Number of degrees of freedom of a double toggle mechanism for punching

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SUMMARY

The discussion centers on the application of the Kutzbach criterion to determine the degrees of freedom (d.o.f) of a double toggle mechanism used for punching. The calculation yields a d.o.f of 2, based on the formula: d.o.f = 3(n-1) - 2j1 - j2, where n equals 5 (the number of links), j1 equals 5 (the number of lower pair joints), and j2 equals 0 (the number of higher pair joints). However, the practical d.o.f is recognized as 1, due to the single input of shaft torque required to rotate link 1. This discrepancy suggests a limitation in the Kutzbach criterion's ability to account for the mechanism's geometry.

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  • Familiarity with mechanical linkages and their classifications
  • Knowledge of lower and higher pair joints in mechanisms
  • Basic principles of torque and its application in mechanical systems
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marellasunny
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This is a mechanism used for crushing rocks/punching holes(when horizontal). When I use the Kutzbach criterion to find the number of degrees of freedom,I get 2. Is this because of the failure of Kutzbach criterion to recognize the geometry of the mechanism or did I go wrong somewhere?

Kutzbach criterion:
$$d.o.f=3(n-1)-2 j_1-j_2$$
where n-number of links(=5 in this case)
j_1- number of lower pair joints(=5 in this case)
j_2-number of higher pair joints(=0 in this case)

P.S: The d.o.f is obviously 1 realistically speaking as there is just 1 input given i.e the shaft torque to rotate link1.
 
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Im actually having the same problem. Any help would be appreciated.
 

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