Pyrotechnics Correction Process Mathematical Model And Thermal Elastic-plastic Analysis

It is well known that weld distortion often occurs unavoidably in sectional hull building. One effective way that most shipyards prefer to use to correct distortion is flame correction. Up to now, this kind of process usually depends on the experience of skilled workers and, as a result, brings about such problems as low efficiency and high costs. On the other hand, the increasing competition over the last few years in the shipbuilding industry has forced shipyards to increase productivity and decrease costs. So the interest in shipbuilding automation, especially in the technology of correcting deformation by flame has increased enormously in recent years. In this paper, the following subjects are discussed:1 This paper introduces the principles and methods of technology of deformation correction by flame, and also sample pieces, parameters in the process, experimental purpose, etc.2 The paper sets up mathematical models which reflect the influence of two parameters such as heating time and length of heating line on this kind of technology; and proves that the models built can be used in practical production.3 The temperature field of the typical plate structure during the process of deformation correction by flame is analyzed, and the numerical analysis of the transient three-dimensional temperature field is completed.4 The factors that cause welding residual stresses are analyzed; and the residual stresses and deformation of typical plate structure are obtained.5 A general finite element program is used to simulate the three dimensional thermo-elastic-plastic process of the technology. By calculation, the results such as stresses, strains and displacements of the plate structure at any time during process of deformation correction are obtained.