KUTZBACH CRITERIA AND GRUBLERS CRITERIA

KUTZBACH CRITERIA
AND
GRUBLERS CRITERIA

By: www.mechaholic.in

Degree Of Freedom in 3D

Degree of Freedom (DOF) of a body is defined as number of independ movement the body has

A body in 3D has 6 Degree of Freesom

3 Rotational

3 Translational

Degree Of Freedom in 2D (Planar)

A body in 2D has 3 Degree of Freesom

1 Rotational

2 Translational

Basic Term

Links

Link is a member or combination of member connecting each other and has relative motion between each other

Kinematic Pair

Lower Pair

It is a pair of link which have surface to surface or area contact between members.

Eg: Nut and Screw Assembly, Slider and Slotted Link

Higher Pair

If a pair has point or line contact between links or member

Eg: Cam And Follower Ball Bearing

KUTZBACH CRITERIA

Kutzbach Criteria is for determining Degree of Freedom of body in Planar Mechanism ( 2D)

Here:

L = Number of Link

J = Number Of Lower Pair

H = Number Of Higher Pair

Example

Formula is DOF = 3 (L-1) 2 J H

DOF = 3 (7-1) 2 (8) (1)

Therefore DOF = 1

GRUBLERS CRITERIA

When Higher Pair (H) = 0 in Kutzbach Criteria then the Equation procured is Grubler's Criteria

Here:

L = Number of Link

J = Number Of Lower Pair

Example

Formula is DOF = 3 (L-1) 2 J

DOF = 3 (8-1) 2 (10)Therefore DOF = 1

Thank You

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