Human Shoulder Response to High Velocity Lateral Impact

Area of Science:

• Biomechanics
• Injury Biomechanics
• Human Subject Research

Background:

• Developing reliable shoulder injury criteria for automotive safety dummies is essential for North Atlantic Treaty Organization (NATO) forces.
• Existing research on human shoulder response to lateral impact covers high-velocity (28 m/s, 3 ms) and low-velocity (4 m/s, 50 ms) conditions.
• Low-velocity impacts typically cause clavicle fractures, with acromion-to-sternum compression (Cmax) proposed as an injury criterion.
• High-velocity impacts often result in humerus fractures and humeral head crushing.

Purpose of the Study:

• To investigate human shoulder response to intermediate-velocity lateral impacts (14 m/s, 9 ms).
• To assess the applicability of existing injury criteria across a broader range of impact velocities and durations.
• To inform the development of a reliable shoulder injury criterion for the EuroSID-2re dummy.

Main Methods:

• Six lateral shoulder impact tests were conducted on three Post Mortem Human Subjects (PMHS).
• A rigid impactor with an aluminum honeycomb was used to control impact duration.
• Shoulder external deflection and applied forces were measured during impacts.

Main Results:

• Impact velocities averaged 14.3 m/s with durations around 9 ms.
• Shoulder external deflection ranged from 40 to 64 mm, with forces between 4.3 kN and 8 kN.
• Four out of six shoulders sustained Abbreviated Injury Scale (AIS) 2 injuries, including dislocations and fractures.
• Injury patterns were similar to low-velocity impacts, despite force responses resembling high-velocity impacts.

Conclusions:

• Human shoulder injury mechanisms at intermediate impact velocities (14 m/s) resemble those seen in lower-velocity automotive impacts.
• The observed acromion-to-sternum deflection values align with existing shoulder injury risk curves.
• Findings support the need for a comprehensive shoulder injury criterion applicable across diverse loading conditions for improved dummy performance.