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Notched fatigue behavior of PEEK
Michacl C Sobieraj1, James E Murphy, Jennifer G Brinkman
1Musculoskeletal Mechanics and Materials Laboratories, Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA. michael.sobieraj@nyumc.org
Biomaterials
|September 25, 2010
Summary
This study investigated the fatigue and fracture behavior of Poly(ether-ether-ketone) (PEEK) in notched orthopaedic implant designs. Results show PEEK predominantly experiences crack initiation over propagation during fatigue loading.
Area of Science:
- Biomaterials Science
- Mechanical Engineering
- Orthopaedic Research
Background:
- Poly(ether-ether-ketone) (PEEK) is a clinically successful load-bearing orthopaedic implant material.
- Orthopaedic implant designs commonly feature stress concentrations (notches).
- Limited research exists on the fatigue behavior of PEEK with notches.
Purpose of the Study:
- To examine the stress-life (S-N) fatigue behavior of unfilled PEEK.
- To investigate the fracture behavior of unfilled PEEK under tension-tension loading.
- To analyze fatigue performance in specimens with varying elastic stress concentration factors.
Main Methods:
- Utilized unfilled PEEK in circumferentially grooved round bar specimens.
- Applied tension-tension loading to assess fatigue and fracture.
- Conducted fractographic analysis using Scanning Electron Microscopy (SEM).
- Estimated crack initiation versus propagation phases of the fatigue life.
Main Results:
- The majority of the loading experienced by PEEK specimens was elastic.
- A small portion of the fatigue life showed detectable changes before gross fracture.
- Fractographic analysis revealed potential fracture micromechanisms.
- Specimens spent the majority of their fatigue life in the crack initiation phase.
Conclusions:
- PEEK exhibits a fatigue life predominantly governed by crack initiation rather than propagation in notched configurations.
- Understanding these fatigue mechanisms is crucial for optimizing PEEK orthopaedic implant design.
- Further research can refine predictive models for PEEK implant longevity.
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