Extracellular Matrix-Contractile Response Coupling of the Aortic Heart Valve Interstitial Cell

2008 ◽  
Author(s):  
David E. Schmidt ◽  
W. David Merryman ◽  
Michael S. Sacks
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Aortic Valve ◽  
Interstitial Cell ◽  
Mechanical Response ◽  
Element Model ◽  
Multi Scale ◽  
Aortic Heart Valve ◽  
Composition And Structure

The role of aortic valve interstitial cell (AVIC) and extracellular matrix (ECM) interactions of the aortic valve (AV) are not well understood. Distinct differences in the composition and structure of the AV leaflet layers (fibrosa and ventricularis) have been shown to influence mechanical properties 1. Our ability to measure the effects of changes in cellular stiffness in the dense collagenous AV leaflets (AVL) 2 offers a unique opportunity to explore the in-situ AVIC stiffness and local AVIC-ECM mechanical interactions. In the present study, a multi-scale finite element model approach was developed based on our simulations of our flexural stiffness experiment 2 were used to develop effective layer dependent mechanical properties. In addition, we present a predictive model for the alteration of AVL tissue mechanical properties resulting from AVIC contraction. This model provides a means to probe the layer dependent properties under the influence of AVIC contraction relative to an intact tissue state. By establishing a procedure to examine ECM stiffness in situ, through coupled experimental and computational methods, insights into relative contributions of ECM components were developed. Finally, in contrast previous study, where tissue stiffness was reported in terms on an instantaneous elastic modules, this work provides a more complete mechanical response of AVL in flexure.

Role of Interfacial Interactions on Mechanical Properties of Biomimetic Composites for Bone Tissue Engineering

2005 ◽  
Vol 898 ◽  
Author(s):  
Devendra Verma ◽  
Rahul Bhowmik ◽  
Bedabibhas Mohanty ◽  
Dinesh R Katti ◽  
Kalpana S Katti
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Mechanical Response ◽  
Density Ratio ◽  
Interfacial Interactions ◽  
Porous Composites ◽  
Properties Of Composites

AbstractInterfaces play an important role in controlling the mechanical properties of composites. Optimum mechanical strength of scaffolds is of prime importance for bone tissue engineering. In the present work, molecular dynamics simulations and experimental studies have been conducted to study effect of interfacial interactions on mechanical properties of composites for bone replacement. In order to mimic biological processes, hydroxyapatite (HAP) is mineralized in presence of polyacrylic acid (PAAc) (in situ HAP). Further, solid and porous composites of in situ HAP with polycaprolactone (PCL) are made. Mechanical tests of composites of in situ HAP with PAAc have shown improved strain recovery, higher modulus/density ratio and also improved mechanical response in simulated body fluid (SBF). Simulation studies indicate potential for calcium bridging between –COO− of PAAc and surface calcium of HAP. This fact is also supported by infrared spectroscopic studies. PAAc modified surfaces of in situ HAP offer means to control the microstructure and mechanical response of porous composites. Nanoindentation experiments indicate that apatite grown on in situ HAP/PCL composites from SBF has improved elastic modulus and hardness. This work gives insight into the interfacial mechanisms responsible for mechanical response as well as bioactivity in biomaterials.

Finite Element Modeling of Selective Laser Melting 316L Stainless Steel Parts for Evaluating the Mechanical Properties

2016 ◽  
Author(s):  
Arman Ahmadi ◽  
Narges Shayesteh Moghaddam ◽  
Mohammad Elahinia ◽  
Haluk E. Karaca ◽  
Reza Mirzaeifar
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Model ◽  
Grain Boundaries ◽  
Mechanical Response ◽  
Element Model ◽  
Polycrystalline Materials ◽  
Microstructural Properties ◽  
Laser Melting

Selective laser melting (SLM) is an additive manufacturing technique in which complex parts can be fabricated directly by melting layers of powder from a CAD model. SLM has a wide range of application in biomedicine and other engineering areas and it has a series of advantages over traditional processing techniques. A large number of variables including laser power, scanning speed, scanning line spacing, layer thickness, material based input parameters, etc. have a considerable effect on SLM process materials. The interaction between these parameters is not completely studied. Limited studies on balling effect in SLM, densifications under different processing conditions, and laser re-melting, have been conducted that involved microstructural investigation. Grain boundaries are amongst the most important microstructural properties in polycrystalline materials with a significant effect on the fracture and plastic deformation. In SLM samples, in addition to the grain boundaries, the microstructure has another set of connecting surfaces between the melt pools. In this study, a computational framework is developed to model the mechanical response of SLM processed materials by considering both the grain boundaries and melt pool boundaries in the material. To this end, a 3D finite element model is developed to investigate the effect of various microstructural properties including the grains size, melt pools size, and pool connectivity on the macroscopic mechanical response of the SLM manufactured materials. A conventional microstructural model for studying polycrystalline materials is modified to incorporate the effect of connecting melt pools beside the grain boundaries. In this model, individual melt pools are approximated as overlapped cylinders each containing several grains and grain boundaries, which are modeled to be attached together by the cohesive zone method. This method has been used in modeling adhesives, bonded interfaces, gaskets, and rock fracture. A traction-separation description of the interface is used as the constitutive response of this model. Anisotropic elasticity and crystal plasticity are used as constitutive laws for the material inside the grains. For the experimental verification, stainless steel 316L flat dog bone samples are fabricated by SLM and tested in tension. During fabrication, the power of laser is constant, and the scan speed is changed to study the effect of fabrication parameters on the mechanical properties of the parts and to compare the result with the finite element model.

Zonal Poisson Effect on the Chondron Deformation in Articular Cartilage under Compression

2007 ◽  
Vol 342-343 ◽  
pp. 133-136
Author(s):  
Jae Bong Choi
Keyword(s):  
Extracellular Matrix ◽  
Articular Cartilage ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Pericellular Matrix ◽  
Poisson Effect ◽  
Type Vi Collagen ◽  
Confocal Images ◽  
Three Dimensional Models

The objective of this study was to quantify the zonal difference of the in situ chondron’s Poisson effect under different magnitudes of compression. Fluorescence immunolabeling for type VI collagen was used to identify the pericellular matrix (PCM) and chondron, and a series of fluorescent confocal images were recorded and reconstructed to form quantitative three-dimensional models. The zonal variations in the mechanical response of the chondron do not appear to be due to zonal differences in PCM properties, but rather seem to result from significant inhomogeneities in relative stiffnesses of the extracellular matrix (ECM) and PCM with depth.

Combining ExoMars’ Ma_MISS and Drill data

2020 ◽  
Author(s):  
Alessandro Frigeri ◽  
Maria Cristina De Sanctis ◽  
Francesca Altieri ◽  
Simone De Angelis ◽  
Marco Ferrari ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Content ◽  
Large Scale ◽  
Mechanical Response ◽  
European Space Agency ◽  
Volcanic Rocks ◽  
Space Agency ◽  
Geophysical Imaging

<p>The ExoMars Rover and Surface Platform planned for launch in 2022 is a large international cooperation between the European Space Agency and Roscosmos with a scientific contribution from NASA.  Thales Alenia Space is the ExoMars mission industrial prime contractor. </p> <p>Besides sensors and instruments characterizing the surface at large scale, the ExoMars’ rover Rosalind Franklin payload features some experiments devoted specifically to the characterization of the first few meters of the Martian subsurface. These experiments are particularly critical for the main ExoMars objective of detecting traces of present or past life forms on Mars, which may have been preserved within the shallow Martian underground [1].</p> <p>Rosalind Franklin will be able to perform both non-invasive geophysical imaging of the underground [2] and subsurface <em>in situ</em> measurements thanks to the Drill unit installed on the rover. The Drill has been developed by Leonardo and its purposes are 1) to collect core samples to be analyzed in the Analytical Laboratory Drawer (ALD) onboard the Rover and 2) to drive the miniaturized spectrometer Ma_MISS within the borehole.   </p> <p>Ma_MISS (Mars Multispectral Imager for Subsurface Studies, [3]) will collect mineralogic measurements from the rocks exposed into the borehole created by the Drill with a spatial resolution of 120 μm down to 2 meters into the Martian subsurface.</p> <p>Rocks are composed of grains of minerals, and their reaction to an applied stress is related to the mechanical behavior of the minerals that compose the rock itself. The mechanical properties of a mineral depend mainly on the strength of the chemical bonds, the orientation of crystals, and the number of impurities in the crystal lattice.</p> <p>In this context, the integration of Ma_MISS measurements and drill telemetry are of great importance.  The mechanical properties of rocks coupled with their mineralogic composition provide a rich source of information to characterize the nature of rocks being explored by ExoMars rover’s drilling activity.</p> <p>Within our study, we are starting to collect telemetry recorded during the Drill unit tests on several samples ranging from sedimentary to volcanic rocks with varying degrees of weathering and water content.  In this first phase of the study, we focused our attention on the variation of torque and penetration speed between different samples, which have been found to be indicative of a particular type of rock or group of rocks and their water content.  </p> <p>We are planning to analyze the same rocks with the Ma_MISS breadboard creating the link between the mineralogy and the mechanical response of the Drill.      </p> <p>This will put the base for a more comprehensive and rich characterization of the <em>in situ</em> subsurface observation by Rosalind Franklin planned at Oxia Planum, Mars in 2023. </p> <p> </p> <p><strong>Acknowledgments: </strong>We thank the European Space Agency (ESA) for developing the ExoMars Project, ROSCOSMOS and Thales Alenia Space for rover development, and Italian Space Agency (ASI) for funding the Ma_MISS experiment (ASI-INAF contract n.2017-48-H.0 for ExoMars MA_MISS phase E/science).</p> <p> </p> <p><strong>References</strong></p> <p>[1] Vago et al., 2017. Astrobiology, 17 6-7. [2] Ciarletti et al., 2017. Astrobiology, 17 6-7. [3] De Sanctis et al., 2017. Astrobiology, 17 6-7.</p>

scholarly journals Multi-Scale Structural and Tensile Mechanical Response of Annulus Fibrosus to Osmotic Loading

2012 ◽  
Author(s):  
Woojin M. Han ◽  
Nandan L. Nerurkar ◽  
Lachlan J. Smith ◽  
Nathan T. Jacobs ◽  
Robert L. Mauck ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intervertebral Disc ◽  
Mechanical Testing ◽  
Biochemical Composition ◽  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Tissue Level ◽  
Multi Scale ◽  
Osmotic Loading

The annulus fibrosus (AF) is a multi-lamellar fibrocartilagenous ring in the intervertebral disc. The variation of biochemical composition from the outer to the inner AF is largely responsible for the heterogeneous mechanical properties. In vitro tissue-level studies require mechanical testing in aqueous buffers to avoid tissue dehydration. The varying glycosaminoglycan (GAG) contents from outer to inner AF suggest that the response to high and low PBS osmolarity may also be different with radial position. Previous studies in tendon and ligament have been conflicting: soaking tendon fascicles in PBS decreased tensile modulus1 and treating ligament in buffer had no effect on modulus.2

Mechanical Characterization of the Decellularized Porcine Small Intestinal Submucosa Extracellular Matrix

2013 ◽  
Author(s):  
Shijia Zhao ◽  
Linxia Gu ◽  
James M. Hammel ◽  
Haili Lang
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Small Intestinal Submucosa ◽  
Trade Name ◽  
Porcine Small Intestinal Submucosa ◽  
Small Intestinal ◽  
Intestinal Submucosa

In this work, the decellularized porcine small intestinal submucosa extracellular matrix (SIS-ECM), obtained from the commercial product under the trade name of CorMatrix, were tested in uniaxial tension. Preconditioning under cyclic loading of 2 N was conducted to stabilize the mechanical response of the tissue. The influence of rehydration time on the mechanical properties of the tissue was evaluated. Results suggested that the stiffness of SIS-ECM decreased with longer rehydration time. Considering the application of CorMatrix in pericardial closure, the native pericardium samples were also tested. The comparison indicated that the native pericardium is softer than rehydrated CorMatrix. This work can facilitate the surgeons to better choose the appropriate rehydration time when conducting the extracardiac implantations, such as pericardial reconstruction, pericardial closure, etc.

Tribological Process Characterization With In-Situ Quantitative Nano-Scale Metrology

2005 ◽  
Author(s):  
Antanas Daugela ◽  
Alex Meyman ◽  
Vladimir Knyazik ◽  
Nikolai Yeremin
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Optical Microscope ◽  
Nano Scale ◽  
Process Characterization ◽  
Microscope Imaging

A novel quantitative nano+micro-tribometer with integrated nanoindenter, SPM and optical microscope imaging has been used to characterize mechanical properties of Cu coated Si wafers at various test stages. A 2D Finite Element Model was developed to study changes on workhardened contacts assessed via nanoindentation experiments.

A Note on Tire Carcass Mechanical Properties

1978 ◽  
Vol 6 (4) ◽  
pp. 248-262
Author(s):  
J. T. Tielking ◽  
R. E. Martin ◽  
R. A. Schapery
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Geometric Nonlinearity ◽  
Elastic Stress ◽  
Uniaxial Stress ◽  
Element Model ◽  
Stress Tests ◽  
Linear Elastic ◽  
Constituent Material

Abstract Uniaxial stress tests were conducted on composite specimens cut from two different locations on a bias tire carcass. These data together with cord data, the Halpin-Tsai “micromechanics” equations, and the linear laminate constitutive equations are used to derive the in-situ rubber modulus as a function of time and to check for consistency among the specimens tested. The main purpose of the first part of the study was to obtain constituent material properties for use in a finite element model of a tire. This model is then employed in the investigation of the influence of uniform rubber modulus on the shape of an inflated tire carcass, and it is concluded that the strain and time dependence of the rubber modulus will introduce some error in a tire structural analysis that uses linear elastic stress-strain equations and permits geometric nonlinearity. It appears that the error will be minimal in a low strain region such as in the sidewall.

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