fatigue analysis of ball joint.ppt

8/10/2019 Fatigue Analysis Of ball joint.ppt

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Fatigue Life cycle Analysis onSteering Knuckle Ball Joint

GUIDE -

Mr.A.R.SURESH M.E

Assistant professor (ss)

Dr.MCET

S.PRADEEP

ME(CAD/CAM)

Dr.MECT-POLLACHI


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OBJECTIVE OF THE PROJECT

Optimized design of a Steering KnuckleBall Joint with increased life condition.


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Broken specimen of a ball joint


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Specimen preliminary investigations

From the broken samples it is found that maximum failure

occurs at the neck region of the ball joint.

Fractured parts are investigated for surface defects throughSEM analysis, and results are collected.


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Chemical Composition of SAE 4135

grade steel

Elements Symbol Unit Specified Values Observed Values

Carbon C % 0.33-0.38 0.334

Silicon Si % 0.15-0.35 0.229

Manganese Mn % 0.70-0.90 0.774

Phosphorus P % 0.035 Max 0.013

Sulphur S % 0.040 Max 0.004

Chromium Cr % 0.80-1.10 1.06

Molybdenum Mo % 0.15-0.25 0.184


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Mechanical Properties

Properties SAE4135

Diameter (d) mm >16-40

Thickness (t) mm 8


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SEM Analysis

a) Origin of the crack b) Fracture features of origin


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SEM - Result

There is enough evidence of micro crack on the surface ofthe neck region just below ball.

The broken samples show that the crack originate from the

top surface as it experience a uni-directional knocking load.


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EXPERIMENTAL DETAILS

INSTRON servo-hydraulic

actuator of 25 KN

capacity

The test frequency

was 0.55 Hz

Fatigue test under cyclic loading

Fatigue test on steering knuckle ball joint

Constant amplitude

cyclic loading with load

ratio of 0.3


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CASEI : Ball joint (30,R1.5,L-54mm)

Boundary and Loading Condition Stress distribution

Total Deformation Life cycle


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CASEII : Ball joint (33,R3,L-64mm)

Boundary and Loading Condition Stress distribution

Total Deformation

Log-Life cycle repeated


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Existing neck region Modified neck region

Angle

Von-Mises Stress

(Mpa)Total deformation (mm) S-N -N

Ratio

Min Max Min Max Fatigue Life(Gerber)

Marrow- Fatiguelife

SWT -Fatigue life

30 0 918.63 0 0.01065 18553 1.87E+05 2.91E+05 0.3

31 0 611.87 0 0.064 35114 3.65E+06 3.89E+06 0.3

32 0.0003 621.87 0 0.0644 33233 3.24E+06 3.47E+06 0.3

33 7.55E-05 599.37 0 0.0683 37876 4.22E+06 4.46E+06 0.3

35 0.00013 609.41 0 0.069 35635 3.68E+06 3.92E+06 0.3

36 0.0002 604.26 0 0.0694 36763 3.94E+06 4.18E+06 0.3

37 0.00015 608.39 0 0.0694 35855 3.73E+06 3.97E+06 0.3

38 0.00015 865.2 0 0.106 10326 2.28E+05 3.21E+05 0.3

Fatigue Strength factor -1 TypeFull Reversed

EXPERIMENTAL DETAILS (Contd)


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Specimen ID

Life

Experimental Software Result

Ball 1-1 2.514E+05 4.222E+06

Ball 1-2 2.544E+05

4.222E+06

Ball 1-3 2.471E+054.222E+06

Ball 1-4 2.504E+054.222E+06

Ball 1-5 2.533E+054.222E+06

Case study 1- Experimental Results Vs Software result


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S-N Curve


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Results of design for Infinite number of cycles

Design for Infinite number of cycles

ParameterExisting Design Improved Design

Min Max Min Max

Von mises stress 7.55E-05 599.37 7.41E-10 380.78

Total deformation 0 0.0683 0 0.043

Stress ratio 0 0.93 2.18E-12 1.5231

Safety margin 0.071 14 -0.343 14

Stress safety factor 0.933 15 0.656 15

S-N Life (Gerber)

Life cycle (cycle) 37876 1.00E+06 1.98E+05 1.00E+06

Equivalent

Alternating stress

(Mpa)

2.26E-05 179.81 2.23E-10 114.23

Safety factor 4.79E-01 15 0.7546 15

Bi-axiality Indication -1 0.9879 -1 0.978

Fatigue Sensitivity 9.17E+03 7.85E+05 4.52E+04 1.00E+06

-N - Life (Marrow )

Life cycle (cycle) 4.21E+06 1.00E+12 2.06E+08 1.00E+12

Damage 1.00E-03 2.37E+02 1.00E-03 4.81E+00

Safety factor 5.34E-01 15 0.84 15Bi-axiality Indication -1 0.9879 -1 0.978


-NLife (SWT )

Life cycle (cycle) 4.46E+06 1.00E+09 2.06E+08 1.00E+12

Damage 1.00E+00 2.24E+02 1.00E-03 4.84E+00

Safety factor 5.34E-01 15 0.84 15

Bi-axiality Indication -1 0.9879 -1 0.978



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Results from analysis

A maximum load of 4000 N applied perpendicular to theaxis of the of the ball joint .

Maximum deformation of 0.010 mm occur at Edge of the

surface.

Maximum stress of 380.3Mpa ( Von Mises )is found out inthe necked region.

When the parameter viz. Radius, angle, length and

diameter increase the fatigue life is increased.


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Conclusion

The software results which were obtained for fatigue lifepredictions reasonably good agreement with the

experimental results.

The increase in the taper angle () the radius but, the life

is decrease first and then increase for the increase in the

taper angle.

For the given tapper angle and radius increase in the length

(L) increase the life of the component.

With the limits of the parameters considered the tapperangle 33radius 3mm and the length 64mm gives the better

life.


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Future Works

The same design study can be utilized for othercomposition of materials.

This design study can be tried for the variable load

application also.

This design study can be tried for fracture surface onbending and torsion loading.


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Thank You

fatigue analysis of ball joint.ppt

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