Thermo-Mechanical Investigations of the Electroplastic Effect

2011 ◽  
Author(s):  
Wesley A. Salandro ◽  
Cristina Bunget ◽  
Laine Mears
Keyword(s):  
Cold Work ◽  
Electrical Energy ◽  
Thermal Softening ◽  
Manufacturing Processes ◽  
Electroplastic Effect ◽  
Forming Load ◽  
Commercially Pure ◽  
Electrically Assisted ◽  
Grade 5 ◽  
Electrically Assisted Manufacturing

Recent development of Electrically-Assisted Manufacturing processes proved the advantages of using the electric current, mainly related with the decrease in the mechanical forming load and improvement in the formability when electrically-assisted forming of metals. The reduction of forming load was formulated previously assuming that a part of the electrical energy input is dissipated into heat, thus producing thermal softening of the material, while the remaining component directly aids the plastic deformation. The fraction of electrical energy applied that assists the deformation process compared to the total amount of electrical energy is given by the electroplastic effect coefficient. The objective of the current research is to investigate the complex effect of the electricity applied during deformation, and to establish a methodology for quantifying the electroplastic effect coefficient. Temperature behavior is observed for varying levels of deformation and previous cold work. Results are used to refine the understanding of the electroplastic effect coefficient, and a new relationship, in the form of a power law, is derived. This model is validated under independent experiments in Grade 2 (commercially pure) and Grade 5 (Ti-6Al-4V) titanium.

Several Factors Affecting the Electroplastic Effect During an Electrically-Assisted Forming Process

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Wesley A. Salandro ◽  
Cristina J. Bunget ◽  
Laine Mears
Keyword(s):  
Electric Current ◽  
Cold Work ◽  
Electrical Power ◽  
Forming Process ◽  
Electroplastic Effect ◽  
Factors Affecting ◽  
Forming Load ◽  
Electrically Assisted ◽  
Grade 5 ◽  
Electrically Assisted Manufacturing

Recent development of electrically-assisted manufacturing (EAM) processes proved the advantages of using the electric current, mainly related with the decrease in the mechanical forming load and improvement in the formability. From EAM experiments, it has been determined that a portion of the applied electrical power contributes toward these forming benefits and the rest is dissipated into heat, defined as the electroplastic effect. The objective of this work is to experimentally investigate several factors that affect the electroplastic effect and the efficiency of the applied electricity. Specifically, the effects of various levels of cold work and contact force are explored on both Grade 2 and Grade 5 Titanium alloys. Thermal and mechanical data prove that these factors notably affect the efficiency of the applied electricity during an electrically-assisted forming (EAF) process.

A Review of Electrically-Assisted Manufacturing With Emphasis on Modeling and Understanding of the Electroplastic Effect

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Brandt J. Ruszkiewicz ◽  
Tyler Grimm ◽  
Ihab Ragai ◽  
Laine Mears ◽  
John T. Roth
Keyword(s):  
Fuel Economy ◽  
Elastic Recovery ◽  
Fuel Efficiency ◽  
High Strength ◽  
Carbon Steels ◽  
Metallic Materials ◽  
Low Carbon ◽  
Electroplastic Effect ◽  
Electrically Assisted ◽  
Electrically Assisted Manufacturing

Increasingly strict fuel efficiency standards have driven the aerospace and automotive industries to improve the fuel economy of their fleets. A key method for feasibly improving the fuel economy is by decreasing the weight, which requires the introduction of materials with high strength to weight ratios into airplane and vehicle designs. Many of these materials are not as formable or machinable as conventional low carbon steels, making production difficult when using traditional forming and machining strategies and capital. Electrical augmentation offers a potential solution to this dilemma through enhancing process capabilities and allowing for continued use of existing equipment. The use of electricity to aid in deformation of metallic materials is termed as electrically assisted manufacturing (EAM). The direct effect of electricity on the deformation of metallic materials is termed as electroplastic effect. This paper presents a summary of the current state-of-the-art in using electric current to augment existing manufacturing processes for processing of higher-strength materials. Advantages of this process include flow stress and forming force reduction, increased formability, decreased elastic recovery, fracture mode transformation from brittle to ductile, decreased overall process energy, and decreased cutting forces in machining. There is currently a lack of agreement as to the underlying mechanisms of the electroplastic effect. Therefore, this paper presents the four main existing theories and the experimental understanding of these theories, along with modeling approaches for understanding and predicting the electroplastic effect.

Modeling the Electroplastic Effect During Electrically-Assisted Forming of 304 Stainless Steel

2012 ◽  
Author(s):  
Wesley A. Salandro ◽  
Cristina Bunget ◽  
Laine Mears
Keyword(s):  
Automotive Industry ◽  
Deformation Process ◽  
304 Stainless Steel ◽  
Electroplastic Effect ◽  
Modeling Methodology ◽  
Electrically Assisted ◽  
Lightweight Alloys ◽  
Current Densities ◽  
Electrically Assisted Manufacturing ◽  
Insight Into

Over the last decade, the Electrically-Assisted Manufacturing (EAM) technique, where electricity is applied to a metal during deformation, has been experimentally proven to increase the workability of many lightweight alloys which are highly desirable to the automotive industry. Recent research by the authors has led to ways of accounting for the formability increases due to the applied electricity, by way of an Electroplastic Effect Coefficient (EEC), and by utilizing this coefficient, simple EAM forming tests can ultimately be modeled. This work provides insight into the authors’ EAM modeling methodology and how it differs from previous EAM modeling attempts. Additionally, from the Electrically-Assisted Forming (EAF) experiments, two methods of accounting for the electroplastic effect will be discussed and compared. Ultimately, these methods will be integrated into the thermo-mechanical model to predict compressive stress-strain profiles for electrically-assisted forming tests under various current densities and die speeds. Finally, the efficiency of applying electricity to the deformation process will be discussed.

Enhancement of the tensile shear strength for joining low-ductility aluminium to high-strength steel by using electrically-assisted mechanical clinching (EAMC)

2021 ◽  
pp. 095440542199565
Author(s):  
Abozar Barimani-Varandi ◽  
Abdolhossein Jalali Aghchai
Keyword(s):  
Shear Strength ◽  
High Strength Steel ◽  
High Strength ◽  
Fe Model ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Electroplastic Effect ◽  
Fracture Displacement ◽  
Electrically Assisted ◽  
Mechanical Clinching

The present work studied the enhancement of the tensile shear strength for joining AA6061-T6 aluminium to galvanized DP590 steel via electrically-assisted mechanical clinching (EAMC) using an integrated 2D FE model. To defeat the difficulties of joining low-ductility aluminium alloy to high-strength steel, the electroplastic effect obtained from the electrically-assisted process was applied to enhance the clinch-ability. For this purpose, the results of experiments performed by the chamfering punches with and without electrically-assisted pre-heating were compared. Joint cross-section, failure load, failure mode, fracture displacement, material flow, and failure mechanism were assessed in order to study the failure behaviour. The results showed that the joints clinched at the EAMC condition failed with the dominant dimpled mechanism observed on the fracture surface of AA6061 side, achieved from the athermal effect of the electroplasticity. Besides, these joints were strengthened 32% with a much more fracture displacement around 20% compared with non-electrically-assisted pre-heating.

Characterization of Flow Stress for Commercially Pure Titanium Subjected to Electrically-Assisted Deformation

2013 ◽  
Author(s):  
James Magargee ◽  
Fabrice Morestin ◽  
Jian Cao
Keyword(s):  
Flow Stress ◽  
Heating Temperature ◽  
Pure Titanium ◽  
Constitutive Models ◽  
Plastic Behavior ◽  
Commercially Pure Titanium ◽  
Coupled Models ◽  
Commercially Pure ◽  
Electrically Assisted ◽  
Tension And Compression

Uniaxial tension tests were conducted on thin commercially pure titanium sheets subjected to electrically-assisted deformation using a new experimental setup to decouple thermal-mechanical and possible electroplastic behavior. The observed absence of stress reductions for specimens air-cooled to near room temperature motivated the need to reevaluate the role of temperature on modeling the plastic behavior of metals subjected to electrically-assisted deformation, an item that is often overlooked when invoking electroplasticity theory. As a result, two empirical constitutive models, a modified-Hollomon and the Johnson-Cook models of plastic flow stress, were used to predict the magnitude of stress reductions caused by the application of constant DC current and the associated Joule heating temperature increase during electrically-assisted tension experiments. Results show that the thermal-mechanical coupled models can effectively predict the mechanical behavior of commercially pure titanium in electrically-assisted tension and compression experiments.

Force Controlled Electrical Pulse Assisted Forming

2020 ◽  
Author(s):  
Tyler J. Grimm ◽  
Amit B. Deshpande ◽  
Laine Mears ◽  
Jianxun Hu
Keyword(s):  
Control Systems ◽  
Stress Level ◽  
Stress Reduction ◽  
Power Supply ◽  
Electrical Current ◽  
Strain Rates ◽  
Control Approach ◽  
Electrically Assisted ◽  
Minimum Stress ◽  
Electrically Assisted Manufacturing

Abstract Electrically-assisted manufacturing refers to the direct application of electrical current to a workpiece during a manufacturing process. This assistance results in several benefits such as flow stress reduction, increased elongation, reduced springback, increased diffusion, and increased precipitation control. These effects are also associated with traditional thermal assistance. However, for over half a decade it has been argued whether or not these observed effects are due to electroplasticity, a term which describes effects that cannot be fully explained through resistive heating. Several theories have been proposed as to the mechanism responsible for these purported athermal effects. Conflicting results within literature have enabled this debate over electroplasticity since its discovery in the mid 20th century. While the effects of electrically-assisted manufacturing are clearly characterized throughout literature, there is a lack of research related to control systems which may be used to take advantage of its effects. Typically, control systems are developed using an empirical approach, requiring extensive testing in order to fully characterize the stress-strain behavior at all conditions. Additionally, current research has primarily focused on reducing flow stresses during electrically-assisted processes without regard for the strength of the material subsequent to forming. Therefore, there is a strong need for a control system which can quickly be deployed for new materials and does not significantly reduce the subsequent strength of the material. Herein, a novel control approach is developed in which electrical pulses are triggered by a predetermined stress level. This stress value would be set according to the manufacturer’s stamping die strength. Once the material reaches this stress value, current is deployed until a minimum stress level is reached. At that point, the electricity is turned off and the material allowed to cool; at that stage the stress begins to elevate and the cycle continues. This approach does not require extensive pre-testing and is robust to a range of strain rate. This type of implementation can also be adapted to different levels of capability. For example, since the current is controlled by force and not by time, a low-current power supply will stay on for each pulse longer than a power supply with higher capabilities; however, each will achieve a similar effect. This study investigates the effect of several different minimum stress levels and strain rates. The strain rates chosen are relatively similar to common stamping process. This system was experimentally tested using 1018 CR steel. This control approach was found to be a successful method of maintaining a desired stress level.

Design of an Electrically Assisted Manufacturing Process

2014 ◽  
pp. 245-253
Author(s):  
Wesley A. Salandro ◽  
Joshua J. Jones ◽  
Cristina Bunget ◽  
Laine Mears ◽  
John T. Roth
Keyword(s):  
Manufacturing Process ◽  
Electrically Assisted ◽  
Electrically Assisted Manufacturing

scholarly journals Electrically-Assisted Manufacturing for Reduction in Forging Forces of Bearing Steels

2020 ◽  
Vol 48 ◽  
pp. 349-357
Author(s):  
Christopher D. Lang ◽  
C.R. Hasbrouck ◽  
Austin S. Hankey ◽  
Paul C. Lynch ◽  
Bryan D. Allison ◽  
...  
Keyword(s):  
Bearing Steels ◽  
Electrically Assisted ◽  
Electrically Assisted Manufacturing

The Microstructural Effects on Magnesium Alloy AZ31B-O While Undergoing an Electrically-Assisted Manufacturing Process

2009 ◽  
Author(s):  
Timothy A. McNeal ◽  
Jeffrey A. Beers ◽  
John T. Roth
Keyword(s):  
Deformation Process ◽  
Microstructural Analysis ◽  
High Strength ◽  
Strength Properties ◽  
High Demand ◽  
Electrically Assisted ◽  
Magnesium Alloy Az31b ◽  
Microstructural Effects ◽  
Lightweight Alloys ◽  
Electrically Assisted Manufacturing

In today’s industry, the need for lightweight alloys with high strength properties is growing. More specifically, magnesium alloys are in high demand. Unfortunately, magnesium’s limited formability hinders its broad range applicability. Previous research has discovered that the tensile formability of this alloy can be increased using electrical pulsing during the deformation process, referred to as Electrically-Assisted Manufacturing (EAM). Although this method increases a material’s formability (i.e. lowers flow stress, increases elongation, and reduces springback), a detailed analysis is required to further evaluate the effects of electricity on the material’s microstructure. The research herein will examine the microstructure of Magnesium AZ31B-O specimens that were deformed under uniaxial tension while electrically pulsed with various pulsing parameters (i.e. different current density/pulse duration combinations). This microstructural analysis will focus on how EAM affected grain size, grain orientation, and twinning. The microstructure of the following different specimen types will be compared: deformed EAM specimens, deformed non-pulsed baseline specimens, and undeformed non-pulsed “as received” specimens.

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