2011 European HyperWorks Technology Conference

Transkript

1 2011 European HyperWorks Technology Conference Topology Optimization Methods applied to Automotive Transmission Housings 1

2 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

3 GETRAG Corporate Group in figures Key facts 2010 Sales Global production Employees 2.6 bn EUR* 2.9 m transmissions 1.2 m axles 13, locations worldwide *consolidated (01/2011) 3

4 Product Portfolio: Largest independent supplier of passenger car transmissions worldwide 4

5 gearbox Principle Sketch of a manual shifted Transaxle Gearbox Torque flow for shifted 1st gear engine gears constant ratio 5

6 Example of a manual transmission in front transverse design Output Shaft Reverse Idler Input Shaft Differential 6

7 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 1 st 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 1 st eigenfrequency 7

8 Topology Optimization for a new transmission housing design 8

9 Modeling gear set and shifting system are fixed and determining the form of the interior of the housing largely 9

10 Modeling The exterior shape is limited by the available space in the car: 10

11 Modeling Fixed points of the optimization model: mass points representing the shifting system bolting positions at the engine flange 11

12 Modeling Tapered roller bearings at the Differential: axial pretension by initial penetration in the contact area 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 12

13 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: - 1 st gear drive and coast - Reverse gear drive and coast - Modal Analysis (1st Eigenmode) 13

14 Result 14

15 implementation of the result Preparation with Ossmooth in HyperMesh for the subsequent use as inspiration source for the design engineer 15

16 implementation of the result

17 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 17

18 Topology Optimization of an existing transmission housing 18

19 Modeling Base: FEM-model for strength analysis with RADIOSS Modeling details: contact: - Bearing rings with housing - Between housing parts Boltings with pretension Nonlinear quasi static load cases: 1 st gear drive and coast rev. gear drive and coast 19

20 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: - 1 st gear drive and coast - Reverse gear drive and coast - Modal Analysis (1st Eigenmode) 20

21 Result Areas with low element density (red) offer weight reduction potential 21

22 Thank you for your attention! 22