Analysis and Modeling of Aortic Tissue Material Properties

2004 ◽  
Author(s):  
Kurosh Darvish ◽  
Libor Lobovsky ◽  
Sang-Hyun Lee
Keyword(s):  
Experimental Data ◽  
Mechanical Behavior ◽  
Material Properties ◽  
Linear Viscoelasticity ◽  
Hyperelastic Material ◽  
Aortic Tissue ◽  
New Material ◽  
Tissue Material

A hyperelastic material with linear viscoelasticity was used to characterize the mechanical behavior of aortic tissue based on literature and new experimental data. It was shown that the previous data led to contradictory uniaxial and biaxial responses. A set of new material properties were identified which closely described the experimental data for strains below 40%.

scholarly journals The interplay of stiffness and force anisotropies drives embryo elongation

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Thanh Thi Kim Vuong-Brender ◽  
Martine Ben Amar ◽  
Julien Pontabry ◽  
Michel Labouesse
Keyword(s):  
Experimental Data ◽  
Material Properties ◽  
Myosin Ii ◽  
Mechanical Forces ◽  
Cell Behaviour ◽  
Cortical Tension ◽  
Actin Cortex ◽  
Stiffness Anisotropy ◽  
Spatiotemporal Changes ◽  
Tissue Material

The morphogenesis of tissues, like the deformation of an object, results from the interplay between their material properties and the mechanical forces exerted on them. The importance of mechanical forces in influencing cell behaviour is widely recognized, whereas the importance of tissue material properties, in particular stiffness, has received much less attention. Using Caenorhabditis elegans as a model, we examine how both aspects contribute to embryonic elongation. Measuring the opening shape of the epidermal actin cortex after laser nano-ablation, we assess the spatiotemporal changes of actomyosin-dependent force and stiffness along the antero-posterior and dorso-ventral axis. Experimental data and analytical modelling show that myosin-II-dependent force anisotropy within the lateral epidermis, and stiffness anisotropy within the fiber-reinforced dorso-ventral epidermis are critical in driving embryonic elongation. Together, our results establish a quantitative link between cortical tension, material properties and morphogenesis of an entire embryo.

Preliminary Murine Aortic Tissue Material Properties From Pressure-Diameter Experiments

2007 ◽  
Author(s):  
Mark E. Rentschler ◽  
B. Timothy Baxter
Keyword(s):  
Material Properties ◽  
Patient Specific ◽  
Aortic Tissue ◽  
Specific Information ◽  
Transverse Diameter ◽  
Impending Rupture ◽  
Abdominal Aortic ◽  
History Of ◽  
Tissue Material ◽  
Progressive Enlargement

Abdominal aortic aneurysm (AAA) is a common and deadly problem. The aortic diameter increases in association with a complex remodeling process that includes changes in the structure and content of key proteins, elastin and collagen. As these changes occur, the tissue mechanical properties also change. The natural history of AAA is progressive enlargement to a point of mechanical tissue failure typically followed by death. Currently, the marker used to predict the risk of impending rupture is the largest transverse diameter. After reaching a diameter threshold of 5.5 cm the aneurysm is surgically repaired. This criterion does not consider any patient-specific information or the known heterogeneity of the aneurysm that may, in some cases, lead to rupture before the aneurysm reaches the standard intervention threshold. Conversely, in many patients, continued observation beyond this threshold is safe.

Materials technology: Innovations and progress

Impact ◽  
2020 ◽  
Vol 2020 (2) ◽  
pp. 52-53
Author(s):  
Lucy Sharp
Keyword(s):  
Material Properties ◽  
New Materials ◽  
Medical Problems ◽  
Technology Innovations ◽  
Societal Challenges ◽  
New Material ◽  
Innovative Materials ◽  
The Creation ◽  
Novel Applications

Materials technology is a constantly evolving discipline, with new materials leading to novel applications. For example, new material properties arise from combining different materials into composites. Researching materials can help solve societal challenges, with the creation of innovative materials resulting in breakthroughs in overcoming hurdles facing humankind, including energy challenges and medical problems. Innovative materials breathe new life into industries and spur on scientific and technological discovery.

scholarly journals Material properties and effect of preconditioning of human sclera, optic nerve, and optic nerve sheath

2021 ◽  
Author(s):  
Joseph Park ◽  
Andrew Shin ◽  
Somaye Jafari ◽  
Joseph L. Demer
Keyword(s):  
Optic Nerve ◽  
Mechanical Behavior ◽  
Material Properties ◽  
Biomechanical Properties ◽  
Ocular Tissues ◽  
Tangent Moduli ◽  
Nonlinear Mechanical ◽  
Human Eyes ◽  
Range Of Variation ◽  
Great Stress

AbstractThe optic nerve (ON) is a recently recognized tractional load on the eye during larger horizontal eye rotations. In order to understand the mechanical behavior of the eye during adduction, it is necessary to characterize material properties of the sclera, ON, and in particular its sheath. We performed tensile loading of specimens taken from fresh postmortem human eyes to characterize the range of variation in their biomechanical properties and determine the effect of preconditioning. We fitted reduced polynomial hyperelastic models to represent the nonlinear tensile behavior of the anterior, equatorial, posterior, and peripapillary sclera, as well as the ON and its sheath. For comparison, we analyzed tangent moduli in low and high strain regions to represent stiffness. Scleral stiffness generally decreased from anterior to posterior ocular regions. The ON had the lowest tangent modulus, but was surrounded by a much stiffer sheath. The low-strain hyperelastic behaviors of adjacent anatomical regions of the ON, ON sheath, and posterior sclera were similar as appropriate to avoid discontinuities at their boundaries. Regional stiffnesses within individual eyes were moderately correlated, implying that mechanical properties in one region of an eye do not reliably reflect properties of another region of that eye, and that potentially pathological combinations could occur in an eye if regional properties are discrepant. Preconditioning modestly stiffened ocular tissues, except peripapillary sclera that softened. The nonlinear mechanical behavior of posterior ocular tissues permits their stresses to match closely at low strains, although progressively increasing strain causes particularly great stress in the peripapillary region.

Dependence of Mechanical Behavior of the Murine Tail Disc on Regional Material Properties: A Parametric Finite Element Study

2005 ◽  
Vol 127 (7) ◽  
pp. 1158-1167 ◽  
Author(s):  
Adam H. Hsieh ◽  
Diane R. Wagner ◽  
Louis Y. Cheng ◽  
Jeffrey C. Lotz
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Nucleus Pulposus ◽  
Material Properties ◽  
Mechanical Response ◽  
Swelling Pressure ◽  
Transient Behavior ◽  
Sensitivity Analyses ◽  
Intact Mouse

In vivo rodent tail models are becoming more widely used for exploring the role of mechanical loading on the initiation and progression of intervertebral disc degeneration. Historically, finite element models (FEMs) have been useful for predicting disc mechanics in humans. However, differences in geometry and tissue properties may limit the predictive utility of these models for rodent discs. Clearly, models that are specific for rodent tail discs and accurately simulate the disc’s transient mechanical behavior would serve as important tools for clarifying disc mechanics in these animal models. An FEM was developed based on the structure, geometry, and scale of the mouse tail disc. Importantly, two sources of time-dependent mechanical behavior were incorporated: viscoelasticity of the matrix, and fluid permeation. In addition, a novel strain-dependent swelling pressure was implemented through the introduction of a dilatational stress in nuclear elements. The model was then validated against data from quasi-static tension-compression and compressive creep experiments performed previously using mouse tail discs. Finally, sensitivity analyses were performed in which material parameters of each disc subregion were individually varied. During disc compression, matrix consolidation was observed to occur preferentially at the periphery of the nucleus pulposus. Sensitivity analyses revealed that disc mechanics was greatly influenced by changes in nucleus pulposus material properties, but rather insensitive to variations in any of the endplate properties. Moreover, three key features of the model—nuclear swelling pressure, lamellar collagen viscoelasticity, and interstitial fluid permeation—were found to be critical for accurate simulation of disc mechanics. In particular, collagen viscoelasticity dominated the transient behavior of the disc during the initial 2200s of creep loading, while fluid permeation governed disc deformation thereafter. The FEM developed in this study exhibited excellent agreement with transient creep behavior of intact mouse tail motion segments. Notably, the model was able to produce spatial variations in nucleus pulposus matrix consolidation that are consistent with previous observations in nuclear cell morphology made in mouse discs using confocal microscopy. Results of this study emphasize the need for including nucleus swelling pressure, collagen viscoelasticity, and fluid permeation when simulating transient changes in matrix and fluid stress/strain. Sensitivity analyses suggest that further characterization of nucleus pulposus material properties should be pursued, due to its significance in steady-state and transient disc mechanical response.

The Role of Topology and Tissue Mechanics in Remora Attachment

2014 ◽  
Vol 1648 ◽  
Author(s):  
Michael Culler ◽  
Keri A. Ledford ◽  
Jason H. Nadler
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Tissue Mechanics ◽  
Unit Cell ◽  
Surface Topology ◽  
Finite Element Models ◽  
Cell Geometry ◽  
Critical Step ◽  
Tissue Material

ABSTRACTRemora fish are capable of fast, reversible and reliable adhesion to a wide variety of both natural and artificial marine hosts through a uniquely evolved dorsal pad. This adhesion is partially attributed to suction, which requires a robust seal between the pad interior and the ambient environment. Understanding the behavior of remora adhesion based on measurable surface parameters and material properties is a critical step when creating artificial, bio-inspired devices. In this work, structural and fluid finite element models (FEM) based on a simplified “unit cell” geometry were developed to predict the behavior of the seal with respect to host/remora surface topology and tissue material properties.

Mechanical Behavior of Functionally Graded Nano-Cylinders Under Radial Pressure Based on Strain Gradient Theory

2018 ◽  
Vol 35 (4) ◽  
pp. 441-454 ◽  
Author(s):  
M. Shishesaz ◽  
M. Hosseini
Keyword(s):  
Mechanical Behavior ◽  
Strain Gradient ◽  
Material Properties ◽  
Scale Effects ◽  
Radial Pressure ◽  
Functionally Graded ◽  
High Order ◽  
Strain Gradient Theory ◽  
Small Scale ◽  
Gradient Theory

ABSTRACTIn this paper, the mechanical behavior of a functionally graded nano-cylinder under a radial pressure is investigated. Strain gradient theory is used to include the small scale effects in this analysis. The variations in material properties along the thickness direction are included based on three different models. Due to slight variations in engineering materials, the Poisson’s ratio is assumed to be constant. The governing equation and its corresponding boundary conditions are obtained using Hamilton’s principle. Due to the complexity of the governed system of differential equations, numerical methods are employed to achieve a solution. The analysis is general and can be reduced to classical elasticity if the material length scale parameters are taken to be zero. The effect of material indexn, variations in material properties and the applied internal and external pressures on the total and high-order stresses, are well examined. For the cases in which the applied external pressure at the inside (or outside) radius is zero, due to small effects in nano-cylinder, some components of the high-order radial stresses do not vanish at the boundaries. Based on the results, the material inhomogeneity indexn, as well as the selected model through which the mechanical properties may vary along the thickness, have significant effects on the radial and circumferential stresses.

scholarly journals Hyperelastic Material Properties of Axonal fibers in Brain White Matter

2021 ◽  
pp. 100035
Author(s):  
Poorya Chavoshnejad ◽  
Guy K. German ◽  
Mir Jalil Razavi
Keyword(s):  
White Matter ◽  
Material Properties ◽  
Hyperelastic Material ◽  
Brain White Matter
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