Study on Electromagnetic Force Characteristics and Deformation Behavior of Plates Loaded via Eddy Current Attraction Effect
Liang Shuai1,2, Wang Yiyi1, Qiu Li1,2, Fang Chunhua1, Jiang Jinbo1
1. College of Electrical Engineering and New Energy China Three Gorges University Yichang 443002 China; 2. Hubei Provincial Key Laboratory for Operation and Control of Cascaded Hydropower Station Yichang 443002 China
Abstract:Conventional electromagnetic forming (EMF) of flat metal plates often yields highly nonuniform deformation and a small effective forming zone, as the unconstrained plate center tends to over-deform into a conical shape. To address this limitation, a sheet-forming approach based on the eddy-current attraction (ECA) effect is proposed. In this method, a solid conductor is placed coaxially inside the EMF drive coil, inducing eddy currents that generate an upward electromagnetic attraction on the plate. This upward force counteracts the excessive downward Lorentz force at the plate’s center, evening out the pressure distribution and suppressing the central “over-punch” deformation. A coupled electromagnetic-solid mechanics finite element model (implemented in COMSOL) is used to analyze the ECA-based loading scheme, enabling systematic variation of the conductor’s material properties and geometry. Simulation results show that a highly conductive insert (e.g. copper or aluminum) produces strong eddy currents and a large upward attraction force, dramatically reducing the net downward force at the plate center. This significantly lowers the peak axial deflection of the plate - in fact, with sufficiently high conductivity, the plate’s center experiences a slight inward collapse instead of bulging upward. In contrast, a less conductive insert (e.g. steel or titanium) yields a much weaker attraction, and the plate deforms in the usual bulging manner with greater central protrusion. These findings confirm that the conductor’s electrical conductivity (and thus the strength of induced eddy currents) strongly influences the deformation behavior. The geometry of the conductor insert is also crucial. Introducing a concave indentation on the conductor’s top face reduces the upward attraction; a deeper concavity further weakens the effect and allows more central bulging, which can improve uniformity by avoiding an overly flattened center. Conversely, giving the conductor a slight convex (bulged) top surface strengthens the attraction and flattens the plate center. Increasing the radial size of an indentation broadens the area of upward pull on the plate and raises the overall displacement, but provides only a limited additional improvement in deformation uniformity. Similarly, increasing the gap (distance) between the conductor and the plate mainly increases the total deformation achieved without significantly compromising deformation evenness. By appropriately tuning the conductor’s conductivity, shape and positioning, the electromagnetic force distribution can be controlled to obtain a much more uniform forming outcome. Overall, the ECA-based loading method greatly expands the uniformly deformed region of the plate. Under the same maximum axial displacement condition, the radial span over which the plate’s deflection stays within 95% of the peak value is about 79.5 mm with the ECA method, compared to only ~21.6 mm for the conventional method. This corresponds to roughly a 3.7-fold increase in the uniform deformation area. Consequently, the final plate shape is significantly flatter and more axisymmetric than that from a standard EMF process. Although the peak deformation is slightly lower due to the opposing attraction force, this trade-off yields a substantially larger area of uniform strain on the workpiece. In summary, inserting a coaxial conductor to harness the ECA effect provides a means to reshape the electromagnetic force field during plate forming. The proposed approach requires only the addition of a conductor inside the coil and can be readily adapted to different plate sizes. By significantly improving deformation uniformity and expanding the effective forming zone, this ECA-based method can enhance electromagnetic sheet forming for a wide range of applications.
梁帅, 王易弋, 邱立, 方春华, 江进波. 基于涡流吸引效应加载的板件电磁力特性及变形行为研究[J]. 电工技术学报, 2026, 41(19): 6449-6461.
Liang Shuai, Wang Yiyi, Qiu Li, Fang Chunhua, Jiang Jinbo. Study on Electromagnetic Force Characteristics and Deformation Behavior of Plates Loaded via Eddy Current Attraction Effect. Transactions of China Electrotechnical Society, 2026, 41(19): 6449-6461.
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