Fatigue damage-fracture mechanics interaction in cortical bone

Y. N. Yeni, David P Fyhrie

Research output: Contribution to journalArticle

65 Scopus citations

Abstract

Fatigue loading causes accumulation of damage that may lead to the initiation of a macrocrack and result in a catastrophic failure of bone. The objective of this study was to examine the influence of fatigue damage on crack growth parameters in bovine cortical bone. Nineteen rectangular beam specimens (4 × 4 × 48 mm) were machined from bovine tibiae. The long axis of the beams was aligned with the long axis of bones. Using a four-point bending fatigue setup, ten specimens were fatigue-damaged to different levels as indicated by stiffness loss. A through-thickness notch was machined at the center of each damaged and undamaged beam. The notched specimens were then monotonically loaded beyond failure using a three-point bending protocol. Critical stress intensity factor, KI, and work to critical load, WQ, were significantly lower in the damaged group than in the undamaged group (p < 0.03). When the undamaged specimens were assigned a percent stiffness loss of zero and pooled with the damaged group, significant negative correlations of percent stiffness loss with KI (R = 0.58, p < 0.01), WQ (R = 0.54, p < 0.02), maximum load, Pmax (R = 0.59, p < 0.008), deflection at maximum load, Δmax (R = 0.48, p < 0.04), structural stiffness, Smax (R = 0.53, p < 0.02), Wmax (R = 0.55, p < 0.02), and load at 1.4 mm deflection (a value beyond failure but without complete fracture), P1.4 (R = 0.47, p < 0.05), were found. Post hoc analysis revealed that the average load-deflection curve from the damaged group was transformable into that from the undamaged group through a special shift on the load-deflection plane. Fatigue damage reduces bone stiffness and resistance to crack initiation, maximum load-carrying capacity, and deflection before and after failure in cortical bone. The data suggest there is a single rule that governs the overall effect of fatigue damage on the fracture behavior of cortical bone.

Original languageEnglish (US)
Pages (from-to)509-514
Number of pages6
JournalBone
Volume30
Issue number3
DOIs
StatePublished - 2002
Externally publishedYes

Keywords

  • Adaptation
  • Cortical bone
  • Fatigue damage
  • Fracture mechanics
  • Stiffness
  • Strength

ASJC Scopus subject areas

  • Physiology
  • Hematology

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