ねじりをうける非対称３層ばりのねじり応力および剛性に関する数値解析

Abstract

In this paper, numerical analyses of torsional stress and rigidity were carried out on two types of nonsymmetrical three-layered sandwich and covered beams subjected to torsion, by utilizing the exact and briefly arranged analytical solution. The following different features of these beams became clear from the numerically calculated results.(1) The maximum shear stress in the sandwich beam with hard core appeared at the middle point of the thicker layer of the outer elastic layers, and for the beam with soft core it appeared at the same point of the thinner outside layer. But for the covered beam, it appeared always in the thicker outside layer.(2) Shear stress in the core of the sandwich beam became highest at both the top and bottom interfaces, and it was highest in the symmetrical beam composition. The maximum stress for the covered beam, which did not appear at the interface, was lowest in the symmetrical beam composition.(3) An appropriate core layer thickness existed in order to reduce shear stress at the interface of two-layered beam by core insertion. In this case, the saturation of stress reduction was induced by inserting a thicker core, and moreover, higher stress than that of the original two-layered beam was induced sometimes at the interface.(4) Torsional rigidity of the symmetrical sandwich beam was lowest for the soft core and highest for the hard core. On the other hand, for the covered beam it was lowest in the symmetrical and highest in the two-layered beam composition. These characteristics for torsional rigidity are controlled by the increase of torsional rigidity of the elastic layer of each beam created by bonding.