volume | PIER Journals

Abstract

This study addresses multi-physics coupling challenges in high-speed sliding electrical contacts for Electromagnetic Launch Systems. A three-dimensional transient finite element model integrating electromagnetic-thermal interactions is established. By combining modified adhesion theory with Holm's contact resistance theory, we derive an analytical expression for dynamic contact resistance (DCR) that incorporates electromagnetic contact pressure, tangential friction, and temperature-dependent conductivity. The proposed localized modeling strategy with rail reverse motion technique efficiently resolves armature motion through coordinate transformation. Governing equations are discretized via the Galerkin method, with interfacial current continuity constraints and thermal partition coefficients enabling precise separation of Joule heating and frictional heat. Numerical results demonstrate robust current continuity compliance and reveal that DCR reaches its minimum during current peaks, exhibiting strong negative correlation with electromagnetic thrust. Tangential friction suppresses resistance rise by expanding the actual contact area, while electromagnetically dominated skin effects generate localized hotspots at contact trailing edges, armature limbs, and throat regions. This work elucidates the coupled frictional-Joule heating mechanisms governing multi-physics interactions, providing critical foundations for thermal management optimization in Electromagnetic Launch Systems.

1. Ma, Weiming and Junyong Lu, "Research progress and challenges of electromagnetic launch technology," Transactions of China Electrotechnical Society, Vol. 38, No. 15, 3943-3959, 2023.
doi:10.19595/j.cnki.1000-6753.tces.230470

2. Ruan, Jinghui, Lixue Chen, Shengguo Xia, Zengji Wang, and Lidong Li, "A review of current distribution in electromagnetic railguns," Transactions of China Electrotechnical Society, Vol. 35, No. 21, 4423-4431, 2020.
doi:10.19595/j.cnki.1000-6753.tces.191586

3. Zhang, Jiawei, Junyong Lu, Sai Tan, Yongsheng Zhang, and Bai Li, "A magnetic diffusion model of electromagnetic launcher considering initial contact pressure," Transactions of China Electrotechnical Society, Vol. 37, No. 2, 488-495, 2022.
doi:10.19595/j.cnki.1000-6753.tces.L90227

4. James, T. E. and D. C. James, "Contact pressure distribution and transition in solid armatures [EM launchers]," IEEE Transactions on Magnetics, Vol. 37, No. 1, 81-85, 2001.
doi:10.1109/20.911796

5. Schneider, M., M. Woetzel, W. Wenning, and D. Walch, "The ISL rapid fire railgun project RAFIRA. Part I: Technical aspects and design considerations," IEEE Transactions on Magnetics, Vol. 45, No. 1, 442-447, 2009.
doi:10.1109/tmag.2008.2008468

6. Barber, J. P. and Y. A. Dreizin, "Model of contact transitioning with ``realistic'' armature-rail interface," IEEE Transactions on Magnetics, Vol. 31, No. 1, 96-100, 1995.
doi:10.1109/20.364721

7. Barber, J. P., A. Challita, B. Maas, and L. Thurmond, "Contact transition in metal armatures (railguns)," IEEE Transactions on Magnetics, Vol. 27, No. 1, 228-232, 1991.
doi:10.1109/20.101031

8. Feng, Deng, Shengguo Xia, Lixue Chen, et al., "Non-uniformity of contact pressure distribution in armature assembly for railguns," High Voltage Engineering, Vol. 41, No. 6, 1873-1878, 2015.
doi:10.13336/j.1003-6520.hve.2015.06.014

9. Rip, L., S. Satapathy, and Kuo-Ta Hsieh, "Effect of geometry change on the current density distribution in C-shaped armatures," IEEE Transactions on Magnetics, Vol. 39, No. 1, 72-75, 2003.
doi:10.1109/tmag.2002.805906

10. Li, Chengxian, Shengguo Xia, Lixue Chen, Junjia He, Yan Xiong, Chendong Zhang, and Jinming Yao, "Simulations on current distribution in railgun under imperfect contact conditions," IEEE Transactions on Plasma Science, Vol. 47, No. 5, 2264-2268, 2019.
doi:10.1109/tps.2019.2907121

11. Yang, Yudong, Chengfang Fu, W. Xue, and H. Zhao, "Numerical calculation of movement electromagnetic field distribution between rail and armature," Journal of Gun Launch & Control, Vol. 35, No. 3, 1-5, 2014.
doi:10.3969/j.issn.1673-6524.2014.03.001

12. Lin, Qinghua and Baoming Li, "Modeling and simulation of electromagnetic railgun launching process based on a transient multi-physical field solver," Acta Armamentarii, Vol. 41, No. 9, 1697-1707, 2020.
doi:10.3969/j.issn.1000-1093.2020.09.001

13. Wu, Xinlong, Xin Yang, Junjie Ye, and Guoyou Liu, "Novel prognostics for IGBTs using wire-bond contact degradation model considering on-chip temperature distribution," IEEE Transactions on Power Electronics, Vol. 40, No. 3, 4411-4424, 2025.
doi:10.1109/tpel.2024.3498350

14. Coffo, M. and J. Gallant, "Simulation of the current distribution and the heat load of a brush projectile in a railgun with the finite element code ANSYS," Acta Physica Polonica A, Vol. 115, No. 6, 1112-1114, 2009.
doi:10.12693/aphyspola.115.1112

15. Li, Bai, Junyong Lu, Sai Tan, Yongsheng Zhang, and Xiyuan Cai, "Research on dynamic wear process of armature surface in high-speed sliding electric contact," Transactions of China Electrotechnical Society, Vol. 38, No. 1, 131-139, 2023.
doi:10.19595/j.cnki.1000-6753.tces.211461

16. Hsieh, K.-T., S. Satapathy, and M.-T. Hsieh, "Effects of pressure-dependent contact resistivity on contact interfacial conditions," IEEE Transactions on Magnetics, Vol. 45, No. 1, 313-318, 2009.
doi:10.1109/tmag.2008.2008876

17. Zhu, Chunyan and Baoming Li, "Analysis of sliding electric contact characteristics in augmented railgun based on the combination of contact resistance and sliding friction coefficient," Defence Technology, Vol. 16, No. 4, 747-752, 2020.
doi:10.1016/j.dt.2019.12.007

18. Chen, Lixue, Junjia He, Zheng Xiao, Shengguo Xia, Deng Feng, and Liangliang Tang, "Experimental study of armature melt wear in solid armature railgun," IEEE Transactions on Plasma Science, Vol. 43, No. 5, 1142-1146, 2015.
doi:10.1109/tps.2015.2418784

19. Jaeger, J. C., "Moving sources of heat and the temperature at sliding contacts," Journal and proceedings of the Royal Society of New South Wales, Vol. 76, No. 3, 203-224, 1942.
doi:10.5962/p.360338

20. Siopis, M. J. and R. W. Neu, "Wear at high sliding speeds and high contact pressures," Wear, Vol. 342, 356-363, 2015.
doi:10.1016/j.wear.2015.09.010

21. Yao, J. and Q. Fu, "Heat partition process at sliding electrical contact interfaces with high-speed and large current," Transactions of China Electrotechnical Society, Vol. 39, No. 17, 5497-5507, 2024.
doi:10.19595/j.cnki.1000-6753.tces.231136

22. Chen, Yun, Weidong Xu, Weiqun Yuan, Y. Zhao, P. Yan, and G. Lan, "Sliding electrical contacts between aluminum armature and different material rails in railgun," High Voltage Engineering, Vol. 39, No. 4, 937-942, 2013.
doi:10.3969/j.issn.1003-6520.2013.04.025

23. Bayati, M. Sajjad, Asghar Keshtkar, and Ahmad Keshtkar, "Thermal computation in railgun by hybrid time domain technique 3-D-FEM-IEM," IEEE Transactions on Plasma Science, Vol. 39, No. 1, 18-21, 2011.
doi:10.1109/tps.2010.2070847

24. Hsieh, K., "A Lagrangian formulation for mechanically, thermally coupled electromagnetic diffusive processes with moving conductors," IEEE Transactions on Magnetics, Vol. 31, No. 1, 604-609, 1995.
doi:10.1109/20.364626

25. Bayati, M. Sajjad and Kambiz Amiri, "Study of various C-shaped armatures in electromagnetic launcher," Applied Computational Electromagnetics Society Journal (ACES), Vol. 30, No. 9, 1029-1034, 2021.

26. Bayati, Mohammad Sajjad and Asghar Keshtkar, "Study of the current distribution, magnetic field, and inductance gradient of rectangular and circular railguns," IEEE Transactions on Plasma Science, Vol. 41, No. 5, 1376-1381, 2013.
doi:10.1109/tps.2013.2251477

27. Sun, Jian, Junsheng Cheng, Qiuliang Wang, Ling Xiong, Yuantao Cong, and Yichen Wang, "Numerical simulation of melt-wave erosion in 2-D solid armature," IEEE Transactions on Plasma Science, Vol. 50, No. 4, 1032-1039, 2022.
doi:10.1109/tps.2022.3158526

28. Tang, Bo, Yingtao Xu, Qinghua Lin, and Baoming Li, "Synergy of melt-wave and electromagnetic force on the transition mechanism in electromagnetic launch," IEEE Transactions on Plasma Science, Vol. 45, No. 7, 1361-1367, 2017.
doi:10.1109/tps.2017.2705220

Dr. Yikang Song

Dr. Pengyu Li

Dr. Junsheng Cheng

Mr. Heyang Wang