Search results for " COMPOSITES"

ELECTROSPUN NANOFIBROUS MATS IN FIBRE REINFORCED EPOXY LAMINATES

POLYMER ELECTROSPUN NANOFIBERS AS INTERLEAVES FOR ENANCHEMENT OF CFRP LAMINATES DELAMINATION RESISTANCE

2019

Electrospinning process is a technique to produce nanoscale fibers that has evinced more interest in recent years due to its versatility and potential for applications in several applications. The mall size and the concomitant ultra-high specific surface area of electrospun nanofibers make them suitable for several applications, such as tissue engineering, biosensors, filtration and advanced polymer composites (1). In particular for carbon fiber reinforced polymers (CFRPs) the huge specific surface area of electrospun nanofibers results in very large interfacial area between nanofibers and polymer matrix and therefore leads to substantial improvement of fiber-matrix interfacial interactions…

Automatic Recognition and Analysis of Scanned Non-crimp Fabrics for Calculation of their Fluid Flow Permeability

2007

Automatic recognition of scanned images of distorted bi-axial fiber bundle arrangements is considered in order to obtain the overall permeability of the formed fiber network. Scanned images are pre-processed with color normalization followed by usage of a threshold to find the pixels belonging to the bundles, the threads keeping the bundles together, and the distinct gaps formed between the bundles. Since the scanned images virtually have a perfect grayscale, the intensity can be treated as a corresponding signal of the image. Next the regular character of the fiber network is investigated using Fourier analysis on the fiber bundles as well as on the threads. The direction, position, and s…

Part program automatic check for three axis CNC machines

2001

Abstract The simulation and verification of NC codes for CNC machining is a very important task. The aim of this work is to limit the number of cutting tests needed to verify the right writing of the part program for a CN milling machine in the intent of saving time, human resources and money. This is obtained through the Boolean operation among solids, in AutoCAD environment, of the volume covered by the tool during the operations ruled by the part program.

Finite element modelling of temperature distribution in the cutting zone in turning processes with differently coated tools

2005

Abstract The aim of this study is to check the applicability of various simulation models to obtain finite element solutions of cutting forces, specific cutting energy and adequate temperatures for a range of coated tool materials and defined cutting conditions. Commercial explicit finite element code Thirdwave AdvantEdge has been used in simulations of orthogonal cutting processes performed by means of uncoated carbide and coated tools. The latter were equipped with progressively increasing number of thin layers including TiC, TiN and Al 2 O 3 films deposited onto ISO P20 carbide substrates. Results showing the tool–chip interfacial friction influencing the temperature distribution fields,…

Advanced models for smart multilayered plates based on Reissner Mixed Variational Theorem

2017

In the present work, families of equivalent singe layer and layer-wise models for the static and free vibrations analysis of magneto-electro-elastic multilayered plates are developed. The models are defined in the framework of a unified formulation, which offers a systematic approach for generating refined plate theories through suitable expansions of the through-the-thickness components of the relevant fields, considering the expansion order as a free parameter. The key features of the developed formulation are: a) the condensation of the electric and magnetic description into the mechanical representation, based on the quasi-static electric-magnetic approximation, which allows to reduce t…

A comparative evaluation of crashworthy composite sandwich structures

2007

Abstract This paper describes an experimental evaluation of the energy absorption properties of a series of novel designs for cost-effective crashworthy composite sandwich structures. All the designs are based on the concept of the “tied-core” sandwich, i.e. the use of additional core reinforcements that act to tie the opposing facings of a sandwich together, thus preventing catastrophic failure under edgewise loading. The design, manufacture and crush testing of hollow rectangular tubes fabricated from six different tied-core concepts is described. Factors that are shown to promote high energy absorption include large, continuous areas of contact between the facings and the ties, non-thin …

Design and optimization of bonded patch repairs of laminated composite structures

2015

International audience; The present study proposes a method for design optimization of external patched repairs. The tensile behavior of notched specimens with patched repair was studied using finite element analysis and compared with experimental results. It was found that high stress concentrations along the transverse edges of circular patches and/or at the longitudinal edges of the hole leads to early damage initiation in the parent plate. The damage initiation site and its propagation depend on the patch in-plane stiffness. The optimal patch design can be characterized by a strength ratio R*. The overall design of the patch repair can be considered using a dimensionless design paramete…

An analytical model for improving precision in single point incremental forming

2007

Abstract In the modern manufacturing scenario and, in particular, in sheet metal forming, the requirement of customised production is still growing. The introduction of incremental forming enables the production of customised components in small lots. In particular, single point incremental forming is characterised by the simplest equipment; any die, in fact, is avoided reducing the necessary tooling to a simple frame, able to clamp the sheet, and a hemispherical punch that imposes the required deformation. This tooling simplicity and the associated process mechanics, in turn, determine a sometimes relevant lack of accuracy. The paper is focused on the investigation of the influence of the …

The Transverse Crack Tension test revisited

2016

Several problems arise when measuring the mode II interlaminar fracture toughness using a Transverse Crack Tension specimen; in particular, the fracture toughness depends on the geometry of the specimen and cannot be considered a material parameter. A preliminary experimental campaign was conducted on TCTs of different sizes but no fracture toughness was measured because the TCTs failed in an unacceptable way, invalidating the tests. A comprehensive numerical and experimental investigation is conducted to identify the main causes of this behaviour and a modification of the geometry of the specimen is proposed. It is believed that the obtained results represent a significant contribution in …