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Comparative cyclic stress–strain and fatigue resistance behavior of electron–beam‐ and gamma‐irradiated ultrahigh molecular weight polyethylene
Author(s) -
Urriés I.,
Medel F. J.,
Ríos R.,
GómezBarrena E.,
Puértolas J. A.
Publication year - 2004
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.30033
Subject(s) - materials science , irradiation , composite material , stress (linguistics) , polyethylene , electron beam processing , ultimate tensile strength , yield (engineering) , cyclic stress , beam (structure) , ultra high molecular weight polyethylene , structural engineering , philosophy , linguistics , physics , nuclear physics , engineering
Fatigue‐related damage in UHMWPE is one of the main causes of long‐term failure in total joint replacements. Crosslinking ultrahigh molecular weight polyethylene (UHMWPE) by gamma or electron‐beam irradiation, in combination with prior or further thermal treatment, enhances its wear resistance against metallic components in total hip replacements, and eventually in knees. However, little information is available on the fatigue response of this modified UHMWPE. The objective of this study was to compare electron‐beam‐irradiated UHMWPE at 50, 100, and 150 kGy, with the well‐known 25 kGy gamma‐irradiated UHMWPE. Two different cyclic tests were performed under tensile stress, with a zero load ratio, R = 0. First, specimens were subjected to a sinusoidal load cycle at 1 Hz, which provided stress–life curves with the use of a failure criterion based on 12% yield strain. Second, specimens were tested under 50 load cycles at a displacement rate of 15 mm/min, which provided information about the evolution of secant modulus and plastic strain. The incubation period was also analyzed. DSC measurements were carried out to check the crystallization effect of irradiation. According to the results of fatigue resistance there was a crossover behavior between gamma‐ and electron‐beam‐irradiated UHMWPE regarding the applied stress. When the stress was higher than the crossover value, the fatigue resistance of γ‐irradiated samples was higher than electron‐beam‐irradiated ones. When the stress was lower, the fatigue behavior was the opposite. The crossover stress depended on the electron‐beam‐irradiation dose. The clinical relevance of this study lies in an improved knowledge of electron‐beam‐irradiated material under extreme mechanical circumstances, such as fatigue. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 152–160, 2004