Browsing by Author "De Jongh, Cornelis Uys"

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    Towards a protocol for evaluating unrestrained torso neck braces.
    (Stellenbosch : Stellenbosch University, 2024-02) De Jongh, Cornelis Uys; Basson, AH; Knox, EH; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: The relatively recent introduction of neck braces for the unrestrained, helmeted rider in extreme activities has necessitated an understanding of the underlying biomechanics resulting from headfirst impacts while wearing these devices. Currently, no established or commonly accepted pathway exists to independently evaluate, and subsequently approve, these devices. The aim of this dissertation is to propose key elements of a protocol for the evaluation of unrestrained torso neck braces resulting in a reliable determination of intervention efficacy. Specific objectives include identifying the relevant neck injury mechanisms from literature, recreating those mechanisms in testing and computational simulations, and identifying applicable neck measures, criteria, and injury risks to evaluate. A further objective is to critically evaluate the proposed methods, measures, and correlates through a case study, using a neck brace. The dissertation presents two tests and a computational model to evaluate neck brace efficacy. The first test, an inverted pendulum test, is proposed to evaluate compression flexion, tension flexion, and tension extension using an HIII ATD neck, and a motorcycle-specific ATD neck (MATD). The second test addresses the most important neck injury mechanism related to motorcycle accidents, compression flexion. This test distinguishes itself from the first test in that the degree of anterior head impact eccentricity is reduced and the baseline impact energy results in neck axial forces approaching injury assessment reference values (IARV). Using a current neck brace as a case study, the proposed tests bring to light important observations in evaluating a neck brace for each mechanism investigated. The ability of the tests to underscore the potential benefits and adverse effects of a neck brace is investigated through the evaluation of the appropriate upper and lower neck response measures. Lastly, a solid-body computational model is proposed to simulate neck response with and without a neck brace for a variety of head impact conditions. These simulations may be used to augment tests that use an HIII ATD neck, considering the challenges associated with using these instruments. The computational model can highlight aspects such as changing neck brace efficacy for varying impact configurations. The proposed method identifies a set of novel methods to visualize and interpret computed neck response data with and without a neck brace when large datasets are created. This work contributes towards the establishment of a novel protocol by which to gauge neck brace performance using applicable biomechanical considerations through testing and computational biomechanics. The chosen loading modalities, neck injury mechanisms, resulting neck response measures, injury criteria, and injury risks evaluated are relevant to the proposed analyses and create a basis for the establishment of a formal testing protocol. A protocol whereby unrestrained torso neck braces can effectively and critically be evaluated will allow product designers to be creative in their endeavors while conforming to a set of safety measures that effectively address important biomechanical considerations required for these device types. The combination of testing and real-world impact simulations enables the efficacy prediction of neck braces to converge with real-world effectiveness.