R. Zitoune | Institut Clement Ader (original) (raw)

Papers by R. Zitoune

Composites Part A: Applied Science and Manufacturing, 2020

$Research paper thumbnail of Comparison of composite specimen fracture with drilled and moulded holes$

Advances in Composites Manufacturing and Process Design, 2015

ABSTRACT

International Journal of Fatigue, 2015

Abstract In this research paper, the influence of two drilling processes on the mechanical behavi... more Abstract In this research paper, the influence of two drilling processes on the mechanical behavior of bolted composite joints was investigated. Two stacking sequences were studied namely, [±45°] 2S and [90/+45/0/−45] S . The composite specimens were drilled using conventional machining (CM) and abrasive water-jet machining (AWJM). Fatigue tests combined with infrared thermography (IR) were used to determine the high cycle fatigue strength and monitor damage accumulation and heat dissipation. Fatigue test results at 65% of the ultimate tensile strength showed that the damage for [±45°] 2S and [90/+45/0/−45] S bolted joints drilled with CM were 65% and 54% respectively. However, when the AWJM was used, the damage accumulated was 25% more compared to CM. This difference was confirmed by IR results which showed that [±45°] 2S bolted joints drilled with CM dissipate 23% more heat than those drilled with AWJM. The current study demonstrated that AWJM extends the high cycle fatigue strength and the fatigue life of bolted composite joints.

European Journal of Environmental and Civil Engineering, 2014

In this paper, a new technique is proposed to confine concrete columns using GFRP-prefabricated b... more In this paper, a new technique is proposed to confine concrete columns using GFRP-prefabricated bonded shells and a shrinkage-compensating cement mortar. The confinement is performed with three identical shells, each of which contains two stepped lap joints at their ends. The main advantage of this technique is that the shells can be directly assembled on site by structural bonding to cover any column shape. The gap between the shells and the column is filled with shrinkage-compensating cement mortar. To evaluate the efficiency of this technique, several concrete specimens were confined, instrumented and tested under monotonic compression. To simulate the actual strengthening conditions, the load was directly applied on the concrete cross-section. The results show clearly the benefits of an efficient confinement in terms of a noticeable increase in the axial strength and ductility where the stress–strain curves are characterised by a third softening phase and the failure mode which spread over the whole length of the shells.

Materials Science Forum, 2013

In this chapter the influence of tool geometry and cutting conditions on cutting forces, surface ... more In this chapter the influence of tool geometry and cutting conditions on cutting forces, surface defects and the percetage of dust generated durring trimming and reaching the pulmonary alveoli is investigated. The surface defects were analysed using a scanning electron microscope and diferent surface roughness measurement devices. It was observed that these leters were highly depend on the cutting condition and the tool geometry, and more important that the effect of cutting parameters can be completely diferent from a tool to an other or even when considering different ranges of cutting parameters (standard cutting speed and high cutting speed). The compressive strenght after machining is also investigated. It is observed that whatever tool geometry, cutting conditions, surface roughnesses (defects) are, the response still the same for all the composite samples except for those machined at cutting temperatures higher than the glass fiber transition.

Composites Part A: Applied Science and Manufacturing, 2021

Abstract Abrasive water jet (AWJ) process has been certified in some aerospace companies for repa... more Abstract Abrasive water jet (AWJ) process has been certified in some aerospace companies for repair applications. However, there is no information in the literature on the influence of the induced damage on the mechanical behaviour of complex materials such as 3D woven CFRP composite. To fill this gap, three texturing levels have been produced and quantified using both surface roughness (Ra) and “crater volume” (Cv) criteria. The specimens have been subjected to tensile static and tension-tension fatigue tests. Contrarily to Ra measurements, a linear correlation was highlighted between the increase in Cv and the degradation of the specimens’ mechanical performances (ultimate tensile stress and fatigue limit). The damage scenario of the textured specimens has been identified via acoustic emission activity, thermal maps and X-ray tomography pictures. Wider cracks and a more intense acoustic activity leading to a greater rise in temperature have been observed when Cv increases (worse quality). However, the small alterations in mechanical properties consecutive to AWJ texturing prove that this technique can be used for surface preparation of 3D woven CFRP parts prior to bounding without damaging them. Moreover, an innovative method, based on the damage accumulation, has been proposed and accurately estimates the endurance limit of the specimens.

Composite Structures, 2020

Journal of Manufacturing Processes

Machining and Machinability of Fiber Reinforced Polymer Composites, 2020

Composite Structures, 2020

Damage and Fracture Mechanics, 2009

The present paper deals with the use of optical fibers with Bragg gratings for the identification... more The present paper deals with the use of optical fibers with Bragg gratings for the identification of process-properties relations for composite structures. This study relates a 7 year-experience in the field of process and mechanical characterization of composite ...