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1.
骨组织内的流体流动不仅为骨细胞的生存提供了充足营养供应及代谢物排放途径,也在骨重建过程中起到关键作用.为了更精确地阐明骨内液体流动的具体形式,这项研究利用骨陷窝-骨细胞的密度,形态和方向等参数来计算骨单元内液体的流动行为.首先,计算出不同形状和方向的骨陷窝周围骨小管的数量及分布情况,其次利用算出的参数以及骨组织其他微结构数据来估计骨组织的渗透率和孔隙率等参数,最后根据计算所得的参数建立骨单元的多孔弹性力学有限元模型,并分析了在轴向位移载荷作用下骨陷窝形状和方向对骨单元内液体渗流行为的影响.结果表明,在所研究的参数范围内不同骨单元模型的相同区域上,骨陷窝形状影响下的骨单元最大压力和流速比最小的分别增加了86%和18%;骨陷窝方向影响下的最大压力和流速比最小的分别增加了125%和56%.伸长形骨陷窝对单个骨单元局部压力的影响远大于扁平形和圆形骨陷窝.骨陷窝从0°绕x轴旋转到90°过程中压力是逐渐降低的,且30°,45°和60°的模型对骨单元内局部流速有显著影响.该模型表示骨陷窝的形状和方向以及骨小管的三维分布对骨单元内液体压力和流速幅值及沿不同方向的流动差异有显著的影响.这项研究将有助于精确量化描述骨内液体的流体行为.  相似文献   

2.
骨组织内的流体流动不仅为骨细胞的生存提供了充足营养供应及代谢物排放途径,也在骨重建过程中起到关键作用. 为了更精确地阐明骨内液体流动的具体形式,这项研究利用骨陷窝-骨细胞的密度,形态和方向等参数来计算骨单元内液体的流动行为. 首先,计算出不同形状和方向的骨陷窝周围骨小管的数量及分布情况,其次利用算出的参数以及骨组织其他微结构数据来估计骨组织的渗透率和孔隙率等参数,最后根据计算所得的参数建立骨单元的多孔弹性力学有限元模型,并分析了在轴向位移载荷作用下骨陷窝形状和方向对骨单元内液体渗流行为的影响. 结果表明,在所研究的参数范围内不同骨单元模型的相同区域上,骨陷窝形状影响下的骨单元最大压力和流速比最小的分别增加了86%和18%;骨陷窝方向影响下的最大压力和流速比最小的分别增加了125%和56%. 伸长形骨陷窝对单个骨单元局部压力的影响远大于扁平形和圆形骨陷窝. 骨陷窝从0°绕$x$轴旋转到90°过程中压力是逐渐降低的,且30°,45°和60°的模型对骨单元内局部流速有显著影响. 该模型表示骨陷窝的形状和方向以及骨小管的三维分布对骨单元内液体压力和流速幅值及沿不同方向的流动差异有显著的影响. 这项研究将有助于精确量化描述骨内液体的流体行为.   相似文献   

3.
人的密质骨的力学性能   总被引:11,自引:0,他引:11  
本文把骨组织看作是一种材料和骨骼系统的粘弹性结构元件,评述了它们的力学性能.首先描述了骨的结构,包括宏观结构、微结构和超微结构.随后是骨的力学性能.第三部分介绍了哈弗氏骨的力学模型.笔者指出,单个哈弗氏骨可考虑为正交铺设的胶原纤维增强的粘弹性厚壁筒.最后讨论了哈弗氏骨的应力-应变关系.显然,简单的弹性关系是不可用于实际的.  相似文献   

4.
徐莲云  侯振德  钟声  王泓 《实验力学》2009,24(4):320-326
骨受力变形时所引起的压力驱动骨内哈佛氏管或骨小管内的液体流动,是骨内出现流动电位的外部原因.由于人体经常受动态载荷作用,研究骨在动态加载过程中流动电位的变化,更有助于了解骨细胞周围电环境的性质.为此,设计了流动电位测试系统,在骨试样两端施加梯形压力波.实验测量了在不同加载速率下流动电位的变化波形.结果显示,加载速率越高,流动电位有减小的趋势.分析认为这是由于微管中局部产生的湍流引起的.  相似文献   

5.
细胞培养液在微流控生物反应器中受到外界物理场(如压力梯度或者电场)作用流动而产生流体剪应力,并进一步刺激种子细胞调控其内部基因的表达,从而促进细胞的分化和生长,这个过程在自然生命组织内的微管中亦是如此.考虑到细胞培养微腔隙中液体流动行为很难实验量化测定,理论建模分析是目前可行的研究手段.因此建立了矩形截面的细胞微流控培养腔理论模型,将外部的物理驱动场(压力梯度与电场)与培养腔内液体的流速、切应力和流率联系起来,分别得到了压力梯度驱动(pressure gradient driven,PGD)、电场驱动(electric field driven,EFD)及力–电协同驱动(pressure-electricity synergic driven,P-ESD)三种驱动方式下的液体流动理论模型.结果表明该理论模型与现有的实验结果基本一致,即力–电协同作用下的解答为压力梯度驱动和电场驱动结果的叠加.细胞培养腔内的流体流速、剪应力及流率幅值均正比于外部物理场强幅值,但随着压力梯度驱动载荷频率的增大而减小,随着电场驱动频率的变化不明显.在压力梯度驱动作用下,细胞贴壁处的切应力随着腔高的增大而线性增大,流率则随着腔高的增大而非线性增大,而电场驱动下的结果不受腔高的影响.生理范围内的温度场变化对压力和电场驱动的结果影响不大.另外,在引起细胞响应的流体切应力水平,电场驱动能提供较大的切应力幅值而压力梯度驱动则能提供较大的流率幅值.该理论模型的建立为细胞微流控生物反应器实验系统的设计及参数优化提供理论参考,同时也为力–电刺激细胞生长、分化机理的研究的提供基础.  相似文献   

6.
人体桡骨支架力学模型及承载性能   总被引:1,自引:0,他引:1  
针对人体骨组织三维网状孔洞分布特点,得到了一种建立人体骨支架力学模型的方法.利用该方法获得了人体桡骨力学模型,导出了桡骨黏弹性本构模型.通过对桡骨力学模型的承载性能分析,得出:当桡骨受到单向轴向压力时,最大应力出现在通孔孔壁上,且应力与应变的关系是非线性的.  相似文献   

7.
细胞培养液在微流控生物反应器中受到外界物理场(如压力梯度或者电场)作用流动而产生流体剪应力,并进一步刺激种子细胞调控其内部基因的表达,从而促进细胞的分化和生长,这个过程在自然生命组织内的微管中亦是如此。考虑到细胞培养微腔隙中液体流动行为很难实验量化测定,理论建模分析是目前可行的研究手段。因此建立了矩形截面的细胞微流控培养腔理论模型,将外部的物理驱动场(压力梯度与电场)与培养腔内液体的流速、切应力和流率联系起来,分别得到了压力梯度驱动(Pressure gradient driven,PGD)、电场驱动(Electric field driven,EFD)及力-电协同驱动(Pressure-electricity synergic driven,P-ESD)三种驱动方式下的液体流动理论模型。结果表明该理论模型与现有的实验结果基本一致,具体地:力-电协同作用下的解答为压力梯度驱动和电场驱动结果的叠加。细胞培养腔内的流体流速、剪应力及流率幅值均正比于外部物理场强幅值,但随着压力梯度驱动载荷频率的增大而减小,随着电场驱动频率的变化不明显。在压力梯度驱动作用下,细胞贴壁处的切应力随着腔高的增大而线性增大,流率则随着腔高的增大而非线性增大,而电场驱动下的结果不受腔高的影响。生理范围内的温度场变化对压力和电场驱动的结果影响不大。另外,在引起细胞响应的流体切应力水平,电场驱动能提供较大的切应力幅值而压力梯度驱动则能提供较大的流率幅值。该理论模型的建立为细胞微流控生物反应器实验系统的设计及参数优化提供理论参考,同时也为力-电刺激细胞生长、分化机理的研究的提供基础。   相似文献   

8.
结合非局部弹性应力/应变梯度耦合本构关系和流体非局部应力关系式,基于Euler梁理论,建立了充流微通道流固耦合波传导模型;根据耦合固体非局部应力/应变梯度弹性效应以及流体非局部效应,分别模拟了微通道和管腔内流体的尺度效应,推导得出了充流微通道在微纳米尺度的波动控制方程和边界条件。通过对控制方程的求解,分析了不同类型尺度效应对微通道的波动和振动特性的影响。结果显示,各类尺度效应对系统的动力学特性影响不同。微通道非局部弹性效应对波动产生阻尼,特别是对波长较短的波传导;而应变梯度弹性效应对波传导有促进作用,且该效应对波动的影响与波长无关;非局部效应和应变梯度效应对微通道刚度产生不同影响,非局部效应降低刚度,应变梯度效应增加刚度。  相似文献   

9.
轴向扩散下简支饱和多孔弹性梁的大挠度分析   总被引:1,自引:1,他引:0  
杨骁  李丽 《固体力学学报》2007,28(3):313-317
基于多孔介质理论和弹性梁的大挠度理论,并考虑轴向变形,在孔隙流体仅沿轴向扩散的假设下,建立了微观不可压饱和多孔弹性梁大挠度弯曲变形的一维非线性数学模型.在此基础上,忽略饱和多孔弹性梁的轴向应变,并利用Galerkin截断法,研究了两端可渗透的简支饱和多孔弹性梁在突加横向均布载荷作用下的拟静态弯曲,给出了饱和多孔梁弯曲时挠度、弯矩和轴力以及孔隙流体压力等效力偶等沿轴线的分布曲线.揭示了大挠度非线性和小挠度线性模型的结果差异,指出大挠度非线性模型的结果小于相应小挠度线性模型的结果,并且这种差异随着载荷的增大而增大.计算表明:当无量纲载荷参数q>5时,应该采用大挠度非线性数学模型进行研究.  相似文献   

10.
利用有限变形弹塑性理论和超弹性理论,研究了组合线性强化弹塑性-超弹性球体在径向拉伸死载荷作用下的空穴生成问题.确定了外载荷与空穴半径的函数关系,给出了空穴形成时应力的分布,讨论了材料硬化参数对外载荷和应力分布的影响.结果表明:空穴半径是以某有限值突然出现的,且存在着上界和下限;拉伸死载荷随着空穴半径的增大先减小再增大;径向应力在空穴处为零而环向应力则在空穴处形成应力集中,其实正是这种应力集中,导致了空穴的出现.本文的研究结论可以为橡胶材料的增韧技术提供一定的理论参考依据.  相似文献   

11.

The lacunar-canalicular system (LCS) is acknowledged to directly participate in bone tissue remodeling. The fluid flow in the LCS is synergic driven by the pressure gradient and electric field loads due to the electro-mechanical properties of bone. In this paper, an idealized annulus Maxwell fluid flow model in bone canaliculus is established, and the analytical solutions of the fluid velocity, the fluid shear stress, and the fluid flow rate are obtained. The results of the fluid flow under pressure gradient driven (PGD), electric field driven (EFD), and pressure-electricity synergic driven (P-ESD) patterns are compared and discussed. The effects of the diameter of canaliculi and osteocyte processes are evaluated. The results show that the P-ESD pattern can combine the regulatory advantages of single PGD and EFD patterns, and the osteocyte process surface can feel a relatively uniform shear stress distribution. As the bone canalicular inner radius increases, the produced shear stress under the PGD or P-ESD pattern increases slightly but changes little under the EFD pattern. The increase in the viscosity makes the flow slow down but does not affect the fluid shear stress (FSS) on the canalicular inner wall and osteocyte process surface. The increase in the high-valent ions does not affect the flow velocity and the flow rate, but the FSS on the canalicular inner wall and osteocyte process surface increases linearly. In this study, the results show that the shear stress sensed by the osteocyte process under the P-ESD pattern can be regulated by changing the pressure gradient and the intensity of electric field, as well as the parameters of the annulus fluid and the canaliculus size, which is helpful for the osteocyte mechanical responses. The established model provides a basis for the study of the mechanisms of electro-mechanical signals stimulating bone tissue (cells) growth.

  相似文献   

12.
A hierarchical model is developed to predict the streaming potential(SP) in the canaliculi of a loaded osteon. Canaliculi are assumed to run straight across the osteon annular cylinder wall, while disregarding the effect of lacuna. SP is generalized by the canalicular fluid flow. Analytical solutions are obtained for the canalicular fluid velocity, pressure, and SP. Results demonstrate that SP amplitude(SPA) is proportional to the pressure difference, strain amplitude, frequency, and strain rate amplitude. However, the key loading factor governing SP is the strain rate, which is a representative loading parameter under the specific physiological state. Moreover, SPA is independent of canalicular length. This model links external loads to the canalicular fluid pressure, velocity, and SP, which can facilitate further understanding of the mechanotransduction and electromechanotransduction mechanisms of bones.  相似文献   

13.
In the paper, two theoretical poroelastic osteon models are presented to compare their poroelastic behaviors, one is the hollow osteon model (Haversian fluid is neglected) and the other is the osteon model with Haversian fluid considered. They both have the same two types of impermeable exterior boundary conditions, one is elastic restraint and the other is displacement constrained, which can be used for analyzing other experiments performed on similarly shaped poroelastic specimens. The obtained analytical pressure and velocity solutions demonstrate the effects of the loading factors and the material parameters, which may have a significant stimulus to the mechanotransduction of bone remodeling signals. Model comparisons indicate: (1) The Haversian fluid can enhance the whole osteonal fluid pressure and velocity fields. (2) In the hollow model, the key loading factor governing the poroelastic behavior of the osteon is strain rate, while in the model with Haversian fluid considered, the strain rate governs only the velocity. (3) The pressure amplitude is proportional to the loading frequency in the hollow model, while in the model with Haversian fluid considered, the loading frequency has little effect on the pressure amplitude.  相似文献   

14.
An extended and reasonable stress boundary condition at an osteon exterior wall is presented to solve the model proposed by Rémond and Naili. The obtained pressure and fluid velocity solutions are used to investigate the osteonal poroelastic behaviors. The following results are obtained. (i) Both the fluid pressure and the velocity amplitudes are proportional to the strain amplitude and the loading frequency. (ii) In the physiological loading state, the key role governing the poroelastic behaviors of the osteon is the strain rate. (iii) At the osteon scale, the pressure is strongly affected by the permeability variations, whereas the fluid velocity is not.  相似文献   

15.
The articular cartilage (AC) can be seen as a biphasic poroelastic material. The cartilage deformation under compression mainly leads to an interstitial fluid flow in the porous solid phase. In this paper, an analytical poroelastic model for the AC under laboratorial mechanical testing is developed. The solutions of interstitial fluid pressure and velocity are obtained. The results show the following facts. (i) Both the pressure and fluid velocity amplitudes are proportional to the strain loading amplitude. (ii) Both the amplitudes of pore fluid pressure and velocity in the AC depend more on the loading amplitude than on the frequency. Thus, in order to obtain the considerable fluid stimulus for the AC cell responses, the most effective way is to increase the loading amplitude rather than the frequency. (iii) Both the interstitial fluid pressure and velocity are strongly affected by permeability variations. This model can be used in experimental tests of the parameters of AC or other poroelastic materials, and in research of mechanotransduction and injury mechanism involved interstitial fluid flow.  相似文献   

16.
根据解剖学发现的人体小腿骨间膜血管和胶原纤维有序排列的特点,建立三维组织间隙液渗流模型,控制方程用Brinkman方程和连续性方程,使用Fluent软件进行数值模拟.计算结果显示,组织液在组织间隙中流动的方向总体是与平行毛细血管的方向相一致的;组织间隙多孔率会影响速度的分布,当多孔率增加时,空间的速度趋于均匀,从而使得最大速度变小,正常生理范围内多孔率的改变对于组织液流动的影响较小.但当多孔率很小时(组织纤维化),会大大影响组织液流动的均匀性;组织间隙平行胶原的存在,会使得组织间隙速度在空间上的分布趋于均匀;另外,间隙流场随血压的增加而增加,随组织压的增加而降低,这与临床和经络研究的发现相一致.  相似文献   

17.
The pulsatile flow of blood through a catheterized artery is analyzed, assuming the blood as a two-fluid model with the suspension of all the erythrocytes in the core region as a Casson fluid and the peripheral region of plasma as a Newtonian fluid. The resulting non-linear implicit system of partial differential equations is solved using perturbation method. The expressions for shear stress, velocity, flow rate, wall shear stress and longitudinal impedance are obtained. The variations of these flow quantities with yield stress, catheter radius ratio, amplitude, pulsatile Reynolds number ratio and peripheral layer thickness are discussed. It is observed that the velocity distribution and flow rate decrease, while, the wall shear, width of the plug flow region and longitudinal impedance increase when the yield stress increases. It is also found that the velocity increases, but, the longitudinal impedance decreases when the thickness of the peripheral layer increases. The wall shear stress decreases non-linearly, while, the longitudinal impedance increases non-linearly when the catheter radius ratio increases. The estimates of the increase in the longitudinal impedance are considerably lower for the present two-fluid model than those of the single-fluid model.  相似文献   

18.
Blood flow through a catheterized artery is analyzed, assuming the flow is steady and blood is treated as a two-fluid model with the suspension of all the erythrocytes in the core region as a Casson fluid and the plasma in the peripheral region as a Newtonian fluid. The expressions for velocity, flow rate, wall shear stress and frictional resistance are obtained. The variations of these flow quantities with yield stress, catheter radius ratio and peripheral layer thickness are discussed. It is noticed that the velocity and flow rate decrease while the wall shear stress and resistance to flow increase when the yield stress or the catheter radius ratio increases while all the other parameters were held fixed. It is found that the velocity and flow rate increase while the wall shear stress and frictional resistance decrease with the increase of the peripheral layer thickness. The estimates of the increase in the frictional resistance are significantly very small for the present two-fluid model than those of the single-fluid Casson model.  相似文献   

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