Influence of internal factor on crack resistance of shell mold by investment models

Evstigneev

et al. 2022

KEM

A mathematical approach to studying the process of establishing the effect of degree of significance of multilayer shell mold material physical properties and macrostructure on the mold stress-strain state is proposed. It is not possible to solve this problem analytically; therefore, a numerical approach was applied, namely, a proven numerical method and a set of author-developed programs. Knowledge of how the basic physical properties of the shell mold materials and shell mold macrostructure affect the shell resistance to cracking allows, even at the design stage of the pilot shell mold structures, virtual modeling of the thermal and deformation processes occurring therein, i.e. prediction the operability of the designed shell mold. Based on the results of modeling the processes of predicting possible shell mold destruction conditions, the most important parameters and factors of crack formation are established and approach to study of new shell mold fabrication processes is defined.

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling of Optimization Process for Shell Mold Material Physical Properties and Structure

Evstigneev

et al. 2022

KEM

Morphological structure of shell mould in investment casting

Evstigneev

Izv. vysš. učebn. zaved., Čern. metall.

et al. 2022

The stress state (SS) of multilayer shell mould (SM) is significantly influenced by its morphological structure, its variants, and the connections between the contacting layers. The purpose of this work is to establish the effect of sliding without friction of one of the layers of SS relative to the neighboring contacting layer on SS of the multilayer SM. The process of determining the stress-strain state (SSS) in the SM is modeled when it is filled with steel, in which there is a surface between the layers, where one layer of the SM is completely sliding relative to the adjacent neighboring layer. The task is to find the geometric location of a given surface by thickness of SM from the condition of the formulated objective function with the corresponding system of constraints. The construction of the mathematical model is based on equations of the linear theory of elasticity, the equations of thermal conductivity, solution of which is carried out by a proven numerical method. In the axisymmetric formulation, a complex three-component system is considered: liquid metal, solid metal, ceramic SM. Solid metal and SM are considered to be isotropic. Crack resistance of the SM is estimated by the stresses arising in it. On contact with the support filler (SF), it is possible to move the SM surface from the SF during the liquid metal cooling. In this case, the contact problem is solved – reassignment of the boundary conditions. An algorithm for solving the problem is compiled. The results of numerical modeling are displayed graphically in the form of plots. A detailed analysis of the obtained results was carried out. The inconsistency of manufacturing such a multilayer mould is shown. The results of the research can be useful in calculations of other functional multilayer shell systems.

Influence of support filler and structure of shell mold on its crack resistance

Izv. vysš. učebn. zaved., Čern. metall.

Chernyshova

et al. 2022

Recently, researchers have been paying more and more attention to the influence of internal and external factors on stress state of shell mold (SM). Internal factors should include morphological structure of SM, its types and connections between the contacting layers. External factors should include all types of force and temperature effects on SM external surface. The purpose of this work was to establish the sliding effect of SM internal layers in contact with each other on the level of SM stress state. The mathematical model for determining the stress-strain state (SSS) in the multilayer SM when it is filled with a liquid metal is presented. Moreover, the SM is made in such a way that its layers can slide relative to each other with the presence of friction. This work is a continuation of the recent works of the authors, where the influence of the temperature factor on the studied SM was estimated. At the same time, SM layers have the same physical and mechanical properties. The problem was solved in the same formulation as in the previous works of the authors. The task was set to determine the influence of the support filler (SF) and the clamp in the upper part of SM on SSS in its sections. The influence of SF was estimated by the amount of friction between the outer surfaces of SM and SF. Just as in the previous works of the authors, the linear theory of elasticity, heat conduction equations, and numerical methods were used to solve the problem. On the contact of SM outer surface with SF surface, the contact problem was solved. Solid phase in the liquid metal during cooling was determined from the equation of interphase transition. Results of the calculations are presented in the form of graphs and plots. It is shown that the absence of friction between the layers reduces the crack resistance of SM multilayer.