Measuring the dynamic mechanical response of hydrated mouse bone by nanoindentation

This study demonstrates a novel approach to characterizing hydrated bone's viscoelastic behavior at lamellar length scales using dynamic indentation techniques. We studied the submicron-level viscoelastic response of bone tissue from two different inbred mouse strains, A/J and B6, with known differences in whole bone and tissue-level mechanical properties. Our results show that bone having a higher collagen content or a lower mineral-to-matrix ratio demonstrates a trend towards a larger viscoelastic response. When normalized for anatomical location relative to biological growth patterns in the antero-medial (AM) cortex, bone tissue from B6 femora, known to have a lower mineral-to-matrix ratio, is shown to exhibit a significantly higher viscoelastic response compared to A/J tissue. Newer bone regions with a higher collagen content (closer to the endosteal edge of the AM cortex) showed a trend towards a larger viscoelastic response. Our study demonstrates the feasibility of this technique for analyzing local composition-property relationships in bone. Further, this technique of viscoelastic nanoindentation mapping of the bone surface at these submicron length scales is shown to be highly advantageous in studying subsurface features, such as porosity, of wet hydrated biological specimens, which are difficult to identify using other methods

Manufacturing and Thermal Shock Characterization of Porous Yttria Stabilized Zirconia for Hydrogen Energy Systems

Porous yttriastabilized zirconia (YSZ), in a composite with NiO, is widely used as a cermet electrode in solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). Given cycles of high temperature in these energy devices, mechanical integrity of the porous YSZ is critical. Pore morphology, as well as properties of the ceramic, ultimately affect the mechanical properties of the cermet electrode. Here, we fabricated porous YSZ sheets via freezing of an aqueous slurry on a cold thermoelectric plate and quantified their flexural properties, both for as-fabricated samples and samples subjected to thermal shock at 200 °C to 500 °C. Results of this work have implications for the hydrogen economy and global decarbonization efforts, in particular for the manufacturing of SOFCs and SOECs

Manufacturing and Thermal Shock Characterization of Porous Yttria Stabilized Zirconia for Hydrogen Energy Systems

Porous yttriastabilized zirconia (YSZ), in a composite with NiO, is widely used as a cermet electrode in solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). Given cycles of high temperature in these energy devices, mechanical integrity of the porous YSZ is critical. Pore morphology, as well as properties of the ceramic, ultimately affect the mechanical properties of the cermet electrode. Here, we fabricated porous YSZ sheets via freezing of an aqueous slurry on a cold thermoelectric plate and quantified their flexural properties, both for as-fabricated samples and samples subjected to thermal shock at 200 °C to 500 °C. Results of this work have implications for the hydrogen economy and global decarbonization efforts, in particular for the manufacturing of SOFCs and SOECs

Nonlinear viscoelastic behavior of human knee ligaments subjected to complex loading histories

The nonlinear viscoelastic structural response of the major human knee ligaments when subjected to complex loading histories is investigated, with emphasis on the collateral ligaments. Bone-ligament-bone specimens are tested in knee distraction loading, where the ligaments are in the anatomical position corresponding to a fully extended knee. Temporal nonlinearities for time scales in the range of

Characterization of the rate-dependent behavior and failure of human knee ligaments

The structural properties of the four major human kneeligaments were investigated at different loading rates.Bone-ligament-bone specimens of the medial and lateralcollateral ligaments and the anterior and posteriorcruciate ligaments, obtained from post-mortem humandonors, were tested in knee distraction loading indisplacement control. All ligaments were tested in theanatomical position corresponding to a fully extendedknee. The rate dependence of the structural response ofthe knee ligaments was investigated by applying loading-unloading cycles at a range of distraction rates. Ramps to failure were applied at knee distraction rates of 0.016 mm/s, 1.6 mm/s, or 1,600 mm/s. Averages and corridors were constructed for the force response and the failure point of the different ligaments and loading rates. The structural response of the knee ligaments was found to depend on the deformation rate, being both stiffer and more linear at high loading rates. This rate dependence was found to be more pronounced at high loading rates

Characterization of the rate-dependent mechanical properties and failure of human knee ligaments

The structural properties of the four major human kneeligaments were investigated at different loading rates.Bone-ligament-bone specimens of the medial and lateralcollateral ligaments and the anterior and posteriorcruciate ligaments, obtained from post-mortem humandonors, were tested in knee distraction loading indisplacement control. All ligaments were tested in theanatomical position corresponding to a fully extendedknee. The rate dependence of the structural response ofthe knee ligaments was investigated by applying loadingunloadingcycles at a range of distraction rates. Rampsto failure were applied at knee distraction rates of 0.016mm/s, 1.6 mm/s, or 1,600 mm/s. Averages and corridorswere constructed for the force response and the failurepoint of the different ligaments and loading rates. Thestructural response of the knee ligaments was found todepend on the deformation rate, being both stiffer andmore linear at high loading rates. This rate dependence was found to be more pronounced at high loading rates

Characterization of the rate-dependent mechanical properties and failure of human knee ligaments

The structural properties of the four major human kneeligaments were investigated at different loading rates.Bone-ligament-bone specimens of the medial and lateralcollateral ligaments and the anterior and posteriorcruciate ligaments, obtained from post-mortem humandonors, were tested in knee distraction loading indisplacement control. All ligaments were tested in theanatomical position corresponding to a fully extendedknee. The rate dependence of the structural response ofthe knee ligaments was investigated by applying loadingunloadingcycles at a range of distraction rates. Rampsto failure were applied at knee distraction rates of 0.016mm/s, 1.6 mm/s, or 1,600 mm/s. Averages and corridorswere constructed for the force response and the failurepoint of the different ligaments and loading rates. Thestructural response of the knee ligaments was found todepend on the deformation rate, being both stiffer andmore linear at high loading rates. This rate dependence was found to be more pronounced at high loading rates