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۱Geometric Feedback in the Bone Remodeling Equation: A Modification on the Adaptive Elasticity Model
اطلاعات انتشار: سیزدهمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۸
In this paper we propose a new set of constitutive equations for bone remodeling that uses the specific surface instead of volume fraction. The theory of small–strain adaptive elasticity proposed by Cowin and Hegedus and a surface remodeling equation are derived to develop the remodeling theory. A relationship between net bone cell activity, bone material property and mechanical stimuli is derived. For illustration, the rate of change of trabecular remodeling is derived for selected geometries. With this model, the effect of bone geometry and mechanical stimuli on the rate of remodeling can be studied.<\div>

۲FREE SURFACE DENSITY& MICRODAMAGE IN THE BONE REMODELING EQUATION
اطلاعات انتشار: سیزدهمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۷
Everyday activities may cause microdamage in bones that is repaired through continuous remodeling. An imbalance in this remodeling process caused by abnormal mechanical demands, fatigue or disease, may predispose bone to more pronounced fracture injuries. The remodeling process is generally viewed as a material response to functional demands that is governed by an intricate relationship between bone
reinforcement and resorption. Here, we analyze the competition between damage and internal remodeling in bones. The analysis is based on a consistent thermodynamic framework of bone remodeling, involving a chemical reaction and mass transfer in the presence of microcracks.<\div>

۳پیش بینی هندسه بخش پروگزیمال استخوان فمور با استفاده از اعمال یک روش بهینه سازی بر روی یک مدل خرپا مانند
نویسنده(ها): ،
اطلاعات انتشار: چهاردهمین کنفرانس مهندسی پزشکی ایران، سال
تعداد صفحات: ۶
This paper presents a new naïve approach for simulating bone remodeling process. It is based on the uniform strength theory of optimization and employs a trusslike model for bone. The truss was subjected to external loads including 5 point loads simulating the hip joint contact forces and 3 muscular forces at the attachment sites of the muscles to the bone and the rest are reactions of ligaments. The strain in the links was calculated and the links with high strains were identified. The initial truss is modified by introducing new links wherever the strain exceeds a prescribed or critical value. The critical value was assumed to be equal to an average of the absolute value of strains in the initial model. Each link which undergoes a high strain is replaced by several new links by adding new nodes around it using Delaunay method. Introducing the new links to the truss, which is conducted according to a weighted arithmetic mean formula, will strengthen the structure and reduce the strain within the respective zone. This procedure was repeated for several times. Convergence was achieved when there were no critical links remaining. This ethod was used to study the 2D shape of proximal femur in the frontal plane and provided results which are in fairly good agreement with CT image of the human proximal femur.

۴Perturbation in Bon's Living Function Caused by Replacing Collagen Fibers With Carbon Nanotubes
اطلاعات انتشار: شانزدهمین کنفرانس مهندسی پزشکی ایران، سال
تعداد صفحات: ۴
Bone is a very dynamic living existent which continuously goes through a coupled process of resorption and formation , a process so– called bone remodeling. It is a well accepted , but undesirable fact that after maturation , bone's quality deteriorates by time . Therefore , a great need appears for fabricating artificial bone and \ or improving the natural bone's mechanical properties. This necessity has attracted numerous researchers from diverse fields of bio–engineering . The composite – like structure of bone encourages researchers to look for a superior fiber for replacing bone's organic as a means of enhancing its properties . Carbon nanotubes (CNTs), due to their similarities with collagen fibers (CFs) and also outstanding mechanical properties , are apparently one suitable candidate for such an applicatio. However , the big differences between their mechanical properties with those of CFs, moreover the high sensitivity of bone sensor cells to exerted mechanical stimli , can raise a concern about the potential drawbcks of employing CNTs (instead of CFs) from the bone remodeling point of view, so , it is hypothesized here that application of CNTs, despite the fact that can considerably increases bone mechanical properties , may have a negative effect on the bone remodeling process, which is absolutely necessary for bone maintenance and health.<\div>

۵Functionalized carbon nanotube as a reinforcing scaffold for mineralization of bone tissue: A mechanical model
اطلاعات انتشار: هفدهمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۴
Based on the idea of bone mineralization and formation on chemically functionalized carbon nanotuebes (CNTs), a representative volume element of hydroxyapatite (bone mineral phase ) aroun a CNT is considered to determine its mechanical response to exial loading.<\div>

۶On the replacement of collagen fibers with carbon nanotubes in bone tissue:A bio–mechanical approach
اطلاعات انتشار: هجدهمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۴
Bone is one of the most dynamic tissues in our body. In order to reach an optimal structure, it undergoes continuous resorption and formation from birth to death. Artificial bone can be produced by the replacement of bone’s natural fibers, i.e. collagen fibers, with artificially made ones (such as carbon nanotubes). However, the great dependency of bone remodeling on the mechanical stimuli, besides considerable differencesbetween the mechanical properties of CNTs and those of CFs, may encourage one to hypothesize that such replacement will cause an imbalance in the rate of normal bone remodeling process. Results of this study show that the application of CNTs instead of CFs causes a significant reduction in strain energy density (SED) within the bone, which cannot be compensated even in the presence of micro–cracks (as stress amplifiers). Based on this research, it is concluded that this abnormal SED distribution in artificial bone matrix can destabilize normal bone remodeling process, and so may cause some abnormalities in both its mechanical and biological functions.<\div>
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