Robustesse : vue d un équipementier automobile

Transcription

1 Robustesse : vue d un équipementier automobile Christophe LEMAITRE / Simulation & Testing Director Steeve LAINE / Simulation Tools & Methods Expert Journée de la conception robuste et fiable. 27 mars 2014

2 Agenda Background R&D mindset change actions Conclusions

3 Background faurecia overview Group revenues: 18 billion 97,500 employees 320 sites in 34 countries #1 in Europe 11% 12% 22% 24% 36% 36% #1 Worldwide in mechanisms & frames #3 Worldwide complete seat #1 Worldwide 28% #1 Worldwide 3

4 Background faurecia overview

5 Background Game field of seating products Regulations : ECE 14 / ECE 17 / FMVSS210 / FMVSS202a / Safety : Front crash / Rear crash / Luggage impact / Low speed Whiplash / Side impact / Functional : Static & Dynamic comfort / Mechanical resistance / Vibration behavior / Acoustics / Fatigue /

6 Background Robustness approach w/ 1 test Main reasons for 1 test validation plan : Development cost and time Safety margin integrated in specifications

7 Background Safety margin integrated in specification SPECIFICATION NOK OK Test + Manufacturing uncertainties REAL TARGET OFFICIAL TARGET Comments : Simple and easy robustness approach to avoid issues in serial life But risk of over engineering Approach used by all OEMs

8 1 : Integrate uncertainties in conformity decision NOK SITUATION OK CONFORMITY DECISION ON TEST REPORT Result

9 1 : Integrate uncertainties in conformity decision NOK SITUATION OK CONFORMITY DECISION ON TEST REPORT + - +LM -LM Result Test uncertainty

10 1 : Integrate uncertainties in conformity decision Without uncertainty integration SAFETY Rear crash 50th + Rear crash 95th - Front crash 50th + Front crash 95th + Whiplash - Luggage crash + REGULATION ECE 14 - Belt - ECE 14 - ISOFIX + ECE 17 - Backrest - ECE 17 - Energy + 20 g FUNCTIONAL Egress/Ingress - Cushion durability + Backrest durability + Freeplay + Noise detection + Sliding effort + With uncertainty integration SAFETY Rear crash 50th +LM Rear crash 95th - Front crash 50th OK Front crash 95th OK Whiplash -LM Luggage crash OK REGULATION ECE 14 - Belt - ECE 14 - ISOFIX OK ECE 17 - Backrest -LM ECE 17 - Energy OK 20 g FUNCTIONAL Egress/Ingress NOK Cushion durability OK Backrest durability +LM Freeplay OK Noise detection +LM Sliding effort OK

11 1 : Integrate uncertainties in conformity decision 3 years practice feedback : R&D now integrates uncertainty in engineering management Lightweight pressure helps R&D to change mindset But communication to OEMs still not done : Long discussions on test uncertainties Specification not compatible with test uncertainty : Ex : Z axis dummy pelvis displacement during front crash : Specification : dz < 30 mm Measurement uncertainty dz ~ 10 mm Mindset not ready 11

12 1 : Integrate uncertainties in conformity decision Without uncertainty integration SAFETY Rear crash 50th + Rear crash 95th - Front crash 50th + Front crash 95th + Whiplash - Luggage crash + REGULATION ECE 14 - Belt - ECE 14 - ISOFIX + ECE 17 - Backrest - ECE 17 - Energy + 20 g FUNCTIONAL Egress/Ingress - Cushion durability + Backrest durability + Freeplay + Noise detection + Sliding effort + With uncertainty integration + safety margin SAFETY Rear crash 50th +LM 3% Rear crash 95th - 20% Front crash 50th OK 31% Front crash 95th OK 46% Whiplash -LM 2% Luggage crash OK 21% REGULATION ECE 14 - Belt - 25% ECE 14 - ISOFIX OK 36% ECE 17 - Backrest -LM 4% ECE 17 - Energy OK 16% 20 g FUNCTIONAL Egress/Ingress NOK 15% Cushion durability OK 26% Backrest durability +LM 4% Freeplay OK 13% Noise detection +LM 3% Sliding effort OK 9% Ongoing next step = to give an information on safety margin

13 2 : Run DoE to get a 1 st robustness assessment D-Optimal on Rear Crash Typical DoE result : 50% of runs OK and NOK!

14 MIN R&D mindset change actions 2 : Run DoE to get a 1 st robustness assessment NOM. Distribution laws for entry variables DOE analysis 3 values used on each entry variable MAX Tested Product Design Variable 2 No consideration on occurrence! + + High probability of overquality if solving of all potential failures! Design Variable 1 Capability analysis Real distribution law on entry variables Highlight real non conformity probability Distribution laws for entry variables Tested Product

15 3 : Run a robustness analysis Classic RSM Principle : injection of capabilities into a simplified mathematical model built from DOE results x 2 DOE Result s x 1 METAMODELING yˆ Mathematical Approximation Ν Ν, Ν = y0 + α ixi + βij xix j + ε i= 1 i, j= 1,1 x3 x4 x 2 x 1 x 5 ε Most Influent Parameters + Error Contribution Capability Simulation Spec Risk MONTE-CARLO Importance Sampling 1 Million runs Instantaneously

16 3 : Run a robustness analysis Classic RSM Post-Processing : Standardized and Guided from A to Z Reliability analysis per performance functions

17 3 : Run a robustness analysis Current limitation to robustness analysis deployment : In a very competitive cost reduction environment Right First Time test is the conclusion of the validation loop Big challenge for FEA upfront design and validation loops

18 4 : Optimization as new angle of attack Principle : sub-systems split + DoE based sensitivity analysis Gradient method for crash x 2 DOE Result s x 1 METAMODELING Design Improvement Proposal Sensitivities Computation x3 x4 Few hundreds of performance functions Objective = best compromised between weight and cost x 2 x 1 x 5 yˆ Mathematical Approximation Ν Ν, Ν = y0 + α ixi + βij xi x j + ε i= 1 i, j= 1,1

19 4 : Optimization as new angle of attack Usual Post-Processing : Design parameters user friendly Optimizer Buckle Force Pelvis X Disp. Towards the best compromised among all performance criteria Of course : R&D teams request for the reversed optimizer

20 4 : Optimization as new angle of attack Statistical Post-Processing : how optimize part inertia? Correlation ( Performance Function Dissipated Energy) Red Area (+1) Stiffness to Minimize dissipated Energy Minimize Perf. function Seat Frame Blue Area (-1) Softness to Maximize dissipated Energy Minimize Perf. function Green Area (0) No influence Podium Analysis : Pelvis displacement lead by seat frame coming from worldwide plate-form Very few impact of Podium on pelvis displacement Conclusion : it s impossible to transform a work horse into a racehorse

21 Conclusions After 3 years of actions, R&D mindset change is partially successful : R&D + management recognize that products are highly optimized and have less safety margin Test labs integrate test uncertainties in conformity decisions and highlight robustness issues CAE teams integrate correlation data in conformity decisions and highlight robustness issues Robustness analysis is still not a standard engineering deliverable Robustness tool was converted successfully into a crash optimization tool 2 main blockers still remains : Engineering Mindset Affordable cost consequence for Consumers Car makers faurecia

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