Showing papers by "Jack R. Vinson published in 2005"

Sandwich Structures: Past, Present, and Future

Abstract: The use of sandwich structures continues to increase rapidly for applications ranging from satellites, aircraft, ships, automobiles, rail cars, wind energy systems, and bridge construction to mention only a few. The many advantages of sandwich constructions, the development of new materials, and the need for high performance, low-weight structures insure that sandwich construction will continue to be in demand. The equations describing the behavior of sandwich structures are usually compatible with the equations developed for composite material thin-walled structures, simply by employing the appropriate in-plane, flexural, and transverse shear stiffness quantities. Only if a very flexible core is used, is a higher order theory needed.

Thermal Stresses in Plates

Abstract: Consider any elastic body with a constant coefficient of thermal expansion, α, in the units of in/in/°F, or equivalent, at a uniform temperature wherein the body is assumed to be free of thermal stresses and strains. If the body is free to deform, and the temperature is raised slowly to a temperature of T degrees from the stress free temperature, the thermal strains produced at any material point can be written as $$ {\varepsilon_{{ij}}}_{{th}} = \alpha \Delta T\left( {{x_i}} \right){\delta_{{ij}}} $$ (5.1) where x 1 are the coordinate directions, and δ ij is the Kronecker delta (δ ij = 1 for i = j, δ ij = 0 for i ≠ j). It should be noted that thermal strains are purely dilatational (i = j); thermal shear strains do not exist.

Governing Equations for Plates and Panels of Sandwich Construction

Abstract: For a sandwich plate or panel, the equilibrium equations and the straindisplacement relations remain the same as they are for a monocoque isotropic or composite laminate plate or panel. See (2.14)-(2.18), (1.16)-(1.21), and (10.47)-(10.52). Only the constitutive equations differ from the monocoque structures. To illustrate how the same methods used to determine the stiffness matrix quantities for a laminated structure given in Figure 10.12 can be used to obtain the stiffness quantities for a sandwich plate, simply define lamina 1 as the lower face, lamina 2 as the core and lamina 3 as the upper face. Therefore, in this example if the materials are isotropic ij ij Q Q , and for face