Carbon nanotubes (CNTs) are one of the strongest known materials. When assembled into fibres, however, their strength becomes impaired by defects, impurities, random orientations and discontinuous lengths. Fabricating CNT fibres with strength reaching that of a single CNT has been an enduring challenge. Here, we demonstrate the fabrication of CNT bundles (CNTBs) that are centimetres long with tensile strength over 80 GPa using ultralong defect-free CNTs. The tensile strength of CNTBs is controlled by the Daniels effect owing to the non-uniformity of the initial strains in the components. We propose a synchronous tightening and relaxing strategy to release these non-uniform initial strains. The fabricated CNTBs, consisting of a large number of components with parallel alignment, defect-free structures, continuous lengths and uniform initial strains, exhibit a tensile strength of 80 GPa (corresponding to an engineering tensile strength of 43 GPa), which is far higher than that of any other strong fibre.

碳纳米管（CNT）是已知的最坚固的材料之一。但是，当组装成纤维时，其强度会因缺陷，杂质，无规取向和不连续的长度而受损。制造强度达到单个CNT强度的CNT纤维一直是一个长期的挑战。在这里，我们演示了使用超长无缺陷CNT制造厘米长，抗拉强度超过80 GPa的CNT束的方法。由于组件中初始应变的不均匀性，CNTB的拉伸强度受丹尼尔斯效应控制。我们提出了同步的紧缩和放松策略来释放这些不均匀的初始应变。制成的CNTB由许多组件组成，这些组件具有平行排列，无缺陷的结构，连续的长度和均匀的初始应变，