Search results for "Composite materials"

Determination of the effective permittivity of dielectric mixtures with the transmission line matrix methodDetermination of the effective permittivit…

2007

In this article, the effective permittivity of two-phase dielectric mixtures is calculated by applying the transmission line matrix (TLM) method. Two slightly different TLM algorithms are considered: a hybrid approach, which combines the TLM method with a subgriding technique based on dual capacitor circuits, to allow a refined description of the material, and a standard or pure TLM approach, which uses a mesh size smaller than the typical dimension of insertions in order to appropriately describe details of the geometry. A study of the statistical distribution of permittivity for insertions in random positions is also presented, showing that the effective permittivity of the mixture tends …

Functionalization of Graphene with Molecules and/or Nanoparticles for Advanced Applications

2019

Graphene is considered the material of the third millennium, due to its extraordinary electronic and mechanical properties, and due to the possibility to modulate its conductivity, flexibility, elasticity, transparency, and biocompatibility by bottom-up approach. The possibility to gather the proper- ties of graphene and graphene oxide with those of functional moieties or nanoparticles is herein reviewed. The synthetic approaches proposed, either covalent or noncovalent, are aimed to tune appropriately graphene’s properties for the realization of materials for advanced uses, such as bio- medical applications, sensors, catalysis, and energy devices. In particular, methods based on covalent l…

Virtual Element based formulations for computational materials micro-mechanics and homogenization

2021

In this thesis, a computational framework for microstructural modelling of transverse behaviour of heterogeneous materials is presented. The context of this research is part of the broad and active field of Computational Micromechanics, which has emerged as an effective tool both to understand the influence of complex microstructure on the macro-mechanical response of engineering materials and to tailor-design innovative materials for specific applications through a proper modification of their microstructure. While the classical continuum approximation does not account for microstructural details within the material, computational micromechanics allows detailed modelling of a heterogeneous…

Adhesive inter-laminar and cohesive inner-layer damage mechanisms for composite materials

2009

Accceleration of Fatigue Tests of Polymer Composite Materials by Using High-Frequency Loadings

2004

The possibility of using high-frequency loading in fatigue tests of polymer composite materials is discussed. A review of studies on the use of high-frequency loading of organic-, carbon-, and glass-fiber-reinforced plastics is presented. The results obtained are compared with those found in conventional low-frequency loadings. A rig for fatigue tests of rigid materials at loading frequencies to 500 Hz is described, and results for an LM-L1 unidirectional glass-fiber plastic in loadings with frequencies of 17 and 400 Hz are given. These results confirm that it is possible to accelerate the fatigue testing of polymer composite materials by considerably increasing the loading frequency. The n…

Thermo-mechanical post-buckling analysis of variable angle tow composite plate assemblies

2017

peer-reviewed The increasing use of composite materials for lightweight structural applications and the extended tailoring capabilities offered by variable stiffness laminates requires rapid and robust analysis tools that adequately describe the mechanical behaviour of such structures. In this work, a Rayleigh–Ritz solution for generally restrained multilayered stiffened variable angle tow plates in the post-buckling regime is presented. The plate model is based on first-order shear deformation theory and accounts for geometrical nonlinearity through von Kármán’s assumptions. General symmetric and unsymmetric stacking sequences are considered and Legendre orthogonal polynomials are employed…

Thermal properties of e-beam cured epoxy/thermoplastic matrices for advanced composite materials

2007

The aim of this work is to investigate the possibility to improve the thermal behaviour of epoxy based systems, cured by ionizing radiation, in order to produce matrices for advanced carbon fibres composites. Blends of two epoxy monomers, difunctional and trifunctional, have been polymerized by e-beam irradiation and the dynamic mechanical thermal properties have been investigated. The increase of the concentration of the trifunctional epoxy monomer in the blend causes a marked increase of the Tg, but strongly decreases the reactivity. Subsequently, blends of the same epoxy monomers with a high Tg thermoplastic toughening agent have been considered and their reactivity and the thermal prope…

Effect of Multi-Impact on Qiqh Carbon/Epoxy Composite LaminateEffect of Multi-Impact on Qiqh Carbon/Epoxy Composite Laminate

2018

This work is motivated by increasingly used of composite structures under severe loading conditions. During their use, these materials are often subjected to impact as for example, in the aeronautical field the fall of hailstone on structure composites. In fact, the low energy traditional impact tests don’t allow to see the evolution of the damage and don’t permit also to compare the best tolerance to impact between different stratifications. The multi-impact tests made it possible to find a solution to this problem. In this work, multi-impact tests are performed on three carbon/epoxy stratifications. The final goal is to predict the durability of the composite structures during impact load…

Progressi sperimentali e numerici nella valutazione dell'integrita strutturale dei solidi mediante Thermoelastic Stress Analysis

2023

Epoxy composites filled with high surface area-carbon fillers

2013

Citation: J. Appl. Phys. 114, 164304 (2013); doi: 10.1063/1.4826529 (Received 24 July 2013; accepted 6 October 2013; published online 22 October 2013) A comprehensive analysis of electrical, electromagnetic (EM), mechanical, and thermal properties of epoxy resin composites filled with 0.25–2.0 wt. % of carbon additives characterized by high surface area, both nano-sized, like carbon nanotubes (CNTs) and carbon black (CBH), and micro-sized exfoliated graphite (EG), was performed. We found that the physical properties of both CNTs- and CBH-based epoxy resin composites increased all together with filler content and even more clearly for CBH than for CNTs. In the case of EG-based composites, go…