超声辅助搅拌摩擦焊是在搅拌摩擦焊过程中增加超声振动,利用超声波效应改善焊缝组织性能的一种新型金属固态焊接技术。本文基于计算流体力学和弹塑性力学理论,建立了1.8 mm厚2024铝合金超声辅助搅拌摩擦焊流场分析模型。对流场分析发现,超声波的导入能够提高材料塑性流动,同时也扩大塑性流动区域;而焊速的提高,导致前进侧将成为焊缝的薄弱环节。 Ultrasonic Assisted Friction Stir Welding is a new type of metal solid state welding technology that adds ultrasonic vibrations during the friction stir welding process and improves the microstructure and properties of the weld by utilizing the ultrasonic effect. Based on computational fluid dynamics (CFD) theory and elasto-plastic theory, a flow field analysis model of ultrasonic assisted friction stir welding of 2024 aluminum alloy is established. The analysis of flow field shows that the introduction of ultrasonic wave can increase the plastic flow of material and enlarge the area of ​​plastic flow. The increase of welding speed leads the forward side to be the weak part of the weld.