Hakim Boudaoud

Vibration Modeling of Multilayer Composite Structures with Viscoelastic Layers.

This work deals with the vibration of orthotropic multilayer sandwich structures with viscoelastic core. A finite element model is derived from a classical zigzag model with shear deformation in the viscoelastic layer. The aim of the present work is to establish numerical models and develop numerical tools to design multilayer composites structures with high damping properties. To fulfill this purpose, a finite element model has been developed for vibration analysis of a sandwich plate (elastic orthotropic)/(viscoelastic orthotropic)/(elastic orthotropic). A numerical study from the variation of the damping properties of the structures was performed according to the faces materials fibers orientation.

Linear and quadratic solid–shell finite elements SHB8PSE and SHB20E for the modeling of piezoelectric sandwich structures

ABSTRACT In this article, hexahedral piezoelectric solid–shell finite element formulations with linear and quadratic interpolation, denoted by SHB8PSE and SHB20E, respectively, are proposed for the modeling of piezoelectric sandwich structures. Compared to conventional solid and shell elements, the solid–shell concept reveals to be very attractive, due to a number of well-established advantages and computational capabilities. More specifically, the present study is devoted to the modeling and analysis of multilayer structures that incorporate piezoelectric materials in the form of layers or patches. The interest in this solid–shell approach is shown through a set of selective and representative benchmark problems. These include numerical tests applied to various configurations of beam, plate and shell structures, both in static and vibration analysis. The results yielded by the proposed formulations are compared with those given by state-of-the-art piezoelectric elements available in ABAQUS, in particular, the C3D20E quadratic hexahedral finite element with piezoelectric degrees of freedom.

Vibration modeling of large repetitive sandwich structures with viscoelastic core

ABSTRACT A double scale asymptotic method (DSAM) is proposed for vibration modeling of large repetitive sandwich structures with a viscoelastic core. The method decomposes the initial nonlinear vibration problem into two small linear ones. The first one is defined on few basic cells while the second is a differential global amplitude equation with complex coefficients. Their numerical computations permit determination of the damping properties as well as pass and stop bands avoiding the direct computation on the whole structure. Viscoelastic frequency dependent core with fractional and anelastic displacement field models are considered. The resulting nonclassical problems are solved by asymptotic numerical method coupled with automatic differentiation. Based on the presented method, a large reduction of the needed computational time and memory is obtained. The accuracy and efficiency of the proposed method are validated with comparisons to the direct simulations by discretization of the whole structure using asymptotic numerical method coupled with automatic differentiation.