Car makers have to reduce consumption of vehicles and so, are continually looking for solutions to lighten components. For powertrain, components generally mean screwed assembly, contact and fitting interfaces, with different kind of loading to take into account (static and dynamic). Hence, we decided to apply with Altair assistance, a process of topology optimization on an assembly of gearbox housing in order to check its feasibility and efficiency. Several steps had to be solved from exhaustive identification of all mechanical constraints to execution of large models with Optistruct. By the end, the process has been defined and implemented on an existing gearbox and will be soon apply on the next one to design. Speakers Philippe Dausse, Modelization Specialist, PSA Peugeot Citroen Automobiles

1. A way to reduce mass of gearbox housing
(with ALTAIR and DPS contribution)
01294_15_00532 - October 1st, 2015
DRD/DCTC/CMEG
Philippe DAUSSE - PSA CAE Specialist
Julien MASSON - ALTAIR Senior Project Engineer
Quentin BARRE - DPS Consultant

2. SUMMARY
1. PSA Group Overview
2. PSA Topology Optimizations
3. Gearbox Application
4. Modelling
5. Conclusions & Prospects
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A way to reduce mass of gearbox housing
DRD/DCTC/CMEG
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

3. PSA - 2014 data
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1- PSA Group Overview
184,800
FINANCING E Q U I P M E N T
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

4. PSA - Worldwide sales in 2014
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DRD/DCTC/CMEG
1- PSA Group Overview
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

5. PSA Topology Optimizations
Powertrain
• Engine, gearbox, chassis and brackets
• Static, modal, NVH, durability
Body shell architecture
• Body-in-white and panels
• Static (stiffness, accidental loads), modal, NVH, crash by linearization
BIW Assembly connections (glue included)
• Body-in-white and panels
• Static and modal (stiffness, exceptional loads)
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DRD/DCTC/CMEG
2- PSA Topology Optimizations
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

6. Gearbox Housing Application
What if gearbox
housing is
designed by
topology
optimization?
Powertrain is
20% of vehicule
weight
Continuous
target to reduce
vehicule weight
Gearbox housing
identified to
have potential
mass saving
 mid 2014 : topology optimization
started on an existing gearbox
 Project carried out with Altair’s
assistance and DPS contribution
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DRD/DCTC/CMEG
2- PSA Topology Optimizations
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

7. Gearbox Definition
Structural interfaces
 Attached to engine by clutch housing interface
 Connected to vehicule by upper and lower engine
mounts
 Internal mechanics (shafts, gears and bearings)
 Bolted interfaces between housings
Structural constraints
 Loads on bearings due to engine torque
 Dynamic loads from engine mounts
 Powertrain vibrations
Manufacturing constraints
 Aluminium casting
 Draw directions constraints
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3- Gearbox Application
Internal mechanics
Housings
Engine
torque
Wheels’
torque
GearboxClutch
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

8. Simulation Objectives
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3- Gearbox Application
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Topology optimization to minimize mass and identify rib locations
Limit bearing deformation under engine torques
Limit global deformation on upper engine mount interface
Powertrain first bending mode greater than 225 Hz
Mode tracking on upper engine mount interface
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

9. DRD/DCTC/CMEG
4- Modelling
Static modelling on gearbox housing
- Select the most significant torques (Bearings Romax loads)
- Freeze bolted and bearing housing interfaces
Add interfaces modelling
- Fasteners
- Contacts (housing / housing and housing / bearing)
Add dynamic modelling
- Modal bending analysis
- Mode tracking on engine mount interface
Gearbox modelling
A progressive approach :
901294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

10. Mechanical modelling NVH modelling
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4- Modelling
Modelling
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11. Mechanical modelling NVH modelling
DRD/DCTC/CMEG
4- Modelling
Simplified modelling of bearing/housing interfaces
Simplified modelling of bolted interfaces
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON
Modelling
Pressure cône angle Rbe2
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12. Mechanical modelling NVH modelling
DRD/DCTC/CMEG
4- Modelling
Condensation of engine and internal gearbox
mechanisms
SE validation with MAC tool
Super element connected to gearbox by MPC
Simplified modelling of bearing/housing interfaces
Simplified modelling of bolted interfaces
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON
Modelling
Pressure cône angle Rbe2
10

13. Mechanical loads NVH loads
DRD/DCTC/CMEG
4- Modelling
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON
Loads
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14. Mechanical loads NVH loads
DRD/DCTC/CMEG
4- Modelling
Romax loads on bearings : Max engine torque for each 6
speeds + rear
Max load applied to upper engine mount
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON
Loads
Optimization criteria:
Axial bearing displacement
Optimization criteria:
Displacement XYZ
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15. Mechanical loads NVH loads
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4- Modelling
Modal analysisRomax loads on bearings : Max engine torque for each 6
speeds + rear
Max load applied to upper engine mount
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON
Loads
Optimization criteria:
Axial bearing displacement
Optimization criteria:
Displacement XYZ
Optimization criteria:
Frequency of the two first
bending modes of the
Powertrain

16. Design variables:
 Element density
Objective :
 Minimize mass
Constraints :
 Max displacements at centers of bearings
 Max displacement at upper engine mount
 1st bending mode of powertrain > 225Hz
Manufacturing constraints :
 Single draw direction on several areas
 No hole
Optimization setup
4- Modelling
DRD/DCTC/CMEG
1201294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON
Non Design SpaceDesign Space

17. 5- Conclusions & Prospects
Obtained topology
DRD/DCTC/CMEG
1301294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

18. Conclusions & Prospects
Achievements
 Topology optimization succeeded on gear box housing assembly
 Topology result  Clear rib pattern
 Potential mass saving of 5-10%
Work in progress
 Assembly of the Gearbox optimization methodology
 Methodology to be applied on a 2016 new gearbox project
 Minimize the internal oil volume using the morphing method (Altair’s proposition)
Future methodology improvement
 Model the contact interface between bearing and housing (impact ribs)
 Reduce calculation time (generalize domain decomposition)
 Criteria improvement for engine mount interface design : uniform stiffness, 1st eigen mode frequency
 Use MMO (Multi Model Optimization)
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5- Conclusions & Prospects
DRD/DCTC/CMEG
01294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON

19. Thank you
Questions & answers?
1501294_15_00532 - October 1st, 2015 - Philippe DAUSSE / Julien MASSON
DRD/DCTC/CMEG