(Problems with)(Problems with)Optimising Brake Disc Design Optimising Brake Disc Design

by Simulationby Simulation

(Problems with)(Problems with)Optimising Brake Disc Design Optimising Brake Disc Design

by Simulationby SimulationOptimising Brake Disc Design Optimising Brake Disc Design

by Simulationby SimulationOptimising Brake Disc Design Optimising Brake Disc Design

by Simulationby Simulation

Bill Young

Senior Consultant, Design and Simulation

Optimising Brake Disc Design Optimising Brake Disc Design by Simulationby Simulation

Optimising Brake Disc Design Optimising Brake Disc Design by Simulationby Simulation

OutlineOutlineOutlineOutline

“Design and Simulation”

Simulation Tools

Optimisation Tools

Opportunities for Optimisation

Simulation ToolsSimulation ToolsSimulation ToolsSimulation Tools

“Horses for courses”

Range of analysis types

Durability

Impact and Safety

Range of software

MSC.Nastran

LS-Dyna (explicit and implicit options)

Durability AnalysisDurability AnalysisDurability AnalysisDurability Analysis

Impact AnalysisImpact AnalysisImpact AnalysisImpact Analysis

Fracture AssessmentFracture AssessmentFracture AssessmentFracture Assessment

CFD - AerodynamicsCFD - AerodynamicsCFD - AerodynamicsCFD - Aerodynamics

Brake Disc AnalysisBrake Disc AnalysisBrake Disc AnalysisBrake Disc Analysis

Mechanical, thermal stress, distortion

Optimisation ToolsOptimisation ToolsOptimisation ToolsOptimisation Tools

“Heuristic approach”

Structural Optimisation – MSC.Nastran SOL 200Element 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

Optimisation InputsOptimisation InputsOptimisation InputsOptimisation Inputs

ObjectiveLightest (cheapest) design allowing…

Variables(Real) design parameters to be changed within design envelope, keeping within…

ConstraintsLimits to structural response

Hill-climbing analogy

Case Study: Case Study: MG TF Suspension ConceptMG TF Suspension Concept

Case Study: Case Study: MG TF Suspension ConceptMG 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

MG TFMG TFMG TFMG TF

Large Impact Load

Weak Points

MG’s Trailing ArmMG’s Trailing ArmConceptConcept

MG’s Trailing ArmMG’s Trailing ArmConceptConcept

Tubular steel fabrication

High strength

Low cost manufacturing

Weight 3.8kg

Investment £150,000

Piece Price £32

11stst Option Option11stst Option Option

22ndnd Option Option22ndnd Option Option

Weight 4.2kg

Investment £10,000

Piece Price £28

Weight 3.2kg

Investment £8,000

Piece Price £16

33rdrd Option Option33rdrd Option Option

Final DesignFinal DesignFinal DesignFinal Design

Spheroidal Graphite Cast Iron 10% lighter than standard cast ironOver twice as strong

From CAD to parts in 5 days

Optimised for weight and performanceUsing analysis at the point of design

Low cost / low investment Half the price of the fabricated option

Trailing Arm Concept DesignTrailing Arm Concept DesignTrailing Arm Concept DesignTrailing Arm Concept Design

Follow-up exercise (Optistruct)

Define packaging spaceBush mountingTetrahedral modelDesign & nondesign zones

Trailing Arm Concept DesignTrailing Arm Concept DesignTrailing Arm Concept DesignTrailing Arm Concept Design

Single load case effect (braking)

Reaction at bushes, general stress determines design

Trailing Arm Concept DesignTrailing Arm Concept DesignTrailing Arm Concept DesignTrailing 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)

Opportunities for OptimisationOpportunities for OptimisationOpportunities for OptimisationOpportunities 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)

Dealing With OpportunitiesDealing With OpportunitiesDealing With OpportunitiesDealing With Opportunities

(Not enough directly relevant data)

Conservative assumptions

Averaged/Extrapolated data

Data from “similar” design

Relative, not absolute

Simplify!

Solving Problems - Seizing Solving Problems - Seizing Opportunities for OptimisationOpportunities for Optimisation

Solving Problems - Seizing Solving Problems - Seizing Opportunities for OptimisationOpportunities for Optimisation

Address Definition of Loads and Restraints (Supports)

Thermal – friction-inducedCFD input to heat transfer/temperature prediction problem?

Mechanical – manufactureCasting/forging simulation for residual stresses?

Mechanical – assemblyPre-load simulation, tolerance sensitivities?

Mechanical – brakingLocal load distribution dependant on other components? Use more sophisticated (assembly) models? Integrate (ADAMS)

The Problem with Problems…The Problem with Problems…The Problem with Problems…The Problem with Problems…

“For every complex problem, there is a solution that is simple, neat, and wrong.”- H. L. Mencken