scholarly journals Неравновесные состояния в ВТСП-композитах второго поколения при сверхкритических импульсных токовых воздействиях

2021 ◽  
Vol 47 (19) ◽  
pp. 22
Author(s):  
И.В. Анищенко ◽  
С.В. Покровский ◽  
М.А. Осипов ◽  
Д.А. Абин ◽  
Д.И. Грицаенко ◽  
...  
Keyword(s):  
Finite Element ◽  
Soft Mode ◽  
Dynamic Resistance ◽  
Pulsed Current ◽  
Resistive State ◽  
Nonstationary Processes ◽  
Current Load ◽  
Superconducting Layer ◽  
Current Pulses ◽  
Load Mode

This paper presents the results of studying the processes of еру HTS composites switching from the superconducting to the resistive state at microsecond current pulses. Two modes of pulsed current load were used: with an amplitude of ~ 1.1 Ic (the so-called "soft" mode) and with an amplitude of ~ 3 Ic ("hard" mode). The possibility of passing supercritical currents through the tape without superconductor characteristics degradation is shown. To explain the processes occurring in the tape during the current pulse, 2D FEA (finite element analyzes) was developed, with the help of which the dynamic resistance of the HTS composite superconducting layer was calculated in the "hard" load mode and nonstationary processes of current redistribution between the different tape layers were demonstrated.

Assessment of finite element analyses of load mode (bending vs. tension) effects for mitigation of judgment on pop-ins caused by splits

2019 ◽  
Vol 205 ◽  
pp. 28-39 ◽  
Author(s):  
Sohei Kanna ◽  
Yoichi Yamashita ◽  
Tomoya Kawabata ◽  
Tetsuya Tagawa ◽  
Yasuhito Imai ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Analyses ◽  
Load Mode

scholarly journals Numerical Analysis of the Deformation Performance of Monopile under Wave and Current Load

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6431
Author(s):  
Libo Chen ◽  
Xiaoyan Yang ◽  
Lichen Li ◽  
Wenbing Wu ◽  
M. Hesham El Naggar ◽  
...  
Keyword(s):  
Finite Element ◽  
Deformation Mechanism ◽  
Large Diameter ◽  
Offshore Wind ◽  
Stokes Wave ◽  
Reverse Direction ◽  
Design Parameters ◽  
Embedment Depth ◽  
Current Load ◽  
Maximum Displacement

The research on the deformation mechanism of monopile foundation supporting offshore wind turbines is significant to optimize the design of a monopile foundation under wave and current load. In this paper, a three-dimensional wave-pile-soil coupling finite element model is proposed to investigate the deformation mechanism of monopile undercurrent and fifth-order Stokes wave. Different from the conventional assumption that there is no slip at the pile-soil interface, Frictional contact is set to simulate the relative movement between monopile and soil. Numerical results indicate that under extreme environmental conditions, the monopile foundation sways within a certain range and the maximum displacement in the loading direction is 1.3 times the displacement in the reverse direction. A further investigation has been made for a large-diameter pipe pile with various design parameters. The finite element analyses reveal that the most efficient way to reduce the deflection of the pile head is by increasing the embedment depth of the monopile. When the embedment depth is limited, increasing the pile diameter is a more effective way to strengthen the foundation than increasing the wall thickness.

Fatigue Life Assessment of a Ship Unloader Crane

2014 ◽  
Vol 945-949 ◽  
pp. 1086-1089
Author(s):  
Bin Xu ◽  
Tao Zhang ◽  
Feng Qi Wu ◽  
Zhen Rong Yan
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Residual Life ◽  
Dynamic Properties ◽  
Life Assessment ◽  
Strength Analysis ◽  
Dynamic Resistance ◽  
Element Analysis ◽  
Experimental Stress Analysis ◽  
Fatigue Life Assessment

Ship unloader crane was widely used in transportation, and uploaded or unloaded cargoes from ships, which could influence efficiency and benefits of transportation greatly. In order to improve the reliability and safety, and decrease its risk in working flow, a method of fatigue life assessment was proposed in this paper. According to related standards and properties of risk, finite element method and experimental stress analysis were integrated to assess the working condition of a ship unloader crane. Finite element models of primary structures subjected to loads were built to achieve dynamic properties, which could supply a basic reference to experiment and guidance to locate the tested positions. Afterwards, wireless dynamic resistance strain-gauges were adopted to execute static and dynamic stress, and the tested results combined with finite element analysis were applied to strength analysis. Based on nominal stress and Miner principle, rainflow method was developed to fatigue life assessment of this ship unloader crane. The final results indicated that residual life of this crane was 4.67 years.

Modeling IPMC Material With Dynamic Surface Characteristics

2009 ◽  
Author(s):  
Deivid Pugal ◽  
Alvo Aabloo ◽  
Kwang J. Kim ◽  
Youngsoo Jung
Keyword(s):  
Finite Element ◽  
Time Moment ◽  
Surface Characteristics ◽  
Dynamic Resistance ◽  
Charge Movement ◽  
Fe Model ◽  
Metal Composite ◽  
Fe Method ◽  
Element Analysis ◽  
Dynamic Surface

This paper presents the Finite Element Analysis (FEA) of an ionic polymer-metal composite (IPMC) material. The IPMC materials are known to bend when electric field is applied on the electrodes. The material also produces potential difference on the electrodes when is bent. Several authors have used the FEA to describe that fenomenon and rather precise basic Finite Element (FE) models already exist. Therefore the current study is mainly focused on the modeling of the electrodes of IPMC. The first goal of this research is to model the electric currents in the electrodes. The basis of the electric current calculations is the Ramo-Shockley theorem, which has been used in the other areas of physics to describe the currents in a circuit due to a charge movement in a media. We have used the theorem to calculate the current density in the continuous electrodes of IPMC due to the ion migration in the backbone polymer. Along the current densities we are able to calculate voltage on the electrode at a given time moment. The model is demonstrated to give some physically reasonable results. However, the model is rather complex and as the solution times are quite large, some possible optimizations have been considered as well. The second goal of this study is to include the dynamic resistance and capacitance of the electrodes in our model. Lot of research has been done to develop a physically reasonable capacitor-resistor model of an IPMC and the results have been promising. Furthermore, some authors have managed to develop partial differential equations (PDE) to describe the model. We try to include some simplified versions of those equations into our physical model. As the FE model for IPMC is nonlinear and gets complicated very fast when additional equations are added, the final sections of this paper briefly considers some novel optimization ideas in regard to modeling IPMC with FE method.

NiMo Nanoparticles Electrodeposited by Pulsed Current and Their Catalytic Properties for Hydrogen Production

2013 ◽  
Vol 16 (3) ◽  
pp. 177-182 ◽  
Author(s):  
Savidra Lucatero ◽  
Gabriel Tamayo ◽  
Diego Crespo ◽  
Ernesto Mariño ◽  
Marcelo Videa
Keyword(s):  
Pulse Current ◽  
Catalytic Properties ◽  
Unit Area ◽  
Catalytic Performance ◽  
Pulsed Current ◽  
Pulse Time ◽  
Current Pulses ◽  
Mo Content ◽  
High Instability

The electrocatalytic activity of NiMo nanoparticles (NPs) fabricated by means of current pulses from a binary electrolyte was characterized using cyclic voltammetry. The pulse current density, jpulse, was varied in the range of 7 to 430 mA/cm2, whereas the pulse time, tpulse, was kept constant at two seconds. Mean NP size, Dmean, ranged within 27 and 38 nm at jpulse values between 15 and 140 mA/cm2; with Dmean increasing as jpulse was higher. NP dispersion (i. e., number of objects per unit area of substrate) was lower when jpulse values were also low (15 and 35 mA/cm2), which showed consistency with a promoted nuclei formation and prolonged NP growth at higher jpulse values. An improved catalytic performance for hydrogen evolution was determined upon increasing jpulse in the range of 7 to 70 mA/cm2 and remaining practically unvaried at higher jpulse values. The electrosynthesis of two distinct catalytic materials was indicated by electrochemical characterization of deposits; the material with greatest catalytic activity also showed high instability, causing a dramatic decay (~80%) in the activity after two consecutive cycles of operation. Ni and Mo content in electrodeposits were both sensitive to variations in jpulse.

scholarly journals Finite‐element analysis of a shielded pulsed‐current induction heater

2010 ◽  
Vol 29 (6) ◽  
pp. 1585-1595
Author(s):  
Ruth V. Sabariego ◽  
Peter Sergeant ◽  
Johan Gyselinck ◽  
Patrick Dular ◽  
Luc Dupré ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pulsed Current ◽  
Element Analysis ◽  
Induction Heater

scholarly journals Predicting Failure in Multi-Bolt Composite Joints Using Finite Element Analysis and Bearing-Bypass Diagrams

2005 ◽  
Vol 293-294 ◽  
pp. 591-598 ◽  
Author(s):  
C.T. McCarthy ◽  
M.A. McCarthy ◽  
Michael D. Gilchrist
Keyword(s):  
Finite Element ◽  
Failure Load ◽  
Three Dimensional ◽  
Element Model ◽  
Composite Joints ◽  
Element Analysis ◽  
Composite Joint ◽  
Dimensional Finite Element ◽  
Load Mode ◽  
Three Dimensional Finite Element

A three-dimensional finite element model of a three-bolt, single-lap composite joint is constructed using the non-linear finite element code MSC.Marc. The model is validated against an experiment where the load distribution in the joint is measured using instrumented bolts. Two different joint configurations are examined, one with neat-fit clearances at each bolt-hole and another with a 240 µm clearance at one hole with neat-fits at the others. Bearing and by-pass stresses are extracted from the model and used in conjunction with published bearing/by-pass diagrams to predict the failure load, mode and location for the joints. It is shown that the proposed model accurately predicts the failure behaviour of the joints, as determined from experiments on three-bolt joints loaded to failure. It is also shown that introducing a clearance into one hole significantly changes the failure sequence, but does not affect the ultimate failure load, mode or location. The proposed method demonstrates a simple approach to predicting damage in complex multi-bolt composite joints.

scholarly journals THE INFLUENCE OF CATHODE MATERIAL ON THE CHARACTERISTICS OF PULSED NEGATIVE CORONA IN OXYGEN

2021 ◽  
pp. 93-98
Author(s):  
V.I. Golota ◽  
B.B. Kadolin ◽  
G.V. Taran ◽  
I.A. Pashchenko
Keyword(s):  
Stainless Steel ◽  
Discharge Current ◽  
Pulse Amplitude ◽  
Maximum Load ◽  
Electrode System ◽  
Half Maximum ◽  
Negative Corona ◽  
Current Pulses ◽  
Ozone Synthesis ◽  
Load Mode

Change in time for the shape of the discharge current pulses of the pulsed negative corona in oxygen with cop-per and stainless steel cathodes has been studied for two discharge modes. The change lies in the decrease of the pulse amplitude and duration at half maximum. It is shown that for stainless steel cathodes, the amount of electric charge transferred in one pulse of the discharge current is 15% greater than for copper cathodes. It is also shown that under the maximum load mode, the amount of charge transferred in one pulse of the discharge current is de-creased with time by 10% for both types of cathodes. It is shown that ozone synthesis in the electrode system with copper cathodes is 25% more efficient.

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