The deformation associated with a ballistic shield defeating a projectile can interact with the user’s upper extremity, resulting in the release of the shield, placing those behind the device at risk. This injury mechanism is known as behind-shield blunt trauma (BSBT). Previous studies investigating these interactions have used testing conditions not representative of those present during these behind-shield events and lacked sufficient testing to determine statistically relevant outcomes.
In the present work, the loading present during ballistic shield deformation was characterized through testing using an Anthropomorphic Test Device (ATD) upper extremity placed behind a level III ballistic shield. Digital image correlation (DIC) and post-impacting X-ray imaging were used to assess the ballistic shield’s deformation. The data collected from ballistic testing informed the development of a projectile used with a pneumatic impactor for the application of BSBT in a lab-based setting.
Using the projectile, ballistic impacts were replicated on the ATD upper extremity and translated to 5th and 95th percentile cadaveric arms. Load data were collected for the hand and forearm using piezoelectric force sensors embedded in the projectile. Similarly, PMHS were impacted in a stepwise fashion of increasing energy until fractures were identified using X-ray imaging.
A novel scaling technique was developed where Partial Least Squares (PLS) was used to determine critical variables relating donor anthropometrics to peak impact force. The scaling equations generated using this technique offer future researchers the opportunity to employ a larger range of specimens when determining injury thresholds for the hand and forearm.
Through the characterization of the conditions present during BSBT, the injury thresholds to these mechanisms were assessed for understudied populations. Additionally, this work presents scaling techniques that could reduce the number of specimens required to determine future upper extremity injury limits. The information presented within this work provides an important step in developing new standards for ballistic shields to better protect users from BSBT. / Thesis / Master of Applied Science (MASc) / The deformation of a ballistic shield associated with stopping a bullet can interact with the user’s arm, causing them to drop the shield and placing the user in further danger.
This work aimed to assess the risks to the hand and forearm over a range of male sizes using mechanical and biomedical tools. Ballistic loading was characterized using a crash test dummy arm to understand the conditions present during the event. The injuries associated with this loading were assessed using cadaveric specimens and a custom projectile for replicating the impacts. Mathematical techniques were used to translate the injury thresholds to the exact user sizes – providing relevant metrics for future ballistic shield standards.
The results of this work present methods for recreating ballistic testing in a lab-based setting and for scaling forces associated with the hand and forearm, allowing future researchers to use a broader range of specimens for injury assessment.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/28907 |
| Date | January 2023 |
| Creators | Burrows, Liam |
| Contributors | Quenneville, Cheryl, Biomedical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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