Research on the characterization and multiscale constitutive model of 2A10 aluminum alloy under transverse ultrasonic vibration-assisted compression

The prediction of microstructural characteristics during the deformation of metals has consistently been a key area of research. Previous studies have shown that ultrasonic vibration-assisted riveting experimentally produces quantitative changes in grain size (GS) and geometrically necessary dislocation (GND) density of rivets. However, existing microscale theoretical models predominantly focus on the prediction of total dislocation density. Moreover, most established models are developed for longitudinal ultrasonic vibration, while few studies have addressed the quantitative prediction of GS and GND density of microstructural characteristics during transverse ultrasonic vibration-assisted forming. Therefore, this study focused on 2A10 aluminum alloy specimens, which are widely used in aviation. Transverse ultrasonic vibration-assisted compression (TUVAC) tests were performed under different ultrasonic amplitudes. Based on the experimental investigation, a multiscale ultrasonic constitutive model incorporating GND density and GS was established, and a VUMAT subroutine was developed to predict the microstructural characteristics of the 2A10 aluminum alloy in TUVAC simulations. The results indicated that the maximum flow stress decreased from 509.7 MPa to 477.4 MPa as the ultrasonic amplitude increased from 0 μm to 21.2 μm. Compared to the original specimen, the intensity of the < 111>||ND fiber texture decreased significantly after simple compression. When transverse ultrasonic vibration was applied during compression, the Copper texture continuously weakened and the Brass texture gradually strengthened with increasing ultrasonic amplitude. In contrast, both the S texture and the < 111>||ND fiber texture initially increased and then decreased. GND density increased nonlinearly while the GS gradually decreased, indicating significant grain refinement. The predicted results of the ultrasonic constitutive model were compared with experimental data. This comparison showed that the average absolute relative error (AARE) for stress remained below 2.2 % under different amplitudes. A comparative analysis of experimental and simulation results revealed that the maximum AARE was approximately 15 % for GND density, approximately 12 % for GS, and below 5 % for microhardness. Thus, the proposed constitutive model can accurately predict both macroscopic mechanical behavior and microstructural characteristics and thereby provides a solid theoretical foundation for further investigation into the micro-mechanisms and performance of ultrasonic-assisted riveting.