Analisi numerica del processo di decoesione nei laminati compositi rinforzati lungo lo spessore

Simulazione numerica della risposta di travi in legno lamellare rinforzate lungo lo spessore con barre di GFRP

Le travi in legno lamellare sono costituite da singole lamine assemblate attraverso giunti adesivi longitudinali e trasversali. Una tecnica per migliorare le propriet`a meccaniche di tali giunti consiste nell’inserimento di rinforzi trasversali in forma di barre FRP. La presente memoria indaga il comportamento di travi lamellari sia da un punto di vista sperimentale che numerico, attraverso la formulazione di un semplice modello di interfaccia bifase (giunto adesivo e rinforzo).

Numerical analysis of delamination in through-thickness reinforced composite laminates

Composite laminates show a high vulnerability to out-of-plane actions, responsible for localized damage between two adjacent laminae, i.e. delamination phenomenon. A recent technological solution to improve the strength of the composite laminates in the thickness direction consists in inserting through-thickness reinforcement. In this paper, the composite delamination is analyzed in the context of non-linear fracture mechanics by an original two-phase interface model able to describe the anisotropic elastic and post-elastic mechanical response given by the presence of the reinforcement fibres. The two phases (adhesive joint or matrix of the composite and the reinforcement) are characterized…

Delamination study of through-thickness reinforced composite laminates via two-phase interface model

A technique to enhance the strength of the composite laminates in the thickness direction consists in inserting through-thickness reinforcement, by which the potential delamination crack faces are bridged in order to increase the interlaminar fracture strength. In this paper, the composite delamination is analyzed in the context of non-linear fracture mechanics making use of the interface concept. The presence of the reinforcement fibres provides an anisotropic elastic and post-elastic mechanical response, which herein is described by an original two-phase interface model. The two phases, namely the adhesive joint (or matrix of the composite) and the reinforcement, are characterized by thei…

Backcalculation of airport pavement moduli and thickness using the Lévy Ant Colony Optimization Algorithm

Interpretation of NDTdata is crucial in any Airport Pavement Management System (APMS), in order to implement strategies to maintain airport pavementssince they allow to estimate their remaining life and related maintenance needs and activities. In this paper, the AntColony Optimization algorithmwasused for backcalculation of pavement moduli from surface deflection data. The algorithm’s performances are illustrated and improvement in prediction quality is demonstrated both in terms of goodness of fitness and computational effort. Moreover, it is proved that the proposed algorithm is also able to predict layer thicknesses, taking into account their variation too.

Delamination study of Z-pinned composite laminates via two-phase interface model.

One of the most effective technique, developed over the last decade, to enhance the strength of the composite laminates in the thickness direction (z-direction), is the through-thickness reinforcement in form of stitching [2], [4] or short rods inserting [3]. These reinforcing fibres, providing direct closure tractions to the potential delamination crack faces (bridging effect), increase the interlaminar fracture toughness. The reinforcement system can be applied extensively to the composite laminate or restricted to those critical structural zones that are subjected to high interlaminar stresses. The through-thickness reinforcement is also used in composite-composite assemblages where, cou…

A nonlocal damage interface model

Modello di interfaccia bifase per la descrizione dei fenomeni di decoesione nei materiali compositi

Una interfaccia elasto-danneggiativa arricchita con termini gradiente

Numerical analysis of the mechanical response of wood glulam beams reinforced through the thickness by FRP rods

The modern use of through-thickness reinforcement in wood glulam (glued laminated) beams, bridging the potential delamination crack faces, has shown to be an effective technological solution to improve their interlaminar fracture strength. In this paper, the behaviour of wood glulam beams is investigated from an experimental and numerical point of view, comparing the mechanical response of unreinforced and reinforced (by FRP rods) beams subjected to four points bending tests. For the numerical analysis, a simple two-phases (joint and reinforcement) interface model has been formulated and implemented in a finite element code. In particular, the classical interface model for adhesive joint, a…