Date on Master's Thesis/Doctoral Dissertation

12-2008

Document Type

Master's Thesis

Degree Name

M. Eng.

Department

Mechanical Engineering

Committee Chair

Bertocci, Gina E.

Subject

Wheelchairs--Design and construction

Abstract

For persons with disabilities, access to transportation is necessary for integration into society. The Americans with Disabilities Act (ADA) has been instrumental in assuring transportation access to individuals with disabilities for purposes of employment, education, and recreation. A substantial number of wheelchair users may not be able to transfer from their wheelchair to a motor vehicle seat during transportation. It is necessary to afford these wheelchair users the same level of safety as occupants seated in motor vehicle seats. The purpose of this study was to investigate the response of a manual wheelchair used as a motor vehicle seat, while the motor vehicle is subjected to rear impact. The specific aims of the study were to (1) identify the most common wheelchair failure mechanisms in a forward facing manual wheelchair subjected to rear impact, (2) develop and validate a computer simulation model of a wheelchair and seated occupant in rear impact, (3) develop wheelchair manufacturer transportation safety design guidelines under rear impact conditions for adult manual wheelchairs, by defining critical loads, wheelchair response, and common failure mechanisms, and (4) develop Wheelchair Tiedown and Occupant Restraint System (WTORS) manufacturer safety design guidelines under rear impact conditions for securing adult manual wheelchairs, by defining critical loads. In the first part of the study, several rear impact sled tests were performed with a commercial, WC19, manual wheelchair in its original configuration. The wheelchair occupant was represented by a midsized male anthropomorphic test device (ATD) and the sled tests were carried out according to the proposed ISO rear impact standard. The first set of sled tests were used to identify common wheelchair failure mechanisms under rear impact conditions: front securement point hardware failure, seatback failure, and failure of the wheelchair frame. A second set of sled tests were conducted with three reinforced, manual, WC19 wheelchairs which did not exhibit failures. Test results from the reinforced wheelchairs were used in the development and validation of a MADYMOTM computer simulation model of the rear impact scenario. During the validation process, key outcome measures from the sled tests were compared to those in the model. Statistical analysis was performed to quantify how well the model outcome measures matched those obtained from sled tests. The model was ultimately deemed validated and used to conduct the parametric sensitivity analysis. In the parametric sensitivity analysis key model parameters were varied, while outcome measures associated with wheelchair component and WTORS loading were monitored. Together with the common wheelchair failure modes, the parametric sensitivity analysis yielded rear impact design guidelines for wheelchair and WTORS, which will aid in the design, development, and ultimately introduction of rear impact crashworthy wheelchairs and WTORS.

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