Development of Finite Slab Method for Calculation of Working Load and Pressure.

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A finite slab method FSM is proposed as a simple technique for calculation of stress distribution and deformation in cold forging. The material to be forged is divided into various deformation regions, called units, as in the upper bound technique. Additionally, each unit is cut into n finite slabs. The stress boundary condition at the interface of units is given by the mean stress in the direction normal to the interface. The stress components are calculated by the use of the conditions of volume constancy and approximate relations such as the Levy-Mises flow rule and the Mises yield criterion. The method is modified into a method of analysis for 3-dimensional forging problems. The programming of basic equations are arranged to a general-purpose soft for the analysis of cold forging. The soft is possible to use for the problems of axial symmetry, near axi-symmetric 3-dimension and system of Cartesian coordinates.The method is applied to some closed die forging, for example, square prism from a cylindrical billet, gear forging, backward extrusion of square cup, etc. The results of calculation on mean pressure are in comparative agreement of experimental results and those of another analytical techniques, such as slab method and upper bound method.