New insights into the multibranching phenomenon of acoustic emission in metals under uniaxial tension

Acoustic emission (AE) is a non-destructive technique widely used for real-time monitoring of material deformation and failure. Recently, a mutibranching phenomenon was observed in AE signals from metals under uniaxial tension, providing a potential indicator for the coexistence of multiple deformation mechanisms. However, this phenomenon has been reported only in studies using the Vallen AE system and not in those employing the Physical Acoustics Corporation (PAC) system. To clarify the origin of this discrepancy, AE signals generated during uniaxial tension tests of both high-purity nickel and low-nickel 316 L stainless steel were simultaneously acquired using both systems. Comparative analysis demonstrates that the observability of the multibranching phenomenon is strongly dependent on the effective resolution of the AE acquisition systems. In the PAC system, limited resolution arising from reduced precision in stored AE parameters and errors introduced during analog-to-digital conversion obscures the multibranching features. Recalculation of AE amplitude and energy from the recorded waveforms can enhances the effective resolution and partly restore the multibranching behavior of AE signals. These results highlight the critical role of acquisition system resolution in AE measurements and provide essential guidance for reliable AE-based identification of deformation mechanisms in metallic materials.