AIRPLANE BEARING BRACKET DESIGN

Lightweight Design 7.50HP MT8006 PROG VT 2016

Master program in Mechanical Engineering

Lecturer: Håkan petersson

Zoelfikar Elghoul Shopin John

Challenge Requirements and Work Envelope

Contents Lightweight Design 7.50HP MT8006 PROG VT 2016 ........................................................................... 1

1. Introduction ..................................................................................................................................... 3

2. Problem Statement ............................................................................................................................. 3

3. Model preparation in inspire ........................................................................................................... 5

4. Load case ........................................................................................................................................ 5

5.Contact Information ......................................................................................................................... 6

6.Connector Definitions ...................................................................................................................... 6

7. Material properties ......................................................................................................................... 7

8. Design improvements during optimization ..................................................................................... 7

9. Optimization results ........................................................................................................................ 8

10.Yield stress ...................................................................................................................................... 9

11.Von mises ..................................................................................................................................... 10

13.Major prinicple stresses after redsian results .............................................................................. 11

13.Vom ises stress ............................................................................................................................ 12

14.Yield stress .................................................................................................................................... 13

15.Manufacturing .............................................................................................................................. 14

........................................................................................................................................................... 14

15. Conclusion ................................................................................................................................... 14

1. Introduction

In this task we will use the software inspire 2015 release which has faster geometry functions

with an updated user interface and expands the scope of complexity of problems can be

addressed, Inspire 2015 version has a new added features from the users include fasteners,

joints and contracts, this features will enable us to quickly model, analyze and optimize our

assemble the brackets. The question is why we will use inspire

Saving 23 % weight compared to initial design

Casting constraints to ensure manufacturability

Inspire design process

Inspire design process Start with the solution and shorten time to market

2. Problem Statement

ALCOA Company launched a Design Contest with the objective to obtain a Bearing Bracket

and behave similarly to a component manufactured with traditional Aerospace processes such

as machining.

The envelope design requirements to design a bracket that could withstand the three load

cases given and do not exceed the envelope highest strength weight ratio possible, the design

Envelope can be seen in

Figure 1 Design Envelope

The Design takes the best practices currently used. Fastener Edge is considered with smoother

transitions between the regions and avoided sharp edges and stress raisers.

Final Design is shown in Figure 2 and has a mass of 228 grams

Figure 2 Final design

3. Model preparation in inspire

Bracket support Plate contact zone type bonded

Rigid elements ( 4 bolt connection)

4. Load case

Horizantal Load 1250

lb

Inclined Load 1875lb Vertical load 2500 lb

5.Contact Information

Contact Contact Image Contact propertiers

Bracket _support

plate contact

contact zone type

bonded

Bracket _support

bearing bracket

contact zone type

bonded

6.Connector Definitions

Pin_Bolt_Bearing Connector

Contact Contact Image propertiers

Bolt _bracket

_support Plate

Contact

4 fasteners

Aligned hole

fasteners automatic

Inspire 2015

enhance

7. Material properties Part Image propertiers

Bracket

15-5PH per

AMS5862

Elastic Modulus (𝐸) =

29,000 KSI = 200,000

MPa = 200 GPa

Poisson Ratio (𝜈) =

0.27

Yield Stress (𝜎𝑦) =

145 KSI = 1000 MPA

Density (𝜌) = 0.283

𝑙𝑏/𝑖𝑛3 = 7833 𝑘𝑔/𝑚3

Material is assumed

to be linear elastic

Fasteners ( 4

Bolts)

Part is fastened by

four high strength

bolts (#10-32)

Support

Part Image properties

support Plate

Support

8. Design improvements during optimization

During the optimization we had many problems so we had realized, there could be a couple of

changes that we could suggest in order to improve the overall Design of the bracket, for

example:

Have the freedom to move the fastener footprints at least +/- 0.100in. In order to avoid

the D-Nose shape like at the end of the bracket and have a straight run out,

Modify the enveloped provided where the bearing arm suddenly changes cross

section. See picture below.

Figure

Used bolts/hi-lites for#10 should have around .5 clearances for the head.

A #10(3/16”) Hi-Lite Tension head has a head diameter of 0.357-0.377 in.

9. Optimization results

Results from inspire 2015 after optimization

Results from inspire 2015 after optimization Fit smoothing

10.Yield stress

Load case 1 94,1% Load case 2 100,9%

Load case 3

11.Von mises

Load case 1 Load case 2

Load case 3

13.Major prinicple stresses after redsian results

s

Load case 1

1.410e+005

lbf/in2

Load case 2

1.331e+005

lbf/in2

Load case 3

1.289e+005

lbf/in2

13.Vom ises stress

1.320e+005

lbf/in2

Load case 2

1.265e+005

lbf/in

Load case3

1.289e+005

lbf/in2

14.Yield stress

Load case 1

Yield stress

91%

Load case 2

Yield stress

87,2

Load case3

Yield

stress88,9%

15.Manufacturing

The bracket is intended to be manufactured by additive manufacturing process.

Recommended Print Direction see figure

Figure.3 print direction

15. Conclusion

The Bracket is sized considering the best practices in inspire 2015 below are the

conclusions.

The stress plots for static cases show a stress of 100.9 % case load 2(more than Yield of

100%). This is due to the stress concentration effect. Ignoring the high stress areas due to Kt,

there is no yielding of the material for any of the static load cases.

Critical details have to be sized for cyclic loading. Sizing the component to Yield with

presence of a stress concentration is highly conservative.

If minor modifications could be done to the envelope provided, we could further optimize and

reduce the weight of the bracket as previously stated

Mass of the original model was 1,833lb. Modified model mass is now 0,502 lb. (228

gram)