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Lateral Shoulder
Background
The Lateral Shoulder tool is used to process simulation results from a lateral hub impact to the shoulder [1]. This tool becomes active when rigid body part ID 5100028 is in the loaded binout data. The goal of the tool is to allow users to compare model outputs to both literature data and to the baseline GHBMC model following internal modifications.
The lateral shoulder impact, as per Koh et al., is simulated with an impact velocity of 4.5 m/s using a 23.4 kg impactor with a diameter of 15 cm. The impact is a 90° lateral impact occurring through the head of the humerus. For this study, deflection is normalized by the half bi-acromial width of the PMHS for comparison to the model and is presented as a percentage. Model shoulder compression is modeled as the difference in length between a node on the acromion and a node on the first thoracic vertebrae. The impact force is modeled as the contact force between the impactor and the shoulder. Experimental corridors were developed from unpadded impacts to 5 male and 1 female PMHS with
an average mass of 68.8 ± 12.0
The boundary condition files for validation cases are available in a directory called “validation_cases” within the Metriks installation folder: e.g. C:/Program Files (x86)/Metriks/validation_cases
When the Lateral Shoulder metric is calculated, two tabs are opened:
| Panel Descriptions for “Lateral Shoulder Impact” Tab | |
|---|---|
| Graphic of impact boundary condition and relevant simulation and post-processing information | Force vs Time response plotted against the Koh et al. (2005) corridors. The user loaded model is plotted in red and the baseline M50-O v5.1 with fracture on is plotted in black. |
| Deflection vs. Time response plotted against the Koh et al. (2005) corridors. The user loaded model is plotted in red and the baseline M50-O v5.1 with fracture on is plotted in black. | |
| Panel Descriptions for “Lateral Shoulder Energies” Tab | |
|---|---|
| Key aspects of the energy balance for the full simulation are reported | Human Body Model Energy Plot |
| Added mass and %Added mass as a function of initial mass are reported for the human body model | |
Data Processing Methods
Time
1. Extract simulation time from binouts
2. Set t = 0 one data point prior to initiation of impact loading (when contact force is > 0 kN)
Compression
1. Calculate Y-Displacement from right acromion (average coordinates of 4 nodes on right acromion flesh) and T1
a. For GHBMC M50-O v5.1.1: Right acromion nodes: 4148XXX (node set ID 4999306) and T1 node: 4300205
b. These default node IDs can be overridden in Human Body Model Settings under Nodes->T1 Anterior and Nodes->Right Acromion
2. Deflection is calculated using the change in the Euclidean norm
3. Normalize deflection by initial half bi-acromial length
a. For GHBMC M50-O v5.1.1: 165.96 mm (Koh Subjects: 157 mm)
b. This default measurement can be overridden in Human Body Model Settings under Measurements->Acromion-T1
Force
1. Extract resultant contact force data for hub to human body model shoulder skin
a. For hub in GHBMC M50-O v5.1.1: RCFORC ID 600000
2. Filter using SAE CFC 180
References
[1] Koh, S.W., Cavanaugh, J.M., Mason, M.J., Petersen, S.A., Marth, D.R., Rouhana, S.W., and Bolte, J.H.t. (2005) Shoulder injury and response due to lateral glenohumeral joint impact: an analysis of combined data. Stapp Car Crash J 49: 291-322.