Validation Case: Hot Upsetting (Shear Friction)
This benchmark is intended to validate hot open-die upsetting under the metal-forming shear-friction law, with emphasis on sticking-limit behavior, barreling sensitivity, and the load response under large plastic deformation.
What this benchmark checks
- Shear-friction formulation with
τ = m k - Friction-limited interface shear stress in bulk metal forming
- Barreling evolution under hot-forming contact conditions
- Load response and strain distribution with strong die interaction
Why this is a separate benchmark
This case is intentionally separated from the Coulomb upsetting benchmark because it validates a different physical law. The target here is not pressure-dependent contact traction of the form τ = μ p, but the bulk-forming shear-friction model τ = m k commonly used in FORGE, DEFORM, QForm, and Simufact workflows.
Keeping both upsetting cases on different pages avoids the impression that they are the same benchmark with only a parameter change. They are distinct validation targets with different constitutive assumptions at the die-workpiece interface.
Reference work
This benchmark is referenced to Ebrahimi, R., and Najafizadeh, A., A New Method for Evaluation of Friction in Bulk Metal Forming, Journal of Materials Processing Technology, 152(2), 136-143, 2004.
Suggested validation outputs
Useful comparison material for this page includes load-stroke curves, final barreling profiles, equivalent strain contours, and the calibrated shear-friction factor used to match the reference case.
Benchmark Data
This table is generated from benchmark CSV data using csv_html.py.
| m | Rt_weldform | Rt_paper | relative_error | relative_error_percent |
|---|---|---|---|---|
| 0.18 | 3.230000 | 3.250000 | 0.006154 | 0.615% |
| 0.24 | 3.160000 | 3.120000 | 0.012821 | 1.282% |
| 0.58 | 3.090000 | 2.900000 | 0.065517 | 6.552% |