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The analysis of the non-linear behavior of delaminated composites panels under compression is considered. A modification to the incremental continuation method (by Riks) for the analysis of the non-linear behavior of damaged composites is proposed to improve the numerical treatment of the analysis of unstable delamination growth. The theoretical formulation of this modification is first presented in conjunction with a general formulation of the continuation method and the modified virtual crack closure technique (MVCCT) for the evaluation of delamination growth. Finally, numerical results for delaminated composite plates through the width and circular delaminations are presented and compared with existing experimental and numerical data.

The static interaction between a laminate and distributed piezoelectric actuators is considered. In particular the problem of the stress concentration at the free edge of the active elements of a piezoelectric composite is investigated. A finite element model for the laminated composite plate is developed using a multi-layer higher-order finite element approach. A typical configuration is considered, in which two active layers are bonded on the top and bottom of a passive substructure. A pure bending case is investigated. The obtained results provide useful information of the typical static response. A parametric study is also performed on the effects of the main geometrical characteristics on the intensity and the extension of edge effect.

The problem of the attenuation of the vibration effects in active cantilever beams has been approached by two strategies, position and velocity control, which have been simulated numerically and analysed experimentally. The numerical simulation has been developed by means of a finite element approach based on an Euler–Bernoulli model and subsequent modal factorisation. Each device as well as each electronic circuit, present in the single-input single-output control system has been modelled and the results of the numerical simulations have been compared with the ones obtained in the experimental tests. A good correspondence has been obtained in all the examined cases.

The present study focuses on the determination of the buckling load and post-buckling behaviour of simply supported laminated composite rectangular panels loaded in shear. The nonlinear structural response is studied with a non-linear finite element approach. In order to determine the accuracy of the procedure, several tests have been performed comparing the finite element solutions for isotropic and laminated composite rectangular panels with existing ones, adopting different sequences of lamination and different length to width ratios. The analysis then considers the behaviour of laminates produced with innovative thermoplastic matrix composites developed in the frame of a national research program.

The post-buckling behaviour of compressed composite laminates in presence of a through-width delamination is considered. A 2D finite element procedure is proposed as an effective and practical tool for the nonlinear analysis of the examined structure. An incremental analysis is performed with the introduction of contact constrains to fully account for the real behaviour of the structure. Some illustrating examples are then presented which show the effect of the geometry of delamination on the post-buckling behaviour. Local and global buckled geometries of the deformed structures are also shown corresponding to different levels of the compressive loading.

The effects of the presence of a delamination on the buckling load of composite laminates under compression are investigated. The linearized buckling analysis for two- and three-dimensional solid finite elements is proposed as an effective and practical tool for the prediction of the critical loads both for bi-dimensional and for tri-dimensional cases. The accuracy of the numerical procedure is assessed by comparing the results with existing analytical solutions obtained from the literature for simple bi-dimensional applications. A tri-dimensional analysis is then presented for the case of a square plate with a circular delamination. The effects of radius and depth of the delamination on the buckling load are also illustrated.

Many single layer and multilayer higher-order theories were recently proposed for the analysis of the three-dimensional stress field that usually occurs in composite laminates especially in critical areas such as free edges. In this paper a finite element analysis based on a multilayer theory is performed in order to predict the complicated pattern of the stress field around the hole of laminates under tension. The numerical results are compared with the ones obtained with other modelling approaches, including single layer higher-order theories. The analysis shows that multilayer-theory-based finite elements can be effectively used in the prediction of the stress response of composite structures in cases of practical interests.

A layerwise polynomial expansion along the thickness direction for displacements is assumed to analyse the behaviour of an arbitrary laminated composite plate. In contrast with other proposed approaches and in order to take into account the transverse normal stress distribution, out-of-plane displacements are not assumed to be constant along the thickness. Based on the proposed kinematic assumptions the continuity of the interlaminar stress components at the interface can be also achieved. A finite element procedure is established and plate models are derived in which the stress field is obtained directly from the constitutive relations and not by the integration of the three-dimensional equilibrium equations. Comparisons among the numerical results obtained with the proposed layerwise models, single-layer models, the classical laminate theory and exact three-dimensional elasticity solutions are presented and briefly discussed.