Civil Engineering Reference
In-Depth Information
FIGURE 4.16
Simulation of the development of flaws due to the instability of billet.
billet, which was injected with an aspect ratio of 2.5, would invariably deform asymmetrically. Asymmetry
was observed for T
1.85; this initial asymmetry does not make the billet unstable. The asymmetry
would, however, result in the forming of a component which would not display symmetry in the flow
patterns. By comparison with the simulation for T
1.85, that for T
1.64 shows sufficient symmetry.
Simulation results for T
1.64 and coefficient of friction of 0.03, 0.02, and 0.01 are shown in
Fig. 4.16(b-
0.03, the billet deforms symmetrically and continues to achieve die-filling. The
stability of the billet is seriously affected when the coefficient of friction is reduced by a marginal
amount. Under a friction condition of
0.02 the base of the billet would slide laterally while retaining
contact over its entire diameter. This would promote the development of a fold at the lower extremities
