Abstract The present study characterizes the creep behavior of carbon nanotube (CNT) sheets under externally applied sustained loads. Creep loads at levels ranging from 85% to 98% of the ultimate tensile strength of the CNT sheet were applied using a tensile tester inside a scanning electron microscope chamber. The microscope enabled in-situ characterization of the microstructural changes in the CNT sheet under the influence of the applied load. The loads were sustained for 1,000,000 s or failure, whichever occurred first. A computational pattern recognition technique was also developed that enabled quantitative approximation of the time dependent changes in distribution of individual CNT orientation with reference to the loading direction. It was observed that the CNTs increasingly aligned along the loading direction during the initial loading phase when the CNT sheet was ramped up to the desired load level. Further microstructural changes by way of individual CNTs continuing to gradually align along the loading direction was observed after the loads were sustained at the desired levels. The pattern recognition computational results validated the experimental findings. Slight relaxation of the CNTs was also observed upon the removal of load once 1,000,000 s was reached.

中文翻译：

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持续负载下碳纳米管片微观结构变化的原位表征

摘要 本研究表征了碳纳米管 (CNT) 板在外部施加的持续载荷下的蠕变行为。使用拉伸测试仪在扫描电子显微镜室内施加 CNT 板极限拉伸强度 85% 至 98% 水平的蠕变载荷。显微镜能够在施加载荷的影响下对 CNT 片中的微观结构变化进行原位表征。负载持续 1,000,000 秒或失败，以先发生者为准。还开发了一种计算模式识别技术，该技术能够定量逼近单个 CNT 取向分布相对于加载方向的时间相关变化。观察到在初始加载阶段，当 CNT 片上升到所需的加载水平时，CNT 越来越多地沿加载方向排列。在负载维持在所需水平后，观察到通过单个 CNT 继续沿负载方向逐渐排列的进一步微观结构变化。模式识别计算结果验证了实验结果。一旦达到 1,000,000 秒，在移除负载时也观察到 CNT 的轻微松弛。模式识别计算结果验证了实验结果。一旦达到 1,000,000 秒，在移除负载时也观察到 CNT 的轻微松弛。模式识别计算结果验证了实验结果。一旦达到 1,000,000 秒，在移除负载时也观察到 CNT 的轻微松弛。