Optimization of Transmission Housings
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GKN Driveline is the world’s leading manufacturer of automotive driveline components like CVJ Systems, AWD Systems, Trans Axle Solutions and eDrive Systems. The global acting company has 22,000 people at 56 facilities in 22 countries working in partnership with vehicle manufacturers to develop driveshaft and geared component technologies for the future. For all transmission systems, the task of the development is to satisfy customer requirements which partly act against each other. Systematically separate and balance design parameters regarding durability, NVH and efficiency to achieve biggest benefit at acceptable cost level. These various requirements and demands leads to challenging optimization work. Traditionally this challenge has been determine using existing designs or ideas based on experience and testing using simulation after design to verify changes. The introduction of numerical optimization methods has significantly changed the way of transmission development. Best concept design that meets design requirements replacing time consuming and costly design iterations. This presentation will show how GKN Driveline, has integrated optimization techniques showing examples of recent development. Speakers Amelin Begovic, GKN Driveline Köping AB
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Optimization of Transmission Housings
- 1. Innovation in topology optimization Transmission housings Amelin Begovic, EATC, 1st October 2015
- 2. 2 GKN Driveline – global footprint
- 3. 3 A complete driveline solution Leadership in all major product lines
- 4. 4 GKN Driveline – product segments CVJ Systems AWD Systems Trans Axle Solutions eDrive Systems CV Joints Sideshafts Propshafts Transfer Units AWD Couplings Disconnects Final Drive Units Differentials Limited Slip & Locking Differentials eAxles eTransmissions eMotors
- 5. 5 AWD Systems – global manufacturing GKN Driveline Bowling Green GKN Driveline Bruneck GKN Driveline Köping GKN Driveline Newton GKN Driveline Tochigi GKN Driveline Nagoya GKN Driveline Shanghai Europe Americas Asia Pacific
- 6. 6 AWD products Rear Drive Unit − Distributes the torque to the rearwheels − Ratio > 1 = Reduces speed and increases torque Rear Drive Module Coupling − Distributes the torque to the Rear Drive Unit − Controlled by the vehicle via the ECU Power Take off Unit − Connected to the gearbox, normally to the differential carrier − Ratio < 1 = Reduces torque and increases speed
- 7. 7 Market constraints Lightweight Efficiency Engine performance Mega platforms − 75% of light vehicles based on mega-platforms Growing popularity of SUVs and AWD Quite and comfortable vehicles Tightening of CO2 and fuel economy targets
- 8. 8 Solution – Dynamic Thinking System approach Proactive product development Virtual analysis and simulation of complete driveline Customer involvement Design maturity Shorter lead time
- 9. 9 Optimization work Yesterday New design start from existing ideas considering.. − Extreme torque requirements − Packaging constrained enviroment − Light weight requiremnts − Design response − … CAE done after CAD Today New design start from new enviroment with new ideas considering directly − Extreme torque requirements − Packaging constrained enviroment − Light weight requirement − Design response − … CAE done before CAD Get new ideas
- 10. 10 Optimization analyzes – Workflow Shorter lead time Faster and more design loops Design maturity The optimization process speeds up and make the product development more efficient regarding time & cost Best concept design that meets design requirements replacing time consuming and costly design iterations Topology optimization towards variables − Stiffness − Eigen frequency − Mobility Generation of machining and manufactural design constraints Design Space Stiffness opt
- 11. 11 OEM1: Frequency Response Analysis Corrective action: After evaluation of optimized FE Model, improvement of PTU fixation was identified − By: Mobility analysis, Modal anlaysis, Strain energy evaluation Implementation of additional fixation point between PTU cover and bracket Issue: Eigen frequency of the PTU due to the weakness of the PTU support Firing frequency of customer diesel engine as a excitation PTU propshaft connection producing resonance frequency Software: HyperMesh, OptiStruct
- 12. 12 Five accelerometers located at different positions, measuring the mobility Each location is measured in x, y, z direction Modal hammer test FE model: 116 Hz Rig test: 114 Hz Correlation with rig testing 1 23 4 5 Y X Z
- 13. 13 1st eigenmode, PTU assembly, Bracket study modification 1st eigenfrequency @ 272 Hz *After modification 1st eigenfrequency @ 162 Hz *Previous design
- 14. 14 Improvement and results Requirement First bending mode > 250Hz Improvements Implemented proposal as stiffener, supports Vehicle validation showed improvement potential up to 264Hz PTU (incl. internal parts) Engine block Transmission Oil pan 1st eigenmode: 161Hz < 250Hz PTU (incl. internal parts) Improvements on bracket/cover Engine block Transmission Oil pan 1st eigenmode: = 𝟏𝟔𝟏 × 𝟏. 𝟔𝟖 ≈ 𝟐𝟕𝟎𝐇𝐳 > 𝟐𝟓𝟎𝐇𝐳
- 15. 15 OEM 2: Weight reduction Corrective action: Material savings Material distribution and balancing Task: Reduce the weight with equivalent or increased stiffness of torque tube Software: HyperWorks, OptiStruct
- 16. 16 Improvement and results Baseline − Weight: ~3500 gr − Requirement: Eigen Frequency >148 Hz Design space − Considering manufacturing constraints Topology optimization Final design − Weight: ~3200 gr − Eigen Frequency: 541 Hz Mass saving cca 12% considering manufacturubility, cost Eigen Frequency requirement fullfiled
- 17. 17 OEM 3: Topology optimization Corrective action: Stiffer and robust structure Task: Increase stiffness Fulfill mobility requirement Increase dynamic performance of the housing Investigate housing senstivity to torsional loading Software: HyperMesh, OptiStruct
- 18. 18 Mounting Mobility The velocity response per unit force through a specified frequency range Analysis used for the dynamic performance of housing stiffness The force is measured in (m/s/N) at each mount and in each vehicle translational direction RBE2 (rigid) links Nodesinthesplitplaneonboth housingandcoverarefixatedinallDOF´s FLH FRH RRH RLH
- 19. 19 Mount support stiffness Prediction of the FDU/RDU housing stiffness Determination of static stiffness for each vehicle axis and at each mount − General requirement for resulting displacement: − Mount stiffness must be 10 times higher compared to static bushing stiffness − Mount stiffness must be 5 times higher compared to dynamic bushing stiffness BC (locked in x, y, z) FRH RRH RLHForce (FX, 1N) @ FLH mount
- 20. 20 Torsional sensitivity Prediction of the FDU/RDU sensitivity to torsional loading Determination of mount accelerations in all vehicle directions at all mounts RBE2 (rigid) links StubshaftslockedinrotationalDOF’s Moment (1Nmm) @ pinion FLH FRH RRH RLH
- 21. 21 Tomorrow.. Start early Customer involvement Proactive product development risk management Virtual analysis and simulation of complete driveline Understand how design respons and transfer vibration further Understand and consider manufacturing variation initially Virtual and Physical Testing collaboration (2 Functions = 1 Discipline)