Применение обратного анализа для определения реологических констант материалов по результатам тестовых формовок круглых мембран

Abstract

The paper is devoted to a problem of determining rheological characteristics of materials from the results of experiments on free forming of sheet blanks to a cylindrical matrix. This information on the material behavior is used in the design of gas forming processes for the production of parts for aerospace industry. Realization of such technologies requires to follow optimum technological regimes, in computer simulations of which one should adequately describe the properties of materials under consideration. A significant disadvantage of the classical experimental method of tensile testing of plate specimens is that an information taken from these tests is related to metal forming in the conditions of uniaxial tension that is not typical for gas forming processes. Experimental method of forming circular membranes considered here allows one to study the behavior of a material in the conditions of biaxial tension. Interpretation of the results is proposed to carry out by an inverse analysis utilizing a special semianalytical model for the solution of the direct task. The key role in this semianalytical model belongs to a dependence of the blank thickness at the dome pole on the dome height, which accounts for the strain rate sensitivity coefficient. This approach was applied for the processing of experimental results obtained by free forming of industrial aluminum alloys. The material characteristics obtained were compared to charecteristics determined by other methods for the same set of experimental data available in the literature. To estimate the efficiency of the method proposed, the characteristics obtained were verified by finite element simulations. For simulations, MSC Nastran software was used. The results of the simulations were found to be in good agreement with the experimental data not only with respect to the dome height but also to the blank thickness at the dome.