Influence of ATD versus PMHS reference sensor inputs on computational brain response in frontal impacts to advanced combat helmet (ACH)

ABSTRACT

Objective: This study analyzed the influence of reference sensor inputs from anthropomorphic test devices (ATDs) versus postmortem human subjects (PMHSs) on simulations of frontal blunt impacts to the advanced combat helmet (ACH).

Methods: A rigid-arm pendulum was used to generate frontal impacts to ACHs mounted on ATDs and PMHS. An appropriately sized ACH was selected according to standard fitting guidelines. The National Operating Committee on Standards for Athletic Equipment (NOCSAE) head was selected for ATD tests due to shape features that enabled a realistic helmet fit. A custom procedure was used to mount a reference sensor internally near the center of gravity (CG) of the PMHS. Reference sensor data from the head CG were used as inputs for the Simulated Injury Monitor (SIMon). Brain responses were assessed with the cumulative strain damage measure set at 10%, or CSDM(10).

Results: Compared to ATD tests, PMHS tests produced 18.7% higher peak linear accelerations and 5.2% higher peak angular velocities. Average times to peak for linear accelerations were relatively similar between ATDs (5.5 ms) and PMHSs (5.8 ms). However, times to peak for angular velocities were higher by a factor of up to 3.4 for PMHSs compared to ATDs. Values for were also higher by a factor of up to 13.1 when PMHS inputs were used for SIMon.

Conclusions: The preliminary findings of this work indicate that small differences in ATD versus PMHS head kinematics could lead to large differences in strain-derived brain injury metrics such as CSDM.

KEYWORDS:

• Anthropomorphic test device (ATD)
• postmortem human subject (PMHS)
• advanced combat helmet (ACH)
• finite element (FE)
• Simulated Injury Monitor (SIMon)
• cumulative strain damage measure (CSDM)

Additional information

Funding

This material is the result of work supported with resources and use of facilities at the Zablocki VA Medical Center (ZVAMC) in Milwaukee, Wisconsin; the Department of Neurosurgery at the Medical College of Wisconsin (MCW); and the U.S. Army Medical Research and Materiel Command in Fort Detrick, Maryland (W81XWH-16-1-0010). N.Y. and F.A.P. are part-time employees of the ZVAMC. Any views expressed in this article are those of the authors and not necessarily representative of the funding organizations.