Analysis of Solute Transport in Cartilaginous Tissue Under Dynamic Unconfined Compression

2003 ◽  
Author(s):  
Hai Yao ◽  
Wei Yong Gu
Keyword(s):  
Dynamic Compression ◽  
Electrical Potential ◽  
Loading Frequency ◽  
Mechanical Forces ◽  
The Finite Element Method ◽  
Unconfined Compression ◽  
Cartilage Sample ◽  
Cartilaginous Tissues ◽  
Transduction Mechanisms ◽  
Theoretical Analyses

Transport of fluid and solutes through the extracellular matrix plays a key role in the nutrition and growth of cartilaginous tissues that lack blood supply. It has been found that the mechanical loading can alter the transport rates of solutes within cartilage [Bonassar, 2000; O’Hara, 1990; Quinn, 2002]. Dynamic compression may enhance the transport of large solutes (e.g., growth factors) within the tissue. Many theoretical analyses have been reported in literature on the transport of fluid and solutes, as well as physical signals (stress, strain, pressure, concentrations, and electrical potential) in cartilage under unconfined compression [Armstrong, 1984; Levenston, 1999; Mow, 2002]. However, little is known as to how the tissue fixed charge density (FCD) affects the transport of fluid and neutral solutes (e.g., glucose and IGF-1) in cartilage sample in dynamic compression. In this study, we numerically analyzed the transport of fluid and solutes, as well as the mechano-electrochemical signals within the cartilage sample in dynamic unconfined compression, using the finite element method (FEM). The objective of this study was to investigate the effects of FCD, loading frequency, and loading platens (permeable vs. impermeable) on the transport of fluid, ions, and neutral solutes within cartilage. This study is essential for the understanding of tissue nutrition and signal transduction mechanisms in cartilage subjected to mechanical forces.

scholarly journals The strain-generated electrical potential in cartilaginous tissues: a role for piezoelectricity

2021 ◽  
Vol 13 (1) ◽  
pp. 91-100
Author(s):  
Philip Poillot ◽  
Christine L. Le Maitre ◽  
Jacques M. Huyghe
Keyword(s):  
Physiological Response ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Electrical Potential ◽  
Evidence Base ◽  
Piezoelectric Response ◽  
Mechanical Forces ◽  
Streaming Potentials ◽  
Cartilaginous Tissues ◽  
Electrical Potentials

AbstractThe strain-generated potential (SGP) is a well-established mechanism in cartilaginous tissues whereby mechanical forces generate electrical potentials. In articular cartilage (AC) and the intervertebral disc (IVD), studies on the SGP have focused on fluid- and ionic-driven effects, namely Donnan, diffusion and streaming potentials. However, recent evidence has indicated a direct coupling between strain and electrical potential. Piezoelectricity is one such mechanism whereby deformation of most biological structures, like collagen, can directly generate an electrical potential. In this review, the SGP in AC and the IVD will be revisited in light of piezoelectricity and mechanotransduction. While the evidence base for physiologically significant piezoelectric responses in tissue is lacking, difficulties in quantifying the physiological response and imperfect measurement techniques may have underestimated the property. Hindering our understanding of the SGP further, numerical models to-date have negated ferroelectric effects in the SGP and have utilised classic Donnan theory that, as evidence argues, may be oversimplified. Moreover, changes in the SGP with degeneration due to an altered extracellular matrix (ECM) indicate that the significance of ionic-driven mechanisms may diminish relative to the piezoelectric response. The SGP, and these mechanisms behind it, are finally discussed in relation to the cell response.

scholarly journals Effects of Tension-Compression Nonlinearity on Solute Transport in Charged Hydrated Fibrous Tissues Under Dynamic Unconfined Compression

2006 ◽  
Vol 129 (3) ◽  
pp. 423-429 ◽  
Author(s):  
Chun-Yuh Huang ◽  
Wei Yong Gu
Keyword(s):  
Solute Transport ◽  
Soft Tissues ◽  
Dynamic Compression ◽  
Fibrous Tissue ◽  
Dynamic Strain ◽  
Unconfined Compression ◽  
Cartilage Sample ◽  
New Model ◽  
Dynamic Loading Conditions ◽  
High Degree

Cartilage is a charged hydrated fibrous tissue exhibiting a high degree of tension-compression nonlinearity (i.e., tissue anisotropy). The effect of tension-compression nonlinearity on solute transport has not been investigated in cartilaginous tissue under dynamic loading conditions. In this study, a new model was developed based on the mechano-electrochemical mixture model [Yao and Gu, 2007, J. Biomech. Model Mechanobiol., 6, pp. 63–72, Lai et al., 1991, J. Biomech. Eng., 113, pp. 245–258], and conewise linear elasticity model [Soltz and Ateshian, 2000, J. Biomech. Eng., 122, pp. 576–586;Curnier et al., 1995, J. Elasticity, 37, pp. 1–38]. The solute desorption in cartilage under unconfined dynamic compression was investigated numerically using this new model. Analyses and results demonstrated that a high degree of tissue tension-compression nonlinearity could enhance the transport of large solutes considerably in the cartilage sample under dynamic unconfined compression, whereas it had little effect on the transport of small solutes (at 5% dynamic strain level). The loading-induced convection is an important mechanism for enhancing the transport of large solutes in the cartilage sample with tension-compression nonlinearity. The dynamic compression also promoted diffusion of large solutes in both tissues with and without tension-compression nonlinearity. These findings provide a new insight into the mechanisms of solute transport in hydrated, fibrous soft tissues.

An Investigation of the Distribution of Electric Potential and Space Charge in a Silicon Nanowire

2014 ◽  
Vol 69 (10-11) ◽  
pp. 597-605 ◽  
Author(s):  
A. Wesam Al-Mufti ◽  
Uda Hashim ◽  
Md. Mijanur Rahman ◽  
Tijjani Adam
Keyword(s):  
Finite Element Method ◽  
Space Charge ◽  
Electric Potential ◽  
Silicon Nanowire ◽  
Electrical Potential ◽  
Comsol Multiphysics ◽  
The Finite Element Method ◽  
Simulation Experiments ◽  
Different Dimensions

AbstractThe distribution of electric potential and space charge in a silicon nanowire has been investigated. First, a model of the nanowire is generated taking into consideration the geometry and physics of the nanowire. The physics of the nanowire was modelled by a set of partial differential equations (PDEs) which were solved using the finite element method (FEM). Comprehensive simulation experiments were performed on the model in order to compute the distribution of potential and space charge. We also determined, through simulation, how the characteristic of the nanowire is affected by its dimensions. The characterization of the resulting nanowire, calculated by COMSOL Multiphysics, shows different dimensions and their effect on space charge and electrical potential

Designing Hierarchical IsoTruss Column Based on Controlling Multi-Buckling Behaviors

2021 ◽  
Author(s):  
Changliang Lai ◽  
Qianqian Sui ◽  
Hualin Fan
Keyword(s):  
Finite Element ◽  
Parametric Design ◽  
Local Buckling ◽  
Fe Model ◽  
The Finite Element Method ◽  
Buckling Modes ◽  
Buckling Behavior ◽  
Global Buckling ◽  
Buckling Failure ◽  
Theoretical Analyses

To develop large-span but ultralight lattice truss columns, a hierarchical IsoTruss column (HITC) was proposed. The multi-buckling behavior of the axially compressed HITC was analyzed by the finite element method (FEM) using a parametric approach in the framework of ANSYS parametric design language (APDL). It was demonstrated that the program enables efficient generation of the finite element (FE) model, while facilitating the parametric design of the HITC. Using this program, the effects of helical angles and brace angles on the buckling behavior of the HITC were investigated. Depending on the helical angles and brace angles, the HITCs mainly have three buckling modes: the global buckling, the first-order local buckling and the second-order local buckling. Theoretical multi-buckling models were established to predict the critical buckling loads. Buckling failure maps based on the theoretical analyses were also developed, which can be useful in preliminary design of such structures.

Cartilage Interstitial Fluid Load Support in Unconfined Compression

2002 ◽  
Author(s):  
Seonghun Park ◽  
Ramaswamy Krishnan ◽  
Steven B. Nicoll ◽  
Gerard A. Ateshian
Keyword(s):  
Articular Cartilage ◽  
Interstitial Fluid ◽  
Articular Surface ◽  
Surface Zone ◽  
Unconfined Compression ◽  
Tissue Samples ◽  
Fluid Load ◽  
Tension And Compression ◽  
Fluid Pressurization ◽  
Theoretical Analyses

Under physiological conditions of loading, articular cartilage is subjected to both compressive strains, normal to the articular surface, and tensile strains, tangential to the articular surface. Previous studies have shown that articular cartilage exhibits a much higher modulus in tension than compression. Theoretical analyses have suggested that this tension-compression nonlinearity enhances the magnitude of interstitial fluid pressurization during loading in unconfined compression, above a theoretical threshold of 33% of the average applied stress. The first hypothesis of this experimental study is that the peak fluid load support in unconfined compression is significantly greater than the 33% theoretical limit predicted for porous permeable tissues modeled with equal moduli in tension and compression [1]. The second hypothesis is that the peak fluid load support is higher at the articular surface side of the tissue samples than near the deep zone, because the disparity between the tensile and compressive moduli is greater at the surface zone.

Glycosaminoglycan and Collagen Remodeling During In Vitro Dynamic Compression of Articular Cartilage: Experiments and Finite Element Modeling

2013 ◽  
Author(s):  
Kevin A. Yamauchi ◽  
Christopher B. Raub ◽  
Albert C. Chen ◽  
Robert L. Sah ◽  
Scott J. Hazelwood ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Dynamic Compression ◽  
Fluid Velocity ◽  
Biomechanical Properties ◽  
Mechanical Stimuli ◽  
Unconfined Compression ◽  
Growth Data ◽  
Collagen Remodeling ◽  
Continuum Mixture Model

The biomechanical properties of articular cartilage (AC) can be altered by chemical and mechanical stimuli. Dynamic unconfined compression (UCC) has been shown to increase biosynthesis at moderate strain amplitudes (1–4%) and frequencies from 0.01Hz. to 0.1Hz [1]. Furthermore, interstitial fluid velocity and maximum principle strain have been proposed as candidates for controlling glycosaminoglycan (GAG) and collagen (COL) remodeling, respectively [2,3]. The goal of this study was to integrate in vitro growth data, including biochemical and microstructural properties, into a computational continuum mixture model to elucidate potential mechanical triggers for AC tissue remodeling.

scholarly journals Penetrating Annulus Fibrosus Injuries Affect Dynamic Compressive Behaviors of the Intervertebral Disc Via Altered Fluid Flow: An Analytical Interpretation

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Arthur J. Michalek ◽  
James C. Iatridis
Keyword(s):  
Fluid Flow ◽  
Nucleus Pulposus ◽  
Annulus Fibrosus ◽  
Fluid Transport ◽  
Dynamic Compression ◽  
Intervertebral Discs ◽  
Mechanical Tests ◽  
Loading Frequency ◽  
Test Protocol ◽  
Transport Pathway

Extensive experimental work on the effects of penetrating annular injuries indicated that large injuries impact axial compressive properties of small animal intervertebral discs, yet there is some disagreement regarding the sensitivity of mechanical tests to small injury sizes. In order to understand the mechanism of injury size sensitivity, this study proposed a simple one dimensional model coupling elastic deformations in the annulus with fluid flow into and out of the nucleus through both porous boundaries and through a penetrating annular injury. The model was evaluated numerically in dynamic compression with parameters obtained by fitting the solution to experimental stress-relaxation data. The model predicted low sensitivity of mechanical changes to injury diameter at both small and large sizes (as measured by low and high ratios of injury diameter to annulus thickness), with a narrow range of high sensitivity in between. The size at which axial mechanics were most sensitive to injury size (i.e., critical injury size) increased with loading frequency. This study provides a quantitative hypothetical model of how penetrating annulus fibrosus injuries in discs with a gelatinous nucleus pulposus may alter disc mechanics by changing nucleus pulposus fluid pressurization through introduction of a new fluid transport pathway though the annulus. This model also explains how puncture-induced biomechanical changes depend on both injury size and test protocol.

scholarly journals Effect of graphite die geometry on energy consumption during spark plasma sintering of zirconium diboride

2021 ◽  
Vol 1 (1) ◽  
pp. 54-61
Author(s):  
Farhad Sadegh Moghanlou ◽  
Mohammad Vajdi ◽  
Milad Sakkaki ◽  
Shahla Azizi
Keyword(s):  
Energy Consumption ◽  
Electrical Potential ◽  
Sintered Sample ◽  
Geometrical Parameters ◽  
The Finite Element Method ◽  
Governing Equations ◽  
Die Geometry ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Galerkin Method

The present work aims to investigate the geometrical parameters of the graphite die on energy consumption needed for sintering of a ZrB2 sample. The Maxwell and electrical charge conservation equations are solved to obtain the electrical potential and current of the system. The governing equations are discretized by the Galerkin method and solved using the finite element method. The electric current distribution is obtained at each geometry and the temperature contours are obtained. The results showed that the height of die has a direct effect on power consumption. This can be attributed to the increased electric resistance and consequent increased Joule heating. On the other hand, increasing the die height resulted in more uniform temperature distribution through the sintered sample.

Effects of Compression on Glucose Consumption in Intervertebral Disc

2008 ◽  
Author(s):  
Chun-Yuh Huang ◽  
Wei Yong Gu
Keyword(s):  
Intervertebral Disc ◽  
Theoretical Study ◽  
Mixture Theory ◽  
Glucose Consumption ◽  
Nutrient Level ◽  
Metabolic Rates ◽  
Unconfined Compression ◽  
Theoretical Formulation ◽  
Tissue Integrity ◽  
Cartilaginous Tissues

Nutrition supply is a concern for the health of avascular cartilaginous tissues such as intervertebral disc (IVD). Maintaining tissue integrity relies on cellular biosynthesis of extracellular matrix, which is an energy demanding process [1]. In the IVD, energy is mainly generated through glycolysis (i.e., glucose consumption). Metabolism of nutrients (e.g., oxygen and glucose) within the IVD depends on local concentrations of nutrients, and coupling effects between nutrient level and metabolic rate [2,3]. Our previous theoretical study had developed a new theoretical formulation by incorporating the metabolic rates of solutes into the mechano-electrochemical mixture theory [4,5]. By using this new theoretical model, the distribution of oxygen and lactate can be predicted within the IVD under static and dynamics compressions [4]. However, the effect of compression on glucose consumption in the IVD has not been studied. The objective of this study was to examine the effects of compression on glucose consumption in the IVD under static and dynamic unconfined compression numerically.

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