Estimated analytical expressions of thermomechanical parameters of molds and cores made of synthetic mixtures on account of anharmonicity

In the study of the behavior of brittle bodies, such as rods and molds from synthetic molding compounds, during changes of their linear and/or bulk sizes, two characteristics of materials are very important - the Poisson's ratio s and the Grüneisen parameter Gr. The first shows the tendency of the material to save its original volume during elastic deformation. The second parameter Gr is a measure of the anharmonicity of the forces acting between atoms (molecules) of a solid. In practice, the acoustic and the thermodynamic parameter are used. For synthetic mixtures plays an important role when the mold is filled with liquid metal and a large temperature gradient occurs on the border metal - mold (core), as well as shrink processes and changes in linear dimensions. The article presents assessment and analytical expressions for the evaluation and calculation of the safety factor of molds and cores made of synthetic mixtures, taking into account anharmonicity and using the Grüneisen parameter. The obtained dependences allow to predict the possibility of obtaining high-quality castings at the stage of making calculations and designing the technological process of their manufacture.