Catálogo de publicaciones - libros

The present study is concerned with the analysis of the transient response of softcore sandwich structures in the postbuckling range using a higher-order geometrically nonlinear shell model including the transverse core compressibility. The transverse compressibility results in the development of a chaotic vibration with unpredictable wrinkling amplitudes and has significant effects on the eigenfrequency.

Dynamic experimental and theoretical methods for sandwich panel structures subjected to water slamming are described, including a unique servo-hydraulic controlled slam test system and a pressure based transient finite element technique. The pressure simulation method accurately represents the pressures observed in slamming tests, and the transient dynamic finite element modelling can simulate sandwich panel responses to a slamming load.

A theoretical approach is provided to investigate the problem of local free vibration of an initially stressed curved sandwich beam. The equation of motion of the skin is derived from energy principles and based upon small displacements away from an initial, loaded equilibrium state. The core material is simplified as an elastic foundation and the skins are considered as composite beams on an elastic foundation. The investigation shows that the vibration frequencies and modes are dependent not only on the flexural rigidity and length of beam and foundation modulus, but also on geometry of curvature and axial compressive/tensile force.

This paper is concerned with the vibration analysis of rectangular, symmetric composite sandwich plates and the layup optimization of top and bottom laminated FRP composite faces. The fundamental frequency of the composite sandwich plate is discussed in the subspace of four in-plane lamination parameters of the laminated FRP composite face, and the optimum laminate configuration which maximizes the fundamental frequency is determined.

The purpose of this work has been to evaluate the possibility of using modified lower order methods — such as the Bernoulli-Euler or Timoshenko beam theories with frequency dependent parameters — to calculate the response of sandwich beams subject to different end conditions. The models have been verified by measurements on a freely suspended asymmetric sandwich beam with aluminium laminates and a plastic foam core, indicating good agreement.

An effective new model for vibration analysis of the layered, and in particular sandwich, one-span, clamped-clamped (C-C) strips and beams is presented in the paper. The model is derived directly from the local linear elasticity model (solution) for the corresponding simply supported (S-S) structures after replacing the Fourier sinus series eigenfunctions with the Bernoulli-Euler eigenfunctions. The approach is verified by comparisons of numerical results obtained with the data available in the literature. Number of layers is unlimited but the model was elaborated for the structures composed of five layers.

This paper presents a study of structural-acoustic optimizations of sandwich structures for minimal sound radiation. A sublaminate modeling approach of sandwich structures with a proper balance of accuracy and computational efficiency is adopted in this work. Finite elements are used to compute the vibration response and acoustic radiation of the structure. The material and geometric properties of an anisotropic sandwich are treated as design parameters. The objective of optimization is to minimize the acoustic power radiated by the structure. A piecewise objective function is studied that includes nonlinear constraints of the optimization problem in a nature way by taking advantages of the pattern search algorithm. Numerical examples are presented to show the effectiveness of the structural-acoustic optimization in terms of the reduction of the radiated sound power.

This talk addresses wave propagation in an unbounded fluid-loaded elastic sandwich plate of symmetric composition. Several aspects are highlighted, including the interaction between shear and flexural waves and the coupling between the “in-phase” and “anti-phase” waves (with respect to transverse deflections of skins).

This paper addresses wave propagation in an unbounded elastic sandwich plate loaded by a layer of viscous compressible fluid. The dispersion equation is derived and the location of dispersion curves as a function of the depth parameter is analyzed. The viscosity-induced attenuation of waves in this wave guide is compared with the wave attenuation in a rigid duct filled with a viscous fluid and in a similar wave guide, where a sandwich plate is replaced by a conventional Kirchhoff plate.

Collision experiments and finite element analysis were carried out to investigate damage on sandwich panels struck by spherical missiles at small velocities. Analytical models based on either quasi-static or dynamic behaviour of structures were developed to calculate impact force during low speed impact on circular sandwich panels. The results of the analytical and numerical models and the experimental measurement were compared. The dependence of damage on both structural parameters and impact variables was investigated.