Magnetostatics simulation by equivalent magnetic dipoles

Orientador: Luiz Otávio Saraiva FerreiraDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: Motivado pelo projeto de dispositivos magnetomecânicos, este trabalho consiste na modelagem e simulação macroscópicas de corpos constituídos de materiais magnéticos, em frequência nula, representados por arranjos de dipolos magnéticos elementares em interação mútua, baseando se no método das fontes equivalentes (ESM, Equivalent Source Methods). O objetivo de modelagem e simulação se divide basicamente: na determinação do campo magnético - inclusive com o traçado das linhas de indução magnética; na determinação da força magnética e na obtenção do torque magnético sobre os corpos. A solução da força magnética e do torque magnético garante o elo de interação do magnetismo com a mecânica, permitindo assim o estudo de dispositivos magnetomecânicos tais como acoplamentos e mancais magnéticos passivos. Os corpos contemplados no estudo são do tipo ímã permanente ferromagnético mole paramagnético ou diamagnético. Um simulador denominado DipMag foi implementado em MATLAB®. Casos de sistemas magnetostáticos foram reproduzidos para a validação do simulador. Foram considerados sistemas com modelos algébricos, um sistema com modelo fenomenológico, e sistemas com modelos numéricos, inclusive com o uso do software FEMM. Constam casos como a determinação da força e torque magnético entre ímãs paralelepipedais, atração entre ímã e corpos ferromagnético mole e paramagnéticos, e a repulsão entre ímã e corpo diamagnético. Em especial, na modelagem e simulação para comparação com o caso experimental, onde um ímã paralelepipedal foi utilizado, obteve-se a polarização magnética equivalente com o uso de um medidor de campo magnético (Gaussmeter ou Teslameter) juntamente com formulação analítica (modelo de Coulomb). Diante das comparações o simulador DipMag foi bem sucedido na determinação do campo magnético externamente aos corpos, na obtenção da força magnética e do torque magnético sobre os corpos. Tendo em vista a forma adotada de representação magnética dos corpos, com a discretização em dipolos magnéticos dispostos em esferas, espera-se que o simulador DipMag possa evoluir da simulação estática para a simulação dinâmica, inclusive com acoplamento a métodos de partículas (por exemplo o DEM, Discrete Element Method). Contudo, espera-se ainda que, no futuro, o desempenho do DipMag seja melhorado com o uso do FMM (Fast Multipole Method) e com o processamento paralelo em GPU'sAbstract: Aiming magnetomechanical devices projects, this master thesis approaches the modeling and macroscopic simulation of bodies composed by basic magnetic materials at null frequency, represented by arrays of elementary magnetic dipoles in mutual interaction, based on the equivalent sources method (ESM). The objectives are: determination of the magnetic field - including mapping of magnetic induction lines, and computation of force and magnetic torque on bodies. The solution of force and magnetic torque ensures the interaction bond between magnetism and mechanics, allowing the study of magnetomechanical devices such as passive magnetic bearings and couplings. The kinds of materials included in this study are: permanent magnets, soft ferromagnetic, paramagnetic or diamagnetic. A simulator called DipMag was implemented in MATLAB®. Cases of magnetostatic systems were reproduced to validate the simulator. Were considered: systems with algebraic models, phenomenological models and numerical models, including the use of the FEMM simulator. Were studied the determination of force and magnetic torque between parallelepipedal magnets, the attraction between a magnet and a soft ferromagnetic and a paramagnetic bodies, and repulsion between a magnet and a diamagnetic body. When in modeling and simulating for comparing our method to the experimental case where a parallelepipedal magnet was used, its equivalent magnetic polarization was calculated from measumerents using a magnetic field meter (Teslameter or Gaussmeter) together with analytical formulation (Coulombian model). Our DipMag simulator was successful on determining magnetic field outside the bodies, obtaining the magnetic force and torque on the magnetic bodies. The method used for representing the magnetic bodies by magnetic dipoles in spheres, opens a pathway for DipMag simulator evolution, from static simulation to dynamic simulation, including the coupling with particle methods like DEM (Discrete Element Method). And it is expected that the DipMag simulator performance can be improved by using FMM (Fast Multipole Method) with parallel processing on GPU's (Graphics Processing Unit)MestradoMecanica dos Sólidos e Projeto MecanicoMestre em Engenharia Mecânic

Design of an Optimally Stiff Axial Magnetic Coupling for Compliant Actuators

International audienceManoeuvrability is one of the essential keys in the development of improved autonomous underwater vehicles for challenging missions. In the last years, more researches were dedicated to the development of new hulls shapes and thrusters to assure more manoeuvrability. The present review explores various enabling technologies used to implement the vectorial thrusters (VT), based on water-jet or propellers. The proposals are analysed in terms of added degrees of freedom, mechanisms, number of necessary actuators, water-tightness, electromagnetomechanical complexity, feasibility, etc. The usage of magnetic coupling thrusters (conventional or reconfigurable) is analysed in details since they can assure the development of competitive full waterproof reconfigurable thrusters, which is a frictionless, flexible, safe, and low-maintenance solution. The current limitations (as for instance the use of non conductive hull) are discussed and ideas are proposed for the improvement of this new generation of underwater thrusters, as extending the magnetic coupling usage to obtain a fully contactless vector thrust transmission

Magnetic design and analysis of a radial reconfigurable magnetic coupling thruster for vectorial AUV propulsion

International audienc

Advances in Reconfigurable Vectorial Thrusters for Adaptive Underwater Robots

International audienceManoeuvrability is one of the essential keys in the development of improved autonomous underwater vehicles for challenging missions. In the last years, more researches were dedicated to the development of new hulls shapes and thrusters to assure more manoeuvrability. The present review explores various enabling technologies used to implement the vectorial thrusters (VT), based on water-jet or propellers. The proposals are analysed in terms of added degrees of freedom, mechanisms, number of necessary actuators, water-tightness, electromagnetomechanical complexity, feasibility, etc. The usage of magnetic coupling thrusters (conventional or reconfigurable) is analysed in details since they can assure the development of competitive full waterproof reconfigurable thrusters, which is a frictionless, flexible, safe, and low-maintenance solution. The current limitations (as for instance the use of non conductive hull) are discussed and ideas are proposed for the improvement of this new generation of underwater thrusters, as extending the magnetic coupling usage to obtain a fully contactless vector thrust transmission

Torque Analysis of a Flat Reconfigurable Magnetic Coupling Thruster for Marine Renewable Energy Systems Maintenance AUVs

International audienceThe concept of reconfigurable magnetic coupling thrusters (RMCT) applied to the vectorial thrust of autonomous underwater vehicles (AUV) has been recently developed and presented. This technology ensures greater robot watertightness with enhanced maneuvering capabilities, which are desired features in agile AUVs for marine renewable energy (MRE) system maintenance. It is possible since in RMCTs the driving torque is magnetically transmitted to the propeller, which has its orientation changed. This work is focused on the coupling and control torque calculation and further analysis of the latest prototype version (Flat-RMCT), in the static condition for the full thrust vector range. For this purpose, a numerical model is implemented and validated with experimental results. The numerical model is based on the finite volume integral method. The results indicate that the minimum magnetic reluctance propensity creates not only the expected magnetic spring effect but also an auto-driving torque due to the non-axial symmetry of coupling rotors, which exists only for reconfigurable couplings. Mathematical functions are proposed to model these effects and they are used to extend the understanding of the coupling. These models can be used to compose a full and accurate dynamic model for a better RMCT simulation, identification, and control

A Task-based Method for Underwater Drones Waterproof Thrusters Power Computation

International audienc