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

Abstract

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.

Investigation of Electrically-Assisted Rolling Process of Corrugated Surface Microstructure with T2 Copper Foil

“…When the ratio of sheet thickness to grain size was small, the formability decreased [11]. The studies show that the current can reduce the flow stress, improve plasticity, and formability, this is called the electroplastic effect [12]. Ross et al [13] presented the direct current (DC) EA compression experiments of Ti-6Al-4V alloy.…”

Numerical Modeling and Experimental Verification for High-Speed Forming of Al5052 with Single Current Pulse

“…Breda et al [12] observed an Influence of stacking fault energy(SFE) in electrically assisted uniaxial tension. Ruszkiewicz et al [13] proposed the constitutive equation of the continuum theory of sintering to include the electric current effect term. However, a few other studies considered electro-plastic effect as a thermally dominated effect.…”

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

“…It has been shown that in steady-state circumstances, the electroplastic effect can be fully modeled and predicted using a conventional energy balance and thermal softening approach that assumes 100% bulk (homogeneous) Joule heating [9,10]. These works use electricity to heat a part but allow the temperature to stabilize before starting deformation.The steady-state modeling approach implemented into a finite element analysis (FEA) cannot predict the transient stress drop caused by pulsed electric current even though the correct temperature profile is predicted [11][12][13].Experimental results comparing the flow stress results of specimen heated in a furnace to the same temperatures seen through electrically assisted deformation found that electrically assisted deformation had a lower stress than thermally assisted, suggesting bulk Joule heating cannot fully explain the transient electroplastic effect [7,[14][15][16][17][18]. Theories have been developed to explain the transient nature of the electroplastic effect; these include (a detailed review of electroplastic theories and models can be found in Ref.…”