WS 7 Lightweight Structures

Transcription

1 WS 7 Lightweight Structures Objective: To develop materials and process technologies that will facilitate the introduction of lightweight solutions into future electric / hybrid vehicle programmes without compromising the overall life cycle impact. BIW Material Technologies Determine suitability of candidate materials and process combinations to minimise the weight of structural automotive applications. Provide robust design and process guidelines for the best assembly and joining methods for a given set of material / joint interfaces. Lightweight seat construction Identify and evaluate materials and process options for lightweight seat structure concepts. Lightweight EV architecture Understand the complexities and develop a scalable architecture model that can be applied to EV, REEV and Series Hybrid vehicles. Lightweight glazing Identify a lightweight glazing solution for each vehicle application that optimises the optical, acoustic and thermal transmission performance. Deliverables Reports on current and emerging technologies Generic part and design data Validated concepts Design and application proposals Design and process guidelines Roadmap to future opportunities LCA indicator Life Cycle Analysis Ensure that materials and process technologies identified are evaluated for their environmental performance to minimise any adverse impact.

2 Approach Stage 1: State-of-the-art tech review Stage 2: Evaluation of emerging tech > Prove concept-readiness (CR) > Stable at E-coat (200 C+) > Structural performance (up to 100 C) > Flex, Crush & Impact > Volume manufacture (50,000+ ppa) > Initial CAE capability. Stage 3: Review of blue-sky opps Core materials evaluation 7.2 Structural battery box 7.3 Joining methods 7.4 Body structure 7.5 Seat 7.6 Vehicle architecture

3 Materials testing approach - coupons Static testing (data for CAE input) > Tensile tests (ISO 527), room/-40/+100 C > Shear tests (+/-45 tension & Iosipescu) Fatigue testing IR & Acoustic Emission Heat = damage event(s) Cooling= Elastic tensile deformation > IR thermography & acoustic emission > Gives rapid fatigue limit determination Dynamic mechanical thermal analyses (DMTA) > Stiffness v temperature > Material processing window > Environmental applicability

4 Specific material properties comparison

5 Selected BIW materials & processes Rapid stamp-formed thermoplastic composites: > Unidirectionally-reinforced laminate PA6 matrix with 60% w.f. aligned glass > Hybrid Laminate + injection-moulding grade LFT > Compatible with existing supply chain Hot-formed UHSS: > Boron steel press-formed at ~900 C > Rapidly quenched in tool Press-formed sheet DP600 steel 5754 aluminium

6 Rapid stamp-forming of thermoplastic composites ~90s process time, +50,000 ppa Similar to metal press-forming Material heated to target temperature (230 C, continuous heating process) Already proven Transferred to heated mould tool (hand or shuttle, 10s, 100 C) Flange sections spring loaded Pressure up to 10MPa (~100bar) Heating to 150 C Mould tool closes and stamp-forms part (<10s) Part cools to de-mould temperature (60s, ~120 C)

7 Light Weight Seating 1. Current Architecture: 20% weight reduction target SOP Future Architecture: 40% weight reduction target SOP Blue Sky Architecture: 65% weight reduction target SOP 2020 The Seat Back Structure was chosen as the area for research Best opportunity for weight reduction by the use of new materials, The learning is expected to be scaleable to all three rows Structure & Mechanisms Plastics Trim Foam

8 Future Architecture: Decision Matrix Weight LCA Knowledge Opportunity STEEL 10-35% ALUMINIUM 20-50% MAGNESIUM 30-50% COMPOSITE MOULDING 45-55% CARBON FIBRE 50-60% RELATIVELY GOOD AVERAGE RELATIVELY POOR It was agreed that a composite solution offered the most opportunity for w/s 7.5, in terms of: potential weight save innovation and new research realistic lead-time investment costs

9 Seating: Initial Concept Work ECE17, FMVSS 202a & 207 Reviewed 6 Key tests identified 3 CAE load cases assessed Topology optimisation in Optistruct conducted Initial CAE assessments were completed with isotropic material assumptions. Project now has the capability to model the structure as an orthotropic model, assessing the composite plies

10 Future Architecture: Design / Proto / Test Summary Prod Benchmark CF Comparator LCVTP Backrest LCVTP + Clamshell LCVTP Hybrid Structure CAE CAE CAE CAE PROD PROTO PROTO PROTO PROTO TEST TEST TEST TEST TEST CORRELATE CORRELATE CORRELATE CORRELATE CORRELATE

11 LCA modelling using Gabi software Fully functional parameterised model is now under development Scenario Analysis will demonstrate the carbon impact of > different materials > different structures > manufacturing processes > locations

12 WELDING What makes a good joining technique? SYSTEM BOUNDARY DIAGRAM 7.3 JOINING TECH SHELF LIFE (HIGH) OPERATIONAL ENVIRONMENT LCA IMPACT STORAGE EASE OF APPLICATION ADHESIVE TYPES END VEHICLE LIFE (DESIGN FOR DISASSEMBLY) REPEATABILITY ASSEMBLY ENVIRONMENT (E.G. DUST) EASE OF AUTOMATION P JOINING TECHNOLOGY 7.3 P E PROPERTIES STATIC STRENGTH DYNAMIC STRENGTH FAILURE MODE STIFFNESS OPERATING ENVIRONMENT TEMPERATURE HUMIDITY TARGET WEIGHT SINGLE STEP (E.G. NO DRILLING) COST EFFECTIVE P YIELD ENVIRONMENTAL STABILITY REPAIRABILITY DURABILITY MECHANICAL FIXINGS GREEN STRENGTH SERVICEABILITY OPERATOR SAFETY/COMFORT OCCUPANT COMFORT TOXICITY FLAMMABILITY ODOUR RESPIRATORY NVH DYNAMIC STIFFNESS KEY DIRECT INTERFACE INDIRECT INTERFACE P PHYSICALLY TOUCHING

13 The choice of technologies...

14 Raw CT images

15 Reconstructed data slice Fibres into plane Fibres horizontal Fibre layup: 90,0,0,90,90,90,0,0,90

16 Simulation of e-coat thermal profile - DMTA average of e-coat data 1 25 C to C.min C isotherm for 15 min 3 ~9 C.min -1 chemical cure starts at 18 mins full stiffness achieved on cooling tan δ peak indicates full cure pocket likely to be similar to a real joint However tests show that the Cure window is very tight. Alpha to modify adhesive to reduce cure temperature

17 Lightweight Architecture - Topology Optimisation Studies 210 kg Angle study Stiffness Practicality Dynamics Serviceability & Manufacturability

18 Secondary Topology Opt Study 74 Permutations 9 Results Model 65

19 LCA - Evolution of Standards First LCA (for Coca Cola) (1969) SETAC oversees 1991 ISO issued 2006 ISO due 2011 ILCD launch due 2013 ISO 14040, 41, 42, 43 issued PAS ISO due

20 Tools & Databases Category Proprietary LCA software Carbon tools Water tools Design tools Automotive tools Other tools Databases Tool/Database GaBi, Simapro, TEAM (examples) Footprint Expert TM Product water footprint tools, Water Footprint Network SolidWorks, Sustainable Minds, IDC, Granta Design, WorldAutoSteel LCA Model JLR Rapid LCA, Daimler Group, Ford, Volkswagen, Volvo, Mazda, Honda, Hyundai, Toyota, General Motors, Nissan EcoReport (for Energy Using Products), Envest (buildings) Proprietary LCA Databases, ELCD/ILCD (European Commission), Industry Association Databases (various), EcoSpold Data Format, Inventory of Carbon and Energy (ICE) Database

21 Intuitive Simple Modular Flags/alerts Signposting Highlights pitfalls Easy reporting Supporting database Standard data collect Data quality Transparent Comparisons Aids targets Numerical Graphics Clear message Training Web based Other issues OVERALL Design Tools & Databases LCA LCA tools eg. GaBi Cost Carbon Footprint ExpertTM No water footprint Design SolidWorks Cost, Uses GaBi Sustainable Minds Auto IDC Granta WorldAuto Steel Rapid LCA Cost Other EcoReport (EuP) Envest (build)

22 Ricardo has developed a simple method for estimating life cycle CO 2 emissions Vehicle Production Fuel Production In-Use Disposal Total Key Systems Source: Ricardo Materials + Production Processes / Energy Vehicle Simulation Lifetime Fuel / Energy Consumption x Well-to-Tank CO 2 factor Tailpipe CO 2 x Lifetime mileage Assumed lifetime mileage to be 150,000 km Note: Zero tailpipe emissions for BEV e.g. CO 2 from generating electricity (UK grid carbon intensity 2010)

23 CO2 in vehicle life (t) Initial results indicate BEV has lower total CO 2 emissions than conventional vehicle PRELIMINARY Total life time CO 2 emissions of conventional vehicle and BEV BEV has ~40% less total CO 2 emissions in its life Tank-to-wheels Well-to-tank Production 10 0 Base Diesel Vehicle BEV has 28% higher embedded CO 2 than conventional vehicle R-GTV Stage 1 BEV BEV embedded CO 2 now ~40% of total, compared to ~20% of conventional vehicle total

24 Summary IR & Acoustic process for quick fatigue testing developed Stamped aligned composite selected a key process for development Stamped top hat parts have been produced in less than 1 minute Tooling for stamped seat has been developed SPR & Adhesive shown to work with thermoplastic composites Adhesive shown to cure in e-coat process 2 stages of architecture optimisation & major system location study LCA tools and processes reviewed, user requirements identified and proposal for a simple to use tool made Full vehicle LCA process developed with initial GTV assessment