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Combined Finite Element Simulation and Regression Modeling for Predicting Final Protrusion Length of Twisted Hairpin Legs in Stators

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Abstract:

This study presents an integrated finite element-based framework for analyzing the final protrusion length of enameled copper hairpins during stator manufacturing. Protrusion uniformity is essential for reliable laser welding, yet it is often degraded by layer-dependent deformation during expanding and twisting. To clarify the mechanisms governing protrusion variation, a bilayer material model for the copper–enamel system was developed and validated using tensile tests, indentation-based inverse characterization, and three-point bending experiments. Mechanically consistent boundary conditions for expanding and twisting were reconstructed from manufacturing observations and incorporated into FE simulations. The results indicate that twisting governs protrusion length through axial material redistribution, whereas expanding mainly serves as a feasibility-enabling step that establishes stable tool engagement. Based on these insights, a physics-guided regression formulation was introduced to relate key twisting kinematics to protrusion length. The proposed framework provides a mechanistic basis for understanding protrusion variability and supports further development toward rapid prediction and variability control.

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Periodical:

Solid State Phenomena (Volume 389)

Pages:

51-58

DOI:

https://doi.org/10.4028/p-L8oWxo

Citation:

Cite this paper

Online since:

April 2026

Authors:

Donghoon Han*, Donghyuk Cho, Seik An, Jeong Whan Yoon

Keywords:

Electric Motor, Finite Element Modelling, Hairpin, Twisting Process

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Creative Commons CC BY 4.0

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* - Corresponding Author

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