Monotonic and fatigue behavior of five clinically relevant conventional and highly crosslinked UHMWPEs in the presence of stress concentrations

Five formulations of clinically relevant UHMWPE (conventional, moderately crosslinked annealed and remelted, and highly crosslinked annealed and remelted) were investigated in a physiologically relevant environment. Their monotonic stress-strain behavior in the presence of notches of two different s...

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Bibliographic Details
Published in:Journal of the mechanical behavior of biomedical materials 2013-12, Vol.28, p.244-253
Main Authors: Sobieraj, Michael C., Murphy, James E., Brinkman, Jennifer G., Kurtz, Steve M., Rimnac, Clare M.
Format: Article
Language:English
Subjects:
Annealing
Biocompatible Materials - chemistry
Constants
Crosslinking
Fatigue failure
Materials Testing
Mathematical models
Polyethylenes
Polyethylenes - chemistry
Radiation Dosage
Stress concentration
Stress, Mechanical
Stress-strain relationships
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Summary:Five formulations of clinically relevant UHMWPE (conventional, moderately crosslinked annealed and remelted, and highly crosslinked annealed and remelted) were investigated in a physiologically relevant environment. Their monotonic stress-strain behavior in the presence of notches of two different severities and at two different displacement rates was examined using a custom developed video based system. It was found that both an elevation of yield stress and a truncation of orientation hardening took place under monotonic loading and that these changes were found to be material and elastic stress concentration factor dependent. The fatigue behavior of these materials was examined using the same geometries via a stress-life approach with failure defined as fracture of the specimen in the 1000 to 100,000 cycle lifetime range. The results were modeled using the Basquin relationship (σ=ANb, where σ=stress and N=lifetime, and A and b are experimentally derived constants) via maximum likelihood estimation methods to account for specimen runout (no failure at 250,000cycles). The conventional material was found to have a greater slope, b, and intercept, A, than the crosslinked materials as well as appearing to have less variance in its failure distributions. [Display omitted] •The notched monotonic and fatigue behavior of five clinically relevant UHMWPEs was investigated in a physiologically relevant environment.•Yield stress was elevated and orientation hardening truncated and these changes were material and elastic stress concentration factor dependent.•The fatigue behavior was modeled using the Basquin relationship (σ=ANb, where σ=stress, N=lifetime, A and b are experimentally derived constants).•The conventional material had greater slope, b, and intercept, A, than crosslinked materials and less variance in its failure distributions.
ISSN:1751-6161
1878-0180
DOI:10.1016/j.jmbbm.2013.07.024