Authors: Wesley Vanlaere, Rudy Van Impe, Guy Lagae, Jan Belis, Peter Buffel, Matthieu De Beule
691
Authors: Bin Gao, Yu Zhou Sun, Jin Bao Wang
Abstract: This paper presents a mesh-free numerical modeling approach for carbon nanotubes (CNTs) subjected to bending loads. The higher-order Cauchy-Born rule was employed to construct the higher-order continuum constitutive model. An initial equilibrium single-walled CNT (SWCNT) was viewed as been formed by rolling up a graphite sheet into a cylindrical shape. The deformation from an original SWCNT to the current configuration was approximated with the moving least-square (MLS) approximation, and the mesh-free computational framework was established in the theoretical scheme of higher-order gradient continuum. Mesh-free numerical simulations were carried out for SWCNTs, and the accuracy and convergence were discussed in comparison with the results of atomistic simulation. The buckling behavior was studied for various types of SWCNTs upon bending, and the buckling mechanism was investigated in virtue of the continuum variables, which showed that the maximum axial compressive strain played a vital role in the development of kinking.
17
Authors: F. Ayari, Ali Zghal, E. Bayraktar
Abstract: In many industrial conditions, light thin titanium shells are well used under various severe loading conditions. It is of interest to know the real conditions that govern the instability of a cracked panel subject to buckling loads in order to conserve as maximum as possible the strength of the structure. Several parameters can be varied in order to achieve this objective. The aim of this study is to determine the evolution of these parameters in order to achieve optimal crack propagation conditions while keeping these parameters within “reasonable” limits of physical and economic feasibility. For the purpose of the current study the considered structure can be regarded as thin cylindrical shell of radius r, thickness t with an initial through crack of length a. The titanium cylindrical shell is sealed on one edge and compression is applied on the other. An additional applied pressure can generates a stress and deformation field around the crack tip that has bending stresses and membrane stresses and appears as a bulge around the crack area. This paper give details of a simulation with FEA numerical analysis that determine governing instability conditions of a Titanium shell under particular loading conditions and to put in light the effect of bulging on the stress intensity factor at the crack tips. This bulging factor measures the severity of the stress intensity in the bulged crack compared to a plane shell subjected to equivalent loading conditions.
490
Authors: Hou Jun Kang, Yue Yu Zhao, Hai Ping Zhu
Abstract: Cable-arch structure is a combined structure, which utilizes flexibility of cable and rigidity of arch. Cable-arch structure has been widely used in bridge engineering. In this work, we proposed a novel mechanical model of cable-arch structure. The out-of-plane buckling and in-plane buckling were studied using the energy method. The formula of critical loads of both the first order out-of-plane buckling and in-plane buckling were derived using Rayleigh-Ritz method. An example is ultimately investigated numerically. The results indicate that the cable can improve considerably the out-of-plane and in-plane stability of arch. Therefore, the research about the stability of cable-arch structure are both valuable not only in theoretical research but also in design of engineering structure.
3061
Authors: Michael J. Richard, Kent A. Harries
Abstract: This paper presents the experimental results of an on-going study investigating the buckling capacity of single-culm and multiple-culm bamboo column elements. Four single-culm columns of species Bambusa Stenostachya were tested to obtain single-culm column capacities as well as control tests to determine the behaviour of short-doweled end-conditions. Three multiple-culm columns were then tested in order to investigate the ultimate capacity and buckling behaviour of these elements. Specifically of interest wasthe effect of bamboo stitching on improving column behaviour in the bamboo culms. Experimental values were compared with theoretical predictions for buckling capacity using the Euler equation. The behaviour of multiple-culm columns was shown to exhibit load redistribution and to mimic the sum of individual culm capacities rather than composite column behaviour. Stitching was shown to be beneficial in enforcing column geometry yet detrimental through introduction of lateral loading to culms. Finally, the apparent effective length factor K was shown to be closer to K=1 than to the value obtained from control tests of the designed end condition.
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