scholarly journals Investigation of Heterogeneous Joule Heating as the Explanation for the Transient Electroplastic Stress Drop in Pulsed Tension of 7075-T6 Aluminum

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Brandt J. Ruszkiewicz ◽  
Laine Mears ◽  
John T. Roth
Keyword(s):  
Electrical Resistivity ◽  
Dislocation Density ◽  
Joule Heating ◽  
Stress Drop ◽  
Element Model ◽  
Bulk Temperature ◽  
Electroplastic Effect ◽  
Bulk Heating ◽  
Full Explanation ◽  
Multiscale Finite Element

The electroplastic effect can be predicted and modeled as a 100% bulk heating/softening phenomenon in the quasi-steady-state; however, these same models do not accurately predict flow stress in transient cases. In this work, heterogeneous Joule heating is examined as the possible cause for the transient stress drop during quasi-static pulsed tension of 7075-T6 aluminum. A multiscale finite element model is constructed where heterogeneous thermal softening is explored through the representation of grains, grain boundaries, and precipitates. Electrical resistivity is modeled as a function of temperature and dislocation density. In order to drive the model to predict the observed stress drop, the bulk temperature of the specimen exceeds experiment, while the dislocation density and grain boundary electrical resistivity exceed published values, thereby suggesting that microscale heterogeneous heating theory is not the full explanation for the transient electroplastic effect. A new theory for explaining the electroplastic effect based on dissolution of bonds is proposed called the Electron Stagnation Theory.

Influence of Joule heating on electrical resistivity in Co-rich amorphous microwires

2021 ◽  
Vol 271 ◽  
pp. 115310
Author(s):  
S.A. Gudoshnikov ◽  
V.I. Odintsov ◽  
A.V. Popova ◽  
S.A. Menshov ◽  
B.Ya. Liubimov ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Joule Heating ◽  
Amorphous Microwires

Coupled Electro-Thermal Mechanical Analyses for SMM Actuators Development

2004 ◽  
Author(s):  
C. Channy Wong ◽  
Randy R. Lober ◽  
Jason D. Hales
Keyword(s):  
Electrical Resistivity ◽  
Temperature Distribution ◽  
Joule Heating ◽  
Temperature Dependent ◽  
Strongly Coupled ◽  
Mechanical Responses ◽  
Thermal Actuators ◽  
Micro Actuators ◽  
And Performance

A coupled-physics analysis code has been developed to simulate the electrical, thermal, and mechanical responses of surface micromachined (SMM) actuators. Our objective is to optimize the design and performance of these micro actuators. Since many new designs of these electro-thermal actuators have shuttles or platforms between beams, calculating the local Joule heating requires a multi-dimensional electrostatics analysis. Moreover, the electrical solution is strongly coupled to the temperature distribution since the electrical resistivity is temperature dependent. Thus, it is essential to perform a more comprehensive simulation that solves the coupled electrostatics, thermal, and mechanical equations. Results of the coupled-physics analyses will be presented.

Transport and Thermodynamic Properties of CeRu2Al10 Controlled by Pressure at around Critical Pressure

2018 ◽  
Vol 941 ◽  
pp. 1378-1383 ◽  
Author(s):  
Yukihiro Kawamura ◽  
Chihiro Sekine ◽  
Kazuyuki Matsubayashi ◽  
Yoshiya Uwatoko ◽  
Takashi Nishioka
Keyword(s):  
Electrical Resistivity ◽  
High Temperature ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Joule Heating ◽  
Ground State ◽  
Critical Pressure ◽  
Antiferromagnetic Ordering ◽  
Temperature Dependences

We present transport and thermodynamic properties of CeRu2Al10 controlled by pressure in a vicinity of a critical pressure PC ~ 4GPa, where antiferromagnetic ordering disappears. The resistivity under pressure was measured with DC four terminal method and the AC specific heat under pressure was measured by Joule heating type technique. The pressure was applied by cubic-anvil-apparatus and palm-cubic-anvil-apparatus. The results of AC specific heat indicate TN holds at high temperature up to 3.9 GPa but suddenly disappears above this pressure. We confirmed TN from thermodynamic properties. Although CeRu2Al10 is in a Kondo semiconducting ground state at 4 GPa, temperature dependences of electrical resistivity at 4.6 GPa and 5.9 GPa indicate metallic ground state in these pressures. CeRu2Al10 does not show superconductivity down to 0.7 K at 4.6 GPa and 5.9 GPa.

scholarly journals Influence of Fluid on Seal and Assembly of Pipeline Fittings Based on the Multiscale Finite Element Model

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yangyang Yan ◽  
Yaping Fan
Keyword(s):  
Contact Area ◽  
High Stress ◽  
Fluid Pressure ◽  
Multiscale Model ◽  
Element Model ◽  
Assembly Method ◽  
Internal Fluid ◽  
Stress Zone ◽  
Multiscale Finite Element ◽  
High Stress Zone

Pipeline fittings with ferrules are applied to connect sections of hydraulic pipelines in aircraft, and their reliability and stability are essential. This paper aims at investigating the influence of internal fluid on the sealing characteristics of pipeline fittings by employing the multiscale model. Changes in the sealing characteristics induced by the fluid pressure switch are studied, and the assembly method under the internal fluid is also explored. The calculated results show that the multiscale model can accurately reflect the changes in the sealing area, and the high-pressure fluid can enhance the sealing reliability. Compared with the contact area, the fluid pressure exerts a greater influence on the change in the area of the high-stress zone. Furthermore, the unrestored sealing area enlarges with the increased maximum fluid pressure, and the change in the area of the high-stress zone is significantly larger than that in the contact area. Moreover, the optimum assembly position of ferrule decreases with the increase in fluid pressure, thus achieving the excellent sealing characteristics.

scholarly journals Modelling the Ability of Rheoencephalography to Measure Cerebral Blood Flow

2019 ◽  
Vol 5 (1) ◽  
pp. 110-113 ◽  
Author(s):  
Konstantin S. Brazovskii ◽  
Jacov S. Pekker ◽  
Oleg S. Umanskii
Keyword(s):  
Blood Flow ◽  
Cerebrospinal Fluid ◽  
Electrical Resistivity ◽  
Cerebral Blood Flow ◽  
Potential Benefit ◽  
Human Head ◽  
Element Model ◽  
History Of ◽  
Electrode Method ◽  
The Brain

Abstract Despite the long history of rheoencephalography (REG), some important aspects of the method are still debatable. Bioimpedance measurements offer great potential benefit for study of the human brain, but the traditional four or six electrode method suffers from potential misinterpretations and lack of accuracy. The objective of this paper is to study the possible mechanism of REG formation by means of numerical modelling using a realistic finite element model of the human head. It is shown that the cardiac related variations in electrical resistivity of the scalp contributes more than 60% to the REG amplitude, whereas the brain and cerebrospinal fluid are mutually compensated by each over.

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