This document discusses hot stamping process simulation using integrated structural and CFD analyses. It presents an approach using Altair's solvers RADIOSS and AcuSolve to efficiently model all physical phenomena in the hot stamping process. RADIOSS is used for structural analysis and AcuSolve for fluid flow analysis. The analyses are coupled indirectly to predict blank temperature, tool temperature during quenching, and final part properties like martensite volume fraction. This approach provides a more accurate simulation of the hot stamping process than traditional methods with assumed tool temperatures.

1. Innovation Intelligence®
Hot Stamping Process Simulation Using
Integrated Structural and CFD Analyses
Hariharasudhan Palaniswamy, Subir Roy
May 7, 2015

2. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Agenda
• Hot Stamping - Press Hardening process
• HyperForm
• HyperWorks™ Approach
• RADIOSS – Hot Stamping simulation
• Hot stamping simulation – Indirect Coupling
• Hot stamping – Simulation strategy
• Summary

3. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Hot Stamping Process
• Stamping process with integrated Heat
treatment (Tempering)
• Heating the blank above 900oC
• Quick Forming
• Rapid cooling in tools
• Hot stamped parts  Higher strength 
significant contribution for weight reduction
• Part Metallurgy
• Part Properties
Altan et al 2002
Garcia et al 2002
Altan et al 2002

4. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Hot stamping Process
• Tailored gradient material properties at desired location from single blank through
localized Heating or in die differential Cooling
• New possibilities for energy management in Crash  Design Innovations
• Part consolidation + weight reduction + Cost reduction
Ralf Hund 2013,
Ignacio Martin 2013,
(A) - Soft zone
UTS 450 – 700 Mpa
Elongation >= 15%
(B) - Hard zone
UTS 1300 – 1500 Mpa
Elongation >= 5%

5. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
• Interaction of various physical phenomena in the process
• Simulation tools used for process design should be able to model all the
phenomena to estimate various process parameters to achieve desired final part
Hot stamping process

6. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
A Complete Solution for Sheet Metal Forming
• Product feasibility analysis with optimization
• Material Utilization / Cost analysis
• Die face design
• Virtual try-out with optimization
• Die stress analysis with optimization
• Modeling advanced stamping processes
• Press hardening
• Composite forming
HyperForm

7. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
HyperForm – Virtual Tryout (Incremental)
• Seamless integration with RADIOSS, the most
accurate solver in the marketplace
• Fully supporting LS-Dyna as an alternate
incremental solver
• Process oriented work flow for fast and intuitive
stamping model setup
• Blank - Metals or Composites, Shell or Solid
elements,
• Room or Elevated temperature
• Automated process for multi-stage transfer and
progressive die simulations
• Tube Bending and Tube Hydroforming model setup
• Optimization enabled for process design
• Efficient post processing tools with automated
reporting

8. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
HyperWorks™ Approach
• Coupled solution with solvers RADIOSS and AcuSolve
• RADIOSS – Non-linear finite element based structural and thermal analysis
solver
• AcuSolve - Incompressible fluid flow solver based on Galerkin Least Square
Finite element Method
• Direct coupling – Large models, Implicit – Explicit combination, High
computation cost and time – Not practical
• Indirect coupling – Efficient

9. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
RADIOSS – Hot stamping simulation
• New material model for Boron steels – Akerstorm 2006
• New time step integration method to significantly reduce quenching simulation time.
• Validation - Numisheet 2008 Benchmark problem

10. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Hot Stamping simulation – Indirect coupling
• Example part – U Channel
• Initial forming simulation in RADIOSS – Predict blank temperature at start of
quenching.
Model setup
Predicted blank temperature –
end of forming

11. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Hot stamping simulation – Indirect coupling
• Cooling simulation – Acusolve - Predict tool temperature during quenching
considering fluid flow in channels
• Step 1 – Steady state flow analysis for fluid velocity and pressure profile
• Step 2 – Transient Thermal analysis with inputs from step 1
Model setup
Predicted blank temperature
– end of forming
Punch – 348 K
Die – 348 K Blank – Initial
Temperature
from RADIOSS
forming run
Cooling channel- Fluid
temperature 298 K and
flow rate 5 l/min

12. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Hot stamping simulation – Indirect coupling
• Cooling simulation– Acusolve
0
100
200
300
400
500
600
700
800
900
0 1 2 3 4 5 6
Toolsurfacetemperature(K)
Time (sec)
Location 1
Location 2
Location 3
Tool temperature – Quenching 5 secs

13. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
• Example part – U Channel
• Quenching simulation– RADIOSS
• Tool temperature history – AcuSolve Cooling Run
Hot stamping simulation – Indirect coupling
Die – Temperature function of time from Acusolve run
Blank – 810 oC
Punch – Temperature function of time from Acusolve run

14. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
• Example part – U Channel
• Quenching simulation– RADIOSS
Hot stamping simulation – Indirect coupling
Constant Tool temperature – 348 K
Traditional simulation
Tool temperature – Variable with time from AcuSolve
Indirect coupled simulation
Martensite Volume
fraction
Martensite Volume fraction – Quenching 5 secs

15. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
• Example part – U Channel
• Quenching simulation– RADIOSS
Hot stamping simulation – Indirect coupling
• Traditional approach results in faster cooling and inaccurate final properties of
the formed part

16. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Hot Stamping - Simulation strategy
Design criteria
Splits,
Wrinkles,
thinning
Hardness,
Tool
temperature,
Cycle time
CAD Input Die face
design
Detailed
design
CAE RADIOSS
RADIOSS +
ACUSOLVE
• Thermo – Mechanical
simulation
• Tool temperature
assumed
• Thermal + Mechanical +
Fluid flow
• Minimal assumptions
Die face, Press
parameters
Cooling channel
size, location, fluid
flow rate, pressure
1. Forming Feasibility 2. Properties Feasibility

17. Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.
Summary
• New material model implemented in RADIOSS to model press hardening steel
and validated.
• Efficient approach that models all the physical phenomena in press hardening
has been proposed using Altair’s Solvers.
• RADIOSS – Mechanical, Thermal and Metallurgy
• AcuSolve – Thermal and Fluid flow
• New approach illustrated the tools effect (thermal and fluid flow) play a
significant role in heat loss and final part hardness.
• The proposed approach is the efficient way to model all the physical phenomena
in press hardening to predict accurate results.