| Currently aluminium alloy materials have been broadly applied in ship manufacturing, due to its lower density, higher strength, excellent corrosion resistance and welding performance. Also aluminium alloy plates have more obvious advantages than traditional ship steel plates. Aiming at the processing of complex curved hull aluminium alloy plate, a new technology, called electromagnetic force assisted line heating (EFALH) for aluminium alloy plate, has been proposed in this thesis. This process utilizes electromagnetic force to promote deformation of aluminium alloy plates during line heating process, which can improve efficiency of deformation and obtain expected deformation when the processing temperature is within the required range. This thesis is concerned with its several pivotal techniques.Firstly, according to the fundamental principle of EFALH, the electromagnetic force assisted line heating device has been developed. Basic working principle of the circuit device and its charge-discharge principle have been analyzed in detail. In addition, the process methods of line heating and EFALH for aluminium plates have been introduced, and both experiments have been conducted, proving the auxiliary effect of electromagnetic force.Secondly, with regard to the process of EFALH, the three-dimensional finite element model has been established by the ANSYS FEM software, and the multi-physics sequential coupling method has been adopted in the numerical simulation, for the 5083 aluminium alloy plate. There is a good agreement between experimental data and simulated results of circuit-electromagnetic coupling, electromagnetic-structural coupling, line heating process and EFALH process for aluminium plates, proving the reliability of the finite element model.Thirdly, on the basis of numerical simulation, the influence rules of main technological parameters of EFALH for aluminium alloy plates on the auxiliary effect of electromagnetic force have been investigated. The parameters include pulse current parameters, thickness of aluminium plates, the gap between the coil and plate, and the temperature field distribution.Lastly, perspective from the cyclicity of pulse electromagnetic force and the cyclic loading and unloading of stress, the forming principle of EFALH has been analyzed. |
