Neck Kinetics

Overview

The neck kinetics tool in Metriks reports time-history data of forward bending (extension/flexion) moment and axial loading (tension/compression) force through the C1 cross section. This data is the underlying data used to calculate N_ij.

Outputs

Panel Descriptions
3D Representation of Cross Section Sensor Plane used for Processing	Summary Tables with Peak Z Force (Compression-Tension), and Y Moment (Flexion-Extension)
	Plot of Force- and Moment-Time histories with both Y-axes sharing the same “zero” position.

Instrumentation Summary

Calculation Methods

Cross-sections through C1 are included in the default instrumentation of the detailed occupant models. The cross-section outputs include solid, shell, and beam element force and moment contributions from the soft and hard tissues cutting through the C1 plane. Forces and moments are calculated and transformed from the centroid of the cross-section plane to the vertebral body center as follows. These transformation methods are based upon a peer reviewed article related to neck kinetics in GHBMC [1].

1. Extract raw simulation data from the cross-section outputs:

a. Cross-section X, Y, Z forces

b. Cross-section X, Y, Z moments

c. Cross-section X, Y, Z centroid coordinates

2. Extract raw coordinates for the points defining the vertebral body center of gravity local coordinate system:

a. Coordinates for origin

b. Coordinates for X-direction vector point

c. Coordinates for Y-direction vector point

3. Calculate the Y-moment seen at the location of the vertebra’s local coordinate system from the forces and moments reported by the cross-section output to the local coordinate system.

a. The X, Y and Z distances between the local coordinate system and the cross-section’s centroid are calculated at each time point.

b. The cross product of this distance and the cross-sectional force components create “transformed moment” term.

c. The cross-section moment is summed with the “transformed moment” term to calculated the “total moment” output

4. Report Y-Moment as the “total moment” value described in Step 3c using N*m

5. Report Z-Force as C1 cross-section force using kN

References

[1] White, N. A., Moreno, D. P., Gayzik, F. S., & Stitzel, J. D. (2015). Cross-sectional neck response of a total human body FE model during simulated frontal and side automobile impacts. Computer methods in biomechanics and biomedical engineering, 18(3), 293-315.