Stress Concentration in Snap Ring Grooves

Jon Shelley

Doug Hogge

Description of Project

Description of Project

Create a Model to Determine Stress in a Snap Ring Groove

Calculate Stress Concentration Factor Create Graph Showing Stress Concentration Compare Results to Actual Snap Ring Groove

Dimensions

Method Used to Accomplish Project

Macro File

Results File

Model – Macro File

!IMPORT PARAMETERSPARRES, CHANGE,ring,exp,

!Keypointsk,1,0,0k,2,0,lk,3,OD/2,lk,4,OD/2,t/2+r

!Material PropertiesMP, EX, 1, 30.00000E+06MP, NUXY, 1,0.27

!Mesh ConstraintsLESIZE,8, , ,12,0, , , ,1 ames,2

!Boundary Conditions and LoadsSFL,8,PRES,-FYload,

!Solve Model/SOLU SOLVE

!Retrieve Outputnsort,s,y*get,syMax,sort,0,max

!Save Output to a File/output,ring,post,,

!Exit Macro File/EXIT,NOSAVE,,,

Model-Geometry

OD (1”- 4”) Ratio (1.02 – 1.1) Height (2”)

Radius (0.005” – 0.015”) Gap (0.1”)

Model-Mesh Original

Elements (53-400) Nodes (200-1,517)

Refined Elements (1,649-10,132) Nodes (5,140 – 31,005)

Mapped and Free Mesh

Model-Boundary Conditions Surface Load Axisymmetric Element Symmetry about X-Axis

Model Verification

Model Verification Radius vs. Stress

0

10000

20000

30000

40000

50000

60000

70000

80000

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

Radius

Str

es

s

Original

Refined

Original – (1 hr) Refined – (7 hrs)

Two Models – (0.5% - 1%) Original vs. Refined – (2% - 11%)

FEA Results

Stress Concentration Factor

  

nom

Kt max

reducednom A

P

2

2

id

Areduced

Loadod

P2

2

LoadRatioKt

2max

DOE

Outside Diameter13 Values (1” – 4”)

Radius4 Values (0.005” 0.007” 0.01” 0.015”)

Ratio of Outside to Inside Diameter9 Values (1.02 – 1.1)

Total of 468 Runs

DOE Results

DOE Stress Results

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

100,000

0 50 100 150 200 250 300 350 400 450 500

Run Number

Str

ess

Stress Increase as Radius Decreases Ratio Increase OD Increases

Stress Concentration PlotStress Concentration of A Snap Ring Groove R=0.007"

0

1

2

3

4

5

6

7

0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009

Radius/Inside Diameter

Kt

Str

es

s C

on

ce

ntr

ati

on

1.02

1.03

1.04

1.05

1.06

1.07

1.08

1.09

1.1

Comparison to Actual Values

ratio od r Chart Kt Calculated SyMax Ansys SyMax Ansys Kt Error1.0504 1 0.005 3.3 36411.62347 36,650 3.322 -0.6534081821.0549 1.5 0.005 4.1 45621.25016 44,458 3.995 2.549053681.0627 2 0.005 4.8 54207.82603 52,996 4.693 2.2356661721.0495 2.5 0.005 4.9 53974.99156 52,668 4.781 2.4213094251.0409 3 0.005 4.8 52011.07065 52,471 4.842 -0.8839643971.0410 3.5 0.005 5.1 55272.72122 56,167 5.182 -1.6170341461.0357 4 0.005 5.2 55782.60446 56,079 5.228 -0.532200925

1.0504 1 0.01 2.7 29791.3283 28,572 2.590 4.0914869051.0549 1.5 0.01 3.21 35718.10073 35,738 3.212 -0.0561879491.0627 2 0.01 3.9 44043.85865 42,297 3.745 3.9662252631.0495 2.5 0.01 3.8 41858.15672 42,044 3.817 -0.4434339591.0409 3 0.01 3.95 42800.77689 41,891 3.866 2.1255382671.0410 3.5 0.01 4.05 43893.04333 44,734 4.128 -1.9165603731.0357 4 0.01 4 42909.69574 44,667 4.164 -4.096053885

Error Between Actual and Calculated Values (0.05% - 4.09%)

Conclusion

Refined model produced less variation but increased processor time

Ansys can be used as a powerful tool for design studies Model should be compared with actual data From our results equations could be found to calculate stress

concentration in snap ring grooves