Impact dissipation of EPS boost foam

• Main Author: Tan, Han Ting
• Other Authors: Alfred Tok Iing Yoong
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/73761
• Institution: Nanyang Technological University

The use of safety helmets, as a head protection device, is critical in protecting a cyclist from head injuries when met with an accident. It serves to provide appropriate protection against head-related injuries for cyclist, especially those engaging in sports with high speeds, which implies potential crashes and falls leading to injuries or even fatality. In a safety helmet, the energy absorbing liner is considered the most important component, since it absorbs and dissipates most of the impact energy during an accident. The final year project aims at investigating the impact dissipation of EPS foams with the use of modified chopsticks to introduce holes within the foam (EPSO). The foam comprises of multiple parallel cylindrical holes induced within for improved performance of impact dissipation properties. The chopsticks were designed to fit the mould and were introduced during the expansion process of manufacturing an EPS foam. Before manufacturing of specimens for testing, more than 40 manufacturing trials have been carried out to understand the EPS manufacturing process better. After familiarizing and perfecting the conditions for the expansion of EPS foams, specimens were manufactured for mechanical testing. Flexure and hardness test were carried out for the EPS samples to better understand the effect of varying density on its mechanical properties. Impact test was also carried out to conclude the impact dissipation performance of the specimens for helmet applications. Experimental results showed that for impact performance, EPSO foams with the inclusion of holes performed better in terms of energy absorption, with up to 4.7 increase in energy absorbed for EPS foams with 6 holes. For hardness performance, foams with higher densities (60g/L±) had the highest hardness, up to 14% higher than lighter densities (30g/L±) foams. For flexural performance, higher density foams had up to 97% higher modulus compared to the lower density foams.