Showing papers by "George A. Kardomateas published in 2015"

Finite Element Formulation Based on the Extended High-Order Sandwich Panel Theory

Abstract: The extended high-order sandwich panel theory was formulated in its one-dimensional version for orthotropic elastic sandwich beams. This theory includes the in-plane rigidity of the core, and the compressibility of the soft core in the transverse direction is also considered. The novelty of this theory is that it allows for three generalized coordinates in the core (the axial and transverse displacements at the centroid of the core, and the rotation at the centroid of the core) instead of just one (midpoint transverse displacement) commonly adopted in other available theories. The theory was derived so that all core/face displacement continuity conditions are fulfilled. It is proven, by comparison to the elasticity solution, that this approach results in superior accuracy, especially for the cases of stiffer cores, for which cases of the other available sandwich computational models cannot correctly predict the stress fields involved. In this paper, a linear finite element is formulated based on the exten...

Transient Blast Response of Sandwich Plates by Dynamic Elasticity

Abstract: The three-dimensional linear dynamic elasticity problem formulation and solution for a generally asymmetric sandwich plate consisting of core and face sheets that are orthotropic, and subjected to blast loading, is presented. Laplace transforms are used to obtain ordinary differential equations in the complex Laplace space (with the variable being the through-thickness coordinate), which are subsequently solved in closed form for a simply supported plate, with the solution involving a cubic characteristic equation with complex coefficients. Subsequently, the time response is obtained by a numerical inverse Laplace transform by use of the Euler method. A realistic material and blast case is used to demonstrate the transient behavior for the displacements and face sheet/core interfacial transverse normal and shear stresses. The elasticity results are compared with the predictions of the first-order shear deformation plate theory as well as a high-order sandwich panel theory. This dynamic elasticity solution...

Blast Response of Sandwich Plates with a Compressible Core: Extended High-Order Approach

Abstract: The transient blast response of a sandwich panel that consists of a compressible core with in-plane rigidity using the extended high-order sandwich panel theory is presented and compared with elasticity closed-form solutions. The mathematical formulation of the extended high-order sandwich panel theory for the transient dynamic response of sandwich plates is described along with a numerical investigation. The extended high-order sandwich panel theory formulation takes into account the shear resistance of the core and its compressibility, which is envisaged through nonidentical displacements of the upper and the lower facesheets and its in-plane rigidity. The equations of motion and the appropriate boundary conditions are derived using the Hamilton’s principle. A numerical investigation is conducted on a simply supported sandwich panel, and its results are compared with a benchmark elasticity closed-form solution. The results include deformed shapes at the first millisecond at various time steps; displacem...