Optimization modeling of crack resistance of ceramic shell mold during cooling of steel casting in it

The article provides a detailed analysis of domestic and foreign research works on the stress-strain state in a shell mold during production of metal castings. Experimental and theoretical studies are important for improving the technology of producing high-quality foundry products. In this paper, the problem of reducing the stress-strain state in a cast ceramic shell mold is formulated and solved by reducing the resulting tensile stresses on its outer surface by performing temperature seams (recesses). The parameter determining crack resistance is the normal tensile stress σ 22 , which occurs on the outer surface of the shell mold at the initial moment of casting the metal and cooling the steel casting in it. The problem under conside­ration is axisymmetric. The shell mold has spherical and cylindrical sections. The authors formulated the objective function, provided a numerical scheme and a developed algorithm for solving the problem based on the equations of linear elasticity theory, equations of thermal conductivity and proven numerical methods. The result of solving the model problem is the optimal geometric location of the temperature seams in the form of annular recesses and their number. Stress fields are shown in the form of plots along the sections of the area under consideration in the presence and absence of temperature seams. For the sake of convincing the proposed method (performing temperature seams), the test example considers the most rigid option, which does not use the factors established earlier in previous studies that affect the reduction of tensile stresses on external surface of the shell mold. The results obtained characterize the resistance of ceramic casting mold to cracking and demonstrate the feasibility and effectiveness of the proposed technology for manufacturing ceramic casting shell molds.