Papers by Author: Mostapha Tarfaoui

Abstract: Bonded fibre reinforced polymers (FRP) have been found to be an efficient method for improving the lifespan of fatigued metallic structures and have attracted much research attention. Steel beams can be reinforced in flexure using FRP plates that rely on adhesively bond. In such plated structures, shear forces are developed in the bonded joint and these will be transferred to FRP plate via the adhesion technique, thus, the interfacial stresses will progress consequently, and the debonding may occurs at the plate ends due to high values of interfacial stresses. This original research leads us to predict the interfacial stresses by a numerical study, using a finite element model under ANSYS software and coupling effects of mechanical and thermal loads with fibre orientation. Finally, a parametric analysis is used to identify effects of various geometrical and material properties on the magnitude of stresses values. This analysis is helpful because of the adaptation in the modelling process. It is shown that the bearing capacity of the adhesive joint is significantly influenced not only by the strength model, but also, by the shear modulus, elastic modulus of FRP and the other parameters..

Abstract: This paper presents an experimental investigation on the behaviour of structural adhesive bonding under quasi-static and moderately high loading rates. It addresses the effects of the loading rate on the strength of the adhesively bonded joints under dynamic tensile. A comparison has been achieved between the strength and the damage of specimens’ made of aluminium and lamina substrates. High rate tests showed ringing in the force/displacement curves.

Abstract: Using the Abaqus software, the goal of this work is the numerical study of the effects of the static loads on the mechanical behavior, the damage and the strength of the aluminum/aluminum and composite/composite assemblies, very much used in the naval field. For an elastic behavior of the adhesive, it is also a question of modeling the damage of the substrates in composite. This paper presents a numerical investigation on the behavior of structural adhesive bounding under quasi-static loading. It is shown the effects of the adhesive thickness, superposition length and staking lay up on the strength of the adhesively bonded joints under static tensile. A comparison between the use of aluminum and composite laminate substrates is presented and an attempt was made to find out the damage kinetic.

Abstract: This paper presents finite element analysis (FEA) of static and dynamic tests of thick filament wound glass/epoxy tubes. The first part involves the validation of elastic properties and identification of damage initiation and its development in dynamic tests. The results of FEA of the dynamic tests without damage appeared satisfactory. An impact model, including material property degradation, is used for damage prediction. The simulated damage is compared with that obtained experimentally. The sizes of projected and cumulated surfaces are of the same order of magnitude as in the experimental measurements.

Abstract: In this work the dynamic responses of bonded top hat stiffened panel have been studied by using finite element analysis model (Abaqus). A symmetrical 2D model was performed and used in the simulations. In the first part, dynamic behavior and impact speed effects at such composite structure have been studied. In the second part, other simulations were carried out by using cohesive elements proposed to predict the delamination might happen under such loading.

Abstract: The mechanical properties of E-glass/epoxy composite at high strain rates are important in evaluating this kind of composite under dynamic and impulsive loading. The in-plane and out-of-plane compressive properties at strain rates from 300 to 2500 s-1 were tested with split Hopkinson pressure bar. Samples were tested in the thickness as well as in-plane direction for seven fibre orientations: 0°, 20°, 30°, 45°, 60°, 70° and 90°. The kinetics of damage and the failure modes were identified using a high-speed photography, infrared camera, optical techniques and a scanning electron microscope. Results of the study were analyzed in terms of maximum stress, Strain at maximum stress, failure modes, damage history and fibres orientation effects. From the experimental data, the stress-strain curves, compressive stiffness, and compressive strain of the composite are rate-sensitive in in-plane and out-of-plane compressive directions. The failure and damage mechanisms are implicitly related to the rise in temperature during static and dynamic compression.