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Study Tests Durability and Life Expectancy of Titanium Wheelchairs
Newswise — A titanium wheelchair can be less than one-half the weight of an aluminum or steel wheelchair, reportedly while maintaining the same strength. To determine whether titanium wheelchairs really do have equal strength and durability, researchers at the Department of Veterans Affairs Human Engineering Research Laboratories recently tested 12 ultralight titanium rigid-frame wheelchairs against the American National Standards Institute (ANSI)/Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) testing standards.
The ANSI/RESNA testing standards are recommended by the U.S. Food and Drug Administration to assess performance and durability and to estimate life expectancy of a wheelchair. According to a study just published in Volume 45, Issue 9 of the Journal of Rehabilitation Research and Development (JRRD), wheelchair manufacturers and designers should perform more careful analyses before commercializing new products.
The durability of the titanium wheelchairs was tested using static, impact, and fatigue strength tests. All of the tested titanium wheelchairs passed the impact strength tests, but six wheelchairs failed the static strength tests. Two types of failures were found in the static strength tests. The first involved a deformation of the armrest mounting plates after a 760 N* downward force was applied on the armrests, which then led to the undamaged armrests bowing outward and impeding hand propulsion. The second involved the handgrips sliding off the handles when a 750 N* backward-pulling force was applied to the handgrips.
Fatigue strength was evaluated by the double-drum and curb-drop tests. Three wheelchairs successfully completed the double-drum and curb-drop tests, but the remaining wheelchairs failed prematurely. The tested group of titanium wheelchairs survived fewer equivalent cycles than was previously reported for aluminum ultralight wheelchairs, but their life expectancy was similar to that of steel lightweight wheelchairs.
Compared with previously tested aluminum ultralight folding and steel lightweight wheelchairs, the tested titanium rigid-frame wheelchairs had significantly less value. The tested wheelchairs had an estimated average usable life of 1.85 to 3.08 years based on the approximation that the intensity of the ANSI/RESNA fatigue tests represents regular use for 3 to 5 years.
* The force that produces an acceleration of 1 meter per second per second when exerted on a mass of 1 kilogram.
To view this article and other recently published wheelchair research, please visit http://www.rehab.research.va.gov/cluster/wheelchair.html.
JRRD is a well-established and respected peer-reviewed journal sponsored by the Department of Veterans Affairs. The journal publishes original research, clinical studies, and reviews covering 28 rehabilitation disciplines. JRRD is widely distributed in print and electronic format to both national and international audiences, reaching more than 500,000 readers across 6 continents in 2007. To learn more about the journal and its publishing policies, please visit www.rehab.research.va.gov/jour/jourindx.html.
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