Application of Air-Bubble Cushioning to Improve the Shock Absorption Performance of Type I Industrial Helmets

The industrial helmet is the most used and effective personal protective equipment to reduce work-related traumatic brain injuries. The Type I industrial helmet is a basic helmet model that is commonly used in construction sites and manufacturers. The purpose of the current study was to investigate if shock absorption performance of these helmets could be improved by using an air-bubble cushioning liner to augment the helmet’s suspension system. Drop impact tests were performed using a commercial drop tower test machine according to the ANSI Z89.1 Type I drop impact protocol. Typical off-the-shelf Type I industrial helmets were utilized in the study. The effects of the air-bubble cushioning on the helmets’ shock absorption performance were evaluated by comparing the original off-the-shelf helmet samples to the helmets equipped with an air-bubble cushioning liner. The air-bubble cushioning liner (thickness 5 mm) was placed between the headform and the helmet when being tested. The impactor had a mass of 3.6 kg and was free-dropped from different heights. The maximal peak transmitted forces for each of the tests have been evaluated and compared. Our results show that the shock absorption effectiveness of the air-bubble cushioning is dependent on the magnitude of the impact force. At lower drop heights (h \u3c 1.63m), the air-bubble cushioning liner has little effect on the transmitted impact forces, however, at higher drop heights (h ≥ 1.73m) the air-bubble cushioning liner effectively reduced the peak transmitted forces. At a drop height of 1.93 m (the highest drop height tested), the air-bubble cushioning liner reduced the peak transmitted force by over 80%. Our results indicate that adding an air-bubble cushioning liner into a basic Type I industrial helmet will substantially increase shock absorption performance for large impact forces

Application of Polyethylene Air-Bubble Cushions to Improve the Shock Absorption Performance of Type I Construction Helmets for Repeated Impacts

BACKGROUND: The use of helmets was considered to be one of the important prevention strategies employed on construction sites. The shock absorption performance of a construction (or industrial) helmet is its most important performance parameter. Industrial helmets will experience cumulative structural damage when being impacted repeatedly with impact magnitudes greater than its endurance limit. OBJECTIVE: The current study is to test if the shock absorption performance of Type I construction helmets subjected to repeated impacts can be improved by applying polyethylene air-bubble cushions to the helmet suspension system. METHODS: Drop impact tests were performed using a commercial drop tower test machine following the ANSI Z89.1 Type I drop impact protocol. Typical off-the-shelf Type I construction helmets were evaluated in the study. A 5 mm thick air-bubble cushioning liner was placed between the headform and the helmet to be tested. Helmets were impacted ten times at different drop heights from 0.61 to 1.73 m. The effects of the air-bubble cushioning liner on the helmets’ shock absorption performance were evaluated by comparing the peak transmitted forces collected from the original off-the-shelf helmet samples to the helmets equipped with air-bubble cushioning liners. RESULTS: Our results showed that a typical Type I construction helmet can be subjected to repeated impacts with a magnitude less than 22 J (corresponding to a drop height 0.61 m) without compromising its shock absorption performance. In comparison, the same construction helmet, when equipped with an air-bubble cushioning liner, can be subjected to repeated impacts of a magnitude of 54 J (corresponding to a drop height 1.52 m) without compromising its shock absorption performance. CONCLUSIONS: The results indicate that the helmet’s shock absorbing endurance limit has been increased by 145% with addition of an air-bubble cushioning liner