High cycle fatigue behavior of implant Ti-6Al-4V in air and simulated body fluid

Ti-6Al-4V implants that function as artificial joints are usually subjected to long-term cyclic loading. To study long-term fatigue behaviors of implant Ti-6Al-4V in vitro and in vivo conditions exceeding 107 cycles, constant stress amplitude fatigue experiments were carried out at ultrasonic freque...

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Published inBio-medical materials and engineering Vol. 24; no. 1; pp. 263 - 269
Main Authors Liu, Yong-jie, Cui, Shi-ming, He, Chao, Li, Jiu-kai, Wang, Qing-yuan
Format Journal Article
LanguageEnglish
Published Netherlands 2014
Subjects
Air
Body Fluids
Equipment Design
Materials Testing
Microscopy, Electron, Scanning
Pressure
Prostheses and Implants
Prosthesis Failure
Reproducibility of Results
Stress, Mechanical
Surface Properties
Tensile Strength
Titanium - chemistry
Ultrasonics
high cycle fatigue
S-N curve
Ti-6Al-4V
simulated body fluid
surface condition
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Summary:Ti-6Al-4V implants that function as artificial joints are usually subjected to long-term cyclic loading. To study long-term fatigue behaviors of implant Ti-6Al-4V in vitro and in vivo conditions exceeding 107 cycles, constant stress amplitude fatigue experiments were carried out at ultrasonic frequency (20 kHz) with two different surface conditions (ground and polished) in ambient air and in a simulated body fluid. The initiation mechanisms of fatigue cracks were investigated with scanning electron microscopy. Improvement of fatigue strength is pronounced for polished specimens below 106 cycles in ambient air since fatigue cracks are initiated from surfaces of specimens. While the cycles exceed 106, surface conditions have no effect on fatigue behaviors because the defects located within the specimens become favorable sites for crack initiation. The endurance limit at 108 cycles of polished Ti-6Al-4V specimens decreases by 7% if it is cycled in simulated body fluid instead of ambient air. Fracture surfaces show that fatigue failure is initiated from surfaces in simulated body fluid. Surface improvement has a beneficial effect on fatigue behaviors of Ti-6Al-4V at high stress amplitudes. The fatigue properties of Ti-6Al-4V deteriorate and the mean endurance limits decrease significantly in simulated body fluid.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0959-2989
1878-3619
DOI:10.3233/BME-130807