integrated design procedures for volume produced cast aluminium automotive components

8/3/2019 Integrated Design Procedures for Volume Produced Cast Aluminium Automotive Components

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F A S T M A T

University of Warwick - Nov 4, 2003

Integrated Design

Procedures forVolume Produced

Cast Aluminium

Automotive Components

Jonathan James John Spittle

Steve Brown Ian Pearce

Tony Firkin Janardan Devlukia

Presentd by Dr. Zongjin Lu, Land Rover



F A S T M A T


Cast Aluminium Components• Automotive Weight Saving

• Need To:

– Minimise Casting Defects

– Achieve Acceptable Properties

• Design Dilemma - Thicker Gauge Sections Give:

– Lower Stresses – Slower Cooling

– Poorer Materials Properties



F A S T M A T


Aluminium alloy LM25 (A356.0) : Al 7Si Mg

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70

Dendrite Arm Spacing, microns

S t r e n

g t h , M P a

0

2

4

6

8

10

12

D u c

t i l i t y , %Strength

Ductilty

Source : A.Wickberg et al, SAE Technical Paper Series 840121,

Mechanical Properties depend on:

• Chemical composition – Si, Mg, Fe, H

• Grain refinement

• Cooling rate during solidification

• Porosity levels

• Heat treatment

Strength

Ductility

DAS

- Al

Si

FeSiAl5



F A S T M A T


Objectives

• Integrate

– Component Design

– Casting Design

• Combine expertise from: – Car Manufacturers

– Foundries

– Suppliers of Casting Simulation Software

• Re-Design a Prototype Component

• Develop New Design Procedures



F A S T M A T


Software Used• Computer Aided Design

• FEM Mesh Generation

• FEM Stress Analysis

• Solidification Simulation:

– Fluid Flow – Liquid Metal Mould Filling

– 3D Finite Difference Solidification Simulation – Prediction of Freezing Times + Porosity



F A S T M A T


Methodology



F A S T M A T


Prototype Component

Rubber

Bush



F A S T M A T


View of component on car



F A S T M A T


Summary of Designs

89889278100Component

Weight

75757575100Section

Thickness

282127137100100Section

Area

11 12 13 14Original



F A S T M A T


Original v New Designs



F A S T M A T


Original ComponentFeeders

Runner

Filter

Sprue

Main Ring

Bosses



F A S T M A T


Final

Filter

Runner



150

MPa

0

75

Von Mises Stress



300

Sec

120

210

Local Freezing Time



75

m

50

63

Dendrite Arm Spacing



180

MPa

100

140

Nominal Yield Strength



40

GPa s

0

20

Max Prin Stress x

Loc Freezing Time



1.0

0

0.5

Von Mises Stress /

Nom Yield Strength



F A S T M A T


Max Values From Mesh

MP / Nom Tensile Strength

VM / Nom Yield Strength

MP x LFT

MP x T80

VM x LFT

VM x T80

Max Principal Stress

Von Mises Stress

0.791.03

0.770.96

31.942.0GPa s

40.346.7GPa s

31.439.4GPa s

39.543.8GPa s

138187MPa

120170MPa

NewOriginal



F A S T M A T


Original New

Original New



F A S T M A T


Strength

Testing

54.5940.33Mean

61.8439.5742.4439.14

58.1141.48

55.9641.12

NewOriginalkN



F A S T M A T


Fatigue Test Results

25

24

21

27

20

20

20

2326

22

0

5

10

15

20

25

1.E+05 1.E+06 1.E+07 1.E+08

Cycles to Failure

L o a d ,

k N

Original Design

New Design



F A S T M A T


Summary

• Developed design procedures thatcombine:

– FEM in-service stress analysis

– Computer model of solidification process

• Prototype Component:

– 36 % increase in strength

– Substantial Increase in Fatigue Life

– 5 % Weight Reduction



F A S T M A T


Future Work

• Possibly Extend Casting Simulation to Include:

– Stress Analysis as Casting Cools

– Residual Stress Determination

• Need Mechanical Property Data for:

– Semi-solid condition

– and just below solidus

integrated design procedures for volume produced cast aluminium automotive components

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