Search results for "Lamination."
showing 10 items of 121 documents
Thermoelastic Stress Analysis of modified Transverse Cut Tensile composite specimens under pure Mode II fatigue delamination
2018
The present work investigates the behaviour of a Transvers Crack Tensile (TCT) specimen undergoing fatigue loading, by means of a Thermoelastic Stress Analysis (TSA) experimental setup. The TCT is a tensile composite specimen where a number of internal layers are cut through the beam width. The presence of such transverse notch favours the formation of interlaminar Mode II delaminations, starting from the notch tips and propagating between the cut and continuous plies. In this work, a modification is adopted to the classic TCT specimen, where insert films, mimicking artificial delaminations, are laid across the notch tips. This is done with the purpose to favour a pure Mode II and a symmetr…
Impedance characterization of the electrochemical environment under a polymer film artificially delaminated
2008
International audience; Knowledge of the electrical conductivity of the zone under a delaminated paint film is one necessary input parameter for the simulation of electrochemically driven underpaint corrosion. In this work, a microelectrode array system has been developed, tested, and applied to measure the spatial distribution of resistivity in the delaminated zone along the metal/polymer interface. The experimental device consists of a linear array of six 100 m diameter stainless steel microelectrodes (100 m in diameter) embedded in a steel substrate. A polymer coatingwas applied and an artificial "delaminated zone"was created using the laser-induced decohesion technique. The electrochemi…
Micromechanisms of load transfer in a unidirectional carbon fibre–reinforced epoxy composite due to fibre failures. Part 1: Micromechanisms and 3D an…
2006
This study gives a detailed analysis of load distributions around fibre breaks in a composite and the mechanisms involved in load transfer. In contrast to other studies reported in the literature the analysis considers different configurations of composite damage from the failure of a few fibres to the failure of many. The model considers the elastic case with and without debonding at the broken fibre/matrix interface. In this way, the usual limitations of the finite element approach are overcome so as to take into account the numbers and interactions of broken fibres whilst maintaining an evaluation of the various fields involved, in particular the stress fields associated with fibre failu…
Effect of areal weight and chemical treatment on the mechanical properties of bidirectional flax fabrics reinforced composites
2010
Abstract In this paper several bidirectional flax fibers, usually used to made curtains, were employed as reinforcement of an epoxy matrix. Four different laminates were made by a vacuum bagging process, with varying both the areal weight and the treatment of the fabric. These structures were mechanically investigated carrying out both tensile and three point flexural tests. In order to evaluate the effect of the identified variables on the mechanical parameters (i.e. Young modulus and maximum stress) a statistical analysis was performed. Finally, by comparing the flax composite with a glass one, the convenience of the replacement of glass fiber was investigated in term of cost, weight and …
3D buckling analysis of multidelaminated composite specimens
2007
The behaviour of thin composite laminates (unidirectional, cross-ply and angle-ply) under compressive loads has been examined in cases where multiple delaminations are present. The problem is solved using the Finite Element Method (FEM) both with linear analyses, based on the eigenvalues research problem, and with nonlinear analyses, based on incremental-iterative procedures. In particular, the role of the delamination length, of the angle of the plies and of the stacking sequence on the critical load is investigated. Results are compared with those found in literature derived from experimental or numerical 2D analyses.
Frictional effect in mode II delamination: Experimental test and numerical simulation
2013
Abstract The present paper proposes an experimental and a numerical analysis of the frictional effect on the mode II delamination. Frictional stresses between the crack edges can absorb and dissipate significant energy contributions in the delamination zones, especially under cyclic loading conditions. The experimental tests are performed for a set of unidirectional End-Notched Flexure (ENF) composite specimens, which are subjected to fatigue loading law with increasing mean value. The numerical analyses are performed considering a cohesive–frictional constitutive model, which is able to reproduce the transition of the interface behavior from the sound elastic condition to the fully cracked…
Solvent-tuned ultrasonic synthesis of 2D coordination polymer nanostructures and flakes
2021
Highlights • Combined ultrasound and solvent assisted synthesis of 2D coordination polymers. • Role of interstitial solvent molecules in the delamination of 2D-CPs. • Influence of the sonication time in delamination and nanostructuration processes. • Morphological and supramolecular transformations in 2D-CPs.
Micromechanisms of load transfer in a unidirectional carbon fibre–reinforced epoxy composite due to fibre failures. Part 2: Influence of viscoelastic…
2006
A local three-dimensional (3D) finite element analysis (FEA), of the mechanisms governing composite damage (in the region around a fibre break), has been carried out. The model considers viscoelastic and plastic matrix behaviours with and without debonding at the broken fibre/matrix interface. The finite element analysis has shown that even a simple viscoelastic law describing the behaviour of the epoxy resin leads to an increasing load on the neighbouring intact fibres, as a function of time. The plastic behaviour of the matrix has been shown to have consequences on reloading after unloading. In contrast to other studies reported in the literature, the calculations were carried out on diff…
Cohesive delamination and frictional contact on joining surface via XFEM
2018
In the present paper, the complex mechanical behaviour of the surfaces joining two different bodies is analysed by a cohesive-frictional interface constitutive model. The kinematical behaviour is characterized by the presence of discontinuous displacement fields, that take place at the internal connecting surfaces, both in the fully cohesive phase and in the delamination one. Generally, in order to catch discontinuous displacement fields, internal connecting surfaces (adhesive layers) are modelled by means of interface elements, which connect, node by node, the meshes of the joined bodies, requiring the mesh to be conforming to the geometry of the single bodies and to the relevant connectin…
Delamination Detection in Carbon Fibre Reinforced Composites Using Electrical Resistance Measurement
2016
In the present study 2-D numerical analysis of strip-type laminated composite specimens with and without damage is considered and numerical investigation is carried out by using a finite element method. The surface and oblique resistances are numerically calculated according to the two-probe and four-probe methods. The electrical conductivity of the composite laminate in the longitudinal direction is constant, while the electrical conductivity in the through-thickness direction is used as a variable in the parametric study. The resistance change due to delamination for each case is estimated by comparing the obtained resistance with the corresponding resistance of the specimen without delam…