Effects of the non-homogeneity and elastic medium on the critical torsional load of the orthotropic cylindrical shell

In this study, the torsional stability problem of non-homogeneous orthotropic composite cylindrical shells in the elastic medium, using the Galerkin method was investigated. The Winkler model is used to describe the reaction of the elastic medium on the cylindrical shell. Mixed boundary conditions are considered. The effects of variations of shell parameters, non-homogeneity, orthotropy and foundation stiffness on the critical torsional load are examined

Dynamic analysis of linear viscoelastic cylindrical and conical helicoidal rods using the mixed FEM

The objective of this study is to investigate the influence of the rotary inertia on dynamic behavior of linear viscoelastic cylindrical and conical helixes by means of the Laplace transform-mixed finite element formulation and solution. The element matrix is based on the Timoshenko beam theory. The influence of rotary inertias is considered in the dynamic analysis, which is original in the literature. Rectangular, sine and step type of impulsive loads are applied on helices having rectangular cross-sections with various aspect ratios. The Kelvin and standard models are used for defining the linear viscoelastic material behavior; and by means of the correspondence principle (the elastic-viscoelastic analogy), the material parameters are replaced with their complex counterparts in the Laplace domain. The analysis is carried out in the Laplace domain and the results are transformed back to time space numerically by modified Durbins algorithm. First, the solution algorithm is verified using the existing open sources in the literature and afterwards some benchmark examples such as conical viscoelastic rods are handled. © 2014 Elsevier Ltd.36130 National Council for Scientific Research: 111M308This research is supported by the Scientific and Technological Research Council of Turkey under Project no. 111M308 and by the Research Foundation of ITU under Project no. 36130 . These supports are gratefully acknowledged by the authors