The student Joseba Mendiguren Olaeta obtained an EXCELLENT CUM LAUDE

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The student Joseba Mendiguren Olaeta obtained an EXCELLENT CUM LAUDE

THESIS

The student Joseba Mendiguren Olaeta obtained an EXCELLENT CUM LAUDE

2026·07·14

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  • Thesis title: Deformazio osteko fenomeno elektriko-plastikoaren bidezko leheneratze elastikoaren murrizketa AA5754H22 aluminio-aleazioan

Court:

  • Presidency: Alaitz Zabala Eguren (Mondragon Unibertsitatea)
  • Vocal: Aitor Madariaga Zabala (Ideko S.Coop.) 
  • Vocal: Pello Jimbert Lacha (UVP/EHU)
  • Vocal: Amaia Torregaray Larruscain (UVP/EHU)
  • Secretary: Zigor Azpilgain Balerdi (Mondragon Unibertsitatea)

Abstract:

Springback remains a major barrier in precision sheet metal forming, especially in lightweight alloys like AA5754. This thesis investigates a novel strategy for springback reduction based on the Post-Forming Electroplastic Effect (PFEPE)-the application of pulsed electric current after plastic deformation to relieve internal stresses without traditional thermal treatment. The research begins with tensile creep-hold experiments, where electrical pulses applied during constant strain led to measurable stress relaxation without compromising mechanical integrity. This effect is then extended to V-bending tests, demonstrating significant springback reductions at moderate energy levels (~800–3000 A·ms/mm²), attributed to dislocation rearrangement and electron–dislocation interactions. A critical energy threshold is identified, beyond which microstructural degradation and recrystallization occur.

Building on these promising results, the study introduces the Post-Forming Through-Thickness Electroplastic Effect (PF-TT-EPE), where pulses are delivered directly through the sheet thickness via electrode-integrated forming dies. Despite its theoretical appeal and potential for seamless industrial integration, the implementation reveals substantial challenges. Localized spark discharge, dielectric breakdown, and tooling damage emerge due to imperfect electrical contact, especially at pulse energies previously deemed safe. Cryogenic testing further suggests that thermal effects alone cannot explain the observed phenomena, pointing toward a complex interplay of electromechanical mechanisms.

This work not only validates the stress-relief potential of post-forming EPE but also defines the current boundaries of its industrial scalability. It provides critical insights into pulse–material interaction, highlights the importance of interface engineering, and charts a roadmap for future research on electrically assisted forming within sustainable manufacturing paradigms.