opportunities to students with disabilities to work on computational modeling remotely. Presentations and seminar talks will be offered to middle and high school students to attract them to participate into biomaterial research. Technical Summary:Coconut endocarp is substantially stronger and stiffer than wood, despite sharing the same major ingredients: cellulose, hemi-cellulose, and lignin. The key to this impressive mechanical performance is a sophisticated structure with many levels of structural hierarchy between the molecular scale and the macroscale. This project’s goal is to develop a rigorous understanding of the endocarp’s structure/property relationships by means of a multi-scale effort integrating novel computational and experimental techniques. A concurrent atomic-continuum (CAC) computational tool will be developed to span all relevant length scales of this materials system naturally. This approach will overcome limitations of current computational approaches, where different length scales are treated with conceptually different models that need to be interfaced. The CAC approach will be used on hierarchical materials for the first time, representing a game changing development for the materials sciences. The experimental efforts will mirror the computational work and provide characterization across all length scales. Scanning probe techniques will play a crucial role in characterizing not only the structure and mechanical properties of nano- and microscale constituents of the endocarp, but also their interfacial interactions. The outcome will be a powerful model that is calibrated and verified across multiple length scales. This model can serve as a basis to establish guidelines for bottom-up hierarchical design of synthetic cellular lightweight materials with outstanding mechanical performance, inspired by the coconut endocarp.This project is jointly funded by the Biomaterials progam (BMAT) in the division of materials research (DMR) and the Established Program to Stimulate Competitive Research (EPSCoR).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.

非技术摘要：椰子的硬壳，称为内果园，是一种具有令人印象深刻的强度，韧性和硬度的轻质材料。与许多生物材料一样，这种出色的行为是由于高度复杂的结构。当研究越来越宏伟时，内质量会在每个放大剂水平上揭示不同的结构。在最大的层面上，可以看到一个由空心通道束组成的多孔网络。较大的宏伟性揭示了一个分级的细胞结构，其中发现了较大的细胞朝向椰子的内部，而较小的细胞向外部发现了较大的细胞。细胞本身具有由许多层组成的墙，这些层中的每一层都由微小的原纤维组成。彻底了解所有这些元素如何共同起作用，使椰子如此强大和艰难是一个重大挑战，尤其是因为它们的规模差异。该项目将开发新型的计算机仿真技术，并能够轻松地以相关尺寸处理这些不同的元素。该项目还将开发新的实验技术，以直接测量和可视化椰子内质量内质体内的不同元素的相互作用，以测试和校准计算机模型。这种集成的计算和实验方法将为椰子结构如何产生其出色的表现提供前所未有的见解。然后，这些见解和方法可用于设计强大而坚固的椰子风格的轻巧应用，例如改善头盔。该项目将为本科生提供研究机会。例如，在夏季，将向本科生提供计算和实验培训系列。包括女性和少数民族学生在内的代表性不足的学生将参加该研究项目。该项目还将为残疾学生提供远程计算建模的机会。将向中学和高中生提供演讲和半词，以吸引他们进行生物材料研究。技术摘要：椰子内质体比木材更强大，更僵硬，制定了相同的主要成分：纤维素，半纤维素和木质素。这种令人印象深刻的机械性能的关键是一个复杂的结构，在分子尺度和宏观尺度之间具有许多水平的结构层次结构。该项目的目标是通过整合新颖的计算和实验技术的多尺度努力来对内质量的结构/财产关系进行严格的了解。将开发一个并发的原子 - 基因图（CAC）计算工具，以跨越该材料系统的所有相关长度尺度。这种方法将克服当前计算方法的局限性，其中不同的长度尺度在概念上不同的模型进行处理，需要接口。 CAC方法将首次使用分层材料，代表材料科学的游戏开发。实验工作将反映计算工作，并在所有长度尺度上提供表征。扫描探针技术将不仅表征纳米和微观构成的内质体的结构和机械性能，而且表征其界面相互作用。结果将是一个强大的模型，可以在多个长度尺度上进行校准和验证。该模型可以作为基础，以建立由椰子内质量启发的合成细胞轻量级材料的自下而上的层次设计，该项目由椰子内质量。该项目共同由生物材料计划（BMAT）在材料研究（DMR）（DMR）（DMR）（DMR）（DMR）和既定的计划中启发竞争性研究（EPSCSCORTER）的计划（EPSCSER）进行了反映。诚实地，使用基金会的智力优点和更广泛的影响审查标准来通过评估来提供支持。