Thermal Response Modeling of Sheet Metals in Uniaxial Tension During Electrically-Assisted Forming

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Joshua J. Jones ◽  
Laine Mears
Keyword(s):  
Fuel Efficiency ◽  
Thermal Response ◽  
High Strength ◽  
Electrical Current ◽  
Applied Current ◽  
Electroplastic Effect ◽  
Electrically Assisted ◽  
Response Modeling ◽  
Deformation Tests ◽  
Good Agreement

For the current practice of improving fuel efficiency and reducing emissions in the automotive sector, it is becoming more common to use low density/high strength materials instead of costly engine/drivetrain technologies. With these materials there are normally many manufacturing difficulties that arise during their incorporation to the vehicle. As a result, new processes which improve the manufacturability of these materials are necessary. This work examines the manufacturing technique of electrically-assisted forming (EAF) where an electrical current is applied to the workpiece during deformation to modify the material's formability. In this work, the thermal response of sheet metal for stationary (i.e., no deformation) and deformation tests using this process are explored and modeled. The results of the model show good agreement for the stationary tests while for the deformation tests, the model predicts that all of the applied electrical current does not generate Joule heating. Thus, this work suggests from the observed response that a portion of the applied current may be directly aiding in deformation (i.e., the electroplastic effect). Additionally, the stress/strain response of Mg AZ31 under tensile forming using EAF is presented and compared to prior experimental work for this material.

Thermal Response Characterization of Sheet Metals During Electrically-Assisted Forming (EAF)

2012 ◽  
Author(s):  
Joshua J. Jones ◽  
Laine Mears
Keyword(s):  
Joule Heating ◽  
Thermal Response ◽  
High Strength ◽  
Electrical Current ◽  
Deformation Model ◽  
Applied Current ◽  
Electrically Assisted ◽  
Lightweight Engineering ◽  
Deformation Tests

For the current practice of lightweight engineering in the automotive sector, it is common to introduce and use low density/high strength materials instead of costly engine/drivetrain technologies. With the introduction of these materials there are commonly many manufacturing difficulties which arise during their incorporation to the vehicle. As a result, new processes which improve the manufacturability of these materials are necessary. This work examines the manufacturing technique of Electrically-Assisted Forming (EAF) where an electrical current is applied to the workpiece during deformation. As a result of the applied current, Joule heating is present which increases the temperature of the material. In this work the thermal response of sheet metal for stationary and deformation tests using this process are explored and modeled. The results of the model show good agreement for the stationary tests while the deformation model predicts that all of the applied electrical current may not be transformed into Joule heating. Thus, this work suggests from the observed response that a portion of the applied current may be directly aiding in deformation (i.e. the Electroplastic Effect).

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.

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.

Interface Characterization of Al–Cu Microlaminates Fabricated By Electrically Assisted Roll Bonding

2017 ◽  
Vol 5 (3) ◽  
Author(s):  
Marzyeh Moradi ◽  
Man-Kwan Ng ◽  
Taekyung Lee ◽  
Jian Cao ◽  
Yoosuf N. Picard
Keyword(s):  
High Current Density ◽  
Strong Dependence ◽  
Electrical Current ◽  
Applied Current ◽  
Simultaneous Application ◽  
Roll Bonding ◽  
Electrically Assisted ◽  
Interface Characteristics ◽  
Peel Tests

Interface characteristics of Al/Cu microlaminates fabricated by an electrically assisted roll bonding (EARB) process were studied to understand the underlying physical/chemical phenomena that lead to bond strength enhancement when applying electrical current during deformation. Peel tests were conducted for the Al/Cu roll-bonded laminates produced under 0 A, 50 A, and 150 A applied current. After peel tests using a microtensile machine, the fractured surfaces of both the Al and Cu–sides were examined using scanning electron microscopy (SEM) for fractography and SEM-based energy dispersive (EDS) analysis. Results revealed the strong dependence of the fracture path and its morphology on the strength of the bond, which is influenced by various phenomena occurring at the interface during EARB, such as microextrusion through surface microcracks, possible formation of intermetallic components and thermal softening during simultaneous application of strain and high current density.

Modeling and Quantification of the Electroplastic Effect When Bending Stainless Steel Sheet Metal

2010 ◽  
Author(s):  
Wesley A. Salandro ◽  
Cristina Bunget ◽  
Laine Mears
Keyword(s):  
Stainless Steel ◽  
Sheet Metal ◽  
Steel Sheet ◽  
Superplastic Forming ◽  
High Strength ◽  
304 Stainless Steel ◽  
Stainless Steel Sheet ◽  
Design Strategies ◽  
Electroplastic Effect ◽  
Electrically Assisted

Automotive manufacturers are continuously striving to meet economic demands by designing and manufacturing more efficient and better performing vehicles. To aid this effort, many manufacturers are using different design strategies such to reduce the overall size/weight of certain automotive components without compromising strength or durability. Stainless steel is a popular material for such uses (i.e. bumpers and fuel tanks) since it possesses both high strength and ductility, and it is relatively light for its strength. However, with current forming processes (e.g., hot working, incremental forming, and superplastic forming), extremely complex components cannot always be easily produced, thus, limiting the potential weight-saving and performance benefits that could be achieved otherwise. Electrically-Assisted Manufacturing (EAM) is an emerging manufacturing technique that has been proven capable of significantly increasing the formability of many automotive alloys, hence the “electroplastic effect”. In this technique, electricity can be applied in many ways (e.g., pulsed, cycled, or continuous) to metals undergoing different types of deformation (e.g., compression, tension, bending). When applied, the electricity lowers the required deformation forces, increases part displacement or elongation, and can reduce or eliminate springback in formed parts. Within this study, the effects of EAM on the bending of 304 Stainless Steel sheet metal will be characterized and modeled for different die widths and electrical flux densities. In previous works, EAM has proven to be highly successful on this particular material. Comparison of 3-point bending force profiles for non-electrical baseline tests and various EAM tests will help to illustrate electricity’s effectiveness. An electroplastic bending coefficient will be introduced and used for modeling an electrically-assisted bending process. Additionally, the springback reductions attained from EAM will be quantified and compared. From this work, a better overall understanding of the effects and benefits of EAM on bending processes will be explained.

scholarly journals Fatigue Performance of Thin Laser Butt Welds in HSLA Steel

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1499
Author(s):  
Patricio G. Riofrío ◽  
Fernando Antunes ◽  
José Ferreira ◽  
António Castanhola Batista ◽  
Carlos Capela
Keyword(s):  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Hsla Steel ◽  
High Strength ◽  
Butt Joints ◽  
Factors Affecting ◽  
Weld Profile ◽  
The Relationship ◽  
Good Agreement ◽  
Significant Factors

This work is focused on understanding the significant factors affecting the fatigue strength of laser-welded butt joints in thin high-strength low-alloy (HSLA) steel. The effects of the weld profile, imperfections, hardness, and residual stresses were considered to explain the results found in the S-N curves of four welded series. The results showed acceptable fatigue strength although the welded series presented multiple-imperfections. The analysis of fatigue behavior at low stress levels through the stress-concentrating effect explained the influence of each factor on the S-N curves of the welded series. The fatigue limits of the welded series predicted through the stress-concentrating effect and by the relationship proposed by Murakami showed good agreement with the experimental results.

scholarly journals Enhancement of Road Freight Vehicle Fuel Efficiency Using Lightweight Flat-Bed Trailers Made of High-Strength Steel Plates

2015 ◽  
Vol 22 (2) ◽  
pp. 65-82 ◽  
Author(s):  
Hong-Seung Roh ◽  
민연주 ◽  
장소영 ◽  
신승진 ◽  
YU, Byeong-Jae ◽  
...  
Keyword(s):  
High Strength Steel ◽  
Fuel Efficiency ◽  
High Strength ◽  
Steel Plates ◽  
Road Freight ◽  
Vehicle Fuel Efficiency

Investigation of Structural and Material Effects on Crashworthiness of Advanced High Strength Steel Columns

2003 ◽  
Author(s):  
Faycal Ben-Yahia ◽  
James A. Nemes ◽  
Farid Hassani
Keyword(s):  
Numerical Study ◽  
Hsla Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Column Height ◽  
Steel Columns ◽  
Advanced High Strength Steels ◽  
Element Simulation ◽  
Formed Channel ◽  
Good Agreement

An experimental and numerical study was performed to evaluate the crashworthiness of several advanced high strength steels. The behavior of two Dual Phase (DP) steels and an HSLA steel are compared by examining the crush response of longeron column specimens, experimentally and computationally. The closed section columns, fabricated by spot welding formed channel sections, in both single hat and double hat configurations were exposed to 182 kg and 454 kg axial impacts at different velocities. Final column height and impact force history were recorded and compared with results of finite element simulation of the columns. Good agreement was found between experiments and computations.

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.

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