In the present work a modified phenomenological model of the shape memory alloy (SMA) constitutive law is proposed that is capable of reproducing some aspects of SMA thermomechanical behavior like superelasticity and the one-way shape memory effect. The modified law uses strain and temperature as control variables, which eliminates the need for transformation correctors in finite element analysis. It is implemented in a structural model developed to analyze three-dimensional (3D) structures made out of thick beam elements with features such as taper and curvature, given that SMA products typically fall in this category of shapes. Moreover, a finite strain and large displacement description is adopted to account for the large deformations exhibited during phase transformation. Results, produced by the proposed model, of simulated tensile, three-point and four-point bending tests are presented and compared with experimental data taken from the literature.

In this paper, a new 1D constitutive model for shape memory alloy using strain and temperature as control variables is presented. The new formulation is restricted to the 1D stress case and takes into account the martensite reorientation and the asymmetry of the SMA behavior in tension and compression. Numerical implementation of the new model in a finite element code was conducted. The numerical results for superelastic behavior in tension and compression tests are presented and were compared to experimental data taken from the literature. Other numerical tests are presented, showing the model’s ability to reproduce the main aspects of SMA behavior such as the shape memory effect and the martensite reorientation under cyclic loading. Finally, to demonstrate the utility of the new constitutive model, a dynamic test of a bi-clamped SMA bending beam under forced oscillation is described.

Nowadays, industrialists, especially those in the automobile and aeronautical transport fields, seek to lighten the weight of different product components by developing new materials lighter than those usually used or by replacing some massive parts with thin-walled hollow parts. This lightening operation is carried out in order to reduce the energy consumption of the manufactured products while guaranteeing optimal mechanical properties of the components and increasing quality and productivity. To achieve these objectives, some research centers have focused their work on the development and characterization of new light materials and some other centers have focused their work on the analysis and understanding of the encountered problems during the machining operation of thin-walled parts. Indeed, various studies have shown that the machining process of thin-walled parts differs from that of rigid parts. This difference comes from the dynamic behavior of the thin-walled parts which is different from that of the massive parts. Therefore, the purpose of this paper is to first highlight some of these problems through the measurement and analysis of the cutting forces and vibrations of tubular parts with different thicknesses in AU4G1T351 aluminum alloy during the turning process. The experimental results highlight that the dynamic behavior of turning process is governed by large radial deformations of the thin-walled workpieces and the influence of this behavior on the variations of the chip thickness and cutting forces is assumed to be preponderant. The second objective is to provide manufacturers with a practical solution to the encountered vibration problems by improving the structural damping of thin-walled parts by additional damping. It is found that the additional structural damping increases the stability of the cutting process and reduces considerably the vibrations amplitudes.

This study is carried out in partnership with the company CAVEO, manufacturer of leaf springs for vehicles. It concerns the development of a numerical model intended to follow the space-time temperature evolution of a leaf during two processing operations: hot cambering and quenching. This leaf is of a parabolic profile, made of EN-51CrV4 steel (AISI-6150). After austenitization, it passes through a cambering operation to confer it the desired deflection and then a quenching operation. This quenching is carried out in an oil bath to achieve better mechanical properties. The prediction of the temperature during quenching involves determining the heat transfer coefficient between the leaf and the oil bath. This coefficient is determined by quenching, under the same conditions as the leaf, using a standard probe of the same steel. The numerical model is based on the resolution of the transient heat equation by considering the heat loss flows towards the heterogeneous environment (ambient air, press contact and quenching oil). The results obtained by this model give the space-time temperature evolution of the leaf from the exit of the heating furnace to the exit of the oil bath. The numerical results are compared to the experimental profiles obtained through thermographic images throughout cambering and quenching operations. These results are consistent with experimental results.

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The drilling operation is considered by manufacturers as complex and difficult process (rapid wear of the cutting edge as well as problems of chip evacuation). Faced with these failures, manufacturers have shifted in recent years towards the drilling process assisted by forced vibrations. This method consist to add an axial oscillation with a low frequency to the classical feed movement of the drill so as to ensure good fragmentation and better chip evacuation. This paper presents a model for prediction of cutting forces during a drilling operation assisted by forced low-frequency vibration. The model allows understanding the interaction between the tool and the workpiece and identifying numerically the three-dimensional evolution of the cutting force components generated by the vibratory drilling operation. The effects of cutting parameters, tool parameters and those of forced vibrations on the cutting forces distributions will be discussed.

The finite element modeling allows manufacturers to reduce the cost of machining operations. During a drilling operation, the chips morphology their sizes and thicknesses have a great effect on the process, whatever the material to be machined. One approach to a 3D simulation of a drilling process with the finite element program Abaqus/Explicit is displayed. We studied the morphology of chips during the drilling process, the influence of cutting parameters on their shape, size and clear velocity. This study allows us to optimize the conditions and cutting parameters for a smooth process.