Mechanical Anisotropy of Individual Osteons in Bone Tissue at High Spatial Resolutions

2009 ◽  
Author(s):  
Davide Carnelli ◽  
Haimin Yao ◽  
Ming Dao ◽  
Pasquale Vena ◽  
Roberto Contro ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cortical Bone ◽  
Mechanical Anisotropy ◽  
Haversian Canal ◽  
Maximum Penetration ◽  
Fundamental Units ◽  
Anisotropy Of Mechanical Properties ◽  
Penetration Depths ◽  
Secondary Osteons ◽  
Mineralized Collagen

Secondary osteons, the fundamental units of cortical bone, consist of cylindrical lamellar composites composed of mineralized collagen fibrils. Due to its lamellar structure, a multiscale knowledge of the mechanical properties of cortical bone is required to understand the biomechanical function of the tissue. In this light, nanoindentation tests were performed along the axial and transverse directions following a radial path from the Haversian canal to the osteonal edges. Different length scales are explored by means of indentations at different maximum penetration depths. Indentation moduli and hardness data were then interpreted in the context of the known microstructure. Results suggest that secondary osteons hierarchical structure is responsible for an observed length scale effect, homogenization phenomena and anisotropy of mechanical properties.

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

2013 ◽  
Vol 10 (81) ◽  
pp. 20120953 ◽  
Author(s):  
Davide Carnelli ◽  
Pasquale Vena ◽  
Ming Dao ◽  
Christine Ortiz ◽  
Roberto Contro
Keyword(s):  
Mechanical Properties ◽  
Cortical Bone ◽  
Mechanical Behaviour ◽  
Long Bone ◽  
Periodic Pattern ◽  
Haversian Canal ◽  
Length Scale ◽  
Lamellar Bone ◽  
Mechanical Modulation ◽  
Secondary Osteons

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 laminate-composite-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.

scholarly journals Analysis of Mechanical Properties and Mechanical Anisotropy in Canine Bone Tissues of Various Ages

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Changqi Luo ◽  
Junyi Liao ◽  
Zhenglin Zhu ◽  
Xiaoyu Wang ◽  
Xiao Lin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Cortical Bone ◽  
Bone Tissue ◽  
Poisson Ratio ◽  
Age Groups ◽  
Distal Region ◽  
Mechanical Anisotropy ◽  
Age Group ◽  
Cross Sectional

The effect of age on mechanical behavior and microstructure anisotropy of bone is often ignored by researchers engaged in the study of biomechanics. The objective of our study was to determine the variations in mechanical properties of canine femoral cortical bone with age and the mechanical anisotropy between the longitudinal and transverse directions. Twelve beagles divided into three age groups (6, 12, and 36 months) were sacrificed and all femurs were extracted. The longitudinal and transverse samples of cortical bone were harvested from three regions of diaphysis (proximal, central, and distal). A nanoindentation technique was used for simultaneously measuring force and displacement of a diamond tip pressed 2000nm into the hydrated bone tissue. An elastic modulus was calculated from the unloading curve with an assumed Poisson ratio of 0.3, while hardness was defined as the maximal force divided by the corresponding contact area. The mechanical properties of cortical bone were determined from 852 indents on two orthogonal cross-sectional surfaces. Mean elastic modulus ranged from 7.56±0.32 GPa up to 21.56±2.35 GPa, while mean hardness ranged from 0.28±0.057 GPa up to 0.84±0.072 GPa. Mechanical properties of canine femoral cortical bone tended to increase with age, but the magnitudes of these increase for each region might be different. The longitudinal mechanical properties were significantly higher than that of transverse direction (P<0.01). A significant anisotropy was found in the mechanical properties while there was no significant correlation between the two orthogonal directions in each age group (r2<0.3). Beyond that, the longitudinal mechanical properties of the distal region in each age group were lower than the proximal and central regions. Hence, mechanical properties in nanostructure of bone tissue must differ mainly among age, sample direction, anatomical sites, and individuals. These results may help a number of researchers develop more accurate constitutive micromechanics models of bone tissue in future studies.

scholarly journals A Slot-Die Technique for the Preparation of Continuous, High-Area, Chitosan-Based Thin Films

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1566
Author(s):  
Oliver J. Pemble ◽  
Maria Bardosova ◽  
Ian M. Povey ◽  
Martyn E. Pemble
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
High Volume ◽  
Mechanical Anisotropy ◽  
Diverse Range ◽  
Direction Parallel ◽  
High Area ◽  
Wide Range ◽  
Slot Die ◽  
Potential Applications

Chitosan-based films have a diverse range of potential applications but are currently limited in terms of commercial use due to a lack of methods specifically designed to produce thin films in high volumes. To address this limitation directly, hydrogels prepared from chitosan, chitosan-tetraethoxy silane, also known as tetraethyl orthosilicate (TEOS) and chitosan-glutaraldehyde have been used to prepare continuous thin films using a slot-die technique which is described in detail. By way of preliminary analysis of the resulting films for comparison purposes with films made by other methods, the mechanical strength of the films produced was assessed. It was found that as expected, the hybrid films made with TEOS and glutaraldehyde both show a higher yield strength than the films made with chitosan alone. In all cases, the mechanical properties of the films were found to compare very favorably with similar measurements reported in the literature. In order to assess the possible influence of the direction in which the hydrogel passes through the slot-die on the mechanical properties of the films, testing was performed on plain chitosan samples cut in a direction parallel to the direction of travel and perpendicular to this direction. It was found that there was no evidence of any mechanical anisotropy induced by the slot die process. The examples presented here serve to illustrate how the slot-die approach may be used to create high-volume, high-area chitosan-based films cheaply and rapidly. It is suggested that an approach of the type described here may facilitate the use of chitosan-based films for a wide range of important applications.

Annealing Effects on Mechanical Properties and Microstructure of AZ31 Alloy Sheet Differential-Speed-Rolled at Low Temperatures

2007 ◽  
Vol 558-559 ◽  
pp. 213-216 ◽  
Author(s):  
Y.G. Jeong ◽  
Woo Jin Kim ◽  
Seo Gou Choi ◽  
Ha Guk Jeong
Keyword(s):  
Mechanical Properties ◽  
Tensile Elongation ◽  
Az31 Alloy ◽  
Alloy Sheet ◽  
Large Drop ◽  
High Anisotropy ◽  
Texture Change ◽  
Annealing Effects ◽  
Anisotropy Of Mechanical Properties ◽  
Differential Speed

For the Magnesium alloy AZ31, hot rolling is usually carried out in the temperature range between 250 and 400°C but the processed sheets usually exhibit high anisotropy in mechanical properties. In the current study, DSR process was found to be effective in improving anisotropy of mechanical properties and ductility at room temperature. Full recrystallization takes place from 200°C and above. A large drop of UTS occurs above 200°C where full recrystallization starts. Tensile elongation increases with annealing temperature but anisotropy degrades from 200°C onwards. Texture change during recrystallization is believed to be responsible for this result.

Research on Anisotropic Fracture Mechanical Behavior of Cortical Bone with Combined Method of Fractal and Gray Level Co-Occurrence Matrix

2021 ◽  
Vol 11 (1) ◽  
pp. 67-75
Author(s):  
Dagang Yin ◽  
Bin Chen ◽  
Huifen Zhou
Keyword(s):  
Mechanical Properties ◽  
Fracture Surface ◽  
Cortical Bone ◽  
Fracture Mechanisms ◽  
Gray Level ◽  
Combined Method ◽  
Characteristic Parameters ◽  
Fracture Surfaces ◽  
Anisotropic Fracture ◽  
Occurrence Matrix

The irregular fracture surface of cortical bone, which is caused by complex multilevel micro-nanostructure, reflects the mechanical properties and fracture mechanisms. It is of great significance to characterize some characteristic parameters from the fracture surfaces of bone. In this research, anisotropic fracture mechanical properties of bovine femoral cortical bone along transverse, longitudinal and radial direction are firstly obtained by three-point bend experiment. Then the fracture routes and fracture surfaces are observed by scanning electron microscope. The observation shows that the formed fracture surfaces, which are caused by different crack routes, are extremely rough and have complex textures. Lastly, the combined method of fractal and gray level co-occurrence matrix are adopted to describe the morphology of fracture surface of cortical bone objectively and quantitatively. It is shown that the fracture surface of cortical bone has obvious fractal characteristics and four statistical texture feature parameters (contrast,angular second moment, correlation and entropy) of GLCM of fracture surfaces can describe a certain fracture texture character. The relationship between the characteristic parameters and macroscopic mechanical properties are established. The quantitative analysis and automatic class identification for the fracture surfaces of cortical bone can be achieved.

Tissue level mechanical properties of cortical bone in skeletally immature and mature dogs

2009 ◽  
Vol 22 (03) ◽  
pp. 210-215 ◽  
Author(s):  
C.A. Phillips ◽  
S.A. Fernandez ◽  
Y. Li ◽  
S.S. Huja
Keyword(s):  
Mechanical Properties ◽  
Cortical Bone ◽  
Tissue Level ◽  
Mechanical Tests ◽  
Indentation Modulus ◽  
Skeletally Immature ◽  
Beagle Dogs ◽  
Cross Sectional ◽  
Specimen Holder ◽  
Immature Group

Summary Objectives: The purpose of this study was to quantify the tissue level mechanical properties of cortical bone of skeletally immature (~five-month-old) Beagle dogs and compare them to data from mature dogs measured in a previous study. Methods: Eight femoral cross sectional specimens (two bone sections / dog) were obtained from four skeletally immature dogs. A pair of calcein bone labels were administered intravenously to the dogs to mark sites of active mineralization prior to euthanasia. Prepared bone specimens were placed in a nanoindenter specimen holder and the previously identified calcein labelled osteons were located. Labelled (n = 128) and neighbouring unlabelled (n = 127) osteons in skeletally immature femurs were examined by instrumented indentation testing. Indents were made to a depth of 500 nm at a loading rate of 10 nm/s. Indentation modulus (IM) and hardness (H) were obtained. Results: The overall IM of the cortical bone in the skeletally mature groups was significantly greater than in the immature group (p = 0.0011), however overall H was not significantly different. The differences between the groups in IM were significant for the unlabelled osteons (p = 0.001), but not for the labelled osteons (p = 0.56). Conclusion: There are differences in the IM of unlabelled osteons in skeletally immature and mature groups of Beagle dogs. In contrast to whole bone mechanical tests, where there are obvious differences between growing and mature bones, there are only small differences in the micro-mechanical properties.

Evaluation of Mechanical Properties of Trabecular and Cortical Bone

2001 ◽  
pp. 47-56 ◽  
Author(s):  
Masako Ito ◽  
Aoi Koga ◽  
Akifumi Nishida ◽  
Ayako Shiraishi ◽  
Motoo Saito ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cortical Bone

scholarly journals Application of Magnetic Noise Method to Control the Mechanical Anisotropy of Ferromagnetic Materials

2019 ◽  
Vol 10 (3) ◽  
pp. 281-292
Author(s):  
V. N. Busko ◽  
A. A. Osipov
Keyword(s):  
Mechanical Properties ◽  
Magnetic Anisotropy ◽  
Sheet Metal ◽  
Elastic Deformation ◽  
Electrical Steel ◽  
Sheet Steel ◽  
Ferromagnetic Materials ◽  
Mechanical Anisotropy ◽  
Magnetic Method ◽  
Magnetic Noise

Presence of anisotropy of the ferromagnetic materials' properties determines the need for its research and control, since it has a significant impact on the basic physicomechanical characteristics of details, products and constructions. The aim of the work was to experimentally investigate the possibility of using the magnetic noise method for non-destructive testing of mechanical properties of ferromagnetic materials particularly value of the coefficient of normal anisotropy Rn of sheet metal, mechanical stresses under elastic deformation of electrical steel and the anisotropy of the physical and mechanical properties of ferromagnetic materials.Since the mechanical anisotropy is related to the magnetic anisotropy, the magnetic method of the Barkhausen effect (MBE) was used in its study, the informative parameters of which belong to the group of magnetic anisotropy. Comparison of the results of anisotropy evaluation on a set of samples of stamped sheet steel using the MBE with values Rn measured by the manufacturer showed their close match. This revealed the possibility of Rn level evaluation using the MBE. Device for circular rotation of the Barkhausen transducer on the sample surface and device for forming of elastic bending stresses in the sample were constructed. To study the magnetic anisotropy in various materials and the impact of elastic tensile and compressive stresses by bending on it using the MBE.It has been found that the elastic deformation in samples of electrical steel leads to dramatic change of the magnetic noise level and the shape of the circular diagrams, taking into account the sign of the stresses generated in the sample. It was established that as a result of cold rolling in the production process, electrical steel samples have a pronounced texture due to the direction of rolled sheet. The created elastic stresses in the considered range practically do not change the texture (induced crystallographic anisotropy) after the material rolling.The results can be useful for studying, monitoring and testing of anisotropy, crystallographic texture, structural heterogeneity of ferromagnetic materials in the form of sheet metal, sheet steel and coil steel, sheet metal forming and for solving other problems using the magnetic noise method in aboratory and workshop conditions.

scholarly journals Longitudinal variation in mechanical competence of bone along the avian humerus.

1995 ◽  
Vol 198 (1) ◽  
pp. 209-212
Author(s):  
R H Bonser
Keyword(s):  
Mechanical Properties ◽  
Trabecular Bone ◽  
Cortical Bone ◽  
Vickers Microhardness ◽  
Bird Species ◽  
Longitudinal Variation ◽  
The Mean ◽  
Compressive Tests

Vickers microhardness tests were used to gauge the mechanical "competence" (ability to resist bending and failure) of cortical and trabecular bone along the humeri of three bird species. Hardness was greatest at the mid-length portion of the shaft. The mean hardness of trabeculae, where present, was between 78.7 and 90.9% of that of the adjacent cortical bone. The possible causes of this are briefly discussed. Microhardness tests offer the opportunity to gauge differences in mechanical properties over small distances and might usefully be applied to test the homogeneity of mechanical properties within specimens for tensile or compressive tests.

Time dependence analysis of mechanical properties of cortical bone

1980 ◽  
Vol 13 (9) ◽  
pp. 796
Author(s):  
J. Victoria ◽  
A. Colino ◽  
C. Hernandez-Ros ◽  
A. Victoria
Keyword(s):  
Mechanical Properties ◽  
Time Dependence ◽  
Cortical Bone ◽  
Dependence Analysis
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