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Optimising Brake Disc Design by Simulation

Optimising Brake Disc Design by Simulation. (Problems with) Optimising Brake Disc Design by Simulation. Optimising Brake Disc Design by Simulation. Bill Young Senior Consultant, Design and Simulation. Outline. “Design and Simulation” Simulation Tools Optimisation Tools

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Optimising Brake Disc Design by Simulation

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  1. Optimising Brake Disc Design by Simulation (Problems with) Optimising Brake Disc Design by Simulation Optimising Brake Disc Design by Simulation Bill Young Senior Consultant, Design and Simulation

  2. Outline • “Design and Simulation” • Simulation Tools • Optimisation Tools • Opportunities for Optimisation

  3. Simulation Tools • “Horses for courses” • Range of analysis types • Durability • Impact and Safety • Range of software • MSC.Nastran • LS-Dyna (explicit and implicit options)

  4. Durability Analysis

  5. Impact Analysis

  6. Fracture Assessment

  7. CFD - Aerodynamics

  8. Brake Disc Analysis • Mechanical, thermal stress, distortion

  9. Optimisation Tools • “Heuristic approach” • Structural Optimisation – MSC.Nastran SOL 200 • Element properties are design variables; nominated objective function is minimised/maximised • Shape (Topology) Optimisation – Optistruct (HyperWorks) • Elements are potential voids; material is distributed most efficiently to address loads • Either process needs feeding with appropriate data

  10. Optimisation Inputs • Objective • Lightest (cheapest) design allowing… • Variables • (Real) design parameters to be changed within design envelope, keeping within… • Constraints • Limits to structural response • Hill-climbing analogy

  11. Case Study: MG TF Suspension Concept • Re-engineer the system to give improved ride and handling • Enhance the vehicle’s “sporty” feel • Prolong product life • Lower manufacturing costs

  12. MG TF

  13. Large Impact Load Weak Points

  14. MG’s Trailing ArmConcept • Tubular steel fabrication • High strength • Low cost manufacturing

  15. 1st Option Weight 3.8kg Investment £150,000 Piece Price £32

  16. 2nd Option Weight 4.2kg Investment £10,000 Piece Price £28

  17. 3rd Option Weight 3.2kg Investment £8,000 Piece Price £16

  18. Final Design • Spheroidal Graphite Cast Iron • 10% lighter than standard cast iron • Over twice as strong • From CAD to parts in 5 days • Optimised for weight and performance • Using analysis at the point of design • Low cost / low investment • Half the price of the fabricated option

  19. Trailing Arm Concept Design • Follow-up exercise (Optistruct) • Define packaging space • Bush mounting • Tetrahedral model • Design & nondesign zones

  20. Trailing Arm Concept Design • Single load case effect (braking) • Reaction at bushes, general stress determines design

  21. Trailing Arm Concept Design • Multiple load cases • Residual shape: load paths • Most effective use of material • But… manufacturing constraints dictate further changes (eg stiffness during machining)

  22. Opportunities for Optimisation • “There are no problems, only opportunities” • Tools and computing power exist • Geometry, (material properties) exist • “Opportunity” lies in defining constraints (combination of loads and limits to responses)

  23. Dealing With Opportunities • (Not enough directly relevant data) • Conservative assumptions • Averaged/Extrapolated data • Data from “similar” design • Relative, not absolute • Simplify!

  24. Solving Problems - Seizing Opportunities for Optimisation • Address Definition of Loads and Restraints (Supports) • Thermal – friction-induced • CFD input to heat transfer/temperature prediction problem? • Mechanical – manufacture • Casting/forging simulation for residual stresses? • Mechanical – assembly • Pre-load simulation, tolerance sensitivities? • Mechanical – braking • Local load distribution dependant on other components? Use more sophisticated (assembly) models? Integrate (ADAMS)

  25. The Problem with Problems… • “For every complex problem, there is a solution that is simple, neat, and wrong.” - H. L. Mencken

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