Age-Related Changes in Structure, Composition and Mechanical Properties of Swine Cortical Bone

2009 ◽  
Author(s):  
Liang Feng ◽  
Rohit Bhargava ◽  
Iwona Jasiuk
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Composition ◽  
Bone Structure ◽  
Experimental Methods ◽  
Biological Processes ◽  
Age Related ◽  
Open Question ◽  
Age Related Changes ◽  
Comprehensive Study

Bone has a complex hierarchical structure spanning from nanometer to macroscopic dimensions. We apply several experimental methods at different structural scales to study the three fundamental aspects of this material: the structure, composition and mechanical properties. As a biological material, bone is constantly under development. These biological processes such as remodeling and aging are known to increase the susceptibility of bone to fracture. The age-related changes in the fracture toughness and other mechanical properties are manifested by the alteration of the bone structure and chemical composition [1]. Various studies addressed the changes in bone’s structure, composition and mechanical properties due to aging [2–5]. However, these studies were confined to only one or two of these aspects, separately. So there is still an open question about how these three aspects are correlated with each others. Thus, a comprehensive study is needed to address it.

Ageing Changes in the Tensile Properties of Tendons: Influence of Collagen Fibril Volume Fraction

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
K. L. Goh ◽  
D. F. Holmes ◽  
H.-Y. Lu ◽  
S. Richardson ◽  
K. E. Kadler ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Collagen Fibril ◽  
Volume Fraction ◽  
Area Fraction ◽  
Sectional Area ◽  
Cross Sectional ◽  
P Values ◽  
Age Related ◽  
Fibril Diameter ◽  
Age Related Changes

Connective tissues are biological composites comprising of collagen fibrils embedded in (and reinforcing) the hydrated proteoglycan-rich (PG) gel within the extracellular matrices (ECMs). Age-related changes to the mechanical properties of tissues are often associated with changes to the structure of the ECM, namely, fibril diameter. However, quantitative attempts to correlate fibril diameter to mechanical properties have yielded inconclusive evidence. Here, we described a novel approach that was based on the rule of mixtures for fiber composites to evaluate the dependence of age-related changes in tendon tensile strength (σ) and stiffness (E) on the collagen fibril cross-sectional area fraction (ρ), which is related to the fibril volume fraction. Tail tendons from C57BL6 mice from age groups 1.6–35.3months old were stretched to failure to determine σ and E. Parallel measurements of ρ as a function of age were made using transmission electron microscopy. Mathematical models (rule of mixtures) of fibrils reinforcing a PG gel in tendons were used to investigate the influence of ρ on ageing changes in σ and E. The magnitudes of σ, E, and ρ increased rapidly from 1.6monthsto4.0months (P-values <0.05) before reaching a constant (age independent) from 4.0monthsto29.0months (P-values >0.05); this trend continued for E and ρ (P-values >0.05) from 29.0monthsto35.3months, but not for σ, which decreased gradually (P-values <0.05). Linear regression analysis revealed that age-related changes in σ and E correlated positively to ρ (P-values <0.05). Collagen fibril cross-sectional area fraction ρ is a significant predictor of ageing changes in σ and E in the tail tendons of C57BL6 mice.

Characteristics of the Al-Brasses Affected Corrosion Properties

2016 ◽  
Vol 844 ◽  
pp. 38-45 ◽  
Author(s):  
Tatiana Liptáková ◽  
Martin Lovíšek ◽  
Branislav Hadzima
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Research Work ◽  
Construction Materials ◽  
Experimental Methods ◽  
Energy Industry ◽  
Corrosion Properties ◽  
Corrosion Resistant ◽  
Operation Conditions ◽  
Similar Chemical

The Al-brasses are considered corrosion resistant construction materials often used to pipe systems in energy industry, where they are exposed to flowing liquids environments. In that system the brasses are loaded chemically and mechanically. The aim of our research work is to compare corrosion properties of four Al-brasses produced by different manufactures because in operation conditions they have dissimilar reliability and durability. The examined Al-brasses have similar chemical composition but differ in microstructure, surface state what affects their corrosion and mechanical properties. The effect of the mentioned parameters on corrosion and mechanical susceptibility to degradation are investigated by chosen experimental methods.

scholarly journals Decorin expression is important for age-related changes in tendon structure and mechanical properties

2013 ◽  
Vol 32 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Andrew A. Dunkman ◽  
Mark R. Buckley ◽  
Michael J. Mienaltowski ◽  
Sheila M. Adams ◽  
Stephen J. Thomas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Age Related ◽  
Age Related Changes

scholarly journals Electroless Ni-P Coatings: Preparation and Evaluation of Fracture Toughness and Scratch Hardness

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Wagner Sade ◽  
Reinaldo Trindade Proença ◽  
Thiago Daniel de Oliveira Moura ◽  
José Roberto Tavares Branco
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Composition ◽  
Scratch Hardness ◽  
Hard Particles ◽  
Steel Aisi ◽  
Electroless Ni ◽  
Preparation And Evaluation ◽  
Phase Relationships ◽  
Thermally Treated

Ni-P chemical coatings have been used to prevent wear, corrosion and as an alternative for hard chromium, since the latter's deposition processing is very harmful to the human health and the environment. In the present paper, Ni-P coatings with 8 and 10% P were deposited in steel AISI 1020 and thermally treated. Ni-1wt%P coatings with incorporation of hard particles of Al2O3 were also investigated. The microstructure and phase relationships were analyzed and correlated with the fracture toughness and scratch hardness of the coatings.The results show that the fracture toughness of the coating was smaller when thermally treated at 400°C for 1 hour and the scratch hardness reached a peak in this temperature. The relation of chemical composition and microstructure with mechanical properties of Ni-P coatings is presented. The phosphorus contents, the crystallization, and the incorporation of hard particles in the coatings change the values of toughness fracture and scratch hardness.

Mechanical Properties of SA508 Gr.4N Model Alloys as a High Strength RPV Steel

2010 ◽  
Author(s):  
Min-Chul Kim ◽  
Ki-Hyoung Lee ◽  
Bong-Sang Lee ◽  
Whung-Whoe Kim
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Impact Toughness ◽  
Power Plants ◽  
Charpy Impact ◽  
Alloying Elements ◽  
Low Alloy Steels ◽  
Charpy Impact Toughness ◽  
Age Related ◽  
Alloy Steels

Demands of RPV materials with higher strength and toughness are rising to increase the power capacity and the operation life of nuclear power plants. The ASME SA508 Gr.4N specification can give a superior toughness and strength to the commercial low alloy steels such as SA508 Gr.3. However, the SA508-Gr.4N steels have not yet been used commercially due to a lack of information of the productivity and the age related properties. While the irradiation embrittlement studies are going-on, the current paper focused on the effects of alloying elements such as Ni, Cr and Mo on the fracture mechanical properties of the SA508 Gr.4N low alloy steels. Various model alloys were fabricated by changing the contents of alloying elements based on the composition range of the ASME specification. Tensile properties, Charpy impact toughness and fracture toughness of the model alloys were evaluated and those properties were discussed with the microstructural characteristics of each alloy. The strengths of the alloys were increased with increase of the Ni and Mo contents while there was no remarkable change of the yield strength with the Cr addition. The Charpy impact and fracture toughness were considerably improved with the increase of Ni, Cr contents. The Mo addition did not change the toughness properties significantly. The Cr contents were more effective on the fracture toughness through changing the carbides precipitation characteristics and the Ni contents were effective on the Charpy impact toughness through changing the effective grain size.

scholarly journals Age-related changes in the mechanical properties of the epimysium in skeletal muscles of rats

2008 ◽  
Vol 41 (2) ◽  
pp. 465-469 ◽  
Author(s):  
Yingxin Gao ◽  
Tatiana Y. Kostrominova ◽  
John A. Faulkner ◽  
Alan S. Wineman
Keyword(s):  
Mechanical Properties ◽  
Skeletal Muscles ◽  
Age Related ◽  
Age Related Changes
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