Mechanical Characterization of a Freestanding Polyvinyl Alcohol Hydrogel Membrane

2008 ◽  
Author(s):  
Edgar J. Montiel ◽  
Kai-Tak Wan
Keyword(s):  
Polyvinyl Alcohol ◽  
Biological Tissues ◽  
Material Strength ◽  
Hydrogel Membranes ◽  
Hydrogel Membrane ◽  
Standard Linear Solid ◽  
Standard Linear ◽  
Deformation Test

The following study presents two methods established for characterizing the mechanical properties of polyvinyl alcohol hydrogel membranes. The first one, an instant deformation test with an automated machine allowed the determination of the elastic properties of the material, while the second permitted the determination of the viscoelastic properties with the use of the standard linear solid model while confirming the previously found elastic results. This is not trivial as clearly old fashioned tests such as the ASTM standard tension test where grips are used to hold the sample are not feasible to perform due to the fragile characteristics of this kind material that resemble delicate biological tissues. The results obtained are consistent with previous publications, where different methods where used, but an increase in the material strength was also found as the number of freezing/thawing cycles increased.

Direct Optical Estimation of Deformation Gradient Tensors Using Lucas-Kanade Digital Image Warping

2013 ◽  
Author(s):  
John J. Boyle ◽  
Guy M. Genin ◽  
Maiko Kume ◽  
Robert B. Pless ◽  
Stavros Thomopoulos
Keyword(s):  
Digital Image ◽  
Accurate Determination ◽  
Deformation Gradient ◽  
Biological Tissues ◽  
Magnetic Resonance Images ◽  
Image Correlation ◽  
Strain Fields ◽  
Established Technique

Mechanical characterization of inhomogeneous and/or geometrically complex biological tissues requires precise and accurate determination of strain fields. Digital image correlation is a well established technique for determining strain fields on the surfaces of deforming materials. The technique involves matching patterns between pairs of images to estimate the displacement of certain regions or features on a sample. 2 Image correlation has also been used to track deformations in dynamic magnetic resonance images of heart and brain. 3

scholarly journals 3D Sensitivity of 8-Electrode FIM through Experimental Study in a Phantom

2014 ◽  
Vol 6 (1) ◽  
pp. 55-65 ◽  
Author(s):  
Samiron Kumar Saha ◽  
Golam Dastegir Al-Quaderi ◽  
K Siddique-e Rabbani
Keyword(s):  
Experimental Study ◽  
Medical Physics ◽  
Central Zone ◽  
Skin Surface ◽  
Biological Tissues ◽  
Impedance Method ◽  
Focusing Effect ◽  
Different Depths

Focused Impedance Method (FIM) is a relatively new technique developed in the Biomedical Physics Laboratory of Dhaka University which allows improved localization of a zone without much increase in the complexity of measurement. Three versions using 8, 6 and 4 electrodes respectively have been conceived and developed. FIM has potential for characterization of biological tissues at depths non-invasively placing electrodes on the skin surface at appropriate locations, leading to detection or diagnosis of diseases or disorders. The present work is an experimental study of the sensitivity of the 8-electrode FIM system at different depths and lateral positions inside a volume conductor with respect to the electrode-positions using a cubical phantom with saline. An object of different conductivity and of size smaller than the electrode separation was placed inside the phantom at different positions to measure the change of FIM value, called sensitivity in this work. The study verified the focusing effect at the central zone where the sensitivity remained high and almost constant laterally for a certain depth, falling sharply outside. At shallow depths, the sensitivity showed enhanced peaks under the electrodes which however, decreased fast with depth. The sensitivity falls off sharply with depth becoming almost constant at greater depths but with greatly reduced value. The sensitivity at off axis positions from the centre also reduced outside the focused zone. Slightly negative zones of sensitivity were observed at lateral positions far from the center of the electrodes, but the values were negligible. This work will help standardize the application of 8-electrode FIM for determination of impedance of organs inside the human body. DOI: http://dx.doi.org/10.3329/bjmp.v6i1.19759 Bangladesh Journal of Medical Physics Vol.6 No.1 2013 55-65

Viscoelastic Behavior of a Centrally Loaded Circular Film Being Clamped at the Circumference

2007 ◽  
Vol 1049 ◽  
Author(s):  
Michelle L Oyen ◽  
Kuo-kang Liu ◽  
Kai-tak Wan
Keyword(s):  
Theoretical Model ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Viscoelastic Response ◽  
Circular Membrane ◽  
Hydrogel Membrane ◽  
Standard Linear Solid ◽  
Standard Linear ◽  
Preliminary Stress ◽  
Relaxation Experiments

AbstractA new theoretical model is constructed for the viscoelastic response of a clamped circular membrane deformed by a spherical indenter, using the classical Maxwell and Standard Linear Solid (SLS) constitutive equations. Preliminary stress-relaxation experiments are performed for a hydrogel membrane and the corresponding data fitted to the SLS-based viscoelastic model.

Visco-Elasticity of Passive Cardiac Muscle

1980 ◽  
Vol 102 (1) ◽  
pp. 57-61 ◽  
Author(s):  
J. G. Pinto ◽  
P. J. Patitucci
Keyword(s):  
Mechanical Behavior ◽  
Cardiac Muscle ◽  
Heart Muscle ◽  
Relaxation Times ◽  
Continuous Distribution ◽  
Biological Tissues ◽  
Constitutive Law ◽  
Strain Behavior ◽  
Standard Linear Solid ◽  
Standard Linear

A quantitative mechanical description of the heart organ requires information on the mechanical behavior of its muscle in reasonable unity and completeness. In this respect, a fundamental constitutive law for soft biological tissues was proposed by Fung in 1972. This article presents evidence to show that Fung’s law is a useful law to describe the mechanical behavior of heart muscle in the unstimulated (diastolic) state with sufficient generality. A visco-elastic relaxation phenomenon is studied in the isolated cardiac muscle of cat and rabbit with the purpose of constructing a mathematical model for relaxation. Experimental results show that passive relaxation behavior of heart muscle can be adequately described by a generalized standard linear solid with a continuous distribution of relaxation times. The form of the relaxation function devised permits the application of linear visco-elasticity theory to the nonlinear cardiac muscle. The relaxation model is used to predict the force-length (stress-strain) behavior of papillary muscle with reasonable accuracy.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

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