Untitled

Akiva, Udi; Wagner, H. Daniel; Weiner, Steve

doi:10.1023/a:1004303926771

Cited by 82 publications

(10 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous attempts to model this anisotropy considered cylindrical osteons to be fibers embedded in a less stiff matrix, [8] a picture which is unlikely to be true given the observed higher stiffness of the older interstitial bone. [4] Later models assess the anisotropy of the elastic modulus as a function of a platelet-like structural array within a collagenous matrix, [9,10] leading to slightly higher absolute values with an anisotropy ratio of 1:2, which is higher but not too different from the nanoindentation (NI) data presented here. Microhardness measurements also showed a decrease in hardness of fibrils indented perpendicularly to their longitudinal bone axis relative to fibrils indented along their axis.…”

Section: Introductionmentioning

confidence: 57%

Tough Lessons From Bone: Extreme Mechanical Anisotropy at the Mesoscale

Seto

Gupta

Zaslansky

et al. 2008

Adv Funct Materials

114

View full text Add to dashboard Cite

Bone is mechanically and structurally anisotropic with oriented collagen fibrils and nanometer‐sized mineral particles aggregating into lamellar or woven bone.[1] Direct measurements of anisotropic mechanical properties of sublamellar tissue constituents are complicated by the existence of an intrinsic hierarchical architecture. Methods such as nanoindentation provide insight into effective modulus values; however, bulk material properties cannot sufficiently be characterized since such measurements represent properties of near‐surface volumes and are partially averaged over fibril orientations.[2–5] In this study, we focus on the material properties of bone at one single level of hierarchy. By measuring properties of individual parallel‐fibered units of fibrollamellar bone under tension under controlled humidity conditions, an unusually high anisotropy is found. Here, we clearly demonstrate ratios as large as 1:20 in elastic modulus and 1:15 in tensile strength between orientations perpendicular and parallel to the main collagen fiber orientation in native wet bone; these ratios reduce to 1:8 and 1:7, respectively, under dry conditions. This extreme anisotropy appears to be caused by the existence of periodic, weak interfaces at the mesoscopic length scale. These interfaces are thought to be relevant to the proper mechanical and physiological performance of bone.

show abstract

Section: Introductionmentioning

confidence: 57%

Tough Lessons From Bone: Extreme Mechanical Anisotropy at the Mesoscale

Seto

Gupta

Zaslansky

et al. 2008

Adv Funct Materials

114

View full text Add to dashboard Cite

show abstract

“…The smallest experimental characteristic length probed (50 nm maximum depth, approximately 400 nm contact diameter) is comparable to the size of a few mineralized collagen fibrils and allowed the evaluation of the mechanical properties of a single sub-layer of fibrils in the lamellar structure; whereas, the largest experimental characteristic length sampled (300 nm maximum depth, approx. 2 mm contact diameter) may accommodate approximately 10-20 bunches of collagen fibrils oriented along multiple directions and, thus, involves multiple sub-layers, whose thickness can vary between few hundreds of nanometres to a couple of microns [22,[33][34][35]. These investigations enabled the identification of a decrease in the values of indentation moduli with the penetration depth (figure 5a) that indicates a possible size effect in the mechanical properties of cortical bone tissue.…”

Section: Discussionmentioning

confidence: 99%

Orientation and size-dependent mechanical modulation within individual secondary osteons in cortical bone tissue

Carnelli

Vena

Dao

et al. 2013

J. R. Soc. Interface.

View full text Add to dashboard Cite

Anisotropy is one of the most peculiar aspects of cortical bone mechanics; however, its anisotropic mechanical behaviour should be treated only with strict relationship to the length scale of investigation. In this study, we focus on quantifying the orientation and size dependence of the spatial mechanical modulation in individual secondary osteons of bovine cortical bone using nanoindentation. Tests were performed on the same osteonal structure in the axial (along the long bone axis) and transverse (normal to the long bone axis) directions along arrays going radially out from the Haversian canal at four different maximum depths on three secondary osteons. Results clearly show a periodic pattern of stiffness with spatial distance across the osteon. The effect of length scale on lamellar bone anisotropy and the critical length at which homogenization of the mechanical properties occurs were determined. Further, a laminatecomposite-based analytical model was applied to the stiffness trends obtained at the highest spatial resolution to evaluate the elastic constants for a sub-layer of mineralized collagen fibrils within an osteonal lamella on the basis of the spatial arrangement of the fibrils. The hierarchical arrangement of lamellar bone is found to be a major determinant for modulation of mechanical properties and anisotropic mechanical behaviour of the tissue.

show abstract

“…Although various models have been proposed by different groups to calculate the tissue modulus, these models invariably correlated the modulus and the hierarchical levels of the materials. The longitudinal modulus can be calculated according to the HalpinTsai model [ 70 ] :…”

Section: Relationship Of Hierarchical Structures and Deformation Mechmentioning

confidence: 99%

Hierarchical Structures of Bone and Bioinspired Bone Tissue Engineering

Liu

Luo

Wang

2016

Small

356

249

View full text Add to dashboard Cite

Bone, as a mineralized composite of inorganic (mostly carbonated hydroxyapatite) and organic (mainly type I collagen) phases, possesses a unique combination of remarkable strength and toughness. Its excellent mechanical properties are related to its hierarchical structures and precise organization of the inorganic and organic phases at the nanoscale: Nanometer-sized hydroxyapatite crystals periodically deposit within the gap zones of collagen fibrils during bone biomineralization process. This hierarchical arrangement produces nanomechanical heterogeneities, which enable a mechanism for high energy dissipation and resistance to fracture. The excellent mechanical properties integrated with the hierarchical nanostructure of bone have inspired chemists and material scientists to develop biomimetic strategies for artificial bone grafts in tissue engineering (TE). This critical review provides a broad overview of the current mechanisms involved in bone biomineralization, and the relationship between bone hierarchical structures and the deformation mechanism. Our goal in this review is to inspire the application of these principles toward bone TE.

show abstract

Untitled

Cited by 82 publications

References 28 publications

Tough Lessons From Bone: Extreme Mechanical Anisotropy at the Mesoscale

Tough Lessons From Bone: Extreme Mechanical Anisotropy at the Mesoscale

Orientation and size-dependent mechanical modulation within individual secondary osteons in cortical bone tissue

Hierarchical Structures of Bone and Bioinspired Bone Tissue Engineering

Contact Info

Product

Resources

About