An Equivalent Homogenization Theoretical Method for Composite Sandwich Cylinders Subjected to Pure Bending

An equivalent theoretical homogenization method was proposed for composite sandwich cylinders subjected to pure bending. Firstly, based on a homogeneous orthotropic layer hypothesis, the trapezoidal corrugated sandwich core was found to be equivalent in a homogenization orthotropic layer with the nine equivalent mechanical properties. Then, Lekhnitskii’s theory, based on a unified connection parameter method, was introduced and applied in the equivalent composite sandwich cylinder. The method developed by Lekhnitskii is suitable for arbitrary combinations of winding layers with different winding angles and materials. Additionally, the bending stiffness of the equivalent sandwich cylinder could be calculated. By developing user subroutine of UMAT, the numerical calculation results were in a good agreement with the results of the proposed method. Further, according to the Hill–Tsai strength criterion and the maximum strain criterion, parametric study was done for specified bending stiffness and specified bending strength. The results show that the influence of core parameters on the specified bending stiffness and strength are lower than that of the skin parameters. Additionally, larger skin thickness and smaller winding angles could improve the specified bending stiffness and specified bending strength of the composite corrugated sandwich cylinders.

On the contact problem of a moving rigid cylindrical punch sliding over an orthotropic layer bonded to an isotropic half plane

In this study, the frictional moving contact problem for an orthotropic layer bonded to an isotropic half plane under the action of a sliding rigid cylindrical punch is considered. Boundary conditions of the problem include the normal and tangential forces applied to the layer with a cylindrical punch moving on the surface of the layer in the lateral direction at a constant velocity V. It is assumed that the contact area is subjected to the sliding condition where Coulomb’⣙s law is used to relate the tangential traction to the normal traction. Using the Fourier integral transform technique and Galilean transformation, the plane contact problem is reduced to a singular integral equation in which the unknowns are the contact stress and the contact width. The singular integral equation is solved numerically using Gauss–Jacobi integration formulae. Numerical results for the contact widths and the contact stresses are given as a solution.