is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. ABSTRACTBurnishing is a cold working surface treatment process in which plastic deformation of surface irregularities occurs by exerting pressure through a very hard and a very smooth roller or ball on a surface to generate a uniform and work-hardened surface. This treatment occurs generally after the machining process. In this study, a new combined machining/burnishing tool is designed and is fabricated. This tool allows for generating simultaneously the machining (turning) and the burnishing of the cylindrical surface using a turning machine. First, turned surfaces at different conditions, sketches, finishing and half finishing were performed using only the cutting tool. The evolutions of a surface roughness parameter and the technological time relative to every test condition have been investigated. Second, using the combined machining/burnishing tool at coarse conditions, the evolutions of the surface roughness and the technological time have been also investigated. A comparison among the parameters obtained under different machining conditions and those obtained using the combined machining/burnishing tool has been carried out. Moreover, the analyses of the layers obtained on the combined machined/burnished surface have shown that the burnishing process induces compressive residual stresses on the subsurface treated specimens.

Unsuitable surface quality is frequently observed in the machining of composites due to their heterogeneity and anisotropic properties. Thus, minimizing the machining damages requires a thorough understanding of the machining process. In this study, two different finite element models were developed using Abaqus/Explicit to simulate the cutting process of unidirectional carbon fiber-reinforced polymer: (i) a macromechanical model based on the homogenization approach and (ii) a micromechanical model in which the composite constituents were treated separately. The effects of CFRP mechanical properties, the energy of breaking and hourglass control were analyzed using a macromechanical model. The results revealed that CFRP properties and the numerical parameters highly influenced the cutting process. A comparative study was also performed between the macromechanical and the micromechanical models to study the mechanisms of chip formation. It was demonstrated that the material removal mechanisms for both models are in good agreement with the experimental observations for different fiber orientation angles.

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This study addresses the sensitivity of material removal regimes in 5083-Aluminum alloy to interactions mechanisms generated during Multi-Scratch Test (MST). A testing device using three conical indenters was firstly developed. Four attack angles and four normal loads ranging, respectively, in 10-60° and 10-25 N, were considered for conducting the experimental trials. The scratch velocity was kept constant to 210 mm min -1 and the maximum scratch distance to 25 mm. The model, developed upon ABAQUS/Explicit, uses JohnsonCook approach for describing both material behavior and damage evolution. Single Scratch Test (SST) and MST reveal same wear regimes, namely, (i) "ploughing", (ii) "transition", and (iii) "cutting" whereas a significant difference was observed in the material removal maps.While ploughing domain neatly decreases to the detriment of transition domain when passing from SST to MST, cutting domains still remain quite comparable. The indenter attack angle is depicted as the most dominant factor in apparent friction coefficient. The three dominating regimes were successfully predicted, using the FE model, in close correlation with tribological parameters. The model was found very useful to highlight the significant role of the separation distance on controlling material flow and damage within the grooves' junction.

Understanding the scratch behaviour of the composite materials is of primary importance. The scratch behaviour of glass fibre reinforced polyester composite was investigated. A new scratch device is designed and developed. Scratch tests at room temperature were carried out, using conical indenter and constant scratching velocity. The main aim of this study is to investigate the effects of tribological parameters on wear mechanisms and friction coefficient. Particularly, the effects of the normal load and the attack angle were presented. The different wear scenario of the composite material during the scratch test was deduced, then supported by an analysis of the glass fibre reinforced polyester composite wear modes using scanning electron microscopy (SEM) observations was performed. The correlation between tribological parameters and wear mechanisms was highlighted through the composite scratch map. Results were compared with those previously published associated with the metallic and the polymeric materials.