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Tibia Moment Correction

Overview​

Due to the implementation of a ball joint in the ankle of the Hybrid-III dummy, there are offsets between the tibia axis, and the ankle and knee joints [1]. Due to these offsets, the y moment in the tibia needs to be corrected in order to accurately report upper and lower y-axis moments.

Calculation​

Calculated based on Zuby et al. [1]

My, upper adjusted=My, upper measured−(Fz, tibia∗0.02832 meters)(Equation 1)\tag{Equation 1}M_{y, \,upper\, adjusted} = M_{y, \, upper \,measured} - (F_{z, \, tibia} * 0.02832\,meters) My, lower adjusted=My, lower measured+(Fz, tibia∗0.006398 meters)(Equation 2)\tag{Equation 2}M_{y, \, lower\, adjusted} = M_{y, \, lower \,measured} + (F_{z, \,tibia} * 0.006398\,meters)

Hybrid III Tibia Zuby

Hybrid-III Dummy Tibia Offsets [1]

References​

[1] Zuby, David S., Joseph M. Nolan, and Christopher P. Sherwood. "Effect of Hybrid III leg geometry on upper tibia bending moments." SAE transactions (2001): 177-189.