Material Model Development and Validation of A High Energy Absorbing Foam Which Used in Flyer’s Helmet

Abstract

Pilot helmets are exposed to many environmental factors during their use. These environmental factors need to be handled very carefully in order not to adversely affect the user's health. In this sense, one of the biggest concerns of engineers is the impact scenarios that can damage the pilot's brain and even cause death. For this reason, pilot helmet designs need to ensure that the helmet has energy absorbing properties to protect the wearer from impacts and at the same time, the helmet should be lightweight to avoid damage on pilot's neck. In this thesis, the finite element model of the energy absorbing foam to be used in the pilot helmet has been created and validated. Expanded polystyrene material is used as energy absorbing foam. In order to understand the dynamic properties of the material, uniaxial compression tests were performed at different speeds. According to the test data obtained, it was modeled in two different ways as crushable foam and low-density foam in LS-Dyna program. A total of four different finite element models were constructed using two different mesh structures for each model. i

In order to prove the accuracy of the finite element model and to determine other parameters, impact tests were performed on four different thickness specimens. Comparative results of all models with impact test are presented. As a result, it is found that the results obtained by finite element analysis are close enough to the experimental results.