Helical Buckling of Slender Beam Structures Surrounded by an Elastic Medium

Harasawa, Susumu; Sato, Motohiro

doi:10.1017/jmech.2014.92

Cited by 4 publications

(1 citation statement)

References 11 publications

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“…Such helical buckling of the tubular strings in the wellbores, or in a wider context, the tubular strings surrounded by an elastic medium [52], shares several features with the waviness of VACNTs:…”

Section: Analogy Between Wavy Vacnts and Helically Buckled Tubular St...mentioning

confidence: 99%

Systematic periodicity in waviness of vertically aligned carbon nanotubes explained by helical buckling

Jahangiri

2017

Nanotechnology

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A hypothesis is proposed in this work to account for the geometry of individual vertically aligned carbon nanotubes (VACNTs) that not only justifies the directionality of their growth, but also explains the origin of the waviness frequently reported for these nanotube forests. Such waviness has fundamental effects on the transport/conduction properties of VACNTs, either through or along them, regarding phenomena such as mass, stress, heat and electricity. Despite the general opinion about randomness of carbon nanotubes (CNTs) tortuosity, we demonstrate here that rules of helical buckling of tubular strings is applicable to VACNTs, based on which a regular 3D helical geometry is proposed for VACNTs, with a 2D sine wave shape side-profile. In this framework, gradual increase of the total free surface energy by growth of CNTs ensues their partial cohesion, driven by van der Waals interactions, to reduce the excess surface energy. On the other hand, their cohesion is accompanied by their deformation and loss of straightness, which in turn, translates to buildup of an elastic strain energy in the system. The balance of the two energies along with the spatial constraints on each CNT at its contact points with neighboring CNTs, is manifested in its helical buckling, that is systematically influenced by nanostructural characteristics of VACNTs, such as their diameter, wall thickness and inter-CNT spacing.

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Section: Analogy Between Wavy Vacnts and Helically Buckled Tubular St...mentioning

confidence: 99%

Systematic periodicity in waviness of vertically aligned carbon nanotubes explained by helical buckling

Jahangiri

2017

Nanotechnology

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Power Law of Critical Buckling in Structural Members Supported by a Winkler Foundation

et al. 2016

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In the fields of engineering, nanoscience, and biomechanics, thin structural members, such as beams, plates, and shells, that are supported by an elastic medium are used in several applications. There is a possibility that these thin structures might buckle under severe loading conditions; higher-order, complicated elastic buckling modes can be found owing to the balance of rigidities between the thin members and elastic supports. In this study, we have shown a new and simple ‘power law’ relation between the critical buckling strain (or loads) and rigidity parameters in structural members supported by an elastic medium, which can be modelled as a Winkler foundation. The following structural members have been considered in this paper: i) a slender beam held by an outer elastic support under axial loading, ii) cylindrical shells supported by an inner elastic core under hydrostatic pressure (plane strain condition), and iii) complete spherical shells that are filled with an inner elastic medium.

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Sensor Configuration Optimizing in Modal Identification by Siege ant Colony Algorithm

2016

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Proper monitor planning is a vital component of structural health monitoring (SHM) project. An extremely important part of the monitor planning is the placement of sensors, usually in the form of acceleration sensors. For the placement of three-dimensional acceleration sensors, the state of practice is to select the sensor configuration by previous experiences. However, this results in a waste of many sensors. A novel method called siege ant colony algorithm (SAC) is proposed in this paper. This method is built on the previous ant colony optimization (ACO) in the direction of improving efficiency and accuracy when applied to optimal sensor placement (OSP) problems in large-scale structure monitoring. This method is applied and compared with standard approaches using the Hanjiang transmission tower.

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Helical Buckling of Slender Beam Structures Surrounded by an Elastic Medium

Cited by 4 publications

References 11 publications

Systematic periodicity in waviness of vertically aligned carbon nanotubes explained by helical buckling

Systematic periodicity in waviness of vertically aligned carbon nanotubes explained by helical buckling

Power Law of Critical Buckling in Structural Members Supported by a Winkler Foundation

Sensor Configuration Optimizing in Modal Identification by Siege ant Colony Algorithm

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