To Calculate the Expansion Mode in Viscoplastic Deformation

Abstract

The article proposes relationships for calculating the technological modes of expansion with heating. The heated deformable material is assumed to be anisotropic, and viscoplastic. During the expansion process, stress relaxation occurs, which is greater the lower the rate of formation. This allows you to increase the degree of expansion and reduce the force of the operation. The kinematics of the process is considered in terms of the velocity of displacements, deformations and the strain rate. The relationships for calculating the expansion force mode are obtained on the basis of the upper-limit plasticity theorem by balancing the powers of external and internal forces. In a plane stress state, the system is reduced from the equilibrium equation and the linear yield condition of an anisotropic material to dependencies for calculating the meridional and circumferential stresses in the deformable region of the workpiece. The Laplace stress equation is used to calculate the effect of the workpiece friction on the mandrel cone. The bending of the blank wall during expansion is taken into account. The relationships obtained on the basis of the equations of fracture kinetics for calculating the damage of the workpiece material are given. It is established that the damageability of some materials decreases with a decrease in the expansion speed, and the damageability of other materials does not depend on the speed, but is determined only by the degree of shape change. Calculated results for high-strength aluminum and titanium alloys and product samples are presented

Please cite this article in English as:

Chernyaev A.V., Platonov V.I. To calculate the expansion mode in viscoplastic deformation. Herald of the Bauman Moscow State Technical University, Series Mechanical Engineering, 2026, no. 1 (156), pp. 74--85 (in Russ.). EDN: BZVTDB

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