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Aluminum Alloy (AA) witnesses extensive applications in the auto-body manufacturing industry where the resistance spot welding is the principal joining method.Because aluminum alloy has high thermal, electrical conductivity, low melting temperature and low yield strength, AA suffers from an inferior weldability.In order to determine the optimal specification from the weldability lobe, a comprehensive model involving electrical-thermal-mechanical and metallurgical analysis is established to investigate the affecting factors and the welding physics with dynamic simulation procedure.The experimentally observed dynamic resistance behavior of Transient Inverse Virtual Variation (TIVV) effect is highlighted since it is a counter-intuitive phenomenon puzzling the dynamic analysis and control of the AA-RSW process.The underlying mechanism of TIVV is theoretically explained on the basis of welding current and temperature distribution simulation analysis.The empirical model describing the TVVE phenomenon is used for modifying the dynamic resistance simulation during the AA spot welding process.The numerical and experimental results show that the proposed multi-disciplinary finite element method (FEM) model agrees with the measured AA welding features, and the modified dynamic resistance model captures the physics of nugget growth and the electrical-thermal behavior under varying welding current and fluctuating heat input.