Failure-analysis of carbon nanotubes and their extreme applications

The study of material failure is crucial for the design of engineering applications,as it can have significant social and economic impacts.Carbon nanotubes(CNTs),with their exceptional electrical,mechanical,and thermal properties,hold immense potential for a wide range of cutting-edge applications such as superstrong fiber,lightning strike protector,and even space elevator.This review provides an overview of the advancement in understanding the mechanical and electrical failure study of CNTs and their assemblies,serving as a comprehensive reference for utilizing CNTs in various forms.To begin,we emphasize the importance of studying material failure and provide a brief introduction to CNTs.Subsequently,we explore the mechanical and electrical failure characteristics of CNTs and their assemblies,along with notable examples of applications that utilize their failure-resistant properties,such as flywheel energy storage and lightning strike protection.Lastly,we present perspectives associated with analyzing CNT failure and its implications for extreme applications.

Mechanical Behavior of Single and Bundled Defect-Free Carbon Nanotubes

CONSPECTUS:Superstrong materials can be utilized in many fields such as bulletproof vests,airframes,suspension bridges,flywheel energy storage,etc.As one of the strongest materials,carbon nanotubes(CNTs)can potentially be used to fabricate superstrong fibers.However,the tensile strength of CNTs is impaired a lot by defects,and the CNT fibers prepared so far have strengths much lower than that of a single CNT,showing a“size effect”.The conventional study of solid mechanics is usually based on the assumption that materials contain defects.Defect-free ultralong CNTs can hopefully help us avoid the“size effect”of nanomaterials and produce superstrong CNT fibers.They would also provide a system for the study of the mechanical behavior of ideal solids with a nonlocalized“quantum stress singularity”.In this Account,we discuss our recent studies on the mechanical behavior of defect-free single CNTs and CNT bundles.First,we introduce the defect-free structure of ultralong CNTs,which is one type of ideal solid.Second,we review the investigation of the static tensile properties and dynamic fatigue resistance and their temperature-dependence of single centimeters long defect-free CNTs.The results showed that defect-free CNTs have superior comprehensive mechanical properties,including superstrength,-toughness,and-durability.Different from traditional materials,the fatigue lifetime and fracture of CNTs are dominated by the first single-bond-sized defect(quantum stress singularity),showing“superbrittleness”.Third,by using a gas flow focusing in situ synthesis method as well as a synchronous tightening and relaxing strengthening strategy,we successfully fabricated CNT bundles with tensile strengths approaching that of single CNTs and showed that the“size effect”can be avoided.In addition,the advantages and promising future of using CNTs in flywheel energy storage are discussed.Finally,we provide our perspectives on the challenges and future directions in this field.

General M-lump,high-order breather,and localized interaction solutions to(2+1)-dimensional generalized Bogoyavlensky-Konopelchenko equation

The(2+1)-dimensional generalized Bogoyavlensky-Konopelchenko equation is a significant physical model.By using the long wave limit method and confining the conjugation conditions on the interrelated solitons,the general M-lump,high-order breather,and localized interaction hybrid solutions are investigated,respectively.Then we implement the numerical simulations to research their dynamical behaviors,which indicate that different parameters have very different dynamic properties and propagation modes of the waves.The method involved can be validly employed to get high-order waves and study their propagation phenomena of many nonlinear equations.

Controlled growth of crossed ultralong carbon nanotubes by gas flow

Carbon nanotubes(CNTs)work as the promising components of miniature electromechanical systems due to their ecellent performances from individual to bundle scales.But it's challenging to achieve precise patterning at nanoscale resolution with controlled position and orientation.Here,we demonstrate a fluidic strategy to interlace one-dimensional(1D)ultralong CNTs into the crossed pattern in a one-step in-situ process.Semi-circular substrates of different diameters were placed in front of the growth substrate to change the path and momentum of gas flow.Such flow perturbation caused by substrates could be markedly reflected within a micro-channel reactor,which led to formation of crossed utralong CNTs at definite positions.Furthermore,precise control over the crossing angle as well as the diameter distribution of CNTs was achieved by varying the CNT length and diameter of semi-circular substrates.Our strategy has offered a feasible route for production of crossed ultralong CNTs and will contribute to multidimensional fluidic assembly of flexible nanomaterals.