This document summarizes a case study on the fatigue failure of a universal joint yoke and drive shaft in a power transmission system. Spectroscopic, metallographic, hardness, and finite element analyses were conducted on both components. The universal joint yoke was made of AISI 5049H low alloy steel and failed due to fatigue at stress concentration points. The drive shaft was made of AISI 94B30H boron steel and its surface hardness was lower than the inner surface, indicating failure originated at the surface. The conclusion was that both failures were due to fatigue and modifications could be made to strengthen high stress areas.

1. CASE STUDY ON
UNIVERSAL JOINT YOKE & DRIVE SHAFT
FATIGUE FAILURE IN POWER
TRANSMISSION SYSTEM
GROUP MEMBERS: -
1. Rupesh N. Waje
2. Rutvij A. Wakalkar
3. Saideep M. Vakte
4. Vinayak J.Umate GUIDED BY: -
5. Sumit M. Khobragade Mr. S. P. Dhavane

2. POWER TRANSMISSION SYSTEM

3. UNIVERSAL JOINT
Universal joint is a positive mechanical joint
used for connecting shafts, whose axes are
inclined at an angle to each other.
FUNCTIONS: -
Used to connect shafts in rotation
High torque transmission efficiency
Permits angular displacement

4. UNIVERSAL JOINT

5. UNIVERSAL JOINT FAILURES
BRINELLING SPALLING END GALLING

6. WELD YOKEFATIGUE/SHOCK BURNED TRUNOIN

7. FATIGUE FAILURE OF UNIVERSAL JOINT
Four analyses has been done as follows:-
• Spectroscopic Analyses
• Metallographic Analyses
• Hardness Measurement
• Finite Element Analyses

8. SPECTROSCOPIC ANAYLYSES
• Material for yoke: - AISI 5046H (Low Alloy Steel)
Mechanical Properties: -
Tensile Strength: - 1750 MPa
Yield Strength: - 1400 MPa
Good combination of strength, toughness, ductility
Fe C Si Mn Cr Mo S P
Yoke
Material
97.91 0.50 0.18 0.92 0.34 0.044 0.035 0.0027
AISI
5046H
98 0.44-0.5 0.23 0.88 0.28 - 0.04 0.035

9. METALLOGRAPHIC ANALYSES
• Microstructure contains Pearlite and Ferrite
• Material not quenched for sake of protection of
toughness
• Fine Pearlite formation as a result of air cooling

10. HARDNESS MEASUREMENT
• Rockwell A scale
• Mean Hardness Value : - 50.2 HRA

11. FINITE ELEMENT ANAYLYSES

12. DRIVE SHAFT
Functions: -
• To transfer the engine torque from gearbox or
differential to wheel
• To compensate for all variations in angle or length
resulting from maneuvering and deflection for
perfect synchronization between joints.

13. DRIVE SHAFT

14. DRIVE SHAFT FAILURES

16. SPECTROSCOPIC ANAYLYSES
• Material for yoke: - AISI 94B30H (Low Alloy Steel)
Mechanical Properties: -
Tensile Strength: - 1700 MPa
Yield Strength: - 1550 MPa
Boron steel having good formability
Fe C Si Mn Cr Ni Mo B S P
Shaft
material
98.21 0.32 0.2 0.81 0.31 0.14 0.059 0.0005 0.022 0.002
7
AISI
94B30H
97.7-
98.49
0.27-
0.33
0.15-
0.30
0.70-
1.05
0.25-
0.55
0.25-
0.65
0.08-
0.15
0.0005-
0.003
0.040 0.035

17. METALLOGRAPHIC ANALYSES
• Decrement in carbon content of surface region
• Structure consists of Martensite and Ferrite
• High Temp. heat treatment

18. HARDNESS MEASUREMENT
• Outer surface hardness is less than inner surface
(10%)

19. FINITE ELEMENT ANAYLYSES

20. CONCLUSION
• Failures of both is result of fatigue process
• High stress points should be identified in case of
universal joint
• Modification can be done at as a material addition to
inner part of yoke.
• Surface heat treatment of drive shaft should be done
at joining

21. THANK YOU