Date of Award

5-2013

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Advisor

Vincent Caccese

Second Committee Member

Mohsen Shahinpoor

Third Committee Member

Zhihe Jin

Abstract

The University of Maine in cooperation with Alba-Technic LLC of Winthrop, Maine; is in the process of developing a product to mitigate head injuries due to falls within the elderly communities such as nursing homes and hospitals where a fall incident is potentially injurious or fatal. The goal of this thesis work is to determine an optimal combination of honeycomb and dilatant materials for protective headwear that reduces the likelihood of injuries such as skull fracture and traumatic brain injury. The work presented is part of a larger effort funded by the National Institutes of Health/National Institute on Aging where the focus is to develop protective headwear that is comfortable and socially acceptable among the elderly. Our work leads to a new method of testing the headwear that would produce consistent results and be more representative of real life falls. Also, through finite element analysis a combination of dilatant and honeycomb materials are optimized to produce the desired impact resistant at a minimal thickness. Preliminary testing of the materials is presented. The honeycombs have been manufactured in house using a patent pending method. Dilatant materials are chosen from a line of protection materials, PORON® XRD™, developed by Rogers Corporation. The materials are ultimately used in prototype headbands that are tested using the Hybrid III ATD head/neck apparatus.

We first present a preliminary study on the honeycomb and dilatant material using Abaqus FEA where the shell thickness, the depth of both the honeycomb and dilatant material, the geometry of the honeycomb, and the modulus of both the honeycomb and dilatant were varied for a complete understanding of the combination. With this information readily available, this thesis contains a preliminary multi variable optimization that gives pareto-optimal solutions where thickness is the constraint. The finite element model resembles a test done by Dr. John Lloyd in a joint effort for the project.

Secondly, this thesis presents a new twin wire testing method utilizing the Hybrid III ATD head/neck assembly where it was designed with the objective to simulate the condition of a fall impact that simultaneously induces linear and angular acceleration components. Currently, there are no testing standards for falls protection devices. Recent test apparatuses, for the most part, have been designed for motorcycle helmets, bike helmets, and an assortment of other helmets. These test apparatuses use rigid headforms which are not viable for head impact situations which consists of both rotational and linear components of acceleration.

Lastly, this thesis presents a physical study of various material combinations for Alba-Technic LLC as part of an effort to develop protective headwear. The materials are analyzed individually as well using an impactor manufactured just for material testing which gives an alternative to finite element analysis as a mean to reassure that the optimization process is indeed, reliable. Based upon these tests, an efficient combination of materials was selected and implemented into prototype headbands that are tested using the Hybrid III ATD head/neck apparatus.

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