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Tunis, Tunisia

Ammar A.A.,Unit of Mechanics | Jallouli M.,Research Unit Intelligent Control | Bouaziz Z.,Unit of Mechanics
International Journal of Automation and Control | Year: 2011

The cutting forces produced during the machining of metals exert a direct influence upon the machining stability, the tool wear and the quality of the machined surface. In this paper, a dynamometer of the cutting forces measurement in milling has been designed and constructed. The latter is based on the utilisation of two extended octagonal rings upon which are stuck strain gauges able to measure the forces in three directions. The signals of the forces have been captured and treated by means a data acquisition system which has also been conceived. The dynamometer has been submitted to a series of tests in order to determine its static and dynamic characteristics. The calibration of this dynamometer has been verified by the finite element method while using the simulation software COSMOS/M. The obtained results have proved that the dynamometer could be used reliably to measure the static and dynamic forces. Copyright © 2011 Inderscience Enterprises Ltd. Source


Ghorbel A.,Unit of Mechanics | Ghorbel A.,Arts et Metiers ParisTech | Saintier N.,Arts et Metiers ParisTech | Dhiab A.,Unit of Mechanics
Procedia Engineering | Year: 2011

Mechanical properties of polymers are very sensitive to environmental conditions in particular temperature. In the case of mechanical testing, thermomechanical coupling induce heat sources to be activated during the deformation and damage processes so that the temperature of the specimen may vary during testing. Depending on the characteristic temporal and spacial scales of the deformation and damage processes involved by the loading this temperature increase might be uniform or highly localized. The aim of the study is to investigate the temperature field evolution of glass fibers reinforced polyamide 6,6 with 0% (PA66GF00), 10% (PA66GF10), 20% (PA66GF20) and 30% (PA66GF30) glass fiber. In addition to infrared thermography, digital image correlation (DIC) was used to quantify deformation localization zones and correlate them to identified heat dissipation sources. Until necking, the heat distribution was found to be nearly homogeneous on PA66GF00 with a well marked thermoelastic region, succeeded by an homogeneous heat increase due to viscoplastic dissipation. Necking is associated to strong heat increase that is localized on the the necking area. The thermal response of short fiber reinforced materials was found to differ markedly from the uncharged one. Strong heterogeneity of the thermal was observed and was associated to localisation processes at different scales (investigated by DIC). The effect of the applied strain rate on the observed thermal heterogenities was investigated. In addition to DIC, the volume damage evolution was monitored using X-ray computed microtomography in particular region. © 2011 Published by Elsevier Ltd. Source


Smaoui M.,Unit of Mechanics | Bouaziz Z.,Unit of Mechanics | Zghal A.,Unit of Mechanics | Baili M.,National Engineering School of Tarbes | Dessein G.,National Engineering School of Tarbes
International Journal of Machining and Machinability of Materials | Year: 2012

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 d x, d y and d z, 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. © 2012 Inderscience Enterprises Ltd. Source

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