Modelling of transients in microcavities with time-varying material properties

2008 ◽  
Author(s):  
N. Sakhnenko ◽  
A. Nerukh ◽  
T. Benson ◽  
P. Sewell
Keyword(s):  
Material Properties ◽  
Time Varying

scholarly journals Safety margin against the fatigue fracture under random loading

2018 ◽  
Vol 165 ◽  
pp. 22033 ◽  
Author(s):  
Martin Garan ◽  
Vladimír Chmelko ◽  
Ervin Schafer
Keyword(s):  
Yield Stress ◽  
Fatigue Fracture ◽  
Cross Section ◽  
Material Properties ◽  
Safety Margin ◽  
Time Varying ◽  
Random Loading ◽  
Fatigue Lifetime ◽  
Loading Process

The fatigue lifetime of the structure in operation is express in the number of working cycles, kilometers or time depending units. By harmonic process of loading is possible to express the safety margin as reserve against the required lifetime in the form of number cycles or amplitude of loading. By nonharmonic character of loading process in operation is difficult to express the level of safety margin as the reserve of loading (safety margin in loading). On the case of towing trailer will be discussed more ways of expression the reserve (safety margin) of structure against the fatigue fracture for required fatigue lifetime. For experimental acquired loading process in the most loaded cross-section will be discussed concept of determination of the level safety as reserve in the form of loading parameters. In the case, when the peaks of loading process exceeding the material yield stress (in the most loaded point of the structure) will be discussed concept of expression of loading in the form of time-varying process of strain. By using the cyclic material properties obtained in mode with controlled total strain is possible the safety margin to express also as the multiple of process loading parameters.

scholarly journals Modeling of Drug Delivery by A Pump Driven Micro-Needle Array System

2016 ◽  
Vol 10 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Kai Chen ◽  
Min Pan ◽  
Zhi-Gang Feng
Keyword(s):  
Mathematical Model ◽  
Material Properties ◽  
Time Varying ◽  
Diffusion Boundary ◽  
System Parameters ◽  
Micro Pump ◽  
Calculation Results ◽  
Spherical Expansion ◽  
Short Time ◽  
And Diffusion

Background: Micro-needles were proposed as one of the alternatives to deliver drugs painlessly passing through stratum corneum in recent years. In this work, a mathematical model is presented to characterize the in fusion flow of a hollow micro-needle array driven by a micro-pump. Methods: By assuming the injection of each micro-needle undergoes a spherical expansion and diffusion, the model is able to calculate the time-varying expansion radius, and the diffusion boundary, provided that the material properties and the micro-needle system parameters are known. Results and Conclusion: The calculation results show that the expansion caused by the infusion of micro-needles stops and the flow rate drops to zero in a short time. However, the diffusion boundary is much bigger than the expansion and the infusion continues if the surrounding material is absorptive. The experimental results of jet infusion through a single needle in silicon rubber and polyacrylamide gel agree with the calculation results qualitatively.

Time-Varying Wave and Current-Induced Scour Around Offshore Wind Turbines

2007 ◽  
Author(s):  
A. W. Nielsen ◽  
E. A. Hansen
Keyword(s):  
Material Properties ◽  
Time Development ◽  
Offshore Wind ◽  
Scour Depth ◽  
Time Varying ◽  
Engineering Model ◽  
Offshore Wind Turbines ◽  
Industry Standard ◽  
Pile Diameter ◽  
Physical Experiments

The paper presents the engineering model, WiTuS (Wind Turbine Scour), which uses the results of several previous published physical experiments with scour around cylinders to determine the time development of the scour hole around the pile due to the actual and the previous wave and current climate. The WiTuS includes: • Time-varying water level, sea states and current. • Seabed material properties. • Description of the scour geometry around the pile. Simulations presented in the paper show that for typical North Sea conditions the scour depth will be around 0.3 times the pile diameter in periods with larger waves, which is a significant reduction from 1.3 times the pile diameter which is often seen as the industry standard.

scholarly journals Concrete Silos: Failures, Design Issues and Repair/Strengthening Methods

2021 ◽  
Vol 11 (12) ◽  
pp. 5675
Author(s):  
Phung Tu ◽  
Vanissorn Vimonsatit
Keyword(s):  
Material Properties ◽  
Discharge Rate ◽  
Dynamic Loads ◽  
Discharge Process ◽  
Time Varying ◽  
Analysis And Design ◽  
Scientific Principles ◽  
Silo Discharge ◽  
And Control ◽  
Varying Mass

Current silo analysis and design methods developed from Janssen’s theory focus mainly on the flow of the granules inside the silo by assuming that the overall silo structure is infinitely rigid. A silo structure during discharge is technically a time varying mass dynamic problem, where the properties of the overall silo structure and the discharge rate and material properties also contribute to the development of the load. The physics of a silo system requires equilibrium between the granules inside the silo, the silo structure as a whole and the surrounding air. The established scientific principles and experimental data require fulfilling such equilibrium to accurately predict the dynamic loads during discharge. This correspondence explains how the equilibrium between the granules inside the silo, the silo structure as a whole and the surrounding air can be achieved to better predict and control the dynamic loads generated by the silo discharge process.

Investigation of microwave heating with time varying material properties

1999 ◽  
Vol 35 (3) ◽  
pp. 1813-1816 ◽  
Author(s):  
J. Braunstein ◽  
K. Connor ◽  
S. Salon ◽  
L. Libelo
Keyword(s):  
Microwave Heating ◽  
Material Properties ◽  
Time Varying

Grain boundary segregation in metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1204-1205
Author(s):  
C.L. Briant
Keyword(s):  
Fracture Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Material Properties ◽  
Electron Spectroscopy ◽  
High Vacuum ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Local Concentration ◽  
The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

Relationships Between Grain Boundary Structure and Material Properties

1980 ◽  
Vol 38 ◽  
pp. 366-369
Author(s):  
Brian Ralph ◽  
Barlow Claire ◽  
Nicola Ecob
Keyword(s):  
Grain Boundary ◽  
Material Properties ◽  
Main Property ◽  
Grain Structure ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Property Changes

This brief review seeks to summarize some of the main property changes which may be induced by altering the grain structure of materials. Where appropriate an interpretation is given of these changes in terms of current theories of grain boundary structure, and some examples from current studies are presented at the end of this paper.

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