scholarly journals Performing an Indirect Coupled Numerical Simulation for Capacitor Discharge Welding of Aluminium Components

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1330
Author(s):  
Johannes Koal ◽  
Martin Baumgarten ◽  
Stefan Heilmann ◽  
Jörg Zschetzsche ◽  
Uwe Füssel
Keyword(s):  
Electrical Contact ◽  
Electrical Contact Resistance ◽  
Capacitor Discharge ◽  
Projection Welding ◽  
Indirect Coupling ◽  
Physical Environments ◽  
Process Characterization ◽  
Experimental Process ◽  
Capacitor Discharge Welding

Capacitor discharge welding (CDW) for projection welding provides very high current pulses in extremely short welding times. This requires a quick follow up behaviour of the electrodes during the softening of the projection. The possibilities of experimental process investigations are strongly limited because of the covered contact zone and short process times. The Finite Element Method (FEM) allows highly resoluted analyses in time and space and is therefore a suitable tool for process characterization and optimization. To utilize this mean of optimization, an indirect multiphysical numerical model has been developed in Ansys Mechanical APDL. This model couples the physical environments of thermal–electric with structural analysis. It can master the complexity of large deformations, short current rise times and high temperature gradients. A typical ring projection has been chosen as the joining task. The selected aluminium alloys are EN-AW-6082 (ring projection) and EN-AW-5083 (sheet metal). This paper presents the investigated material data, the model design and the methodology for an indirect coupling of the thermal–electric with the structural physic. The electrical contact resistance is adapted to the measured voltage in the experiment. The limits of the model in Ansys Mechanical APDL are due to large mesh deformation and decreasing element stiffness. Further modelling possibilities, which can handle the limits, are described.

Interfacial structures of dissimilar materials joined by capacitor-discharge welding

1994 ◽  
Vol 52 ◽  
pp. 534-535
Author(s):  
C. P. Doğan ◽  
R. D. Wilson ◽  
J. A. Hawk
Keyword(s):  
Rapid Solidification ◽  
Fusion Zone ◽  
Dissimilar Materials ◽  
Solidification Process ◽  
Weld Interface ◽  
Capacitor Discharge ◽  
Fine Grained ◽  
Iron Aluminum ◽  
Conductive Ceramics ◽  
Capacitor Discharge Welding

Capacitor Discharge Welding is a rapid solidification technique for joining conductive materials that results in a narrow fusion zone and almost no heat affected zone. As a result, the microstructures and properties of the bulk materials are essentially continuous across the weld interface. During the joining process, one of the materials to be joined acts as the anode and the other acts as the cathode. The anode and cathode are brought together with a concomitant discharge of a capacitor bank, creating an arc which melts the materials at the joining surfaces and welds them together (Fig. 1). As the electrodes impact, the arc is extinguished, and the molten interface cools at rates that can exceed 106 K/s. This process results in reduced porosity in the fusion zone, a fine-grained weldment, and a reduced tendency for hot cracking.At the U.S. Bureau of Mines, we are currently examining the possibilities of using capacitor discharge welding to join dissimilar metals, metals to intermetallics, and metals to conductive ceramics. In this particular study, we will examine the microstructural characteristics of iron-aluminum welds in detail, focussing our attention primarily on interfaces produced during the rapid solidification process.

scholarly journals The Route for Ultra-High Recording Density Using Probe-Based Data Storage Device

NANO ◽  
2015 ◽  
Vol 10 (08) ◽  
pp. 1550118 ◽  
Author(s):  
Lei Wang ◽  
Jing Wen ◽  
CiHui Yang ◽  
Shan Gai ◽  
YuanXiu Peng
Keyword(s):  
Phase Change ◽  
Data Storage ◽  
Electrical Contact ◽  
Crystal Nucleation ◽  
Access Time ◽  
Storage Device ◽  
Electrical Contact Resistance ◽  
Low Energy Consumption ◽  
Modeling Techniques ◽  
Second Period

Phase-change probe memory using Ge2Sb2Te5 has been considered as one of the promising candidates as next-generation data storage device due to its ultra-high density, low energy consumption, short access time and long retention time. In order to utmostly mimic the practical setup, and thus fully explore the potential of phase-change probe memory for 10 Tbit/in2 target, some advanced modeling techniques that include threshold-switching, electrical contact resistance, thermal boundary resistance and crystal nucleation-growth, are introduced into the already-established electrothermal model to simulate the write and read performance of phase-change probe memory using an optimal media stack design. The resulting predictions clearly demonstrate the capability of phase-change probe memory to record 10 Tbit/in2 density under pico Joule energy within micro second period.

Discrete drops in the electrical contact resistance during nanoindentation of a bulk metallic glass

2016 ◽  
Vol 108 (18) ◽  
pp. 181903 ◽  
Author(s):  
Gaurav Singh ◽  
R. L. Narayan ◽  
A. M. Asiri ◽  
U. Ramamurty
Keyword(s):  
Metallic Glass ◽  
Contact Resistance ◽  
Bulk Metallic Glass ◽  
Electrical Contact ◽  
Electrical Contact Resistance

Tracking the Rise of Geriatric Emergency Departments in the United States

2018 ◽  
Vol 39 (8) ◽  
pp. 871-879 ◽  
Author(s):  
John G. Schumacher ◽  
Jon Mark Hirshon ◽  
Phillip Magidson ◽  
Marilyn Chrisman ◽  
Terisita Hogan
Keyword(s):  
Emergency Department ◽  
Emergency Care ◽  
Emergency Departments ◽  
The United States ◽  
Transitions Of Care ◽  
Emergency Department Care ◽  
Equipment And Supplies ◽  
Care Services ◽  
Physical Environments

The traditional model of emergency care no longer fits the growing needs of the over 20 million older adults annually seeking emergency department care. In 2007 a tailored “geriatric emergency department” model was introduced and rapidly replicated among hospitals, rising steeply over the past 5 years. This survey examined all U.S. emergency departments self-identifying themselves as Geriatric Emergency Departments (GEDs) and providing enhanced geriatric emergency care services. It was guided by the recently adopted Geriatric Emergency Department Guidelines and examined domains including, GED identity, staffing, and administration; education, equipment, and supplies; policies, procedures, and protocols; follow-up and transitions of care; and quality improvement. Results reveal a heterogeneous mix of GED staffing, procedures, physical environments and that GEDs’ familiarity with the GED Guidelines is low. Findings will inform emergency departments and gerontologists nationwide about key GED model elements and will help hospitals to improve ED services for their older adult patients.

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