Static Mechanical Properties of Helically Constructed Polyurethane Vascular Grafts Before and after Implantation

1987 ◽  
Vol 110 ◽  
Author(s):  
Miranda L. Weygang ◽  
J. Michael Lee ◽  
Gregory J. Wilson ◽  
Petr Klement ◽  
Allen G. Binnington
Keyword(s):  
Mechanical Properties ◽  
Vascular Graft ◽  
Elastic Moduli ◽  
Vascular Grafts ◽  
Definitive Evidence ◽  
Hydraulic Impedance ◽  
Before And After ◽  
Static Mechanical ◽  
The Subject ◽  
Static Mechanical Properties

AbstractThe influence of mechanical properties on the acute and chronic success of vascular grafts remains the subject of considerable debate. It is widely held that the matching of some set of mechanical properties at the anastomosis between a natural vessel and a vascular graft will optimize the likelihood of clinical sucess. Investigations in this area have largely concentrated on compliance (defined as the percentage change in diameter per unit change in pressure) as the parameter to be matched across the anastomosis. However, compliance represents only one out of a set of candidate parameters (including elastic moduli, Poisson ratios, admittance, distensibility, and hydraulic impedance among others) and there is no definitive evidence that it is in any way the most important mechanical parameter to be considered. As well, the concentration on compliance has resulted in the failure to examine the importance of the longitudinal behavior of the vascular grafts. The longitudinal properties of any vessel can profoundly influence the observed circumferential behavior; however, this is, at best, only implicit in the onedimensional compliance parameter.

Effect of bronchomotor tone on static mechanical properties of lung and ventilation distribution

1987 ◽  
Vol 63 (6) ◽  
pp. 2278-2285 ◽  
Author(s):  
A. B. Crawford ◽  
M. Makowska ◽  
L. A. Engel
Keyword(s):  
Mechanical Properties ◽  
Normal Subjects ◽  
Elastic Recoil ◽  
Ventilation Distribution ◽  
Ventilation Inhomogeneity ◽  
Before And After ◽  
Static Mechanical ◽  
Lung Periphery ◽  
Static Mechanical Properties ◽  
Bronchomotor Tone

To study the relationship between bronchomotor tone, static mechanical properties of the lung, and ventilation distribution, we measured the pressure-volume (P-V) curve of the lung and several ventilatory indexes before and after intravenous atropine in eight normal subjects. The indexes of ventilation distribution were derived from multiple breath N2 washouts by a recently developed analysis (7,8). The latter not only provides a sensitive measure of overall ventilation inhomogeneity but distinguishes between the convection-dependent inhomogeneity (CDI) among larger lung units and that due to the interaction of convection and diffusion (DCDI) within the lung periphery. Atropine decreased lung elastic recoil but distensibility, as defined by the exponent (K) in the monoexponential analysis of the P-V data, was unchanged. The overall ventilation inhomogeneity increased by 37% after atropine (P less than 0.02) due to an increase in the CDI component. More importantly, there was a significant correlation between the loss of lung recoil (but not K) and each of the indexes of CDI among the subjects. There was no correlation between the changes in lung recoil and in DCDI. Our findings indicate that normal bronchomotor tone contributes to the elastic recoil of the lung. Furthermore, the tone is distributed in a way that enhances the uniformity of ventilation distribution among diffusion-independent lung units. Presumably this is achieved by minimizing interacinar intrinsic inequalities in static mechanical properties.

scholarly journals Temperature-Dependent Creep Behavior and Quasi-Static Mechanical Properties of Heat-Treated Wood

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 968
Author(s):  
Dong Xing ◽  
Xinzhou Wang ◽  
Siqun Wang
Keyword(s):  
Mechanical Properties ◽  
Creep Behavior ◽  
Cell Walls ◽  
Treated Wood ◽  
Crosslinking Reaction ◽  
Depth Sensing ◽  
Temperature Dependent ◽  
Heat Treated ◽  
Static Mechanical ◽  
Static Mechanical Properties

In this paper, Berkovich depth-sensing indentation has been used to study the effects of the temperature-dependent quasi-static mechanical properties and creep deformation of heat-treated wood at temperatures from 20 °C to 180 °C. The characteristics of the load–depth curve, creep strain rate, creep compliance, and creep stress exponent of heat-treated wood are evaluated. The results showed that high temperature heat treatment improved the hardness of wood cell walls and reduced the creep rate of wood cell walls. This is mainly due to the improvement of the crystallinity of the cellulose, and the recondensation and crosslinking reaction of the lignocellulose structure. The Burgers model is well fitted to study the creep behavior of heat-treated wood cell walls under different temperatures.

Quasi-static mechanical properties of novel generalized Resch-pattern composite foldcores

2020 ◽  
pp. 095440622094000
Author(s):  
Antao Deng ◽  
Bin Ji ◽  
Xiang Zhou
Keyword(s):  
Mechanical Properties ◽  
Design Method ◽  
Absorption Capacity ◽  
Woven Fabrics ◽  
Geometric Design ◽  
Honeycomb Core ◽  
Reinforced Plastic ◽  
Static Mechanical ◽  
Laminate Thickness ◽  
Static Mechanical Properties

A new geometric design method for foldcores based on the generalized Resch patterns that allow face-to-face bonding interfaces between the core and the skins is proposed. Based on the geometric design method, a systematic numerical investigation on the quasi-static mechanical properties of the generalized Resch-based foldcores made of carbon fiber-reinforced plastic (CFRP) woven fabrics subjected to compression and shear loads is performed using the finite element method that is validated by experiments. The relationships between the mechanical properties and various geometric parameters as well as laminate thickness of the generalized Resch-based CFRP foldcores are revealed. Additionally, the mechanical properties of the generalized Resch-based CFRP foldcore are compared to those of the standard Resch-based, Miura-based foldcore, the honeycomb core, and the aluminum counterpart. It is found that the generalized Resch-based CFRP foldcore performs more stably than the honeycomb core under compression and has higher compressive and shear stiffnesses than the standard Resch-based and Miura-based foldcores and absorbs as nearly twice energy under compression as the Miura-based foldcore does. When compared with the aluminum counterpart, the CFRP model has higher weight-specific stiffness and strength but lower energy absorption capacity under shearing. The results presented in this paper can serve as the useful guideline for the design of the generalized Resch-based composite foldcore sandwich structures for various performance goals.

A Study on Estimation of S-N Curves for Structural Steels Based on their Static Mechanical Properties

2014 ◽  
Vol 891-892 ◽  
pp. 1639-1644 ◽  
Author(s):  
Kazutaka Mukoyama ◽  
Koushu Hanaki ◽  
Kenji Okada ◽  
Akiyoshi Sakaida ◽  
Atsushi Sugeta ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Evaluation Method ◽  
Materials Science ◽  
Estimation Method ◽  
Structural Steels ◽  
Metallic Materials ◽  
Fatigue Reliability ◽  
Regression Parameters ◽  
Static Mechanical ◽  
Static Mechanical Properties

The aim of this study is to develop a statistical estimation method of S-N curve for iron and structural steels by using their static mechanical properties. In this study, firstly, the S-N data for pure iron and structural steels were extracted from "Database on fatigue strength of Metallic Materials" published by the Society of Materials Science, Japan (JSMS) and S-N curve regression model was applied based on the JSMS standard, "Standard Evaluation Method of Fatigue Reliability for Metallic Materials -Standard Regression Method of S-N Curve-". Secondly, correlations between regression parameters and static mechanical properties were investigated. As a result, the relationship between the regression parameters and static mechanical properties (e.g. fatigue limit E and static tensile strength σB) showed strong correlations, respectively. Using these correlations, it is revealed that S-N curve for iron and structural steels can be predicted easily from the static mechanical properties.

Simulation studies to analyze the static mechanical properties of helical Savonius vertical axis wind turbine blade

2020 ◽  
Vol 33 ◽  
pp. 3737-3745
Author(s):  
S. Seralathan ◽  
Ch. Pavan Veera Sai Ganesh ◽  
Bhanu Prakash Reddy Venganna ◽  
N. Sai Srinivas ◽  
B. Lokesh Chowdary ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Vertical Axis ◽  
Wind Turbine Blade ◽  
Simulation Studies ◽  
Vertical Axis Wind Turbine ◽  
Static Mechanical ◽  
Static Mechanical Properties
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