Biologically Inspired Autonomic Structural Materials with Controlled Toughening and Healing

结构健康监测(SHM)在过去几年中有了显著的发展，这是由于该技术提高了安全性和性能，以及潜在的挽救生命的能力。目前SHM系统的进步导致了各种能够识别损坏的技术；然而，几乎没有策略可以利用这些信息来对环境或物质条件做出快速反应，以修复或保护系统。与这些现代的SHM系统不同，生物系统不仅可以检测到损伤的存在，还可以通过刺激反应行为做出反应来修复损伤。这项研究计划的重点是使用先进的复合材料来模拟生物系统对损伤的反应。这一努力将在结构健康监测和自主结构材料之间架起一座桥梁，以便SHM系统能够以受控的方式检测和响应损坏。现有的修复技术是有问题的，因为它们不能被控制，并且没有提供感知反应来报告损伤的存在、修复的开始或恢复的强度。一种独特的材料和传感器组合将被用来模拟骨骼在破裂时表现出的增韧反应之一。这里开发的自主系统将使用光纤来感知损伤的存在，并自主启动修复。通过利用光纤在损伤存在时释放的能量作为刺激，以及热激活形状记忆聚合物(SMPS)的最新进展，将发生响应行为。研究的结果将是一种材料系统，可以通过刺激感知损伤的存在，阻止其传播，并启动受控愈合。这项工作将1)对最近开发的反应性聚合物进行建模和表征，2)表征裂纹尖端局部模数变化造成的裂纹钝化，3)使用网络工程来制造集成了传感器网络、计算和逻辑的复合材料，使系统能够在没有人为干预的情况下对损伤做出反应。该研究计划将把SHM从损伤检测推进到一个集成的材料系统，该系统可以像生物系统一样以自主的方式识别损伤并对其做出反应。

Structural health monitoring (SHM) has seen significant growth over the past few years due to the safety and performance enhancing benefits as well as the potential life saving capabilities offered by the technology. Current advances in SHM systems have lead to a variety of techniques capable of identifying damage; however, few strategies exist for using this information to quickly react to the environmental or material conditions to repair or protect the system. Unlike these modern SHM systems, biological systems can not only detect the presence of damage but react to heal it through stimulus responsive behavior. This research plan focuses on the use of advanced composite materials to mimic the response of biological systems to damage. This effort will provide a bridge between structural health monitoring and autonomic structural materials such that the SHM system can detect and respond to damage in a controlled fashion. Existing healing techniques are problematic because they cannot be controlled and provide no sensing response to report the presence of damage, the initiation of healing, or the strength recovered. A unique combination of materials and sensors will be used to mimic the one of the toughening responses exhibited by bone when subjected to cracking. The autonomous system developed here will use optical fibers to sense the presence of damage and autonomously initiate healing. Responsive behavior will occur by using the energy released from the optical fiber in the presence of damage as stimulus and the recent advances in thermally activated shape memory polymers (SMPs).The outcome of the research will be a material system that can sense the presence of damage, arrest its propagation and initiate controlled healing through stimulus. The work will 1) model and characterize recently developed reactive polymers, 2) characterize the crack blunting from a localized modulus change at the crack tip, and 3) use cyberengineering to fabricate a composite material with integrated sensor networks, computing and logic to allow the system to respond to damage without human intervention. The research program will advance SHM from damage detection to an integrated material system which can identify and react to damage in an autonomous manner as biological systems do.