Introduction

*CONTROL_TIMESTEP
Billet Upset
LS-DYNA Manual Section: *CONTROL_TIMESTEP

Example: Billet Upset

Filename: control_timestep.billet-forge.k

Description:
A rod of steel is forged between two dies. The billet upset problem is a
measure of friction under forming conditions.

Model:
The billet material is isotropic elastic-plastic, and the model has
1 * 8 symmetry. The billet measures 2.25 inches in height and 1.26 inches in
radius. The die compresses the billet 1.60 inches. The relationship between
the shear friction and the normal pressure is bilinear.

Input:
The mass scaling time step size is set to 12 microseconds (*CONTRO L_TIMESTEP).
The billet nodes contact the die surfaces (*CONTACT_NODES_TO_SURFACE).
The Coulomb frictional constant is 0.10 and the constant shear is 2,055 psi.
A half sine wave defines the velocity of the die (*BOUNDARY_PRESCRIBED_MOTION).

Results:
The results show that effective plastic strains with and without time-step
control are the same. CPU savings is approximately 33% on the cray J90 using
1 cpu..

Reference:
Avitzur, B., Lee, C. H. and Altan, T.