Plastic Yielding Around Nanovoids

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Assessment of Debonding-Induced Toughening in Nanocomposites

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Energy absorption capability of nanomodified glass/epoxy laminates

Abstract The impact response of standard and clay-modified vacuum-infused glass/epoxy laminates was investigated. The activity was oriented to evaluate the enhancements in the energy absorption capability of the laminates due to the nanomodification. Nanomodification was achieved by using Cloisite 30B nanoclays by Southern Clay. Low velocity impact tests were carried out on flat samples of about 4 mm thicknessby a drop-weight tower. The results clearly indicate that the nanomodified laminates have a greater capability to absorb the impact energy (with up to 30% increases in dissipated energy) with respect to the standard laminates, also in combination with a decrease of the peak impact force (from 10 to 15%). In some ways, this behaviour can be partly justified by the larger damage exhibited by nanomodified laminates, with projected damage areas more than double the damage areas of standard panels, for the same impact energy

Viscoelastic material behaviour of PBT-GF30 under thermo-mechanical cyclic loading

Abstract This paper deals with the simulation of the behaviour of a short glass fibre reinforced polybutylene terephthalate (PBT-GF30) under thermo-mechanical cyclic loading. Thermo-mechanical fatigue (TMF) tests, consisting of thermal cycling with a superimposed constant strain, have been carried out in the temperature ranges of -40 °C to 120 °C and -40 °C to 40 °C, applying different mean strain values. The main goal of the work is to model the stress trend during TMF cycles and assess the performance of a linear viscoelastic material model. A linear viscoelastic model has been implemented in ABAQUS 6.9-1 by means of Prony series, using the UTRS subroutine to model the time-temperature shift. The stress-time trend during TMF tests is discussed, comparing the simulated versus the experimental stress results. In particular, the maximum and minimum values within each cycle are considered, in order to evaluate the performance of the material model. Linear viscoelastic simulations show good agreement between experimental tests and FE analysis, both for plain and notched specimen

Multifunctional Epoxy/Nanocomposites Based on Natural Moroccan Clays with High Antimicrobial Activity: Morphological, Thermal and Mechanical Properties

In this study, a series of new epoxy/clay nanocomposites (ECN) has been prepared and characterized in order to investigate the properties and compare the effect of the unmodified Moroccan clay on the structure and properties of the composite materials. Five natural clays have been used to reinforce the neat epoxy resin with 1% wt and 5% wt achieving the clay dispersion only through strong milling and mechanical stirring without previous organic modifications of the clays. The quality of clay dispersion in the epoxy matrix and the morphology of nanocomposites have been studied by transmission electron microscopy (TEM), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The mechanical and thermal properties have also been investigated. The antimicrobial activity of the nanocomposites has been tested against E. coli and S. aureus in order to evaluate their applicability as advanced antimicrobial materials. The results showed that the epoxy/crude clay nanocomposites exhibited a high inhibition action attending 99% against both bacteria in the case of the clay labeled A5

Multifunctional Epoxy/Nanocomposites Based on Natural Moroccan Clays with High Antimicrobial Activity: Morphological, Thermal and Mechanical Properties

In this study, a series of new epoxy/clay nanocomposites (ECN) has been prepared and characterized in order to investigate the properties and compare the effect of the unmodified Moroccan clay on the structure and properties of the composite materials. Five natural clays have been used to reinforce the neat epoxy resin with 1% wt and 5% wt achieving the clay dispersion only through strong milling and mechanical stirring without previous organic modifications of the clays. The quality of clay dispersion in the epoxy matrix and the morphology of nanocomposites have been studied by transmission electron microscopy (TEM), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The mechanical and thermal properties have also been investigated. The antimicrobial activity of the nanocomposites has been tested against E. coli and S. aureus in order to evaluate their applicability as advanced antimicrobial materials. The results showed that the epoxy/crude clay nanocomposites exhibited a high inhibition action attending 99% against both bacteria in the case of the clay labeled A5

Data for: Characterisation and analysis of transverse crack-induced delamination in cross-ply composite laminates under fatigue loadings

The file contains the entire set of experimental data obtained in the work:Characterisation and analysis of transverse crack-induced delamination in cross-ply composite laminates under fatigue loadings.The meaning of the symbols is reported in the same paper.Abstract of the work:The delamination growth represents one of the main phenomena involved in the fatigue damage evolution in composite laminates. With the aim of characterising qualitatively and quantitatively this mechanism and its interaction with the other damage modes occurring during the fatigue life, an experimental campaign was carried out on glass/epoxy infused laminates. Two lay-ups were adopted, namely [02/904]s and [0/902]s. The damage evolution was characterised at the macro and micro-scales. The adopted macro-scale damage indicators were the laminate stiffness drop, the crack density and the delamination ratio, of which the evolution along with the fatigue cycles is shown. Damage evolution and final failure were seen to be sensitive to scale effect. Micro-scale edge observations were useful to understand the interaction between transverse cracks, delamination and fibre failure, all these mechanisms concurring in the laminate final failure

Comportamento a fatica di giunzioni incollate in materiale composito

Viene presentato un modello per la stima della vita a fatica di giunzioni incollate in materiale composito, basato sulla meccanica del danneggiamento, gi\ue0 presentata in [1,2]. L\u2019intera vita a fatica del giunto \ue8 considerata come sequenza di una fase di innesco di una o pi\uf9 cricche, seguita da una fase di propagazione, fino al suo cedimento finale. La fase di innesco \ue8 modellata considerando l\u2019intensit\ue0 dei campi di tensione valutati sul giunto non criccato; la fase di propagazione \ue8 stimata integrando una legge tipo Paris, che lega la velocit\ue0 di propagazione della cricca con la variazione del tasso di rilascio dell\u2019energia di deformazione (Strain Energy Release Rate, SERR). La validazione del modello ha dato risultati in buon accordo con i dati sperimental