Download or read book The Deformation and Fracture of Human Cortical Bone Across Multiple Length scales written by Elizabeth Ann Zimmermann and published by . This book was released on 2011 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: The complex structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen molecules and hydroxyapatite crystals at the nanoscale to the osteonal structures at near-millimeter dimensions. There is a need to understand how all levels of the structure contribute to the deformation and fracture resistance of cortical bone under physiological loading conditions and how structural changes due to aging and disease lead to diminished mechanical properties. The first part of this thesis addresses the latter by using non-enzymatic crosslinking measurements and in situ small- and wide-angle x-ray scattering/diffraction to characterize changes in the bone structure at sub-micron dimensions, while synchrotron x-ray computed micro-tomography and in situ fracture-toughness measurements in the scanning electron microscope were performed to characterize corresponding changes at micron-scale dimensions. This multi-scale analysis allows us to better understand how load is transferred across multiple length-scales and how biological aging impacts energy absorption throughout the structure. The second part of this thesis addresses the fracture toughness of human cortical bone under multiaxial loading. Most studies to date have only considered the toughness of bone under mode I (tensile) loading conditions; however, due to the complex, anisotropic structure of cortical bone, the mode I fracture toughness is not necessarily the limiting value. Thus, this research investigates the effects of combined tensile and shear loading at the crack tip on the initiation and crack-growth toughnesses to better understand how bone fractures under physiologically relevant loading conditions.

Download or read book Bioinspired Structures and Design written by Wole Soboyejo and published by Cambridge University Press. This book was released on 2020-09-17 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master simple to advanced biomaterials and structures with this essential text. Featuring topics ranging from bionanoengineered materials to bio-inspired structures for spacecraft and bio-inspired robots, and covering issues such as motility, sensing, control and morphology, this highly illustrated text walks the reader through key scientific and practical engineering principles, discussing properties, applications and design. Presenting case studies for the design of materials and structures at the nano, micro, meso and macro-scales, and written by some of the leading experts on the subject, this is the ideal introduction to this emerging field for students in engineering and science as well as researchers.

Download or read book Age related Changes in the Plasticity and Toughness of Human Cortical Bone at Multiple Length scales written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen and hydroxyapatite at the nanoscale to osteonal structures at nearmillimeter dimensions, which all provide the basis for its mechanical properties. To resist fracture, bone's toughness is derived intrinsically through plasticity (e.g., fibrillar sliding) at structural-scales typically below a micron and extrinsically (i.e., during crack growth) through mechanisms (e.g., crack deflection/bridging) generated at larger structural-scales. Biological factors such as aging lead to a markedly increased fracture risk, which is often associated with an age-related loss in bone mass (bone quantity). However, we find that age-related structural changes can significantly degrade the fracture resistance (bone quality) over multiple lengthscales. Using in situ small-/wide-angle x-ray scattering/diffraction to characterize sub-micron structural changes and synchrotron x-ray computed tomography and in situ fracture-toughness measurements in the scanning electron microscope to characterize effects at micron-scales, we show how these age-related structural changes at differing size-scales degrade both the intrinsic and extrinsic toughness of bone. Specifically, we attribute the loss in toughness to increased non-enzymatic collagen cross-linking which suppresses plasticity at nanoscale dimensions and to an increased osteonal density which limits the potency of crack-bridging mechanisms at micron-scales. The link between these processes is that the increased stiffness of the cross-linked collagen requires energy to be absorbed by?plastic? deformation at higher structural levels, which occurs by the process of microcracking.

Download or read book On the Multiscale Origins of Fracture Resistance in Human Bone and Its Biological Degradation written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Akin to other mineralized tissues, human cortical bone can resist deformation and fracture due to the nature of its hierarchical structure, which spans the molecular to macroscopic length-scales. Deformation at the smallest scales, mainly through the composite action of the mineral and collagen, contributes to bone?s strength or intrinsic fracture resistance, while crack-tip shielding mechanisms active on the microstructural scale contribute to the extrinsic fracture resistance once cracking begins. The efficiency with which these structural features can resist fracture at both small and large length-scales becomes severely degraded with such factors as aging, irradiation and disease. Indeed aging and irradiation can cause changes to the cross-link profile at fibrillar length-scales as well as changes at the three orders of magnitude larger scale of the osteonal structures, both of which combine to inhibit the bone's overall resistance to the initiation and growth of cracks.

Download or read book 3D Orientation Distribution and Deformation of Mineral Crystals in Human Cortical Bone written by Chandan Shome and published by . This book was released on 2013 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bone fragility fracture has been a major healthcare concern for a long time. Due to having hierarchical structure at different length scales, bone fragility fracture is directly related to structural hierarchy from macro scale to nano scale. In nano level mineral crystals and collagen fibrils construct mineral-collagen composite structure. Mineral crystals and collagen fibrils are aligned preferentially in primary loading directions to cope with external loading conditions. In situ behavior of mineral and collagen phases is vital which could affect bone nanomechanics and could alter tissue fragility. This thesis is a preliminary study of a long-term project of correlating ultrastructural behavior to bulk behavior of bone. The first objective of this study was to develop 3D orientation distribution model of mineral crystals in bone based on experimental observations & using Bivariate Gaussian curve fitting technique. 3D orientation distribution of mineral crystals in bone was estimated in Cartesian coordinate system. The second objective of this study was to estimate the in situ strain tensors of a set of mineral crystals that are aligned along longitudinal axis of bone under uniaxial compressive load. Using experimental data obtained from synchrotron X-ray scattering technique, a novel approach was implemented to obtain local strain tensor of mineral crystals. Obtained results indicate that subset of mineral crystals aligned in the loading direction is most likely deformed in a transversely isotropic manner. Also, existence of a significant amount of shear strain in transverse plane (x-y) suggests that interfacial sliding between mineral crystals and surrounding matrix likely to be occurred. In addition, shear components in longitudinal planes (y-z & z-x) are smaller compared to that in transverse plane(x-y).

Download or read book Fracture Characterization of Cortical Bone at the Micrometer and Nanometer Length Scales written by Oke Orieka and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture Aging and Disease in Bone written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: From a public health perspective, developing a detailed mechanistic understanding of the well-known increase in fracture risk of human bone with age is essential. This also represents a challenge from materials science and fracture mechanics viewpoints. Bone has a complex, hierarchical structure with characteristic features ranging from nanometer to macroscopic dimensions; it is therefore significantly more complex than most engineering materials. Nevertheless, by examining the micro-/nano-structural changes accompanying the process of aging using appropriate multiscale experimental methods and relating them to fracture mechanics data, it is possible to obtain a quantitative picture of how bone resists fracture. As human cortical bone exhibits rising ex vivo crack-growth resistance with crack extension, its fracture toughness must be evaluated in terms of resistance-curve (R-curve) behavior. While the crack initiation toughness declines with age, the more striking finding is that the crack-growth toughness declines even more significantly and is essentially absent in bone from donors exceeding 85 years in age. To explain such an age-induced deterioration in the toughness of bone, we evaluate its fracture properties at multiple length scales, specifically at the molecular and nanodimensions using pico-force atomic-force microscopy, nanoindentation and vibrational spectroscopies, at the microscale using electron microscopy and hard/soft x-ray computed tomography, and at the macroscale using R-curve measurements. We show that the reduction in crack-growth toughness is associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging, and that this occurs at relatively coarse size-scales in the range of tens to hundreds of micrometers. Finally, we briefly describe how specific clinical treatments, e.g., with steroid hormones to treat various inflammatory conditions, can prematurely damage bone, thereby reducing its fracture resistance, whereas regulating the level of the cytokine TGF-beta can offer significant improvements in the stiffness, strength and toughness of bone, and as such may be considered as a therapeutic target to treat increased bone fragility induced by aging, drugs, and disease.

Download or read book On the Effect of X ray Irradiation on the Deformation and Fracture Behavior of Human Cortical Bone written by and published by . This book was released on 2010 with total page 1475 pages. Available in PDF, EPUB and Kindle. Book excerpt: In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistance-curve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the progressive elimination of the bone's capacity for plastic deformation which restricts the intrinsic toughening from the formation 'plastic zones' around crack-like defects. Deep-ultraviolet Raman spectroscopy indicated that this behavior could be related to degradation in the collagen integrity.

Download or read book A Hierarchical Approach to Characterizing the Fracture Behavior of Bone Utilizing Synchrotron Radiation written by Holly Dana Barth and published by . This book was released on 2011 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bone has a complex hierarchical microstructure that spans from the nanoscale of the collagen molecules to the macroscopic physiological scale. In order to assess bone's risk of fracture with issues such as aging, disease, or irradiation it is critical to have a clear mechanistic framework which analyzes bone's deformation and fracture behavior at each structurally significant length scale. In this context, this present study seeks to characterize the fracture properties of bone by applying a hierarchical approach. Accordingly, this study utilizes x-ray microtomography from synchrotron radiation in order to identify the crack-resistant extrinsic mechanisms in different types of cortical bone. It was found that bone, which is a highly anisotropic material, displays toughening through crack deflection, out of plane twist and crack bridging. Next this study utilizes in situ tensile tests with x-ray scattering to investigate the submicron deformation in bone; at this length scale bone toughens intrinsically through plasticity mechanisms such as fibrillar sliding. Lastly, this study uses this mechanistic framework to evaluate the effects of irradiation on the fracture properties of bone. Here it was found that bone exposed to high doses of irradiation, greater than 70 kGy (Gy=J/Kg), leads to a severe progressive dose dependent degradation in strength, ductility, and toughness which is attributed to a change in the crack path (extrinsic effect) and a degradation of the collagen integrity from altered collagen cross-link (intrinsic effect). Overall, the goal of this work is to outline a framework that can be applied to future studies investigating the effects of disease and aging on bone.

Download or read book Fracture and Fatigue Characterisation of Cortical Bone Tissue written by Marcelo F. S. F. de Moura and published by CRC Press. This book was released on 2024-09-09 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fracture and Fatigue Characterisation of Cortical Bone Tissue is a key guide to bone fracture and fatigue, focusing on quasi-static and fatigue-fracture characterisation of cortical bone tissue. Discussing the fundamental aspects of fracture mechanics and fatigue, which are applicable to many orthotropic materials, this book examines novel, cutting-edge approaches to analyse and model bone fracture and fatigue. As the population ages across the globe, bone fracture and fatigue has become a fundamental part of mechanical and biomedical engineering research. Beginning with a thorough description of fracture mechanics and fatigue, the book describes non-linear fracture mechanics under quasi-static and fatigue analyses. It goes on to present a cohesive zone modelling method which is appropriate for mode I, mode II and mixed-mode I+II loading. Presenting the latest research, this book describes cutting-edge fracture tests, new methods for data reduction purposes and numerical models based on cohesive zone modelling. This book is key to aiding both students and professionals in applying fundamental theories and methods to cortical bone tissue. The book will be of interest to students and professionals working in mechanical engineering and biomedical engineering, including work on quasi-static fracture, fracture under fatigue loading, artificial bones and fracture mechanisms.

Download or read book Engineered Biomaterials written by Rishabha Malviya and published by Springer Nature. This book was released on 2023-12-28 with total page 623 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights recent advances focusing on the synthesis methods of engineered biomaterials and their applications. The book discusses recent applications of various approaches and technology in improving the functional properties and biological activities of biopolymers. It includes two major sections: the first section introduces a range of methods which lead to materials with enhanced properties for a range of practical applications, along with the positives and limitations of the techniques. The second section covers recent trends and advances in application of engineered biomaterials that assist materials scientists and researchers in mapping out the future of these new improved materials through value addition in order to enhance their use. Contributions in the book are done by prominent researchers from industry, academia, and government/private research laboratories across the globe. The book summarizes in a fairly comprehensive manner many of the recent technical advancements in the area of biopolymers. The book is intended to serve as a reference resource in the area of polymers science.

Download or read book Focus on Bio Image Informatics written by Winnok H. De Vos and published by Springer. This book was released on 2016-05-20 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume of Advances Anatomy Embryology and Cell Biology focuses on the emerging field of bio-image informatics, presenting novel and exciting ways of handling and interpreting large image data sets. A collection of focused reviews written by key players in the field highlights the major directions and provides an excellent reference work for both young and experienced researchers.

Download or read book Degradation Mechanics of Bone and Bone Like Materials Via Multiscale Analysis written by MD Farzad Sarker and published by . This book was released on 2014 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bone fracture is a common health risk for older people suffering from bone disease like osteoporosis. The more severe the osteoporosis is the more structural degradation in bones occurs, which eventually makes bones more fracture prone. The mechanical behavior of bone depends on the structural response of bone constituents over a broad range of length scales spanning from the nanoscale collagen fibril level to the macroscale trabeculae level. As such, in order to understand bone fracture, it is important to know the structure-property relations of bone material over the entire length of scale. Surprisingly, a quantitative understanding of bone fracture toughness is still not well understood, which the premise of the current study is. The multiscale analysis of bone is performed by considering five distinctive microstructures of bone, namely, the nano scale, submicron scale, micron scale, macro scale and trabecular bone itself. These substructures span almost over 9 order of length scales. By considering the nanoscale collagen fibril, the building block of bone composed of collagen protein (TC) and hydroxyapatite (HAP) mineral crystal, as a discontinuous fiber reinforced composite structure, the Halpin-Tsai relation for discontinuous fiber reinforced composites were used as the initial process for calculating mechanical properties of HAP and TC in nano scale. From the hierarchical level 2 to level 5, a self-similar approach was used to determine the mechanical properties of subsequent microstructures. Then, these properties were applied on several finite element models consisting of several fully three dimensional solid trabecular model (obtained from direct micro CT scan) and five different "approximated spongy" microstructures with appropriate boundary conditions. Each approximated model represents a simplified microstructure of the trabecular network. Critical stress intensity factor or fracture toughness was calculated from linear elastic fracture mechanics theories using the constitutive model developed from multi-scale analysis. The effects of trabecular thickness on Mode I fracture toughness were studied with different models of different thickness and their relations were analyzed. A comparative study of structural stiffness and anisotropy was conducted between the CT scan image based real bone microstructure and approximated simplified bone like microstructures. Finally, a 3D printing based manufacturing method was adopted to fabricate and characterize SiC nanoparticle reinforced nanocomposites using the micro CT image we studied. The stress-strain response was measured and deformation mechanism was studied.

Download or read book Forcefields for Atomistic Scale Simulations Materials and Applications written by Akarsh Verma and published by Springer Nature. This book was released on 2022-08-19 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the forcefields/interatomic potentials that are used in the atomistic-scale and molecular dynamics simulations. It covers mechanisms, salient features, formulations, important aspects and case studies of various forcefields utilized for characterizing various materials (such as nuclear materials and nanomaterials) and applications. This book gives many help to students and researchers who are studying the forcefield potentials and introduces various applications of atomistic-scale simulations to professors who are researching molecular dynamics.

Download or read book Experimental Study of Deformation and Microcracking in Human Cortical Bone written by Vincent Ebacher and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanics and Physics of Fracture written by Laurent Ponson and published by Springer Nature. This book was released on 2023-03-31 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: The volume provides a comprehensive understanding of the macroscopic failure behavior of solids from the description of the microscopic failure processes and their coupling with the microstructure. Several fundamental questions were addressed: the relation between the microstructural features of materials and their fracture properties and crack trajectories; the role of damage mechanisms and non-linear deformations near the crack tip on the failure behavior of solids; and finally the role of dynamic inertial effects during fast fracture was more briefly evoked. The chapters provide a pedagogical overview of recently developed concepts and tools, that permit to perform the transition from small scales to large ones in fracture problems, thus introducing basic rules for the rational design of tough solids.

Download or read book Bones written by John D. Currey and published by Princeton University Press. This book was released on 2013-10-31 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a comprehensive and accessible overview of what is known about the structure and mechanics of bone, bones, and teeth. In it, John Currey incorporates critical new concepts and findings from the two decades of research since the publication of his highly regarded The Mechanical Adaptations of Bones. Crucially, Currey shows how bone structure and bone's mechanical properties are intimately bound up with each other and how the mechanical properties of the material interact with the structure of whole bones to produce an adapted structure. For bone tissue, the book discusses stiffness, strength, viscoelasticity, fatigue, and fracture mechanics properties. For whole bones, subjects dealt with include buckling, the optimum hollowness of long bones, impact fracture, and properties of cancellous bone. The effects of mineralization on stiffness and toughness and the role of microcracking in the fracture process receive particular attention. As a zoologist, Currey views bone and bones as solutions to the design problems that vertebrates have faced during their evolution and throughout the book considers what bones have been adapted to do. He covers the full range of bones and bony tissues, as well as dentin and enamel, and uses both human and non-human examples. Copiously illustrated, engagingly written, and assuming little in the way of prior knowledge or mathematical background, Bones is both an ideal introduction to the field and also a reference sure to be frequently consulted by practicing researchers.