Curvature Change Analysis of SMART Fibers Used for Temperature Adaptive Insulation

2019 ◽  
Author(s):  
Cameron Ripa ◽  
Andrew Latulippe ◽  
Hongwei Sun ◽  
Stephen Fossey ◽  
Christopher Drew
Keyword(s):  
Temperature Change ◽  
Coefficient Of Thermal Expansion ◽  
Bath Temperature ◽  
Image Correlation ◽  
Radius Of Curvature ◽  
Change Analysis ◽  
Thickness Change ◽  
Different Temperatures ◽  
Dependence Relationship ◽  
Relationship Of

Abstract A new method of characterizing the curvature change in thermally adaptive fibers is introduced in this paper. Based on the same principle as bi-metallic strips commonly found in thermostats, multi-component polymer fibers can be created to change their geometrical form in response to a temperature change. This works by creating fibers from two or more materials that have a mismatched Coefficient of Thermal Expansion (CTE). A temperature change leads to a change in curvature of these fibers. When fibers interact in an insulation batting structure, a temperature change leads to a thickness change in the insulation. While these fibers have visually been observed to function, there was no method to quantitatively characterize their curvature performance. This paper introduces a method that can be used to quantify fiber performance by tracking change in curvature over a specific temperature range. This is accomplished by suspending fibers on the surface of a liquid bath and changing the bath temperature. Digital images of the fiber are taken at different temperatures and analyzed using software to determine the radius of curvature. Absolute change in curvature was found to be as high as 0.5% per degree °C from 20 to −20°C for certain samples. A trend was also noted between higher initial curvature and lower overall performance. Digital image correlation was further used to investigate the time-dependence relationship of fiber curvature. Future experiments can be performed with this setup to characterize and compare curvature change performance of different fibers accurately.

scholarly journals Potential Functions and Thermodynamic Properties of UC, UN, and UH

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Shuang-Ling Tang ◽  
Yu Wang ◽  
Qi-Ying Xia ◽  
Xue-Hai Ju
Keyword(s):  
Configuration Interaction ◽  
Density Functional ◽  
Least Square Method ◽  
Potential Functions ◽  
Least Square ◽  
Basis Set ◽  
Dissociation Energies ◽  
Anharmonicity Constant ◽  
Different Temperatures ◽  
Relationship Of

Potential energy surface scanning for UC, UN, and UH was performed by configuration interaction (CI), coupled cluster singles and doubles (CCSD) excitation, quadratic configuration interaction (QCISD (T)), and density functional theory PBE1 (DFT-PBE1) methods in coupling with the ECP80MWB_AVQZ + 2f basis set for uranium and 6 − 311 + G∗ for carbon, hydrogen, and nitrogen. The dissociation energies of UC, UN, and UH are 5.7960, 4.5077, and 2.6999 eV at the QCISD (T) levels, respectively. The calculated energy was fitted to the potential functions of Morse, Lennard-Jones, and Rydberg by using the least square method. The anharmonicity constant of UC is 0.0047160. The anharmonic frequency of UC is 780.27 cm−1 which was obtained based on the PBE1 results. For UN, the anharmonicity constant is 0.0049827. The anharmonic frequency is 812.65 cm−1 which was obtained through the PBE1 results. For UH, the anharmonicity constant is 0.017300. The anharmonic frequency obtained via the QCISD (T) results is 1449.8 cm−1. The heat capacity and entropy in different temperatures were calculated using anharmonic frequencies. These properties are in good accordance with the direct DFT-UPBE1 results (for UC and UN) and QCISD (T) results (for UH). The relationship of entropy with temperature was established.

scholarly journals Determination of Load-Carrying Capacity of C-Profile Glued Ti-Al Column under Temperature Environment

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3013
Author(s):  
Leszek Czechowski
Keyword(s):  
Carrying Capacity ◽  
Tensile Tests ◽  
Discrete Models ◽  
Image Correlation ◽  
Load Carrying Capacity ◽  
Lagrange Equations ◽  
Load Carrying ◽  
Different Temperatures ◽  
Influence Of Temperature On

The paper deals with an examination of the behaviour of glued Ti-Al column under compression at elevated temperature. The tests of compressed columns with initial load were performed at different temperatures to obtain their characteristics and the load-carrying capacity. The deformations of columns during tests were registered by employing non-contact Digital Image Correlation Aramis® System. The numerical computations based on finite element method by using two different discrete models were carried out to validate the empirical results. To solve the problems, true stress-logarithmic strain curves of one-directional tensile tests dependent on temperature both for considered metals and glue were implemented to software. Numerical estimations based on Green–Lagrange equations for large deflections and strains were conducted. The paper reveals the influence of temperature on the behaviour of compressed C-profile Ti-Al columns. It was verified how the load-carrying capacity of glued bi-metal column decreases with an increase in the temperature increment. The achieved maximum loads at temperature 200 °C dropped by 2.5 times related to maximum loads at ambient temperature.

Relationships among pressure, tension, and shape of the diaphragm

1983 ◽  
Vol 55 (6) ◽  
pp. 1899-1905 ◽  
Author(s):  
W. A. Whitelaw ◽  
L. E. Hajdo ◽  
J. A. Wallace
Keyword(s):  
Cross Section ◽  
Radius Of Curvature ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Residual Capacity ◽  
Best Fitting ◽  
Pressure Generator ◽  
Free Membrane ◽  
Relationship Of ◽  
Shape Changes

The shape of the diaphragm dome was calculated from transdiaphragmatic pressure and tension in the diaphragm. It was assumed that the muscle acts as a free membrane, attached at its edges to the inside of a vertical rib cage circular in cross section, that the attachments are inferior to the point at which the dome makes contract with the rib cage, and that the abdomen is filled with fluid with a hydrostatic gradient in pressure. The shape is different from a section of a sphere, with a radius of curvature substantially greater at the apex of the dome than at the sides. Observed shapes of human hemidiaphragm domes at functional residual capacity are not spherical but closely match the calculated shapes. Best-fitting shapes correspond to transdiaphragmatic pressures of about 3 cmH2O transdiaphragmatic pressure, suggesting that such a pressure and corresponding tension are present in the human diaphragm when it is at rest in an erect subject. In this model; as lung volume increases and the diaphragm shortens, its shape changes in such a way that the ratio between transdiaphragmatic pressure and tension in the diaphragm remains nearly constant, rather than increasing with volume. Such a model can explain the observation that the length-tension relationship of the muscle is much more important than curvature in determining the effectiveness of the diaphragm as a pressure generator.

Material Characterization and Mid-Span Bending Capacity With Finite Element Simulated Predictions

2011 ◽  
Author(s):  
Walter Anderson ◽  
Ahmadreza Eshghinejad ◽  
Mohammad Elahinia
Keyword(s):  
Finite Element ◽  
Load Capacity ◽  
Tensile Tests ◽  
Unified Model ◽  
Radius Of Curvature ◽  
Maximum Displacement ◽  
Test Fixture ◽  
Different Temperatures ◽  
Bending Capacity ◽  
Force Displacement

Intelligent materials have been the subject of research for many years. Shape memory alloys (SMAs) are a type of intelligent material that has been targeted for many different uses; such as actuators, sensors and structural supports. SMAs are attractive as actuators due to their large energy density. Although a great deal of information is available on the axial load capacity and on the tip force for SMA tweezer-like devices, there is not enough information about the load capacity at mid-span, especially at the macro-level. Imposed displacement at mid-span experimental evaluation of an SMA beam in the austenitic and martensitic regimes has been studied. To this end, a specimen of near equi-atomic nitinol was heat-treated (shape set) into a ‘U’ shape and loaded into a custom test fixture such that the boundary conditions of the beam are approximated as roller-roller; and the sample was deformed at different temperatures while reaction forces were measured. The displacement is near maximum displacement of the U shape without causing a change in concavity, thus full-scale capacity is shown. Additionally, Unified Model (finite element) predictions of the experimental response are also presented, with good agreement. Due to the robust nature of the Unified Model, geometric parameter variations (wire diameter and radius of curvature) were then simulated to encompass the design envelop for such an actuator. The material properties needed as inputs to the Unified Model were obtained from constant temperature tensile tests of a specimen subjected to the same heat treatment (shape set straight). The resultant critical stresses were then extracted using the tangent method similar to the one described in ASTM F-2082. It is worth noting that the specimen was trained before the stress value extraction, but the transversely loaded specimen was not trained due to the difficulty involved (inherent uneven stress distribution). The contribution of this work is the presentation of experimental results for transverse (mid-span) loading of a nitinol wire and the simulation results allowing for design of a proper actuator with known constraints on force, displacement or temperature (2 of 3 needed). In other words, this work could be used as a type of 3D look-up table; e.g. for a desired force/displacement, the required temperatures are given. Future work includes developing a sensor-less control strategy for simultaneous force/displacement control.

Reflection of government performance from foreign exchange market through engineered mechanism using conditional copula model

2021 ◽  
Vol 40 (1) ◽  
pp. 833-847
Author(s):  
Y. A. Khan ◽  
Y. M. Chu ◽  
S. Z. Abbas
Keyword(s):  
Foreign Exchange Market ◽  
Foreign Currency ◽  
Common Factor ◽  
Common Factors ◽  
Government Performance ◽  
Copula Modeling ◽  
Conditional Copula ◽  
Dependence Relationship ◽  
Method Of Assessment ◽  
Relationship Of

This paper investigates governments’ performance in the country. We achieved this objective differently. We employed an inverse method of assessment, with the utilization of factor copula modeling technique, to study the dependence relationship of exchange rates returns as auxiliary variables, the performance of political and army government tenures in the country in the last two decades are evaluated. Through factor analysis, common factors for the exchange rate are obtained. The analysis shows that conditioned on the common factors, the dependence amongst the elected currencies are strongly asymmetric in most of the tenures except the term of Pakistan Muslim League-Nawaz, and condition on common factor Clayton copula demonstrating hypothesis is more suitable. However, we perceive high left tail reliance among foreign currency returns during Pakistan Muslim League-Nawaz tenure, and the condition on common factor Gumbel copula molding assumption is more appropriate. We are signifying the foulest government performance in the country among all occupancies under consideration.

scholarly journals Predicting the Tensile Behavior of Ti-6.6Al-3.3Mo-1.8Zr-0.29Si Alloy via the Temperature-Dependent Crystal Plasticity Method

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3138
Author(s):  
Jun Zhang ◽  
Yang Wang ◽  
Peng Wang ◽  
Junhong Chen ◽  
Songlin Zheng
Keyword(s):  
Crystal Plasticity ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Published Data ◽  
Initial Yield Stress ◽  
Polycrystal Plasticity ◽  
Different Temperatures ◽  
Polycrystalline Model ◽  
Critical Resolved Shear Stress ◽  
Relationship Of

Uniaxial tensile flow properties of a duplex Ti-6.6Al-3.3Mo-1.8Zr-0.29Si alloy in a temperature range from 213 K to 573 K are investigated through crystal plasticity modelling. Experimental results indicate that the initial yield stress of the alloy decreases as the temperature increases, while its work-hardening behavior displays temperature insensitivity. Considering such properties of the alloy, the dependence of the initial critical resolved shear stress (CRSS) on temperature is taken into account in the polycrystal plasticity modelling. Good coincidence is obtained between modelling and the experimental results. The determined values of CRSS for slip systems are comparable to the published data. The proposed polycrystalline model provides an alternative method for better understanding the microstructure–property relationship of α + β titanium alloys at different temperatures in the future.

scholarly journals Effects of Climate and Land Use changes on Vegetation Dynamics in the Yangtze River Delta, China Based on Abrupt Change Analysis

2020 ◽  
Vol 12 (5) ◽  
pp. 1955
Author(s):  
Lei Wan ◽  
Huiyu Liu ◽  
Haibo Gong ◽  
Yujia Ren
Keyword(s):  
Land Use ◽  
Vegetation Dynamics ◽  
Abrupt Change ◽  
Land Use Changes ◽  
Yangtze River Delta ◽  
Change Analysis ◽  
Land Use Types ◽  
Natural Land ◽  
Abrupt Change Analysis ◽  
Relationship Of

Vegetation dynamics is thought to be affected by climate and land use changes. However, how the effects vary after abrupt vegetation changes remains unclear. Based on the Mann-Kendall trend and abrupt change analysis, we monitored vegetation dynamics and its abrupt change in the Yangtze River delta during 1982–2016. With the correlation analysis, we revealed the relationship of vegetation dynamics with climate changes (temperature and precipitation) pixel-by-pixel and then with land use changes analysis we studied the effects of land use changes (unchanged or changed land use) on their relationship. Results showed that: (1) the Normalized Vegetation Index (NDVI) during growing season that is represented as GSN (growing season NDVI) showed an overall increasing trend and had an abrupt change in 2000. After then, the area percentages with decreasing GSN trend increased in cropland and built-up land, mainly located in the eastern, while those with increasing GSN trend increased in woodland and grassland, mainly located in the southern. Changed land use, except the land conversions from/to built-up land, is more favor for vegetation greening than unchanged land use (2) after abrupt change, the significant positive correlation between precipitation and GSN increased in all unchanged land use types, especially for woodland and grassland (natural land use) and changed land use except built-up land conversion. Meanwhile, the insignificant positive correlation between temperature and GSN increased in woodland, while decreased in the cropland and built-up land in the northwest (3) after abrupt change, precipitation became more important and favor, especially for natural land use. However, temperature became less important and favor for all land use types, especially for built-up land. This research indicates that abrupt change analysis will help to effectively monitor vegetation trend and to accurately assess the relationship of vegetation dynamics with climate and land use changes.

Effect Analysis of Temperature on the Rubber Material Stress-Strain Relationship

2014 ◽  
Vol 977 ◽  
pp. 116-119 ◽  
Author(s):  
Yu Liang Yang ◽  
Liang Qiao ◽  
Cong Wang ◽  
Fei Lu ◽  
Xiao Hui Kang
Keyword(s):  
Environmental Temperature ◽  
Testing Machine ◽  
Test Results ◽  
Stress Strain ◽  
Rubber Material ◽  
Effect Analysis ◽  
Universal Testing ◽  
Different Temperatures ◽  
Strain Relationship ◽  
Relationship Of

For the effect of environmental temperature on the rubber material stress-strain relationships, rubber tensile specimens, compression specimens and shear specimens were made. Through the electronic universal testing machine Instron 5500R, the stress-strain curves of three kinds of specimens at different temperatures were obtained. The test results showed that the stress-strain relationship of rubber material was typically nonlinear. As the temperature increased, the elastic modulus of rubber material decreased.

Self-correction method of out-of-plane motions in two-dimensional digital image correlation

2016 ◽  
Vol 232 (9) ◽  
pp. 1672-1676 ◽  
Author(s):  
Wentao Yan ◽  
Feng Lin
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Correlation Method ◽  
Correction Method ◽  
Image Correlation ◽  
Two Dimensional ◽  
Monitoring Method ◽  
Strain Monitoring ◽  
Out Of Plane ◽  
Relationship Of

Strain monitoring is very important in the manufacturing, assembling, installation and servicing processes in both mechanical and civil engineering fields. Two-dimensional digital image correlation is a simple, efficient strain monitoring method, but one major bottleneck is the unacceptable error due to the unavoidable out-of-plane motions of the object in practice. We propose a “self-correction” method: employing the originally extracted strain values in different directions to correct the errors due to out-of-plane motions. It is applicable to many engineering applications with known relationship of strains in different directions. A uniaxial tension test was conducted to demonstrate the effectiveness and practicality of this self-correction method. Compared with other correction methods, this method is not only simpler but also more efficient in correcting errors due to the lens distortion caused by self-heating. Both the experiment and theoretical analyses demonstrate that this self-correction method maintains the high accuracy of the digital image correlation method.

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