This paper describes an alternative method for helmet design using finite element analysis (FEA). While previous research has illustrated the use of FEA as a tool to simulate standard helmet tests, the objective of this research was to use FEA as a tool to optimize the performance characteristics of the energy absorbing (EA) liner of an existing Navy helicopter pilot helmet (i.e., the HGU-84/P). Three dimensional finite element models (FEM) of the helmet components and the test headform were developed using MSC software and material properties were estimated from published data and physical tests. A 6.0 m/s flat anvil impact was then simulated at three different sites on the helmet using MSC.Dytran software and these simulations served as the baseline. Full scale impact tests were performed with an examplar helmet in order to confirm the validity of the simulations as well as the helmet shell and liner material properties.

A group of candidate EA materials were obtained and physical impact tests were conducted in order to quantify the stress-strain characteristics of each candidate material. These stress-strain characteristics were then used to define the material properties of the existing HGU-84/P helmet liner FEM, effectively replacing the existing helmet EA liner with one fabricated from the candidate material. Whenever possible, a given EA liner material was evaluated over a range of densities. This allowed the researchers to study the effect of manipulating the EA liner density properties of the helmet without the necessity of conducting physical tests.

A total of 13 EA materials in different densities were evaluated by conducting over 120 FEM impact simulations at each of the three impact sites. The performance of a given EA liner material was evaluated by comparing simulation results with the peak headform acceleration values obtained from physical tests of the actual HGU-84/P helmet. The simulation results effectively predicted trends in liner material performance and making it possible to identify a small group of EA liner materials with a good likelihood of providing improved impact protection.

The results of this research clearly illustrate that FEA can be an effective tool for the analysis and design of both new and existing helmet designs. Simulation of various helmet liner materials allows for the evaluation of multiple material configurations, without the expense associated with production and testing of physical prototypes. This research and development tool can be particularly useful in the evaluation of new energy absorbing materials in applications where production and testing of individual helmet samples is quite costly (e.g., advanced composite helmet designs) and for applications where the geometric properties of the helmet are fixed (e.g., existing helmet designs).