Advanced Materials Research Vol. 698

Abstract: This paper presents the interest of an original absorber of vibration in order to reduce chatter vibration in turning process. The device is composed of a linear oscillator corresponding to a flexible cutting tool subject to chatter strongly coupled to a Nonlinear Energy Sink (NES), with purely cubic stiffness. The novelty of this work is the use of a nonlinear cutting law, more accurate for modeling the cutting process. The delayed equations of motion are analyzed using a combination of the method of multiple scales and harmonic balance. Different types of responses regimes are revealed such as periodic response and also Strongly Modulated Response (SMR). Analytic results are then compared with numerical simulations. Finally, the potential of the NES is demonstrated to control chatter in turning process.

Abstract: The present paper highlights the importance of size effect consideration during the modelling of material removal by cutting tool, especially when passing from maco-to-micro scales. For that, the presented study concerns an orthogonal case of down-cut milling where the chip thickness is evolving. Consequently, to capture the scale effect when passing from macro to micro dimensions, the theory of gradient plasticity were adopted.

Abstract: Assembling composite structures requires a significant number of drillings. During machining, defects appear on the surface of the drilled hole. This paper outlines that the criterion Ra is not adapted to reliably characterize the surface quality on composites. In particular, various tests have shown significant variations of the value of Ra according to the angular position of measurement, as well as the filtering artefacts. This study puts forward a new methodology to characterize the surface quality of a composite hole. To this end, a study of sensitivity of the various criteria proposed by standard ISO4287 was conducted. Various geometries of tool are also tested in the experimental phase. The impact of cutting parameters and tool wear are analyzed based on this new methodology.

Abstract: Developments in additive manufacturing add possibilities to produce three-dimensional industrial parts. Nowadays, customized parts can be obtained in short period directly from digital data. One of major recent evolutions of additive manufacturing is the ability to produce functionally graded material (FGM) parts. These materials can be characterized by the variation in composition and structure gradually over the volume. The use of these materials is particularly attractive in fields such as aeronautical or biomedical where the multimaterial parts allow to modify locally mechanical, chemical, physical or biochemical properties. To move from the design to the fabrication of FGM parts, the necessary steps include representation of the part and determination of a manufacturing strategy to control the process.

Abstract: The present article addresses the influence of milling on the surface integrity of Ti-6Al-4V. Observation of the machined surface from a macroscopic perspective (naked eye) has highlighted an orange peel phenomenon. Under the machined surface no plastically deformed layer or lengthening of the grains were observed. As far as microhardness is concerned, a slightly softened zone was noted under the machined surface. Diffusion of vanadium from phase β to phase α also occurred but without resulting change to the microstructure. Measurement of microhardness and residual stresses showed that the finishing pass predominated over the roughing pass in terms of its influence on surface integrity. The response surface methodology was used in order to highlight those parameters influencing surface integrity. Its application and processing showed that the most influential factor is the nose radius for roughness and the cutting speed for residual stresses.