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Specific modulus

About: Specific modulus is a(n) research topic. Over the lifetime, 1047 publication(s) have been published within this topic receiving 17699 citation(s).
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Journal ArticleDOI
Jianping Lu1Institutions (1)
Abstract: Elastic properties of carbon nanotubes and nanoropes are investigated using an empirical force-constant model. For single and multiwall nanotubes the elastic moduli are shown to be insensitive to structural details such as the helicity, the radius, and the number of walls. The tensile Young's modulus and the torsion shear modulus of tubes are comparable to that of the diamond, while the bulk modulus is smaller. Nanoropes composed of single wall nanotubes have the ideal elastic properties of high tensile stiffness and light weight.

1,373 citations


Journal ArticleDOI
Abstract: The elastic coefficients for an arbitrary rectangular coordinate system are calculated as a function of direction cosines in the crystal. Young's modulus, shear modulus, and Poisson's ratio are defined in general and values tabulated for some of the more important directions in the crystal. Graphs of these moduli are also plotted as a function of crystal direction for orientations in the (100) and (110) planes as well as planes determined by the [110] direction and any perpendicular direction.

1,156 citations


Journal ArticleDOI
Xiefei Zhang1, Qingwen Li1, Terry G. Holesinger1, Paul N. Arendt1  +9 moreInstitutions (5)
Abstract: From the stone ages to modern history, new materials have often been the enablers of revolutionary technologies. [1] For a wide variety of envisioned applications in space exploration, energy-efficient aircraft, and armor, materials must be significantly stronger, stiffer, and lighter than what is currently available. Carbon nanotubes (CNTs) have extremely high strength, [2–5] very high stiffness, [6,7] low density, good chemical stability, and high thermal and electrical conductivities. [8] These superior properties make CNTs very attractive for many structural applications and technologies. Here we report CNT fibers that are many times stronger and stiffer per weight than the best existing engineering fibers and over twenty times better than other reported CNT fibers. Additionally, our CNT fibers are nonbrittle and tough, making them far superior to existing materials for preventing catastrophic failure. These new CNT fibers will not only make tens of thousands of products stronger, lighter, safer, and more energy efficient, but they will also bring to fruition many envisioned technologies that have been to date unavailable because of material restrictions. Strong, stiff, and lightweight are critical property requirements for materials that are used in the construction of space shuttles, airplanes, and space structures. These properties are assessed by a material’s specific strength and specific stiffness, which are defined as the strength or stiffness (Young’s modulus) of a material divided by its density. [9] The combination of high strength, high stiffness, and low density affords CNTs with extremely high values for specific strength and specific stiffness. The most effective way to utilize these properties is to assemble CNTs into fibers. However, despite extensive worldwide efforts to date, the specific strength and specific stiffness of CNT fibers that have been reported by various research groups are much lower than currently available commercial fibers. [10–22] In early studies, researchers attempted to reinforce polymer fibers with short CNTs, but the reinforcement was limited by several issues, including poor dispersion, poor alignment, poor load transfer, and a low CNT volume fraction. [10–15] Recently, pure CNT fibers (also called yarns) were reported with and without twisting. [16–22] For example, Zhang et al. [20] demonstrated that spinning from aligned CNT

397 citations


Journal ArticleDOI
Abstract: Fracture specific stiffness and fluid flow through a single fracture under normal stress are implicitly related through the geometry of the void space and contact area that comprise the fracture. Data from thirteen different rock samples, each containing a single fracture, show that relationships between fracture specific stiffness and fluid flow through a fracture fall into two general classes of behavior. Fractures either fall on a loosely-defined universal curve relating fluid flow to fracture specific stiffness, or else the flow is weakly dependent on fracture specific stiffness. The second relationship shows that flow decreases slowly with increasing fracture specific stiffness. The first relationship shows that flow decreases rapidly for increases in fracture specific stiffness. To understand this behavior, computer simulations on simulated single fractures were performed to calculate fluid flow, fracture displacement, and fracture specific stiffness as a function of normal stress. Simulated fractures with spatially correlated and uncorrelated aperture distributions were studied. Fractures with spatially uncorrelated aperture distributions tend to exhibit a weak dependence of fluid flow on fracture specific stiffness because these fractures tend to have multiple connected paths across the sample which can support flow with uniformly distributed contact area. Thus an increment in stress will increase the stiffness of the fracture without greatly reducing the amount of fluid flow. On the other hand, fractures with spatially correlated aperture distributions tend to belong to the universal relationship because correlated fractures tend to have only one or two dominant flow paths and the contact area is limited to a few regions resulting in a compliant fracture. Thus an increment in stress on a spatially correlated fracture will result in an increase in stiffness and rapid decrease in fluid flow. These spatial correlations in fracture void geometry can be differentiated in the laboratory based on the observed fracture specific stiffness–fluid flow relationship for a single fracture under normal loading.

319 citations


Journal ArticleDOI
Jianping Lu1Institutions (1)
Abstract: Elastic properties of single- and multilayered nanotubes are calculated using an empirical model. It is predicted that the nanotubes are the strongest materials. The Young's modulus and the shear modulus are comparable to that of the diamond, but the bulk modulus is almost twice as large. Elastic moduli are shown to be insensitive to details of nanotube structure such as helicity, tube radius and number of layers. These unusual properties ensure that nanotubes will have a wide range of potential applications.

245 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
202142
202033
201930
201832
201743