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.