Access Type

Open Access Dissertation

Date of Award

January 2013

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Biomedical Engineering

First Advisor

King H. Yang

Second Advisor

Chris A. VanEe

Abstract

Injuries in motor vehicle accidents continue to be a serious and costly societal problem. Automotive safety researchers have observed noticeable lateral bending of the anthropomorphic test device (ATD) neck prior to or in conjunction with head impact with the vehicle roof in rollover crash tests. Since there is scant data available about the effects of lateral bending on overall compressive tolerance of the human cervical spine, it is unknown if the presence of lateral bending is important to consider during impacts with the apex of the head. Compressive injury tolerance has historically been reported by identifying the axial force at the time of injury measured at the base of the neck, however, axial force at failure exhibits variation and this has been attributed to the alignment of the cervical vertebra and the end conditions of test methodology used. Robust and sensitive injury metrics for human compressive cervical spine tolerance that can be applied to a wide range of loading conditions and head-neck postures would be useful in evaluating and developing mechanically meaningful and robust anthropomorphic test devices (ATDs) and their associated injury assessment reference values (IARVs). As the Hybrid III ATD continues to be used in automotive rollover applications, interpretation of measured neck loads in this testing mode would be aided by a better understanding of human cervical spine response and tolerance in compression dominated combined loading scenarios and their correlation to Hybrid III ATD neck responses.

The effects of lateral bending on the compressive cervical spine dynamic response and tolerance was investigated through post mortem human subject (PMHS) head-neck complex experimentation. Similar to findings of previous researchers, the initial cervical posture influenced the mechanical response of the spine and the loads at failure. The results were combined with available historical compressive cervical spine tolerance studies that include head and neck dynamics, cervical kinetics and known end conditions. A re-evaluation of the axial force tolerance of the PMHS cervical spine as well as derivation of a mechanistically relevant eccentricity based injury tolerance metric that can be applied to a wider range of loading vectors and initial cervical spine postures were conducted. Finally, the Hybrid III ATD neck compressive injury assessment reference values (IARVs) were evaluated through reconstruction of PMHS experiments with known injury outcomes using the Hybrid III head and neck assembly. Results are consistent with the currently defined IARVs and provide additional experimental support of the IARVs in loading modes that are known to result in PMHS compressive cervical injuries.

Download

Share

COinS