Super-strong, super-tough and super-fatigue-resistant materials are facing huge demand in many fields such as aerospace, military equipment, body armor, large bridges, sports equipment, and artificial muscles. Carbon nanotubes are typical one-dimensional nanomaterials, and are currently known materials with the highest mechanical strength and toughness. Both their macroscopic strength and toughness are more than an order of magnitude higher than the currently widely used materials such as carbon fiber and aramid. However, due to its small size and difficult to be tested, the fatigue behavior and fatigue failure mechanism of a single carbon nanotube are difficult problems that have not been clarified in this field for a long time. Since fatigue can occur when the stress level is much lower than the static fracture strength, exploring fatigue behavior and potential failure mechanisms is of great significance for the application of new materials and long-term reliability assessment.
The team of Professor Wei Fei and Associate Professor Zhang Rufan from the Department of Chemical Engineering of Tsinghua University tested the fatigue resistance of a single ultra-long carbon nanotube with a centimeter-level length for the first time. The related results were titled "Super-durable Ultralong Carbon Nanotubes", which was published online in Science on August 28, Beijing time. The corresponding authors of the paper are Professor Wei Fei and Associate Professor Zhang Rufan from the Department of Chemical Engineering of Tsinghua University. The first author is Bai Yunxiang, a 2016 PhD student in the Department of Chemical Engineering of Tsinghua University. Other authors involved in the research include Master student Yue Hongjie, PhD students Shen Boyuan and Sun Silei from the Department of Chemical Engineering of Tsinghua University. Professor Li Xide, Professor Xu Zhiping, Associate Professor Wang Haidong and PhD students Wang Jin and Wang Zhijun from the School of Aeronautics and Astronautics of Tsinghua University.
In order to carry out the fatigue mechanical behavior test of a single centimeter-length carbon nanotube, the research team designed and built a non-contact acoustic-resonance-test (ART). Compared with the nanomaterial test system based on electron microscope, the ART system has many advantages. The system not only avoids the sample damage caused by the electron beam, but also makes it possible to test the fatigue of one-dimensional nanomaterials with a length of cm, and also solves the problem. Small size sample clamping and high cycle load application problems.