Catálogo de publicaciones - libros

A theory for laminated and sandwich beams is developed based on far-field stress and strain solutions called Fundamental State Solutions. Through-thickness stress and strain moments of the Fundamental Solutions are used to obtain homogenized axial, flexural and shear stiffness as well as a shear-strain moment correction. A sequence of beam models with similarity to the Timoshenko model are obtained. Excellent agreement is shown for all stress and strain components when compared to accurate two-dimensional finite element results.

In this paper we use a trigonometric layerwise deformation theory for modelling symmetric composite plates. We use a meshless discretization method based on global multiquadric radial basis functions. The results obtained are compared with solutions derived from other models and numerical techniques. The results show that the use of trigonometric layerwise deformation theory discretized with multiquadrics provides very good solutions for composite plates and excellent solutions for sandwich plates.

A higher-order theory for the analysis of cylindrical and conical sandwich shells with flexible core is presented. The governing differential equations are derived on the basis of a three-layer model and solved by numerical integration. The theory is veri.ed by comparison of achieved results to those published in the literature and to finite element computations.

The dynamic behavior of sandwich panels with a flexible core and debonded region with and without contact is studied. The investigation uses the high-order theory of sandwich panels and considers geometrical nonlinear effects and the nonlinearity associated with the contact characteristics of the delaminated surfaces. The rotary inertia of the face-sheets and the core and the high order velocity and acceleration fields through the depth of the core are included. The dynamic governing equations, boundary conditions and continuity requirements are derived through the Hamilton principle. Numerical results that reveal the influence of the contact characteristics on the dynamic response of the sandwich panel are also presented and discussed.

The bending behavior of sandwich panels with a “soft” core hosting embedded rigid inserts is analytically investigated. Three approaches for the mathematical modeling of the sandwich panel hosting the rigid insert are discussed. In addition, the continuity conditions between the regions hosting the rigid insert and the adjacent sandwich regions are derived. Numerical results that demonstrate the capabilities of the model and highlight some of the effects that characterize the response of the panel are also presented.

Reinforced sandwich panels are frequently used in refrigerated trailer construction. There is a need to reinforce the sandwich panels because they can achieve some very large dimensions and consequently loose their ability to support the working loads. Work has been developed in the field of elastic and fracture behaviour of several sandwich beams with Z reinforcements. It was concluded that some reinforcements highly increase the beams rigidity. A few specialized analytical models were developed for linear elastic analysis, and some numerical models were built to analyze the different types of beams tested experimentally in three-point bending. The models contribute to a better understanding of the deformation phenomena involved and help in isolating and characterising the critical terms of divergence between theory and experiment. The present work contributes to the establishment of design and analysis parameters necessary to this type of construction.

The paper considers wrinkling of orthotropic faces of a shallow sandwich shell with an isotropic core for a general case of in-plane multi-axial loading. The principal axes of loading do not necessarily coincide with the principal axes of orthotropy and curvature. The technique of the obtained closed-form solutions are based on minimization of critical forces with respect to wavelengths and angles of wrinkling.

Finite solution for deformation of a sandwich panel by two systems of forces applied symmetrically and nonsymmetrically to the upper and lower faces were examined. The simple estimates of transverse normal stresses in the midlayer of a sandwich panel at squeezing from the infinite system of ribs located on either face surface have been deduced.

The present study is concerned with a triangular higher-order finite element for sandwich plates with transversely compressible core. The element formulation utilizes a v. Kármán type multilayer theory, adopting the discrete Kirchhoff approach for the contribution of the face sheets and a simplified three-dimensional formulation for the core. The discretized nonlinear problem is solved by the Newton-Raphson method.

A finite element for the static and stability analysis of sandwich plates is formulated based on a three-layer sandwich model and its underlying differential equations. The Kirchhoff-Love hypothesis is assumed for the face sheets. The core is modelled by a three-dimensional material law neglecting the in-plane core stiffnesses. A stability analysis is performed on the basis of the geometric stiffness matrix considering the membrane prestresses of the face sheets.