Micromechanisms of fatigue crack growth in polycarbonate polyurethane: Time dependent and hydration effects
| Autor: | Samuel C. Li, Audrey C. Ford, Amrita Srinivasan, Lisa A. Pruitt, Hannah M. Gramling, Jessica V. Sov |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Materials science
0206 medical engineering Variable time Polyurethanes Biomedical Engineering 02 engineering and technology Elastomer Biomaterials chemistry.chemical_compound Deflection (engineering) Tensile Strength mental disorders Materials Testing Composite material Polycarbonate Tensile testing Polyurethane chemistry.chemical_classification Polycarboxylate Cement Polymer Paris' law 021001 nanoscience & nanotechnology 020601 biomedical engineering Elasticity chemistry Mechanics of Materials visual_art visual_art.visual_art_medium Stress Mechanical 0210 nano-technology |
| Zdroj: | Journal of the mechanical behavior of biomedical materials. 79 |
| ISSN: | 1878-0180 |
| Popis: | Polycarbonate polyurethane has cartilage-like, hygroscopic, and elastomeric properties that make it an attractive material for orthopedic joint replacement application. However, little data exists on the cyclic loading and fracture behavior of polycarbonate polyurethane. This study investigates the mechanisms of fatigue crack growth in polycarbonate polyurethane with respect to time dependent effects and conditioning. We studied two commercially available polycarbonate polyurethanes, Bionate® 75D and 80A. Tension testing was performed on specimens at variable time points after being removed from hydration and variable strain rates. Fatigue crack propagation characterized three aspects of loading. Study 1 investigated the impact of continuous loading (24h/day) versus intermittent loading (8-10h/day) allowing for relaxation overnight. Study 2 evaluated the effect of frequency and study 3 examined the impact of hydration on the fatigue crack propagation in polycarbonate polyurethane. Samples loaded intermittently failed instantaneously and prematurely upon reloading while samples loaded continuously sustained longer stable cracks. Crack growth for samples tested at 2 and 5Hz was largely planar with little crack deflection. However, samples tested at 10Hz showed high degrees of crack tip deflection and multiple crack fronts. Crack growth in hydrated samples proceeded with much greater ductile crack mouth opening displacement than dry samples. An understanding of the failure mechanisms of this polymer is important to assess the long-term structural integrity of this material for use in load-bearing orthopedic implant applications. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect