Failure of knuckle joint

The most common mode of failure is overloading. Operating forces of the application produce loads that exceed the clamp load and the joint works itself loose, or fails catastrophically. It occur due to shear forces and twisting moment.

we know the knuckle pin is used in knuckle joint to join the two shafts together and mode of failure of knuckle joint is failure due to crushing and failure due to shearing.when we exceed the designed load at the ends of the shafts then failure occurs.

Failure due to shearing:-

P= 2X shearing stress 

X shearing area

Failure due to crushing:-
P= crushing stress 

X crushing area

A knuckle joint has nine possible modes of failure. They are:

1. Failure of rod end by tension
2. Failure of rod end by double shear
3. Failure of rod end by crushing
4. Failure of forked ends by tension
5. Failure of forked ends by double shear
6. Failure of forked ends by crushing
7. Failure of knuckle pin by tension
8. Failure of knuckle pin by double shear
9. Failure of knuckle pin by bending