The Experimental Analysis And Numerical Simulation Of Ship Hull Plate Forming By Resistance Heating

In the shipbuilding industry, line heating forming has been the most important process of hyperbolic hull plate forming, and the most important characteristic is dieless forming. After local heating, the steel plate produce the residual plastic deformation and reach bent into shape because of the characteristic of thermal expansion and contraction. At present, the heat source of line heating forming generally was oxygen acetylene flame. The flame heating has some advantages such as simple equipment, small size, flexible operation and so on, but there are many defects of the flame heat source, such as large pollutant and bad working environment. So induction heating and laser heating methods are put forward. But the two kinds of heat sources have their inherent shortcomings, not suitable for the application of the shipyard.In order to solve problems of the flame heating process, a new heating method was proposed. Resistance heating uses the electrical signal, which can achieve the precise control of energy input, especially without pollution in the forming process, and it also has the flexibility of line heating. This is what the traditional line heating can’t achieve, resistance heating for thick plate forming will be a major innovation of the line heating technology.Resistance heating forming is a complex nonlinear process, electrical thermal structural direct coupling finite element model was established by using the FEA software ABAQUS. And on the heating resistance forming process parameters were analyzed. By numerical simulation, it compared the resistance heating with flame heating of the temperature field characteristics and deformation; analysed influence of the key parameters on the temperature field distribution, such as electrode size and shape, plate thickness and heating rate; it analysed the relationship between temperature field parameters and angular distortion, and analysed the distribution and formation of stress and strain. Finally the resistance heating forming process was experimented and verified.The results of the study show that:(1) the resistance heating temperature field distribution is more conducive to the deformation than flame heating, the energy utilization rate was higher, nominal width increased 47.2%, angular distortion relative increased 37.5% under the same heat affected zone;(2) through the analysis of the simulation results of the resistance heating, the relationship among the temperature field parameters and the electrode size, the plate thickness, heating rate ware obtained.(3) Invspoly function can be used as a function to describe the temperature field of electric resistance heating.(4) When the nominal depth is small, angular distortion was determined by nominal width and heating area, smaller isotherm slope is more conducive to the angular deformation; under the same nominal width, angular distortion increased first and then decreased with the increase of nominal depth, when nominal depth is equal to one of three in thickness, the angular distortion was maximum.(5) the experimental results was close to the simulation, and the error is 5.3%, which shows that the accuracy of numerical simulation is better. and can be used as a reference. The experiment proves that the resistance heating is feasible to replace the traditional flame heating.