Topology Optimization Methods applied to Automotive Transmission Housings

© GETRAG Getriebe und Zahnradfabrik, 2011-11-09, Maurice Dietzel

Hermann Hagenmeyer GmbH & Cie KG 1

2011 European HyperWorks Technology Conference

„Topology Optimization Methods applied to

Automotive Transmission Housings“


Hermann Hagenmeyer GmbH & Cie KG

Agenda

Introduction

- Corporate Information

- overview

Topology Optimization for a new transmission housing design

- modeling

- result

Topology Optimization of an existing transmission housing

- modeling

- result

2



GETRAG Corporate Group in figures

24 locations worldwide

13,500 Employees

2.9 m transmissions

1.2 m axles

Global production

2.6 bn EUR* Sales

Key facts 2010

*consolidated

(01/2011)



Product Portfolio:

Largest independent supplier of passenger car transmissions worldwide



Principle Sketch of a manual shifted Transaxle Gearbox

gears

constant ratio

Torque flow for

shifted 1st gear

engine

gearb

ox



Example of a manual transmission in front transverse design

Input Shaft

Output Shaft

Reverse Idler

Differential



optimization approaches

1. For a new design: optimal shape within a given design space

• optimization objective:

• Minimize mass

• boundary conditions:

• Max. allowable stresses

• Max. allowable displacements at the bearing seats

• Lower limit for 1st eigenfrequency

2. For an existing design: weight reduction

• optimization objective:

• Maximize stiffness

• boundary conditions:

• Mass smaller than the initial mass (e.g. -10%)

• Max. allowable displacements at the bearing seats

• Lower limit for 1st eigenfrequency



Topology Optimization for a new

transmission housing design



Modeling

gear set and shifting system are fixed and determining the form of the

interior of the housing largely



Modeling

The exterior shape is limited by the available space in the car:



Modeling

Fixed points of the optimization model:

bolting positions at

the engine flange

mass points representing

the shifting system



Modeling

Tapered roller bearings at the Differential:

The replacement outer bearing ring is

coupled via RBE3 with the housing

Contact between the

replacement bearing rings.

Contact between differential cage and

inner replacement bearing ring

axial pretension by

initial penetration in

the contact area



Modeling

Optimization Objective:

- Minimize mass

Boundary Conditions :

- Max. allowable stresses (depends on material)

- Max. allowable displacements at the bearing seats

- Lower limit for 1st eigenfrequency >= 300Hz

Load Cases:

- 1st gear drive and coast

- Reverse gear drive and coast

- Modal Analysis (1st Eigenmode)



Result



implementation of the result

Preparation with Ossmooth in HyperMesh for the subsequent use

as inspiration source for the design engineer


Hermann Hagenmeyer GmbH & Cie KG

implementation of the result



Summary

The optimization result shows pronounced accumulations of

material:

> Reason: The used element edge length of 5 mm is relatively

large but necessary to get results over night.

- To get a more realistic casting wall thickness it is necessary to

use 1mm to 2mm edge length for the mesh.

Outlook:

- constantly increasing computer hardware performance makes

topology optimization more and more attractive



Topology Optimization of an existing

transmission housing



• contact: - Bearing rings with housing

- Between housing parts

• Boltings with pretension

• Nonlinear quasi static load cases: • 1st gear drive and coast

• rev. gear drive and coast

Modeling

Base: FEM-model for strength analysis with RADIOSS

Modeling details:



Modeling

Optimization Objective:

- Maximize stiffness

Boundary Conditions:

- Mass smaller than the initial mass (e.g. -10%)

- Max. allowable displacements at the bearing seats

- Lower limit for 1st eigenfrequency

Load Cases:

- 1st gear drive and coast

- Reverse gear drive and coast

- Modal Analysis (1st Eigenmode)



Result

Areas with low element density (red) offer weight reduction potential



Thank you for

your attention!

Topology Optimization Methods applied to Automotive Transmission Housings

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