Asymptotic behavior of the solution of an axisymmetric problem of elasticity theory for a sphere with variable elasticity modules

2020 ◽  
Vol 25 (12) ◽  
pp. 2231-2251 ◽  
Author(s):  
Natiq K Akhmedov ◽  
Natavan S Gasanova

In the paper the axisymmetric problem of elasticity theory is studied for the radially inhomogeneous sphere of small thickness that does not contain any of the poles 0 and [Formula: see text]. Here the case is considered when the elasticity modules vary linearly with respect to the radius. It is assumed that the lateral surface of the sphere is free of stresses, and at the ends of the sphere (at the conical sections) the stresses are set, leaving it in equilibrium. A characteristic equation is obtained and, based on its asymptotic analysis, the existence of three groups of roots is established with respect to the small parameter characterizing the thickness of the sphere. The corresponding homogeneous solutions are constructed, depending on the roots of the characteristic equation. It is shown that the penetrating solution corresponds to the first group of roots. The second group of roots corresponds to the solution of the edge effect type, similar to the edge effect in the applied theory of shells. The third group of roots corresponds to the boundary layer type solution localized in the conical sections. The solution corresponding to the first and second groups of roots determines the internal stress–strain state of the sphere. In the first term of the asymptotic, they can be considered as a solution in the applied theory of shells. The question of satisfying the boundary conditions at the ends (on the conical sections) of the sphere is considered using the variational Lagrange principle.

2020 ◽  
Vol 20 (12) ◽  
pp. 2050137
Author(s):  
Hamid Zeighampour ◽  
Yaghoub Tadi Beni ◽  
Yaser Kiani

In this paper, the axial buckling of boron nitride nanotubes (BNNTs) is investigated by considering the effects of surface and electric field. To achieve this purpose, the surface elasticity theory is exploited and the results are compared with the molecular dynamic simulation in order to validate the accuracy of the applied theory. In the molecular dynamics simulation, the potential between boron and nitride atoms is considered as Tersoff type. The Timoshenko beam theory is adopted to model BNNT. Moreover, two types of zigzag and armchair BNNTs are considered. In this study, the effects of surface, electric field, length, and thickness of BNNT on the critical buckling load are investigated. According to the results, the critical load of zigzag BNNT depends on the electric field. However, the electric field would not affect the critical load of the armchair BNNT. It should be noted that the surface residual tension and surface Lamé’s constants of BNNT have considerable impact on the critical load of BNNT. For lower values of electric field and smaller dimensions of BNNT, the critical load would be more dependent on the surface effect regarding the results. Furthermore, as an efficient non-classical continuum mechanic approach, the surface elasticity theory can fill the potential gap between the classical continuum mechanic and molecular dynamics simulation.


1981 ◽  
Vol 20 (3) ◽  
pp. 388 ◽  
Author(s):  
K. Kikuchi ◽  
T. Morikawa ◽  
J. Shimada ◽  
K. Sakurai

2003 ◽  
Vol 48 (1) ◽  
pp. 42-45 ◽  
Author(s):  
G. G. Sebryakov ◽  
M. D. Kovalenko ◽  
N. N. Tsybin

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