Year

2020

Season

Spring

Paper Type

Master's Thesis

College

College of Computing, Engineering & Construction

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Engineering

NACO controlled Corporate Body

University of North Florida. School of Engineering

First Advisor

Grant Bevill

Second Advisor

James Sorce

Third Advisor

Alexandra Schonning

Abstract

Struck-by accidents are a leading cause of traumatic brain injuries in the construction industry. While hard hats are the conventional means of industrial head protection, the current test standard to evaluate hard hat performance does not assess their ability to mitigate head accelerations from such impacts. To address this gap in knowledge, three investigations were pursued as part of this thesis. First, a variety of commercially available hard-hat designs – differentiated by shell design, number of suspension points, and suspension tightening system – were tested for their ability to attenuate accelerations during vertical impacts to the head. All hard-hats appreciably reduced head acceleration to the unprotected condition. However, neither the addition of extra suspension points nor variations in suspension tightening mechanism appreciably influenced performance. Second, the same hard hat designs were tested for their ability to attenuate head accelerations when subjected to impacts in two different head orientations – upright and forward-flexed by 30°. Impacts to the forward-flexed head resulted in the largest measured angular accelerations, and hard-hats were least effective at mitigating angular accelerations in this head position. Additionally, no correlations were observed between hard hat performance in an upright head orientation versus forward-flexed orientation. Results from this study provide insight into why impacts to a forward-flexed head are prevalent in epidemiological data, and also suggest that current hard-hat designs may not be optimized for impacts to a forward-flexed head. Lastly, a validated finite element model of a hard-hat was developed that accounted for more geometric detail than other models previously seen in literature. This validation process highlighted the importance of specific design features present in a hard-hat (such as headband attachments) and their influence in construction worker’s safety against head injuries. Taken together, the work here represents a significant advance towards improving occupational safety in the construction sector.

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