Nonsteady Plain-Strain Ideal Plastic Flow Considering Elastic Dead Zone
Ever since the ideal forming theory has been developed for process design purposes, application has been limited to sheet forming and, for bulk forming, to two-dimensional steady flow. Here, application for the nonsteady case was made under the plane-strain condition. In the ideal flow, material elements deform following the minimum plastic work path (or mostly proportional true strain path) so that the ideal plane-strain flow can be effectively described using the two-dimensional orthogonal convective coordinate system. Besides kinematics, schemes to optimize preform shapes for a prescribed final part shape and also to define the evolution of shapes and fhctionless boundary tractions were developed. For demonstration purposes, numerical calculations were made for an automotive part under forging.
KeywordsNonsteady ideal bulk forming Rigid perfect plasticity Method of characteristics Orthogonal convective coordinate system
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