Cold and Hot Forging: Fundamentals and Applications
Chapter 5: Plastic Deformation: Complex State of Stress and Flow Rules
This chapter covers the fundamentals of metal flow and the tools and techniques used to predict and control it. It begins by illustrating the local state of stress in a metal cylinder during upset forging and showing how stress components can be expressed in matrix form. It then explains how to determine the onset of yielding, which corresponds to the start of plastic deformation and the flow of metal within the workpiece. The chapter then goes on to present two important yield criteria, one based on shear stress (Tresca criterion), the other on distortion energy (von Mises criterion). It compares and contrasts the two methods and demonstrates their use as flow rules. It also explains how to calculate effective strain and strain rate and includes a brief discussion on the mechanical energy consumed during deformation.
Gracious Ngaile, Plastic Deformation: Complex State of Stress and Flow Rules, Cold and Hot Forging: Fundamentals and Applications, Edited By Taylan Altan, Gracious Ngaile, Gangshu Shen, ASM International, 2005, p 51–57, https://doi.org/10.31399/asm.tb.chffa.t51040051
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