Comparative Study to Optimize Surface Roughness of the Titanium Alloy Ti-6Al-4V by Applying Taguchi, RSM and TLBO Methods

Titanium alloys are used in aeronautics and the shipbuilding industry for their good intrinsic properties, namely low density (40% less than steel), very good mechanical properties and resistance to corrosion. The purpose of this study is to optimize the cutting conditions during the turning of Ti-6Al-4V titanium alloy with Minimum of Quantity of Lubrication (MQL) conditions leading to minimize the surface roughness (Ra). The tests were carried out according to a Taguchi L18 design plan by varying four input factors namely: the cutting speed, the feed rate, the depth of cut and the cutting tool material (coated carbide with (PVD) (GC1125) and uncoated carbide (H13A)). Analysis of variance (ANOVA) was used to found the contribution of each factor and to determine which parameters had a significant influence on the surface roughness. The treatment of the results made it possible to propose a mathematical model, which allows predicting Ra. In addition, Taguchi Signal/Noise (S/N) analysis was used in order to optimize the cutting conditions permitting to minimize Ra. The Desirability Function (DF) was also determined. In addition, the obtained results were compared to the one determined using Response Surface Methodology (RSM) and Teaching and Learning Based Optimization (TLBO). It is important to note that the TLBO method gave a very satisfactory result

Behaviour of reinforced columns with E_Glass fiber and carbon fiber

Externally bonded reinforcement using Fiber Reinforced Polymer (FRP) is a good response to the concern represented by the need for rehabilitation of concrete structures. These techniques are more and more attractive because of their fast and low labour costs, very good strength to weight ratio, good fatigue properties, and non-corrosive characteristics of FRP. The present work is an experimental study investigating the mechanical behaviour under a uni-axial loading of short concrete columns reinforced by composite materials. These are constituted of glass fibers GFRP (bidirectional fabric of two surface densities 500 and 300 g/m2), carbon CFRP (unidirectional sheet of density per unit area of 230 g/m2) and polyester and epoxy resin respectively. The investigation aims at demonstrating the effectiveness of FRP reinforcement through highlighting the effect of thickness (FRP number of folds), the nature of the reinforcement (glass, carbon or Hybrid), and the orientation of the fibers. The axial lengths shortening along with the radial expansion are measured using the strain gauges glued to the outer surfaces of the composite jacket via a Wheatstone bridge. These measurements are saved to a PC through an acquisition card. The results obtained clearly show that the columns reinforced with CFRP folds allow an important increase in the compressive rupture stress in comparison with those reinforced with GFRP folds. The gains in compressive strength, in axial and in radial strains of the confined concrete with the different FRPs used are identified and quantified. It has further been demonstrated that the tested columns mechanisms depend strongly on the type of fiber reinforcements

Effet de l'orientation des fibres et leur type (CFRP/GFRP) sur le comportement des colonnes en béton (S06)

L'actuel travail est une étude expérimentale menée sur le comportement des colonnes courtes en béton renforcées (confinées) par collage extérieur des plis unidirectionnels et bidirectionnels de fibres de carbone (CFRP) et de verre_E (GFRP) respectivement sollicitées en compression uniaxiale. Plusieurs orientations sont effectuées pour mieux cerner l'effet de l'orientation des fibres sur le comportement de ces colonnes, l'étude prouve que l'empilement (0/90)2 est celui qui donne le bon comportement. A cet effet, un confinement par cette orientation à été réalisé mais cette fois en utilisant les fibres de carbone (CFRP). Des jauges d'extensomètrie sont collées sur les surfaces externes de l'enveloppe composite dans le but de mesurer le raccourcissement axial et l'expansion radiale par l'intermédiaire d'un pont de Wheatstone. Les résultats obtenus montrent bien que les colonnes renforcées par les plis de fibres de carbone permettent une augmentation appréciable de la contrainte à la rupture en compression comparativement avec celles confinées par les fibres de verre_E. Le type de rupture des colonnes confinées dépend fortement de l'orientation des fibres et du type de renfort

Characterization of a novel natural cellulosic fiber from<i> Juncus effusus</i> L.

International audienceThis study aims to assess the morphology and properties of fibers extracted from a wild natural plant largely available in Algeria known as Juncus effusus L. (JE). The morphology and diameter of the fiber bundles extracted from the stem of the JE plant were characterized by optical and scanning electron microscopy. The functional groups of the extracted lignocellulosic JE fibers were studied by FTIR, their thermal degradation behavior was investigated by TGA and their crystallinity was determined using X-ray diffraction technique. In addition, mechanical characterization was carried out using tensile tests on the lignocellulosic fiber in order to evaluate their strength, strain at break and Young's modulus. In view of the dispersion in the obtained experimental results, the latter were analyzed using the Weibull statistical laws with two and three parameters

Failure analysis of biocomposite sandwich pipe under internal pressure – Application for high pressure gas transportation pipelines MEDGAZ

In this paper, analytical and 3D numerical models are developed to investigate the mechanical behavior of sandwich pipe under internal pressure loading. The suggested models provide an exact solution for stresses, strains and displacement on the sandwich pipe, which is made of epoxy material for the core layer and reinforced materials with an alternate-ply for the skin layers. The aim of this analysis is to evaluate the potential applications of jute and pineapple leaf fiber (PALF) bio-fibers in order to replace glass synthetic fibers generally employed in sandwich pipes. In this subject, a failure analytical analysis was developed using TSAI-WU criterion. The results of stress, strain and displacement distribution through the thickness are presented for the analytical and numerical models. The comparison between the both models results show a very good agreement. In order to increase the rigidity of a biocomposite sandwich and reduce the gap compared with a synthetic sandwich, a gradual reinforcing of layer numbers was chosen, which permitted the best behavior. The ultimate pressure and safety factors obtained by increasing biocomposite layers are significant for composite transportation pressure pipelines, especially for sandwich pipe based on PALF/epoxy.This work has been funded partially by the DGRSDT, Algeria and Portuguese national funds of FCT/MCTES (PIDDAC) through the base funding from the UIDB/00690/2020 (CIMO) research unit.info:eu-repo/semantics/publishedVersio

Repair of reinforced concrete beams in shear using composite materials PRFG subjected to cyclic loading

Nowadays, finding new approaches to attenuate the effects of the catastrophic shear failure mode for reinforced concrete beams is a major challenge. Generally the bending failure is ductile. It allows a redistribution of the stresses providing an early warning, whereas the rupture by shear is fragile and sudden which can lead to detrimental consequences for the structures. This research focuses on the repair of deep beams in reinforced concrete shear subjected to 4-point bending. After being preloaded at different levels of their ultimate loads, the beams are repaired by bonding a composite material made of an epoxy resin reinforced by glass fibers. The main objective of this study is to contribute to the mastery of a new method developed by the authors that consists by banding the cracks in critical zones in order to avoid fragile ruptures due to the shear force. This new technique led to better results in terms of mechanical properties when compared to conventional methods, notably the absence of the debonding of the composite found in the case of the repairs of the beams by bands or U-shaped composites. The feasibility, the performances and the behavior of the beams have been examined. The experimental approach adopted using this new technique has shown the influence of the type of loading on the fatigue behavior. In addition, the repair performed led to a considerable improvement in the fatigue durability of the preloaded beam