Ali Zghal

Correlation between welding and hardening parameters of friction stir welded joints of 2017 aluminum alloy

Abstract An experimental study was undertaken to express the hardening Swift law according to friction stir welding (FSW) aluminum alloy 2017. Tensile tests of welded joints were run in accordance with face centered composite design. Two types of identified models based on least square method and response surface method were used to assess the contribution of FSW independent factors on the hardening parameters. These models were introduced into finite-element code “Abaqus” to simulate tensile tests of welded joints. The relative average deviation criterion, between the experimental data and the numerical simulations of tension-elongation of tensile tests, shows good agreement between the experimental results and the predicted hardening models. These results can be used to perform multi-criteria optimization for carrying out specific welds or conducting numerical simulation of plastic deformation of forming process of FSW parts such as hydroforming, bending and forging.

Effect of Cooling on Mechanical Properties and Residual Stresses in Aluminium AA2017 Friction Stir Welds

Friction stir welding (FSW) is a relatively new joining technique particularly for aluminium alloys that are difficult to fusion weld. The most common applications are aircraft structures where the cost and weight can be reduced by using new joining techniques instead of riveting.The paper has investigated the effect of cooling on the distribution of residual stresses in friction stir welding of AA2017 aluminium alloy. An attempt has been made to examines the possibility to modify the residual stress state in the joint by applying cooling fluid during FSW processes. The results show that the magnitude of the tensile stress can be reduced significantly in the weld region and we can produce compressive stresses which can be beneficial e.g. for reducing crack propagation speed.

Compensation of a ball end tool trajectory in complex surface milling

This work is consecrated to the minimising of machining errors based on a method for the compensation of the trajectory to be machined in hemispherical milling. This compensation is found to be necessary because of the tool deflection due to the cutting forces. In order to remedy to the machining errors, caused by this deflection, a compensation method has been proposed. The latter is inspired from the mirror method, since the compensated position is going to be determined as being the trajectory reflection, deviated onto the mirror. The advantage of this proposed method is that it takes into account the three deflections dx, dyand dz, respectively to the directions X, Y and Z. After that, two-parallel machinings, separated by a groove and achieved absolutely in the same conditions and with the same tool, are carried out, on the same complex part. The first machining is with compensation, but the second is without compensation. The coordinates of the two obtained surfaces are recorded by a 3D measuring machine. The comparison of the two-surfaces shows the presence of an important correction of the tool trajectory, and reveals a similarity between the part obtained by simulation and the one conceived in CAM.

COST EVALUATION FOR WELDING PROCESS BY USING PREPARING FEATURES

Abstract This paper presents an approach for costing of weld preparation. The approach introduces the concept of preparing feature for the preparation of the welding joint edges. A generation of manufacturing process method is detailed. This method use production rules and respects the geometrical and technological parameters. A cost function uses an analytical method elaborated to formulate the time for weld preparation according to the different parameters of preparing feature. The estimating is based upon an evaluation of machine implementation, labour and consumable costs. At last, and to show the developed method interested and the efficiency of the model, we have treated an example of stiffened plate.