Kutzbach Criterion

Kutzbach Criterion

DOF of a mechanism in space can be determined as follows:

In mechanism one link should be fixed. Therefore total no. of movable links are in mechanism is (N-1)

Any pair having 1 DOF will impose 5 restraints on the mechanism, which reduces its total degree of freedom by 5P1.

Any pair having 2 DOF will impose 4 restraints on the mechanism, which reduces its total degree of freedom by 4P2

Similarly, the other pairs having 3, 4 and 5 degrees of freedom reduce the degrees of freedom of mechanism. Thus,

Thus,

Hence,

F = 6 (N-1) – 5 P1 – 4 P2 – 3 P3 – 2 P4 – 1P5 – 0P6

Hence,

F = 6 (N-1) – 5 P1 – 4 P2 – 3 P3 – 2 P4 – 1P5

The above equation is the general form of Kutzbach criterion. This is applicable to any type of mechanism including a spatial mechanism.

 

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