Kozakevych T. Methods of analysis and optimization of structural and residual stress states for steel plates subjected to heating by moving heat sources

The procedure of analysis and optimization of residual phase and stress states for thin low carbon and low alloy steel plates subjected to local high temperature heating by moving normally distributed heat sources and subsequent monotonic cooling is proposed. The methods, based on finite elements method and weighted residues method, for numerical solution of the constituent problems of initial complex problem of mechanics taking into account structural transformations (determination of temperature field, calculation of phase constituents contents, determination of residual stresses) are constructed. The procedure of parametric optimization the characteristics of moving distributed heat sources (with single or several centers of localization) was developed to increase the plasticity of the zone of thermal influence according to the criterion of minimum of maximal contents of martensite with reducing the level of residual stresses is constructed. The residual stresses and phase distributions in the plates considered are determined and analyzed with single (main) source and single and two additional sources for different (optimal including) centers of their localization and power parameters, as well with one source taking into account the chemical composition of steel and certain thermal and technological conditions of heating (alloying contents, general uniform heating; local additional heating defined by stationary temperature field; variable parameter of scattering characterizing the energy distribution in the source).