Multiscale approach to mechanical behavior of polymeric nanocomposites: an application of T1p(13C) relaxation experiments at variable spin-locking fields

The degeneration mechanism of viscoelastic food material in specific processing mode affects the formulation of food material processing technology. On the other hand, it determines the taste of food in the chewing process. The viscoelastic food material was taken as the research object, and experimental data were obtained through stress relaxation experiments and strain relaxation experiments of texture analyzer material. Based on Maxwell model and Kelvin model, describing small deformation of the nonlinear viscoelastic constitutive model, building a composite model was proposed. By making analysis and comparison between constructed composite model and Maxwell model and Kelvin model, it was verified that the constructed composite model can be better described as the mechanical behavior of viscoelastic food material under the mode of compressed chewing, which is also providing a more precise theoretical model for the processing and development of viscoelastic food material.

Download Full-text

Study of the Viscoelastic Behavior and Molecular Weight Distribution of Polyisobutylene

Rubber Chemistry and Technology ◽

10.5254/1.3543494 ◽

1954 ◽

Vol 27 (2) ◽

pp. 393-414

Author(s):

Kensal E. Van Holde ◽

J. W. Williams

Keyword(s):

Molecular Weight ◽

Experimental Investigation ◽

Stress Relaxation ◽

Mechanical Behavior ◽

Weight Distribution ◽

Viscoelastic Behavior ◽

Elastic Behavior ◽

High Polymer ◽

Relaxation Experiments ◽

Mechanical Studies

Abstract The viscoelastic behavior of linear high polymers has commanded considerable attention in recent years. The very thorough studies by Fox and Flory of the melt viscosity of polystyrene and polyisobutylene, the stress relaxation experiments of Tobolsky and coworkers, and dynamic-mechanical studies by Ferry have contributed greatly to our knowledge of the mechanical behavior of these interesting substances. However, there are many facets of this subject which have not received thorough experimental investigation. In particular, there has been no detailed study of the effect of molecular weight and polydispersity on the elastic behavior of viscoelastic materials. It was felt, therefore, that a study of the viscoelastic behavior of a series of very carefully characterized samples of a representative linear high polymer would contribute substantially to the understanding of this subject. The polymer chosen was polyisobutylene, which displays both flow and elastic behavior at room temperatures.

Download Full-text

Multiscale Approach to the Mechanical Behavior of Epoxy Impregnated Nb3Sn Coils for the 11 T Dipole

IEEE Transactions on Applied Superconductivity ◽

10.1109/tasc.2018.2807373 ◽

2018 ◽

Vol 28 (3) ◽

pp. 1-6 ◽

Cited By ~ 10

Author(s):

Michael Daly ◽

Christian H. Loffler ◽

David Smekens ◽

A. T. Fontenla ◽

Oscar Sacristan de Frutos ◽

...

Keyword(s):

Mechanical Behavior ◽

Multiscale Approach

Download Full-text

A Coupled Multiscale Approach to Modeling Aortic Valve Mechanics in Health and Disease

Applied Sciences ◽

10.3390/app11188332 ◽

2021 ◽

Vol 11 (18) ◽

pp. 8332

Author(s):

Ahmed A. Bakhaty ◽

Sanjay Govindjee ◽

Mohammad R. K. Mofrad

Keyword(s):

Aortic Valve ◽

Aortic Stenosis ◽

Mechanical Behavior ◽

Three Dimensional ◽

Interstitial Cells ◽

Multiscale Approach ◽

Valvular Interstitial Cells ◽

Calcific Aortic Stenosis ◽

Multiple Length Scales ◽

Health And Disease

Mechano-biological processes in the aortic valve span multiple length scales ranging from the molecular and cell to tissue and organ levels. The valvular interstitial cells residing within the valve cusps sense and actively respond to leaflet tissue deformations caused by the valve opening and closing during the cardiac cycle. Abnormalities in these biomechanical processes are believed to impact the matrix-maintenance function of the valvular interstitial cells, thereby initiating valvular disease processes such as calcific aortic stenosis. Understanding the mechanical behavior of valvular interstitial cells in maintaining tissue homeostasis in response to leaflet tissue deformation is therefore key to understanding the function of the aortic valve in health and disease. In this study, we applied a multiscale computational homogenization technique (also known as “FE2”) to aortic valve leaflet tissue to study the three-dimensional mechanical behavior of the valvular interstitial cells in response to organ-scale mechanical loading. We further considered calcific aortic stenosis with the aim of understanding the likely relationship between the valvular interstitial cell deformations and calcification. We find that the presence of calcified nodules leads to an increased strain profile that drives further growth of calcification.

Download Full-text

Computational Multiscale Approach to the Mechanical Behavior and Transport Behavior of Wood

Computational Structural Engineering ◽

10.1007/978-90-481-2822-8_8 ◽

2009 ◽

pp. 79-85

Author(s):

K. Hofstetter ◽

J. Eitelberger ◽

T. K. Bader ◽

Ch. Hellmich ◽

J. Eberhardsteiner

Keyword(s):

Mechanical Behavior ◽

Multiscale Approach ◽

Transport Behavior

Download Full-text

Towards Building a Multiscale Mechanical Model for the Prediction of Acute Subdural Hematomas

Volume 4: Advanced Manufacturing Processes; Biomedical Engineering; Multiscale Mechanics of Biological Tissues; Sciences, Engineering and Education; Multiphysics; Emerging Technologies for Inspection ◽

10.1115/esda2012-82457 ◽

2012 ◽

Cited By ~ 3

Author(s):

Mathieu Nierenberger ◽

Daniel George ◽

Daniel Baumgartner ◽

Yves Rémond ◽

Saïd Ahzi ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Behavior ◽

Multiple Scales ◽

Fluid Collection ◽

Acute Subdural Hematoma ◽

Physical Parameters ◽

Multiscale Approach ◽

Subdural Space ◽

Vascular Walls ◽

Bridging Veins

Acute subdural hematoma (ASDH) is a potentially devastating, yet curable, extra axial fluid collection within the subdural space situated between the skull and the cortex. It is often due to rupture of bridging veins crossing this subdural space, caused by the brain-skull relative motion. To be able to predict ASDH, a numerical model reflecting the mechanical properties of vascular walls is attractive. With this in mind, a suitable approach consists in modeling the material microstructure at different scales. In a former work [1, 2], R. Abdel Rahman studied the mechanical properties of the bridging veins – superior sagittal sinus junction when a human head is submitted to shock. This work showed the apparition of ASDH over a given value of head rotational acceleration. But lacks in the knowledge of microstructure and of the constituents mechanical properties were put forward in understanding the relations between material mechanical behavior and the apparition of ASDH. Therefore we chose to adopt a multiscale approach to model ASDH apparition. In the current work, several experimental observations have been set up to obtain a sufficient knowledge of the vein wall microstructure which was imprecisely documented to date. Stained thin slices of human brain were observed by optical microscopy. In addition, microtomography was used to assess the collagen fibers orientations. These observations allowed the identification of the different scales needed for modeling the microstructure. Many authors [3–6] deal with the mechanical behavior of vascular walls and of their various constituents but none of them consider multiple scales for modeling [7]. The next step of this work consists in improving the predictive capabilities of the existing model by going down the scales and taking microstructure into account. This methodology enabled the introduction of only physical parameters into the model, which is essential for future predictive capabilities. Finally, a failure criterion for the bridging veins taking into account the different scales has been created and is still being improved. It allows the evaluation of specific disease influence like collagen damage due to physiology. Besides it provides a prediction tool for ASDH useable for optimization of various shock absorbers.

Download Full-text