Nicolas Buiron

A multiscale model of magnetostriction strain and stress effect

Abstract The aim of this paper is to predict the reversible evolution of macroscopic magnetostriction strains and magnetisation in textured non-oriented soft ferromagnetic materials. The model takes account of both the domain wall displacements and the magnetisation rotations. The anisotropic macroscopic behaviour is derived from a statistical description of the magnetic domain structure by homogenisation techniques.

Magnetic Pulse Welding: An Innovative Joining Technology for Similar and Dissimilar Metal Pairs

Once it was widely thought to be an exceptional innovative welding solution, the magnetic pulse welding, dragged the related manufacturing industries and particular‐ ly automobile companies for its complex assembly solutions in early 2000s. Although this technique has been implemented by some giant manufacturers for various joining tasks, the process still has not been well adopted by industries. However, in recent years, many researchers turned their attention to the potential applications and insight investigations of this process due to the existence of bottlenecks and the prime novelty of this technique. This chapter clearly highlights the process, applications, require‐ ments, interfacial kinematics of the welding, numerical predictions of interfacial behaviours and multi-physics simulations. This chapter recommends that the overall outlook of the process is promising while it requires extra attention in the individual welding cases and its material combinations.

Thermal Effect during Electromagnetic Pulse Welding Process

Magnetic pulse welding (MPW) is a solid state joining process, successfully utilized to join dissimilar metals. This advantage attracted manufacturing industries to fabricate hybrid materials to attain materials with a combination of multiple attributes. The high speed impact during the welding process causes various interfacial phenomena, which have been reported in previous research studies. Combined high speed collision, Joule heating due to eddy current and plastic heat dissipation cause noticeable heating in the workpiece. The heating from the plastic work and collision energy could particularly be significant at the vicinity of the interface compared to other regions of the workpiece. The Joule heating due to eddy current affects the entire workpiece that is prominent before the collision. There is a sharp increase of the temperature at the onset of weld formation due to dissipation of plastic work during the collision. 3D simulations of coupled electromagnetic-mechanical-thermal were carried out to investigate the heating due to the combined Joule heating and plastic dissipation. A case study of MPW, consist of a one turn coil combined with a field shaper, is used to investigate the welding process. The simulations were performed using LS-DYNA®, which has the capability of using both finite and boundary elements to solve the thermo-mechanical problem during electromagnetic forming. The predicted temperature distributions from numerical simulations show expected phenomena of Joule heating and plastic heat dissipation while the analytical approach used to estimate the localized increase in temperature due to supersonic gaseous compression. Minimizing the heating effect by identifying the influencing factors could help to optimize and control the quality of the magnetic pulse welded parts.

Macroscopic model of magnetostriction based on energy minimization

This paper introduces a model of magnetostriction based on minimization of total energy. An identification of each term from measurements of the magnetization and magnetostriction is presented, assumptions supporting the model are mentioned. To validate the proposed model, a comparison between experiments - on FeSi single sheet - and the calculation method including the model is described in detail. Finally, the model is integrated in a finite elements simulation, the results from the computations are verified with measurements on an in-house test bench.